Automatic 12V Lead Acid Battery Charger

Home > Circuits > Power Supply > Automatic 12V Lead Acid Battery Charger

Search:

Author Views Views Today Rank Comments

526,555 77 224

This charger will charge any 12V lead acid battery including flooded, gel and AGM. It is fully automatic and will charge at a rate up to about 4A until the battery voltage reaches a preset point at which it will switch to a very low current float charge. If the battery voltage drops again the charger will begin charging until the voltage once again reaches the cut off point. In this way it can be left connected to a battery indefinitely to maintain full charge without causing damage. An LED indicates when the battery is fully charged.

Schematic

Parts

PartTotal Qty.

Description Substitutions

R1, R3 2 330 Ohm 1/4W ResistorR2 1 100 Ohm 1/4W PotR4, R5, R7, R8

4 82 Ohm 2W Resistor

R6 1 100 Ohm 1/4W ResistorR9 1 1K 1/4W ResistorC1 1 220uF 25V Electrolytic CapacitorD1 1 P600 Diode Any 50V 5A or

greater rectifier diode

D2 1 1N4004 Diode 1N4002, 1N4007D3 1 5.6V Zener DiodeD4 1 LED (Red, Green or Yellow)Q1 1 BT136 TRIACQ2 1 BRX49 SCRT1 1 12V 4A Transformer See NotesF1 1 3A FuseS1 1 SPST Switch, 120VAC 5A

MISC 1Wire, Board, Heatsink For U1, Case, Binding Posts or Alligator Clips For Output, Fuse Holder

Notes1. R2 will have to be adjusted to set the proper finish charge voltage.

Flooded and gel batteries are generally charged to 13.8V. If you are cycling the battery (AGM or gel) then 14.5V to 14.9V is generally recommended by battery manufacturers. To set up the charger, set the pot to midway, turn on the charger and then connect a battery to it's output. Monitor the charge with a voltmeter until the battery reaches the proper end voltage and then adjust the pot until the LED glows steadily. The charger has now been set. To charge multiple battery types you can mount the pot on the front of the case and have each position marked for the appropriate voltage.

2. Q1 will need a heatsink. If the circuit is mounted in a case then a small fan might be necessary and can generally be powered right off the output of D1.

3. T1 is a transformer with a primary voltage appropriate to your location (120V, 220V, etc.) and a secondary around 12V. Using a higher voltage secondary (16V-18V) will allow you to charge 16V batteries sometimes used in racing applications.

4. If the circuit is powered off, the battery should be disconnected from it's output otherwise the circuit will drain the battery slowly.

Related Circuits6V to 12V Converter, Portable CD Player Adapter For Car, Car Battery Charger, Automatic 12V Lead Acid Battery Charger, Solid State Tesla

Coil/High Voltage Generator, 12VDC To 120VAC Inverter, LASER Power Supply, Power Supply, High Current Power Supply, Dual Polarity Power

Supply, High Voltage High Current Power Supply, Transformerless Power Supply, Fixed Voltage Power Supply, Voltage Inverter, Voltage Inverter II,

Automatic Load Sensing Power Switch, 12V To 24V DC-DC Converter, Solid State Tesla Coil

CommentsAdd A Comment

emmanuelAutomatic 12V Lead Acid

Battery ChargerFriday, May 18, 2012 4:26:23 AM

Dr. thanks for the good work, Please how long will it take to charge 12V 200AH battery and how will i change the design to charge the battery within 5hrs Please send me the reply if possible with the circuit diagram to my email

tjolle62Automatic 12V Lead Acid

Battery ChargerTuesday, May 08, 2012 5:45:05

PMHello, I'm going to build this nice gel charger and i womder what values and components do i need to change for a 24V feed ?

wempireAutomatic 12V Lead Acid

Battery ChargerSaturday, April 28, 2012 4:48:55

AMthird class circuit dont try to assemble otherwise you will loos your mony and time

anonymousAutomatic 12V Lead Acid

Battery ChargerWednesday, March 21, 2012

12:32:03 PMDoes this circuit really works? What is the charging time for a fully discharged battery? What will be the approximate cost(in Indian rupees) of building this?

E.L. GabrielAutomatic 12V Lead Acid

Battery ChargerThursday, March 08, 2012

11:42:49 AMHello, and thanks for a good circuit, it is easy to build and to modify' I've made two of these and two of my friends are very happy. For starters, I substituted the 4x2 watt resistors,for 5watt ceramic type, added adjustable fan cooling using separate power supply. Next time I make another I'll add volt and amp gauges. Thanks once again

RynAutomatic 12V Lead Acid

Battery ChargerTuesday, March 06, 2012

11:44:16 AMcan i know , how the triac in this circuit operate? And the overall operation for the circuit ? TQ

mjAutomatic 6V Lead Acid

Battery ChargerThursday, February 02, 2012

4:23:05 AMhi sir Can this circuit be modified using 6V battery?

JimmieAutomatic 12V Lead Acid

Battery ChargerWednesday, January 25, 2012

11:44:22 AMHow long does it take,n how much in $

ATHAutomatic 12V Lead Acid

Battery ChargerSunday, January 22, 2012

4:47:07 PMCan I use BT138 or BT137 instead of BT136 ?, (75 ohm 4w) instead of (82 ohm 4w) resistors ?, are there any equivalents to brx49 ?

albyAutomatic 12V Lead Acid

Battery ChargerMonday, January 16, 2012

9:50:23 AMWould like to have a go at this one & was wondering if anyone has the layout for the PC board

The last 10 comments are currently shown. Show All Comments.

Add A Comment

Name:

Email:

Subject:

Comments:

Anti Spam Code:Please enter the exact text shown in the image

above into the box below. Browser cookies must be enabled to comment on

circuits.

