Charging issue

[Pete7]

I have a 3 wire 10SI alternator on a farmall 340. Tractor sat for the winter. Started it today and the battery was pretty weak but it started. Noticed that I was not seeing any charging on the amp gauge. Showing a slight discharge that increased if I turned the lights on. Put a multimeter on the battery and it shows about 12.3 volts at rest and about 14.3 when running at medium rpm. . So I’m thinking the alternator is working but why doesn’t the amp gauge show its charging? What am I missing here?

 

[Charlie M]

Sounds like a bad gauge to me unless something got in there and chewed some wires.

 

[Powered By IH]

Is this just a first-time thing or has this always been happening?

 

[DaveBN]

Are you looking at an amp meter or a volt meter? 14.3V sounds right to me.
Dave.

 

[Pete7]

Is this just a first-time thing or has this always been happening?

This just started to happen after it had been sitting for the winter. Basically, the amp gauge shows discharge and the multimeter shows charge (14.3 v) Can an amp gauge work to show discharge but not work to show charge? I have a second multimeter that I can use to check if the first multimeter if broken, but that seems unlikely.

 

[MARK ROBKE]

I don't know the wiring specifics on this, but I believe the amp gauge is inline in the accessory circuit, and you could check voltage on both sides of the gauge. I believe from your description, the gauge is completing the circuit, but the gauge needle is stuck. Bad gauge. Mark.

 

[Jim Becker]

I think the most likely explanation is that the wiring is incorrect and the current from the alternator is not going through ammeter. Another, less likely explanation is that the battery is going bat and refusing to accept much charge current.

 

[Pete7]

I think the most likely explanation is that the wiring is incorrect and the current from the alternator is not going through ammeter. Another, less likely explanation is that the battery is going bat and refusing to accept much charge current.

Hi Jim…. I think the wiring is right cause it’s been working ok for the last 16 years. I think I fried the amp meter. It’s a 20 amp meter on a 10si alternator that puts out 60 amps. Tractor sat all winter, battery was low and the alternator gave the meter more amps than it could handle? I ordered a new bigger amp meter so we’ll see.

 

[gbsmith]

that is most likely what happened BTDT, most of the time it will force the gauge to far toward charge and hang it up

 

[Pete7]

that is most likely what happened BTDT, most of the time it will force the gauge to far toward charge and hang it up

Replaced the amp gauge today and it’s now showing a nice charge. Guess I just learned that an amp gauge can break but still be able to show a discharge.