alternator and Battery

HenryO) · Mar 9, 2013

When left hooked up the alternator the battery gets drained. I understand that I need a diiode betweeen the two and some said go to Radio shack but they only have 2-3 amp diodes. What amp diode do I really need and where else do you get them Thanks

David G · Mar 9, 2013

That is plenty big if you put the diode in the right place.

How are you hooking things up?

gregger · Mar 9, 2013

need to fix or replace the alternator

John B. · Mar 9, 2013

Can you post a picture?
We need more details to help you!

John B. · Mar 9, 2013

WE need to know what this is on?
Did you install an alternator on a positive ground system and not change the battery connections?
Did you convert from 6 volts to 12 volts?
Does the alternator have an internal regulator?
Does it have an external voltage regulator?

HenryO) · Mar 9, 2013

I recently bought a 1948 Farmall H that has been converted to 12 Vlts. The seller had received the tractor with a collection of about 40 others from an estate sale. That said it has an alternator that works but charges off the scale when the tractor is running. If you turn it all off and leave the battery disconnected it drains the battery over night. It was suggested that a diode be placed in the wire to the battery. Went to radio shack and all they have is 2-3 amp diodes and said that if the alternator puts out more than that it will cook the diode????? If I remember right, most alternators put out 14.4 Volts and about 40 amps. I may be all wrong but I Would appreciate learning about this.

HenryO) · Mar 9, 2013

I mean connected battery , NNOT Disconnected

Bob M · Mar 9, 2013

A couple of possibilities:

1 - A fault inside the alternator (shorted diode bridge). Fix is a new diode bridge, or replace the alternator.

2 - Alternator is wired wrong. Presuming it's a Delco with an internal regulator, you need to add either a diode or a current-limiting lamp (warning lamp) in the circuit feeding the #1 aux terminal. Diode can be a 1N4001, 1N4004 or similar - less than $1 at Radio Shack.

Punch the link for a diagram.
alternator wiring diagram

old · Mar 9, 2013

Radio shack part #276-1661 is what I use. It is way over kill but that way if is likely to last longer. A pack of them is around $3 for 4 of them

Janicholson · Mar 9, 2013

The small diode is placed in the exciting circuit of a Delco 10SI (or Hitachi) alternator. If the alternator is one of these two. we can give you instant information. if it is totally different, we need to be certain what we give advice about.
Charging too much, and draining the battery is common with a mis-wired, or faulty alternator. My guess is possibly both. Jim

Bob seND · Mar 9, 2013

This is the diode that prevents backfeed from the alternator to the coil allowing you to shut off the tractor with the switch. Your battery drain may be a different problem.

http://www.ebay.com/itm/190606808980?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

alternator and Battery

HenryO)

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David G

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gregger

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John B.

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John B.

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HenryO)

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HenryO)

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Bob M

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old

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Janicholson

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Bob seND

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