Privacy PolicyUnlike many units, this battery charger continuously charges at maximum current, tapering off only near full battery voltage. In this unit, the full load current of the supply transformer/rectifier section was 4.4A. It tapers off to 4A at 13.5V, 3A at 14.0V, 2A at 14.5V and 0A at 15.0V.

Circuit operation:

Transistor Q1, diodes D1-D3 and resistor R1 form a simple constant current source. R1 effectively sets the current through Q1 - the voltage across this resistor plus Q1's emitter-base voltage is equal to the voltage across D1-D3. Assuming 0.7V across each diode and across Q1's base-emitter junction, the current through R1 is approximately 1.4/0.34 = 4.1A. IC ensures that Q1 (and thus the constant current source) is turned on.

When the battery has fully charged, the current through IC drops to a very low value and so Q1 turns off (since there is no longer any base-emitter current). R2 limits the current through IC. It allows enough current to flow through the regulator so that Q1 is fully on for battery

voltages up to about 13.5V. Decreasing the value of R2 effectively increases the final battery voltage by raising the current cutoff point. Conversely, a diode in series with one of the battery leads will reduce the fully-charged voltage by about 0.7V.

Circuit diagram:

12 Volt Car Battery Charger Circuit Diagram

Parts:

ResistorsR1 = 0.32RR2 = 8.2R

CapacitorsC1 = 10,000uF - 63V

SemiconductorsD1 = 1N4004D2 = 1N4004D3 = 1N4004Q1 = MJ1504IC = 7815 REGBR1 = 1N4004x4

MiscellaneousB1 = 12 Volt Battery

Notes: Charger's input voltages are 20 volt AC R1 and R2 are high wattage resistor like 2W, 3W, 5W and could

be above. Select wattage on your choice.

Q1 and IC requires a good heatsink. If they are mounted on the same heatsink and will throttle the circuit back if Q1 gets too hot.

12v DC to 12v DC Battery Charger Circuit

You cannot charge a 12v battery from a 12v battery. The battery being charged creates a "floating charge" or "floating voltage" that is higher than the charging voltage and the charging stops.

The following circuit produces a voltage higher than 12v via a CHARGE PUMP arrangement in which the energy in an electrolytic is fed to a battery to charge it. The circuit produces about 900mA "charge current" and the diodes and transistors must be fitted with heat sinks. The LEDs are designed to prevent the two output transistors turning ON at the same time. The lower output transistor does not start to turn on until the voltage is above 5v and the top transistor does not turn on until the voltage drops 4v from the positive rail. This means both transistors will be turned on when the voltage passes a mid-point-gap of 4v. The transition is so fast that no wasted current (short-circuit current) flows via the two output transistors (as per our test).

Circuit diagram:

12v DC to 12v DC Battery Charger Circuit diagram

The electrolytic charges to about 10v via the lower transistor and top diode. The top BD679 then pulls the negative of the 2200u electrolytic towards the 12v6 rail and the positive is higher than 12v6 by a theoretical 10v, however we talk about the energy in the electrolytic and in our circuit it is capable of delivering a current flow of about 900mA. This energy is passed to the battery via the lower diode. Most batteries should not be charged faster than the "14-hour-rate." This basically means a flat battery will be charged in 14 hours. To do this, divide the AHr capacity by 14 to get the charge-rate. For example, a 17AHr battery should

be charged at 1.2A or less. For lower-capacity batteries, the 2200u can be reduced to 1,000u. Charging is about 80% efficient. In other words, delivering 120% of the AHr capacity of a battery will fully charge it.

UPS Battery ChargerOptionsypically, the UPS contains the batterycharger, battery and inverterinside of an enclosure. The batterylife is shortened at increased temperature,so it’s important to keep the temperatureinside the enclosure as low as practicallypossible. Also the charging voltage has tobe adjusted as a function of the batterytemperature. Finally, the battery chargerhas to function under a wide range of inputvoltages and protect itself during overvoltageor voltage-surge conditions. Thebattery charger keeps the UPS batteryfully charged during normal input-voltagerange. When the alternate current (ac)power line voltage goes out of normalrange (geographical area defined), thepower turns off and the battery suppliesthe power to the load. When the line voltagereturns within the normal range, thebattery is recharged.Linear Power SupplyThe linear power supply (continuous energyflow) is most commonly used due tolow cost, but is has low efficiency, isbulky and is limited to single-voltage input.It uses a line-powered 50Hz/60Hz,iron-core, step-down transformer that isenergized and dissipates heat all the time.

TThis, added to the low efficiency ofthe linear regulator, translates into a

higher temperature inside the enclosure(shared with the battery). The immediatelower cost benefit of this solution hidesthe higher long-term cost, due to a shorterbattery lifetime and an increased maintenancetime. The weight and volume makethe mechanical design of the UPS moredifficult.Discrete Ringing Choke CircuitThe ringing choke circuit is another continuousenergy flow power supply, limitedlike the linear to single-voltage input, butusing higher frequency to pass the energyto the load, reducing the transformer size.The efficiency is also improved, but thecircuit is highly dependent on the components’tolerance and it is difficult to designand manufacture.Switch-Mode Power SupplyThe switch-mode power supply (SMPS)transfers the energy to the load discontinuously.The SMPS offers a lower costof ownership solution because it:extends the battery life by maintaininga lower battery temperature, andreduces the maintenance due to betterreliability.These benefits derive from the higherefficiency of the SMPS (cooler operation).The SMPS is also powered from the line,but it stores energy in an input capacitorand transfers it to the load as needed, inhigh-frequency increments, by switchingon and off. A solid-state switch, controlledby a pulse-width modulation(PWM) controller, accomplishes theswitching.Figure 1. IC (U1 in Figure 3) functional block diagram.Figure 2. SMPS schematic.CY12.2nF*BT1

