Dead Automatic Battery Charger for Autos. Please help me troubleshoot.

[Rioriorio]

Model: Schumacher SSC-1500A It has 3 power settings, 2 amps, 6 amps, and 15 amps

Symptoms: Not fully charging batteries anymore. It will still partially charge batteries, but not all the way.
The charger turns on and the display turns on also.

I opened up the case and there was a capacitor bulged so I replaced it, but the charger still doesn't work. I replaced the one on the second picture right next to the big red/black cable.

I do have an esr capacitor meter and I'll have to check to see if my multimeters at home have a diode setting.

I'm including pictures of the circuit boards.

Attached to the heat sinks (assuming they're heat sinks, the tall long metal pieces) are what appear to be transistors)

Could someone please help me figure out what's wrong with this so I can fix it?

This first picture is of the circuit board on the display. The other pictures of circuit boards are of the main one inside.
.


Thanks.

 

[Gryd3]

Just to confirm some details:
How much does it actually charge? A 'little' or 'most' of the way?
If you can get some battery measurements as well..
-Prior to charge.
-Immediately after beginning to charge.
-Immediately before stopping charge.
-After charge.

It would be nice to know at what stage of the charging process it is stopping. Hopefully this gives us more info.
Do any of the lights for the display mis-behave? Does the 'charging' light simply stay lit, or does it light the 'charged' light even though the battery is not charged?

 

[Rioriorio]

This is off memory of a van I was trying to charge a week or so ago. The charger at the beginning said it was about 6% charged. When "finished" it topped of around 50% charge. I say finished in quotes because that's where it stopped, not because the charger said it was done.

It will display voltage (I'm assuming being output by the charger) at the highest setting it doesn't reach 12 volts. It is in the 11s.

None of the display lights misbehave that I can tell. It just stays on "charging".

When I first got it and you'd put it on the highest setting, it would bog down like it was really working and it was. Now there's no real audible change in the charger switching between settings.

 

[Gryd3]

Can you please tell us what cap/caps you swapped out that were bulged?
Can you get a clear pic of the bottom where all the traces are? (Good pics so far by the way)

Just seems like it isn't adjusting it's output current... so I'm thinking it's something in the control logic portion of the board.

 

[Rioriorio]

I changed out one capacitor. It was a 25v 2200uf. On the yellowish pic with the screwdriver visible, it is the one located right above the big black/red wire.

When you say a pic of the bottom where the traces are, do you mean like this:

 

[Gryd3]

I changed out one capacitor. It was a 25v 2200uf. On the yellowish pic with the screwdriver visible, it is the one located right above the big black/red wire.

When you say a pic of the bottom where the traces are, do you mean like this:

View attachment 17136

Exactly like this!

Wow. A new user who takes great pics.. I like you already.
This will allow us to determine what is connected to what...
I'll take a close look when I get home tonight and see if something jumps out at me.

 

[debe]

I would be suspicious of that Relay, especialy if it carries the charge current. It doesn't look big enough to carry 15A for long. It may have burnt contacts in it, have had similar problems with that size relay in other power supplies. Also check for poor solder conections on the board.

 

[Rioriorio]

I would be suspicious of that Relay, especialy if it carries the charge current. It doesn't look big enough to carry 15A for long. It may have burnt contacts in it, have had similar problems with that size relay in other power supplies. Also check for poor solder conections on the board.

Thank you for your input. I'm not that knowledgeable about this stuff. Can you tell me (or describe on my pictures) what relay you're referring to? How would I test it if I wanted to?

 

[debe]

The relay is the black rectangular box by C10 electrolytic.Im wondering if you realy should be attempting to repair a unit that has mains voltage on it quote ( Im not knowledgeable about this stuff)

 

[Rioriorio]

I tested all the capacitors I could see on the board with my esr meter and they checked out. I also checked most diodes with my meter with diode setting.

I have a question about a couple of them.

First one (identified as TR1 in the photos) is attached to the bottom heat sink by a screw. It is a P15NK50Z and from the data sheet I found is called a Zener-protected SuperMESH™ Power MOSFET. Using my diode tester connecting the middle wire to negative and positive to the right pin I get a reading of 455 (.455?). When I reverse them it goes to 1 like I'm assuming it should. The left side is switched I believe and there's no reading from the middle wire to the left wire both ways. I'm linking the datasheet. Is this OK, or how do I test it? http://www.farnell.com/datasheets/1690167.pdf

The second one (identified as D5 in the photos) is attached to the heat sink at the top of the circuit board. I've identified it as a 30A Schottky Barrier Rectifier. When I use my diode tester black to middle wire and red to right I get a reading of 244 (.244?). I get the same reading on the left wire. When they're reversed they both go to 1 (the manual says this is what it should do). On the datasheet it says you should expect a voltage drop of .58 (580?). So is this rectifier bad? Am I doing it wrong? If this is bad, would it cause that capacitor to bulge? http://www.diodes.com/datasheets/MBR(F)3045CT.pdf


I really appreciate your guys' help.

