Battery charger blunder

gab

Well-known Member
Not very proud of it but was in a hurry yesterday morning, needed to move a garden tractor with a weak batt. and hooked it up wrong, been hooking up chargers for over 50 years. Circuit breaker tripped followed by a wisp of smoke. Both button diodes are junk, one was covered with little solder flakes or something. I've got a big charger but I like this one better, had it since 1977. The diodes are hard to read but looks like AR 004 and one had the arrow toward the plate in the back, dropped the other one but think it was in the same direction. Are the little diodes the kind of thing Radio Shack would have or where would you look?
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Rat Shack may have them but that's my least favorite store. Any old fashion electronic shops near you?? If not do as posted below E Bay etc. I wouldn't buy less then 20 or 30 amp diodes and to the extent possible provide a heat sink to dissipate their heat and/or mount where air flow is good or near any internal fan (if it has one).

John T
 
Slang terms for them are "pellet diodes" or "button diodes".

They can be hard to find, sometimes on ebay, but I don't see any on there at the moment.

Below is a link to them at a power tool repair parts co's website that has a kit available, price isn't too bad, but shipping $$ gets it up there.
<img src = "http://cdn3.volusion.com/4mpcs.dyg25/v/vspfiles/photos/RR50-2.jpg?1471586267">



Or, if you has a basic understanding of electronics, you can replace them with a bridge rectifier such as a KBPC5010. (Only 3 of the 4 terminals an two of the diodes are used.) You can find those on ebay for $1 and up. Rated 50 Amps at 1000 PIV.

<img src = "http://www.datasheetq.com/image/Cnelectr/KBPC5010.gif">




Another alternative is to find a rectifier out of a Delco alternator and snap apart the heat sink and use two of the appropriate diodes mounted to the heat sink. If you are frugal, you can use one that has a failed diode, since there are three on each half and only two are needed for this project. I have disassembled photos somewhere, can't find them at the moment.

<img src = "http://www.econofix.com/delcorect2.jpg">

Which half you use depends upon whether the cathodes or anodes of the original diodes were in contact with the aluminum heat sink plate.
Century diodes
 

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