+-F1 3.15A/250V+C1 33uF/450VR84.7 1/8W4

10Q12N39043+ C4 560uF/35VR9

11.5K 1%43RTN

85-265 VACD7 UF5402CX10.1uF/X2D1VR1P6KE150D4 1N4007 J2-3+C6 4.7uF/35VD6 BAV20R5 1 1/2W*RT1THERMISTOR (NTC)

ND5UF10051D2LED112

2 9R1011.5K 1%R1147.5K 1%

5*TP21C30.1uF/50VR647, 1/8WL23.3uH, 2.65AJ2-1R126.8k

LD3J1-2R1

1M 1/4W 1R7470, 1/8W

EF-20917uHR36.8, 1/8WL1 J2-210mH/0.3ATP1U2PC817A5R4 1 1/2WC70.1uF/50V 2+C247uF/10VJ1-1

FDSCMCONTROL

U1TOP233YC8+ 0.1uF/50V C5220uF/35V3

OPTIONAL2R2910k 1/4W+14VDC

T1U3TL431CLP2 31

4

The transformer has a ferrite core thatis a much smaller and lighter than the linear’siron-core counterpart, making theUPS design easier. Also, a SMPS can beused worldwide because it accepts universalinput voltages.SMPS with IntegratedSwitcher/Controller IC

The integrated switcher/controller ICfunctional block diagram is shown inFigure 1.The power supply schematic is shownin Figure 2, and the power supply’s infraredand visible pictures are shown in Figure3. This solution brings the followingbenefits, when compared with the discreteSMPS:Figure 3. SMPS infrared and visible pictures.Output ShuntResistors, 64C.TOP233Y , 60C.Lower total solution cost is the result offewer components, tighter IC tolerances,and built-in features that eliminate or reducethe cost of external components.Tighter temperature and absolute ICtolerances afford a more accurate design.The added tolerances of the numerousparts in a discrete design lead to oversizingthe SMPS to meet the powe rrequirements.Built-in features save the cost ofcomponents necessary to implement thevarious functions. The undervoltage/over-voltage thresholds andmaximum duty cycle reduction are implementedwith one resistor. The overtemperatureshutdown simplifies thethermal protection. The fully integratedsoft-start (10ms) saves the cost of componentsneeded for the soft-start and allowsuse of cheaper RCD clamps and more efficientSchottky output diodes. Cycleskipping at low/no load eliminates thedummy load resistor. The remoteON/OFF synchronization reduces the systeminterface’s implementation cost. Theincreased maximum duty cycle (78 percent)allows a smaller/cheaper input capacitorand a more efficient Schottky outputrectifier to be used. The increasedPWM gain (-22 percent/mA) reduces linefrequency output ripple. The nominalswitching frequency of 132kHz reducestransformer size with no EMI penalty. The

frequency jitter allows a smaller/cheaperEMI filter to be used.Shorter design cycle is facilitated byreadily available reference designs; byfaster agencies approvals, as the SMPS isBenefits FeaturesLower Total Solution Cost Fewer components, improved tolerances, built-in features:Under-voltage/over-voltage (UV/OV) thresholds andmaximum duty cycle (DCmax) reduction, overtemperatureshutdown, fully integrated soft-start, cycleskipping, remote ON/OFF synchronization, increasedmaximum duty cycle and PWM gain, 132kHz switchingfrequency, and frequency jitter.Shorter Design Cycle Reference design, easier agencies approvals (EMI andsafety: creepage, isolation), and software tools.Simplified Design Fewer components, smaller PCB area, simpler thermaldesign, auto-restart, and built-in protection.Higher Reliability Fewer components, wide creepage, built-in protection:UV/OV, current limit, over-temperature shutdown, andfully integrated soft-start.Energy-Saving High efficiency and cycle skipping (stand-by mode).Reduced Radiated EMI Frequency jitter and smaller PCB area.Versatility Programmable under-voltage/over-voltage, output-currentlimit, output-voltage, and output-voltage temperatu recompensation.designed to meet EMI and safety standards;and by readily available powersupply design tools.Simplified design refers to both SMPS(fewer components, simpler system interface,simpler thermal design, and built-inprotection) and the UPS (smaller SMPSand reduced heat generation).Higher reliability results from fewercomponents, wide creepage distance betweenD and S pins, and the IC built-inprotection features.Fewer components is achieved byintegrating the MOSFET switch, the controllerand the ancillary circuitry into onemonolithic (one die) IC. Figure 1 showsthe functional block diagram of the IC(U1 in Figure 2).The IC operates in PWM with a currentlimit mode, thus controlling the outputshort-circuit current, and has overtemperatureshutdown, protecting the supplyin case of excessive ambient temperature.

A wide creepage distance betweenthe D and S pins gives the IC a higherimmunity to arcing and eliminates the requirementto short adjacent pins duringsafety-agency approval testing. Built-inprotection features contribute to the higherreliability of the integrated SMPS.Line under-voltage detection preventsturn-off glitches and line over-voltageshutdown extends the line-surge limit (theDC rail is allowed to rise up to 700Vdcwithout device damage). The power supplypassed the surge test defined byIEC/UL 1000-4-5 Class 3 and was designedto meet the safety requirements ofIEC950/UL1950.The hysteretic thermal shutdown allowsautomatic recovery when the ambienttemperature returns within the operatingrange. Large thermal hysteresis preventsPC board overheating. The soft-startreduces component stress and outputvoltageovershoot.Energy saving takes place at full load dueto high efficiency (>75 percent), and atlight or no-load due to cycle skipping.Reduced Radiated EMI. The power supplypassed the conducted EMI test(CISPR22B) using a low-cost filter (madepossible by the 4kHz frequency jitter) anda PCB with small area and proper layout.02468101214160.00 0.50 1.00 1.50 2.00 2.50Iout(A)Vout(Vdc)85Vac, 60Hz 265Vac, 60Hz

