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Cooked - lead acid battery charging module in car jump starter

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Carl

New Member
I have cooked the charging circuit for a sealed lead acid battery by accidently attaching a 15V supply for another device instead of the 12V supply that it was expecting.

Now, when I plug in the correct DC power supply, the red charge LED lights briefly, then the relay clicks and the red charge LED goes out. The relay remains switched until the DC power is removed, it doesn’t charge the sealed lead acid battery, which is deeply discharged...

I have attached a photo of the charging cct board.

My best guess is that I have killed the transistor, and that it is just a case of replacing it. It is marked S9013 H 331... Is any transistor marked S9013H a suitable alternative?

The only other thing that looks killable is the little orange diode it has a big blue black ring and the number 2 there may be additional markings on the underside...I can de-solder if it is a suspect and you can’t guess what it is.

Both electrolytics are marked 4 7µf 25V (I don’t know whether the space is supposed to indicate a decimal) but am guessing these are ok as they are rated above my applied voltage.

The black diode is marked, 66*N I can’t read the * because of the way the diode is soldered, there may not be a character at all, I can de-solder it if you think it is a suspect.

I haven't done any electronics since A-Level physics, so if somebody can guess what or which bits are most likely to be damaged I would be eternally grateful. I am worried that the longer the lead acid is discharged the less likely it is to take a charge again.

Kind regards, Carl
 

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audioguru

Well-Known Member
Most Helpful Member
I doubt that you can buy an S9013 Wing-Shing Chinese transistor anywhere.
Fairchild sells an SS9013 Korean transistor that is better.
I would just use a common 2N4401 transistor. The pins are the same.
 

Carl

New Member
Thankyou very much for the quick reply!

I am sure Wing-Shing corp would be most upset to learn that the Koreans build a better transistor ;)

I have ordered a 2N4401, will let you know if it works.

Thanks again,

Carl
 

HiTech

Well-Known Member
That 330 ohm (grey bodied) resistor looks stressed. Pull one end and measure it. That 3rd band looks to be brown from the photo making it 330ohms..... notice the discoloration at the center of the resistor? The other diodes can be tested easily as well. In fact the whole circuit board can be tested in 15minutes since there are so few components.
 

Carl

New Member
Thankyou, will test, large, rather browned looking resistor.

Am going to try replacing the transistor first, waiting for replacement to arrive.

Could you give me a hint on how to test the diodes, and indeed what the little orange diode is likely to be?
 

shokjok

Member
Test the diodes with an ohmmeter, or out-of-circuit with a resistor inline with an LED. If you can provide us with a PCB underside layout we can assist you further.
I recently fixed a Porter Cable charger with an ICS1702N charge controller, obsolete since 1991. Got the data sheet online, checked the batteries and probed the PCB with a multimeter. Replaced a switch and fuse, and it works fine now.
 
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Carl

New Member
Evening, sorry it has been a long time since I posted on the thread but it took a while to get the parts together and try some things, I have got some charge into the lead acid, so hopefuly if one of you with some understanding of transistor circuits could give me a hand I might be able to fix it...

I have now produced a cct diagram for the board, attached, I have drawn some of the parts pictorially, dotted lines show guess work on my part (I am fairly confident about the relay, calling the orange glass diode a zenner is pure guess work.)

Transistor is now a 2N4401.

Browned resistor is 2.7 Ohm, I have worked out that brown band is in fact a browned gold band and put it back thinking it is just outside tollerance.

As before, when I plug in the correct DC power supply to charge it, the red charge LED lights briefly, then the relay clicks and the red charge LED goes out. The relay remains switched until the DC power is removed, the battery is definately not fully charged.

I have included on the cct diagram voltages measured at various points on the board with the DC supply attached and the relay actuated.

I am guessing that my prime suspect is the orange glass diode, which might or might not be a zenner, can any body work out what the correct spec would be based on the diagram and voltages?
I can't see why the resistor being slightly out would effect things, but as I say I am pretty poor on transistor ccts, if this looks suspect to anybody please let me know and I will change it out.

Would be very grateful for any help, really don't want to be throwing things in landfill,

Kind regards, Craig

P.s. The voltage provided by the other dc charger is not very different from the measured voltage of the one I connected accidently, so that may not have been the cause of the problem...
 

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