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Battery Charger Rebuild

Ramper

Well-known member
Joined
Nov 30, 2010
Messages
1,484
Location
Southern MN
I have an old battery charger that I would like to rebuild. The cords (120V in and 12V out) need to be replaced. I am wondering about changing the old rectifiers for a new bridge rectifier (bridge). My questions is how.

The power comes in and one leg goes to a switch (6V or 12V) then that come into the transformer via the black and yellow wires on the bottom. The other leg comes right to the top of the transformer. I have checked all of these and they have continuity between them and the switch works.

Coming off the transformer on wire goes to a ammeter and then the two other (smaller) wires go to the rectifiers (mounted to the back wall). One wire comes off the rectifiers to a "block" (maybe a fuse?) and then goes to the clamps. The other clamp connects to the ammeter. The "block" has continuity between the posts.

Do I just replace the rectifier with a bridge (where do I hook the leads off the transformer) and I assume I hook the wire coming off the rectifiers to the positive output from the bridge. This would leave the negative post open.
 

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Bert_

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Joined
Dec 24, 2016
Messages
9,924
Location
NW Iowa
Why do you want to replace the rectifiers? Do they test bad?

No idea how many amps your charger puts out so I don't think your going to get many recommendations for output cables.
 

nadogail

Well-known member
Joined
Jan 23, 2009
Messages
32,370
Location
Coronado, CA
IMHO, first change the AC power and DC output cables, then plug it in while watching for smoke.

Assuming no smoke or sparks, hook up a battery and test the Battery Charger under load.

If it works don't fix it.
 

walta

Well-known member
Joined
Jan 13, 2017
Messages
2,322
Location
Dutzow Missouri
Looks like a 1950s Selenium rectifier. If you change to a modern rectifier the output voltage will be too high without other modifications.

Be safe and make sure your charger has a grounded cord.

You may enjoy this video

Walta
 
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Milton Shaw

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Joined
Feb 11, 2011
Messages
4,868
I thought that was the magic smoke instead of fog. That's what normally shows up after you /me/we have tried to repair something.
 
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