Figure 4. SMPS Vout vs Iout.Versatility refers to the application of thecircuit for different input-voltage rangeswith different under-voltage/over-voltagethresholds and various output-current/voltage requirements (Figure 4). It alsorefers to the output-voltage compensation

based on battery temperature (Figure 5).Low-Power UPS TopologiesThe external UPS (outside the PC) is thedominant solution for PC backup power.The built-in UPS is restricted to an insignificantvolume of applications and willnot be discussed. Of the external UPSs,the “Passive” for the low-end and the“Active Standby” for mid-range technologyare the most frequently used with apower level of <2kVA and a transfer timeof about 4msec.The Passive-Standby UPSThis is the most common UPS type usedfor protecting PCs in environments withinfrequent power failures. There is nopower conversion and no monitoring ofthe ac power line (passive) during normaloperation, and the transfer switch connectsthe filtered ac power line as the primarypower source. In case of power failure(voltage out of range), the transferswitch switches over to the backup powersource (battery and inverter). The inverteronly starts when the power fails, hence thename "standby".The Active-Standby UPSThis is the most common UPS used forsmall business, Internet and departmentalservers. In this design, the ac line is continuouslymonitored (active). The inverteralso provides regulation, operating to correctbrownout conditions, which wouldotherwise force the UPS to switch to batteryoperation. This allows the UPS to operateat sites with very poor power. Thetransfer switch disconnects the primarypower and connects the backup power(battery and inverter) only when thepower line fails.Figure 5. SMPS battery-charging voltage temperature compensation.1 3 . 01 3 . 11 3 . 21 3 . 31 3 . 41 3 . 51 3 . 61 3 . 71 3 . 81 3 . 91 4 . 0

1 4 . 11 4 . 21 4 . 31 4 . 41 4 . 51 4 . 61 4 . 7- 1 0 - 5 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0 5 5T e m p ( C )Vout(Vdc)

High limitLow limitCalculated valueMeasured value

ConclusionHigher levels of IC integration lead tolower system cost and lower cost of ownership.The ease of designing and qualifyinga power supply using these ICs dramaticallyreduces the time to market. Thevalue of the presented solution, in bothlower cost and shorter time to market,should be compelling benefits to considerit for existing or new designs. D GDGCopyright © 2001 Power Pulse is a registeredtrademark of, and published by, Darnell.Com Inc.Materials may not be reproduced or republishedwithout written permission from Darnell.Com Inc.Darnell.Com Inc. shall not be responsible for anyrepresentations, statements of fact, or individualopinions made by advertisers or authors inPower Pulse . The views expressed here arethose of the author(s) and do not necessarily reflectthe opinion or agreement of Darnell.Com Inc.Inquiries should be addressed to Darnell.ComInc., 1159-B Pomona Road, Corona, California92882.LINELOADBATTERYSurgeProtection FilterTransferSwitch

~ = = ~BatteryChargerDC to ACConvert.

Passive standby UPS operating diagram.LINELOADBATTERYSurgeProtection FilterTransferSwitch

~~

=Battery =ChargerDC to ACConvert.

Active standby UPS operating diagram.

Top of Form

Turn on more accessible mode Skip to main content Turn off more accessible mode Heime

Sign In

|

Heime

Home

Heime CategoriesPhotoPhotos shown in Sandnes FotoklubbGeneralPortugalOther BlogsMike JohnstonLinksE-PostMidlertidig adresseVedlegg (privat)

Heime > Posts > Repair instructions for APC Back-UPS RS 500

27.12.2006Repair instructions for APC Back-UPS RS 500I have two of these units with the same fault and I have also read about this problem on usenet. The problem is that the Back-UPS RS 500 stop charging the battery. For me it was easy and not expensive to repair them. If you have some experience with soldering it should be easy for you too to do the repair work. Before you start, remove mains power and the battery. This unit is generating high voltage from a 12 volts battery and a battery like this contain a lot of energy. Please take notice of any safety precautions.

VærMRTGPentax Photo GalleryPrivat albumE-post mini

Here is the front panel with model name. I suppose yours are similar.

Remove the two screws on the back panel

Lift the panel out at the bottom. It snaps in position at the top and you maybe have to use some force to take it off completely.

Lift out the side panel and disconnect the red and black battery wire. Make sure you know where to reconnect those wires when assembling the unit.

Take a sheet of paper and make a drawing of the circuit board and all the wires to the transformer and back panel. Disconnect all the wires and remove both the transformer and back panel.

Remove the circuit board on the front panel.

Remove the main board. It is fastened with two clips on the back side.

Main board with the faulty capacitor.

Charging unit and the faulty capacitor.

Make sure you take notice of the polarity of this capacitor.

Replace the capacitor with a new one with similar or better specification. I bought mine from here: Elfa

After the unit is assembled, connect it to the mains and measure the voltage at the battery terminals without a battery connected. It should be approx. 13.6 Volts.

Disconnect from the mains and mount and connect the battery. You probably have to buy a new battery if the old one has been completely discharged and been like that for several weeks. Batteries are easily damaged if discharged over a long time. Connect it to the mains and measure that it is charging the battery. The voltage should be rising slowly up to 13.6 Volts.Posted at 18:36 by Stig Vidar Hovland | Category: General | Permalink | Email this PostComments (101)Comments It works!Thank you for this very detailed fixit. My RS500 failed a few days ago with this problem and replacing the capacitor (with a 33uF 35v component) does seem to have fixed it. I'm watching the

battery charge back up again as I type this.