 

[Rioriorio]

I would be suspicious of that Relay, especialy if it carries the charge current. It doesn't look big enough to carry 15A for long. It may have burnt contacts in it, have had similar problems with that size relay in other power supplies. Also check for poor solder conections on the board.

Are you referring to the small black box that says SANYOU on it?

 

[Rioriorio]

The relay is the black rectangular box by C10 electrolytic.Im wondering if you realy should be attempting to repair a unit that has mains voltage on it quote ( Im not knowledgeable about this stuff)

Probably not, but I'm going to give it a shot.

 

[Rioriorio]

Here's the datasheet for the relay. If it's fried, it might explain why it turns partially on. It just can't hit that next gear so to speak.

http://www.datasheets360.com/pdf/-8402106954705881493

 

[debe]

Are you referring to the small black box that says SANYOU on it?

Yes that's the one & its pretty mutch at its limits in that application. Tr1 is the main switching MOSFET, if the powersupply is aleast firing up then this is probably not faulty. As its on the Mains side of the SMPS. Unfortunately the photo onf the PCB track side is not realy sharp enough but there looks to be poor solder joints. Pictures realy need to be taken using Macro on a camera.

 

[KrisBlueNZ]

1. The capacitor you replaced should have been a low ESR type. Is that what you used? Do you still have the original? You said it's 2200 µF, 25V, but can you list ALL of the markings on it?

2. TR1 is very unlikely to be the problem. When the main switching MOSFET in a switching power supply fails, it usually fails short and th fuse blows.

3. The measurements you got for D5 are normal; the voltage is low because it's a Schottky diode, not a standard diode.

4. You could check the components in the discoloured area to the left of the big transformer. These are the suppression components and if there's a problem there, it could restrict the output voltage I guess.

5. Can you take another photo of the top side of the power board with the wires pulled away so we can see what's behind them? Also, if possible, take the photo from further away, using a zoom lens, so the tall components don't block out so much of the parts that are next to them. Take the photo at exactly 90° to the board, pointing at the exact centre.

6. What type of batteries have you tried to charge? How many of each type? Were they in known good condition?

7. How does the charge percentage display behave? Does it count steadily to 100% and does the charger stop when it reaches 100%? Does the charger continue after 100% is reached? Is it supposed to?

8. There are several reviews at http://www.amazon.com/Schumacher-SSC-1500A-CA-SpeedCharge-Charger-Battery/product-reviews/B000H961YI that mention that the charge state indication hits 100% before the battery is fully charged.

9. Can you confirm that the only connection to the control board is the five wires at the top right corner that connect to "J1"?

10. (For future reference, the wires on this connector are: 0V; circuitry +ve supply from U4; relay control; battery voltage; output voltage control to optocoupler.)

11. That charger doesn't appear to have any way to measure the actual charge current. Unless there is something attached to the fat wires that run from the power board to the battery clamps.

Edit: Yes, debe's suggestion of possible damage to the relay is worth checking out as well. While the unit is trying to charge a battery, but the displayed voltage is low, measure the DC voltage across the relay contact. It should be very low - less than 0.01V. If it's higher, you need to replace the relay.

 

[davenn]

6. What type of batteries have you tried to charge? How many of each type? Were they in known good condition?

this is a critical question ... as I have been assuming, because of the look of the charger and the switchable current outputs, that it's for lead-acid batteries say a 12V car battery

This leads to this comment from me about something very early in your posts that no one addressed ....

It will display voltage (I'm assuming being output by the charger) at the highest setting it doesn't reach 12 volts. It is in the 11s.

you CANNOT charge a 12V lead-acid battery on 11 - 12V ... the charger should be putting out around 13.5 - 14.5V, else the battery will never charge correctly

so maybe you should be looking at why there is only 11 - 12V on the charger output

Dave

 

[KrisBlueNZ]

you CANNOT charge a 12V lead-acid battery on 11 - 12V ... the charger should be putting out around 13.5 - 14.5V, else the battery will never charge correctly
so maybe you should be looking at why there is only 11 - 12V on the charger output

We are. That's why debe asked about the relay and I suggested checking the suppression components in the power supply.

 

[davenn]

That's why debe asked about the relay

He was addressing the current carrying capability if the relay
not specifically why there is only 11-12V instead of 13+ V

though your added edit may possibly cover that problem

I also missed your point 4 comment

 

[debe]

On the display board I suspect U1 is a microprocessor chip which controls the output voltage on the output volt control to opto on the main board. The question is where is the processor sensing the battery voltage?? If theres a poor conection in the relay contacts or poor solder joints, then this will upset the whole operation. (this is just mere speculation of course)

 

[davenn]

but a good possibility

in the ol' days battery chargers were so basic ... a transformer a bridge rectifier and a 6V/12V switch