Looking for some help fixing a car battery charger.

Thread Starter

robert Digiacomo

Joined Dec 14, 2014
7
Hello I accidentally arced my battery charger that worked yesterday. I hear the transformer humming, but no voltage at the leads. I think the problem may be the disc diodes, but am not sure. I would like to repair this as cheap as possible even if the circuit becomes changed. Any help would be greatly appreciated. Thanks

https://www.flickr.com/photos/128266543@N05/
 

flat5

Joined Nov 13, 2008
403
Good pictures. In the upper right pic you show a diode. Check that first. Is there a fuse?
Do you have a digital multimeter or a volt/ohm meter?
 

bwilliams60

Joined Nov 18, 2012
1,409
Do you have a DVOM? Does it have a diode test function? If so, disconnect the button diodes and test them with the DVOM. In one direction you will get 0.5 - 0.7 V and the other way you should get O.L. Start with that and go from there. Make sure power supply is disconnected from wall before testing :)
 

Thread Starter

robert Digiacomo

Joined Dec 14, 2014
7
Good pictures. In the upper right pic you show a diode. Check that first. Is there a fuse?
Do you have a digital multimeter or a volt/ohm meter?
I have a meter. I don't get any reading from the spade connection of both diodes to the metal that it is soldered to. I don't know if they are both opened or I'm testing them wrong. I know how to test a standard inline diode though. The black fuse (I think) in in the 1st picture on the base of the unit reads 10A 12V and has continuity.
 

Thread Starter

robert Digiacomo

Joined Dec 14, 2014
7
Do you have a DVOM? Does it have a diode test function? If so, disconnect the button diodes and test them with the DVOM. In one direction you will get 0.5 - 0.7 V and the other way you should get O.L. Start with that and go from there. Make sure power supply is disconnected from wall before testing :)
I am grounding the black DVOM probe to the metal plate and getting .478 volts for top and .429 volts for the bottom. When I reverse the probes I got zero for both. So the diodes seem good correct? Thanks
 

Thread Starter

robert Digiacomo

Joined Dec 14, 2014
7
Flat5 just wanted to let you know with my earlier post I had my meter set to continuity instead of the diode function, so I was not getting a reading for the diodes.
 

flat5

Joined Nov 13, 2008
403
After the resistance checks if nothing obvious found I would power the thing up and do voltage checks from the transformer secondary. Be careful. If you don't know how to check AC & DC voltages then don't do so.
Read up on it first.
 

Thread Starter

robert Digiacomo

Joined Dec 14, 2014
7
After the resistance checks if nothing obvious found I would power the thing up and do voltage checks from the transformer secondary. Be careful. If you don't know how to check AC & DC voltages then don't do so.
Read up on it first.[/QUOTE
On the line with the zener diode and heat shrink that goes to the thermal circuit breaker/fuse (seen in the pictures) I pealed away the heat shrink and found another zener diode and 2 very old looking diodes that look like minniture crayons and everything tested out well. Off the secondary side of the transformer I got an AC reading of 28.3 Volts.
 

flat5

Joined Nov 13, 2008
403
OK, connect the negative (black) lead of the meter to the output ground clip and poke around to see where you lose the positive DC voltage.
 

Thread Starter

robert Digiacomo

Joined Dec 14, 2014
7
Okay, with your setup I found that the secondary of the coil is producing 14VAC. That 14AC drops down to .5 AC after the diodes and remains there throughout the circuit. I could not find any DC voltage. What is the sensor in pic 2 is that where the DC voltage is produced?
 

flat5

Joined Nov 13, 2008
403
The DC voltage is produced by the action of the diodes.
You might find it interesting to fix this thing but I would advise you to buy a new modern charger.
They protect the battery, are light weight, and know when to lower the charge rate.
Many have the option to charge a motorcycle or car battery. Some can detect 6v, 12v, 24v batteries.
They are intelligent and cost about $25 or less.

Edit: Just found

http://www.banggood.com/20B10B-Car-...r-150AH-Storage-Battery-Charger-p-960910.html

http://www.banggood.com/10B-Car-Storage-Battery-Charger-150AH-Storage-Battery-Charger-p-960911.html
 
Last edited:

Thread Starter

robert Digiacomo

Joined Dec 14, 2014
7
Okay, I figured out I was mis-testing. I found that if I connect the negative on my meter to the negative clip on the charger I find my 12VDC on the metal plate not on any of wires or tabs. I eventually traced the 12 VDC though the back of the amp meter on the battery charger. Last place to look was on the positive lead/clip of the battery charger, and I had no current there. Found out I had a frayed or cut wire right where the wire ties onto the chargers positive clamp. Sorry about the confusion, I'm just not really used to using my meter. Anyhow I got the charger from my grandfather who probably had it for 50 years, so I'm happy to report it lives on, and now he can stop rolling over in his grave. Thank you all. Bob
 
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