I wonder what causes this capacitor to fail? According to my meter it is open circuit and exhibits no capacitance at all and that is a very unusual failure mode!

Anyway, thank you again for a very timely posting - you've saved me from spending some money on a new unit. The power of the Internet!

John L (G3WGV), England.at 30.12.2006 11:27Fabulous¡¡¡¡Thanks, fabulous tip, I above thank for you and the people like You Ricardo at 09.01.2007 16:27Just as you wroteIt worked like a charm i replaced it with a 22uF x 25V 85°C Capacitor it works!! Now i have to check if the battery is dead... Thank you a lotat 25.01.2007 03:42thanksthanks, my RS 500 again live. Mirob, Slovakia at 05.02.2007 21:42Thanks!!Same problem here!!! Thanks for the tip, I'll fetch the soldering iron ASAP 8-)at 28.04.2007 20:29Thanks so muchAPC said my battery had died, but I tried this and my UPS is as good as new! Unusual that this is happening on a large number of devices, and disappointing that APC gave me the wrong "solution" when I even linked them to this page to see if they would admit the capacitor was at fault. However, as an electrical engineering student, this was very fun too! Thanks so much for your advice.at 11.05.2007 17:19GONZALOmuy buena solucion hace meses que buscaba la solucion. Gracias ( thanks you)at 12.06.2007 17:09APC USED WRONG CAPReplace with a 105c cap not a 85c that was in it. A 85c cap works good with 60hz, A switching power supply has a much higher freq and a 85c cap with over heat and develop high ESR, due to drying out. Clarence Southwest Monitors & Printers POS SWMP@VERIZON.NET at 27.08.2007 01:14THX U SO MUCH

I LEAVE IN INDONESIA, I HAVE SOME TROUBLE WITH MY RS500, NOW WITH YOUR BLOG, MY RS500 WA COME BACK AGAIN.... I REPLACE WITH SAME CAPASITOR 22uf 16v 85c. MAY BE, I WANT TO RE-REPLACE WITH 105c CAPACITOR FOR LONG LIFE COMPONENT. THX FOR U ALL.at 21.09.2007 22:54PERMIT FOR RE-VIEW IN INDONESIAN LANGUAGEI WANT TO RE-VIEW OR TRANSLATE TO INDONESIAN LANGUAGE WITH COMPLATE U'R PHOTO IN MY BLOG, I WILL PUT YOUR LINK, FOR ORIGINALITY SOURCE. THX U.

SVH: That is OK. It would be fine if you give me a link to your translation.at 21.09.2007 22:57ThanksCured mine fine, I think I may replace the other caps as several are reading a bit high with my ESR meter, the faulty one would not give any reading. now all I need is some non corrosive silicone to dampen the buzz from the inductors. Ben. NB I used a 105c 35V 22UF low esr capacitor. Thanks for saving me the time of finding the fault.at 25.10.2007 16:19Mi agradecimiento a esta solucion !!!!!!!!!Desde Buenos Aires Argentina, agradezco sinceramente de corazon, la solucion brindada por este tutorial.- Ya daba por perdida mi confiable APC RS 500, cuando descubri esta solucion, por la decima parte de un dolar , volvio a tener vida la tan valiosa ups.- Recomendare este link en los foros de electronica sin duda.-Gracias a su autor.-

Thanks !!!!!!!!at 04.03.2008 22:42Mi agradecimiento a esta solucion !!!!!!!!!Desde Buenos Aires Argentina, agradezco sinceramente de corazon, la solucion brindada por este tutorial.- Ya daba por perdida mi confiable APC RS 500, cuando descubri esta solucion, por la decima parte de un dolar , volvio a tener vida la tan valiosa ups.- Recomendare este link en los foros de electronica sin duda.-Gracias a su autor.-

Thanks !!!!!!!!at 04.03.2008 22:43APC upgraded the cap for the new buildsThe C7 had used a 50V 22uF 105c with unknown manufacturer. Other caps are gold color Jamicon.at 07.03.2008 08:40EXCELENTE!! Muchas graciasEste tutorial es excelente, le cambié a 4 UPSs el condensador y están cargando perfectamente.

Gracias de nuevo.at 17.03.2008 16:00UPS APC BR 1500Hello My name is Willan Can you help me? I have have a UPS APC BR1500, and in this moment it is on OVERLOAD state, I repleced the batt and it dont operate, so I see all the electronical elements and I did not found nothing

Please, if you have any idea you can help me?

PD I am sorry my english is very very bad

I from Ecuadorat 19.03.2008 21:51works !Hi folks, it worked for my APC. It was 1 year broken and now it is charging a new battery. Thanks U and the web.

Sleyoat 29.03.2008 16:07RS 500 Alive again!!Excellent fix!! I was just about to buy a replacement UPS. Many thanks.

Neville UKat 03.05.2008 19:37APC Backup 500UPSDo you have anything on fixing power relay? My unit charges the battery but when unpluged from external power it fails to transfer load to battery supply.

Harryat 11.05.2008 21:27APC BE500-ASUsing another apc product. Everything is fine except circuit not charging the battery. How to identify the batery charging capacitor? How do you check faulty capacitors?at 25.07.2008 16:33Excellent jobIndeed works.

Thanks at 26.07.2008 18:21Anyone seen an overheating problem?

Congratulations on the capacitor replacement instructions -- but I have a different problem with my RS500 (BR500I, 240 V version).

It's a new unit, and as soon as I plugged it in it started to give off a scorching smell that has not gone away after 24 hours. The hot spot seems to be near the top vent, on the left-hand side as you look at the front of the unit.

This is a replacement for an RS500 that failed with overheating around R28 on the main board -- I suspected the K2608 MOSFET nearby but am not enough of an electronics person to be confident of diagnosing a fault.

Does anyone else have experience of overheating with these units?at 21.08.2008 18:15WorkingThanks from Finland friends.at 08.10.2008 23:30many thanks to u...I have one exactly the same problem and the capacitor replacement indeed fix the problem.

regards, john_t Subic Bay, Philippines.at 20.11.2008 09:15R28 overheat as wellBCB was burned around R28 of my APC, even plastic case was bit meltedat 09.12.2008 13:37RS 500 discharging batteryMy UPS disarching battery, what problem? at 18.12.2008 19:26Resisters probhi in my unit the large resisters have been damaged (burnt out) can you please post or email me there codes or values thanks par_0020 <at> hotmail.comat 05.05.2009 12:22BackUPS500Where can I find repair solutions like this for my APC BackUPS 500?

It is operational with power coming from the battery but when AC power returns, nothing happens. It operates as if there is no AC power at the input.

This is a very good repair guide here. at 02.06.2009 15:56R28 overheating?Hello, I have same issue with overheating, I have two RS500 with smoked top and PCB, one of

them was deformed by high temp just above R28 and R29. I also hear some stertorous noise when main power cord is plugged into UPS. How to fix that?

Thanks.at 26.06.2009 16:29RS500s overheatingI forgot to mention, there are different dates on PCBs, older one is APC C2001 08/03/2002 640-0259_REV05 and second one is APC C2004 640-0259A_REV06, both have same issue and newer one overheated more.at 26.06.2009 16:35Overheating problemsSorry, but I can't help you here. I have a few RS500, but all of them are working and in continous use. It isn't easy for anyone to tell what is wrong with your units, but if someone has experience with this spesific problem, please send me some text and photos and I could add them to the blog.Stig Vidar Hovland at 26.06.2009 22:54Inductor buzz driving me nutsI bought one of these last week and i already want to throw it away. The buzz is killing me any sugestions? Would realy apreciate it. Thanksat 18.07.2009 05:53same problem but no power indicator oni have the same problem, but i have bought a new one, prolink ups. when i read your post, i tried to fix the problem. first thing that i do is plug the power cable and turn on the power. but no sign of power on (no lights on). do you think that if i replace the capacitor, ill fix all the problem?? please reply, i really need your help. thanksat 30.08.2009 20:24back ups ra500 up side very hot one of place]

how i repaire at 06.09.2009 08:56Thank you very muchi've repaired 2 unit (same symtom) and it work like a new one, by replaced all cap (85->105c) i hope it won't need any cap replacement again for 2-3 years :Dat 12.09.2009 09:39Similar to .... CS 650 APC noisy resistor buzzI wish I had the same fault..... Got a new CS 650 that is driving me crazy with the charger control circuit with audible noise. You wouldn't believe it but the noise is comming from a RESISTOR # R3 on this rev6 board. (March 2008) I've never heard of a resistor making this much noise. Has any tech experienced this - however works yet it produces high frequency noise. Weird.

Capacitors - chokes are fine. at 04.10.2009 11:38More radical modificationWell, designers of this circuits were… (censored)

I have had the same problem, analyzed the switching power supply and found the same problem. Consulting the data sheet of UC3842B, the 22µF capacitor seems to be underestimated.

At least in RS500 230V version REV05 one of resistor around eats permanently about 2 Watts and generates a lot of heat.

That is why I decided to do a more radical change:

Replace the capacitor with much larger one: 220µF.

Remove the parallel 3.3kΩ resistor R139 without any replacement.

Replace large hot 50kΩ resistor R28 by 220kΩ of the same size (probably even more is possible).

It decreases power current by 2 Watts and temperature there by 40°C at cost of 1 second delay after connecting the power plug.

Purpose of such modification:

Original design used a very hard divisor that divides the plug voltage to supply ~10mA. It is nearly enough for running the oscillator, so 22µF was (nearly) enough.

But the divisor should be used just to start oscillation. Once the oscillator runs, it is powered from the transformer and the divisor is not needed. You can verify this fact by disconnecting the large divisor resistor, touch, and remove. Oscillator runs.

The datasheet says, that when there is no power to run oscillator, the IC eats less than 0.5mA.

It means, that the divisor could be designed to provide only 0.5mA, not 10mA.

In this case, capacitor must be larger (e. g. 220µF), because the complete start of the oscillator is powered nearly exclusively from it. It must have enough juice to keep voltage above the minimal voltage until the transformer start to give power.

Happy hacking

Stanislav, http://www.penguin.cz/~utx/at 08.11.2009 01:13A zillion thanks!!Following an overnight power surge I noticed in the morning the three lower leds flashing

continuously and no backup power. So I soldered off of an old pentiumII motherboard a 16V 22μF 105C capacitor and replaced the one shown in this tutorial. I plugged in and for a few seconds the three lower leds flashed till the power on (green) led lit (I guess meaning that the battery was completely uncharged and now it is charging).

Many thanks again at 08.11.2009 12:36More radical modification documentedHallo.

I just documented my more radical modification described above:

http://www.penguin.cz/~utx/apc-ups/

Apropos, if anybody is able to read values on R138 and R150, please let me know. My UPS had them damaged so it was imposible to measure them or read the value. They are replaced by 10R on my images, but I am not sure, whether it is correct.

Thanks, Stanislavat 09.11.2009 00:28RS 500 is in the second life!Hallo,

Thanks a lot for this repair instruction - the best I've ever seen! My RS 500 is now working again, I used a capacitor with 47uF/16V because it was sunday and there was no original capacitor in my box. RS500 runs very well with 47uF!

best regards, Bill from Germanyat 13.11.2009 22:25Lot of thanksWe have the same problem ,it was not charging the battery so i have seen your procedure for repairing and now it is up to the mark

Another thing plz tell us the specification of Resistor R28 in circuit boared of UPS .

Junaidat 23.12.2009 06:36Thank you twice..I had two apc 500 units with this problem, both of them are fine thanks to you! So thank you twice!

Alkis from Athens, Greeceat 22.01.2010 14:59Thanks and thanks.Newer version of RS 500 unit with 50V 22uF capacitor fixed with replacement from an old Base10-T network card. at 30.01.2010 11:57Thanks !!100uF/35V 105C Works :-)

Matonyat 11.02.2010 07:23suwatThanks a lot. My APC BR500i work again.at 25.03.2010 14:38lost battery backup outputLast month, during a power failure I plugged my APC BE500U-CN into a120V generator that has the ground potential of 40V and now it started beeping, and does not offer any battery backup power. The battery measures 13Volts AND THE units battery charging leads show 13.5V with battery removed. any ideas how to fix?at 30.04.2010 15:56rs 500 alarmCould somebody tell how to disable the alarm in this model... apc rs 500... take in account that I not an engineer....thanks

dapal55@yahoo.esat 12.05.2010 14:48HelloFollowing an overnight power surge I noticed in the morning the three lower leds flashing continuously and no backup power. So I soldered off of an old pentiumII motherboard a 16V 22μF 105C capacitor and replaced the one shown in this tutorial ( I plugged in and for a few seconds the three lower leds flashed till the power on (green) led lit (I guess meaning that the battery was completely uncharged and now it is charging).at 14.05.2010 12:11resistance valueKindly tell the value of resistance R28.at 12.06.2010 12:30resistor valueR28 = 56Kat 15.06.2010 03:17RESISTORKINDLY THE VALUE OF R26at 22.06.2010 12:25resistor

resistance value R29 email at peweelocsin@yahoo.comat 22.06.2010 13:35APS CS 500, always "On Battery", can't turn offIt is a very nice tutorial. I found it when i did a research about repairing my CS 500.

When the unit is connected on power source there is a yellow light "On battery", even when there is no battery inside. The unit won't turn off. Do u have any idea what i should do?

Thanks in advance.at 03.08.2010 12:38Resistor values apc RS 500Thanks for the nice tutorial and great solution to my problematic rs 500. I would like to help some other users and publish values of resistors that may be erased because of overheating.2W 5%, R29=3,3K 2W, R75=2,2R 2W, R157=20R 1/4W.at 17.09.2010 12:02Thanks my friend!!I just replasced the capasitor and the r28 resistor and it works!at 02.10.2010 14:44GraciassssExcelente tutorial, recupere 2 UPS. at 04.10.2010 19:06overloadHi, I have have a UPS APC CS500, and in this moment it is on OVERLOAD state.at 19.10.2010 20:16thanks!I have just repaired my ups using your instructions. at 20.10.2010 18:45UPS APC RS1500 OverloadHi, I have have a UPS APC RS1500, and in this moment it is on OVERLOAD state. how i repaire at 06.12.2010 17:20A zillion thanks AGAIN!!Almost one year following heimes' instructions, [comment 8.11.2009: A zillion thanks!! Following an overnight power surge I noticed......uncharged and now it is charging). Many thanks again], my rs500 died again!!! I followed the more radical modification http://www.penguin.cz/~utx/hardware/APC_UPS_RS-500/ and guess what:

It's ALIVE again (cost <1euro)

Many thanks to all the electronics gurusat 12.01.2011 18:13

CS 500This text help me solve similar problem. On CS500 from AC input it goes to fuse(SMD) then to gretz(4 diode) and to charger. After gretz it has similar capacitor(10uF 450V 85C) which was blown and made short circuit dameging PCB(+&- undernith capacitor are VERY close), blowing fuse and stop charging battery(and not doing self-test). After replaceing capatitor, fuse and repairing PCB everything OK! Thanksat 16.01.2011 18:22radical modification on CS500 rev06?can anyone confirm the "radical modification" (http://www.penguin.cz/~utx/hardware/APC_UPS_RS-500/) works also on cs 500 rev06? thanks marco at 07.02.2011 21:56elektronikoMuy bueno el articulo si no es mucha moelstia podrian ayudarme a buscar el diagrama del APC UPS RS-800 el problema es que se apaga por ratos Graciasat 26.02.2011 12:17want ups diagram i am manjula i want 600VA ups circuit diagram my mail id-sntmanjula@yahoo.comat 07.03.2011 11:19Great workThank you very much for that great tutorial! Greetings from Patagonia Sebat 20.04.2011 14:07ThanksWorked perfect for me although I did not see any damage on capacitor on my RS 500. Greetings from Switzerlandat 28.05.2011 09:25R138 and R150Looking at the pcb, I founded these two resistors, C65 and C66, are snubbers that protect the contacts for two of the tree existing relays; there are places not populated for the third relay (C67 and R152). I think that two relays are used for the regulation of the AC incoming from the wall, and the third is for transfer the supply from AC to inverter during the outages. Perhaps the best decision is to replace the resistors for other of 10 ohm, but made from metalfilm and with 1 watt or more.

I replaced C7 and the unit satrted to work fine again, but it is very noisy now, at least it seems to me with the whole circuit of the original case; is the any clue for the reason of this?.

Excuse me by my basic english, is not my native language; tahnks!.

Hernánat 29.05.2011 17:25Cool!!!!!!!It's working!!! I'll write a dissertation about this)))!!)!)!)!at 08.06.2011 09:56workthanks, my RS 500 again live. mclareniak, Slovakiaat 24.06.2011 08:24ThxWork!!! thank for the tip! cómo descubrio la solucion?at 30.06.2011 23:08ThxSorry.... Brain bug: P

how discovered the solution?at 30.06.2011 23:09contribution i thing this is the diagram of the circuit

http://www.eserviceinfo.com/downloadsm/3842/APC_UPS%20500.html

thanks for the post VNCat 12.07.2011 16:16what is r28 where can i buy the r28 resistor or what ever its called from ? mine has burnt out and make the case turn yellow i found the capacitor in the 1st post on ebay but dont know any thing about r28 so any info would be good.

thanx at 29.07.2011 02:47Worked well on REV08I have replaced C7 Capacitor and my UPS started to charge the battery again. Thanks for the article.at 03.08.2011 15:56arora 1000vablackat 12.08.2011 08:23It works!Thank you very much! It was the same problem for me, but how you've understand that problem is in this capacitor? In my case bad capacitor was 12uF --- it's not very bad. Original value was 22uF, 50V. More over, may be you know, Is is a capacitor problem or bad circuit design?

at 23.08.2011 23:21Not worked on battery My UPS RS 1000 is not holding on battery supply for more thant 30 second.. Pls advice me.at 26.08.2011 09:21Thanks Now it works ,Faults was in power storage!It fail to store power for along time.at 13.09.2011 07:09RS800 - BypassHi,

i am planning to use RS800 as inverter , off-grid power do you know who to bypass / reset the relay to switch to battery mode without prior ac inputat 19.10.2011 02:50Great!My Back-UPS RS 500 rev 06 is back in duty with new 22uF/50V/105c for nearly no cost ;) Thanks!at 21.10.2011 01:42OverloadHi, I have have a APC BACKUP-UPS 800, and in this moment it is on OVERLOAD state. When I checked the out put connections with line tester it shows both wire live ( Phase & neutral ). Please let me know the problem. Thanks in advance.

bk35@hotmail.comat 04.11.2011 10:12RS 1000 not working anybody here knows how the RS 1000 works or have circuit diagram hereat 20.11.2011 13:58Great !!!Thank you man. Very useful guide. Thank you again :)at 05.12.2011 09:27How to Modifywhat should i change or modify if APC Back-UPS RS 500 use with large battery.. at 12.12.2011 17:12UPS Manufactureing / Assembling Helo, Thanks for your advise regarding RS-500 Repairing , it really works,.

I am planning to have manufacturing UPS, Assembling UPS, so can you provide me detailed information to how to assembling/manufactre UPS. Email : gisplindia@gmail.com Contact : +91-9428222374

Thanks dear ,

From : Dhaval Chauhan, India. at 05.01.2012 10:13Still WorksThanks very much. Changed the cap and all is well.at 09.01.2012 09:34solved!!!!thank master..solved my problemat 12.01.2012 18:20Indian Model is differentMy UPS mother board is completely different, and i could not figured out which capacitor was faulty. mine is Indian version, can somebody help me??

baba dot maal gmail.com Thanks at 13.01.2012 14:15Charging again!Thank you!

A-P,Finlandat 10.02.2012 22:48Spot on Fix!Thank you so much for posting this. At C7 I used a 47uF 35v 105C cap I had hanging around ands it seems to be fine.

Nice one. Thank you.

Jon (Australia)at 11.02.2012 09:41Thank youI just made Stanislav's modification on a REV06, it works nice now. So after some years you still deserve a thank you everybody :D !at 19.02.2012 12:52br500can my br500 replace the battre with 12v 50ah?at 09.03.2012 12:17how to repair..how about the socomec sicon ups net0600-pe how to repair .. the ups is not charging, what should i do to repair ..., anybody there can help.. thks

cris (philippines)at 18.03.2012 04:49

thanks a lot thank lot for share i can fix the problem on my UPS RS500 just change another one cap 22 mF with a new one

thnks so muchat 06.05.2012 22:07how to repair CS 500 ?I have a Ups APC CS 500 I changed all transistors and few capacitors. Ups shows me is overload and off. What are the possible faults on Ups, some of your suggestion ? Help me, thank you, Best regards, Nikica Subat (from Croatia). at 13.05.2012 12:27It was unused for 1 yearThank you very much for the information. I searched in google for the same fault that I have with model RS 800 and suddenly I found information for model RS 500. 1 year it was unused into my storehouse with the same fault. I changed the capacitor, which seemed to be okay with a new and repaired the damage. Thanks again for your help for a component with the least of cost repair my ups. If anyone know what is the corresponding capacitor for model RS 800 with the same fault please report it here.at 07.06.2012 07:45overloadHi all!

I've an apc rs800 Ups shows me is overload. I'm changed the battery's. The 12V and the IC11( KA7812 ) good!

Another apc rs800 Ups is switching between inverter and AC mode.

What are the possible faults on Ups, some of your suggestion ? Help me, thank you, Best regards, Frank webmaster100@freemail.huat 28.06.2012 13:33yellow on battery led blinking Hi to every body, i have the same problem, but i've got another motherboard, exactly 640-0287c_rev08 , and I can't find the capacity mentioned before. Is there anybody with same problem and same mb, that have solved ?at 06.07.2012 13:26 yellow on battery led blinking #2thank you

flavio (Italy)at 06.07.2012 13:28 apc sc 620 if power on ups continious ly buzzer i have apc sc 620 if power on ups continious ly buzzer and red light on and no 220 volts out putat 19.07.2012 14:32UPS faultsMy UPS indicates the beep tone as A\C not connected, but power cable had been connected to the main line (fuse and power wire also good). whats wrong with it? (inverter works well)at 28.07.2012 15:24Add CommentTitle *

Body *

Attachments

Use this page to add attachments to an item.

Name

CaptchaWebPart

Enter the code shown above: *

*Incorrect Code

(Note: If you cannot read the numbers in the above image, reload the page to generate a new one.)

Bottom of Form