Backhoe alternator not charging

[LeeB]

The alternator on my backhoe isn't charging the battery. I can jump the field and it will then charge. Obvious answer is no voltage to the field wire. Without a wiring diagram it's hard to tell where the voltage comes from. Any reason not to put a permanent hot jumper to the field wire?

[Bandmill Bandit]

The alternator on my backhoe isn't charging the battery. I can jump the field and it will then charge. Obvious answer is no voltage to the field wire. Without a wiring diagram it's hard to tell where the voltage comes from. Any reason not to put a permanent hot jumper to the field wire?

The power should come from the switched side of the key so it energizes the field when the switch is in the on position.
 
What kind, type and model alternator? When you put power to field and the alternator works then you got an issue between switch and field terminal. Just run a new wire.
 
Other wise internal parts including regulator, rectifier/bridge etc are not a dificult change job. But I doubt it one of them but but cant know for sure till I know what the alternator is.
 
Alternators are mostly easy to fix. Parts not as easy to get any more but you can find most of them online for a good price.

If its an older Case or JD hoe probably a 55 or 80 amp delco C10 or similar but I am kinda guessing.
   

[Southside]

You can change the alternator so it excites off or RPM and does not need the second feed.  

[Unclefish]

If you can't fix that one we went with a Bosch brushless alternator if it has the the J180 mount. expecicial when stuff sits for a while .  Easy hook up 1 positive wire and 1 ground wire to case. A little expensive but it will be the last time you need to mess with it. AL9960LH if I can remember correctly. They might make other 1 to now.

[LeeB]

It's a new one on there now. I changed before I checked if the old one would charge if flashed. The volt meter also does not work so obviously it's also in the same wiring sequence.  Google searches tells me there is a alternator light in the system that if burnt will cause this issue. I checked all the bulbs and they look ok but I don't know which one is the alternator light. Guess I can try switching them around and see if I can get it to work.

[scsmith42]

Lee, what brand of backhoe?

I recently ran into a similar problem on my John Deere 270 skid steer.  Turns out that a short in the headlights was causing the voltage to drop going to the alternator, and whenever the lights were turned on the alternator would not excite.  

That was not a quick troubleshoot, to say the least...

[Bandmill Bandit]

Knowing what hoe brand, year, and model will help us help you and yes a light bulb is part of some older systems and can cause the issue.  

[LeeB]

It's a case 580L II series. I believe it's a 98 if I remember correctly. Did some more troubleshooting today and actually foiund my owners manual. At least I now know where the alternator light is. As far as that goes, none of the warning lights are working and now that i think of it, I don't recall that they ever did. It does have a horn that sounds when you turn on the key that goes silent once the engine starts. I'm considering running a wire to the horn from the alternator. I suppose it could be that the connectors at the instrument panel are corroded and I did try to get the connector lose but was afraid of braking it. It's all somewhat brittle with age. 

[Al_Smith]

You get to tinkering with older outdoor equipment you can run into corrosion problems on the wiring connections  .It does not take much to cause problems on low voltage stuff ,drives a person nuts trying to figure it out.
Older stuff using either a generator or an alternator often use external regulators .If I have problems with them,which I have I just hang a GM one wire alternator on the them and never have another problem .

[Ben Cut-wright]

It's a case 580L II series. I believe it's a 98 if I remember correctly. Did some more troubleshooting today and actually foiund my owners manual. At least I now know where the alternator light is. As far as that goes, none of the warning lights are working and now that i think of it, I don't recall that they ever did. It does have a horn that sounds when you turn on the key that goes silent once the engine starts. I'm considering running a wire to the horn from the alternator. I suppose it could be that the connectors at the instrument panel are corroded and I did try to get the connector lose but was afraid of braking it. It's all somewhat brittle with age.

Is that the Bosch 12V universal alternator or something else? 

Volt meter gauges are do not contribute to alternator function. 

Where are you thinking to attach this wire  you consider "run the wire from the horn to the alternator"?  I would not do that.

Whatever you are doing to make the alternator begin charging is risky at best, not something that should be continued. 

[mike_belben]

Check the charge light bulb!  It is an indicator but it is also in series with the field wire voltage.  No bulby no chargy.

When the key is clicked on, power flows to bulb. Other leg goes to a dead alternator so its grounded.  bulb will be full lit because of the 12vdc difference across its legs.  

When you run the engine the alternator comes on and ramps up output volts.  the bulb now has volts on both legs so it goes out.  A dim bulb while running means a low voltage issue at the alternator. A bulb that works and stays full lit means no charge.

An alternator thats working will have a magnetic field around the center of the case and a higher voltage than the battery resting volts.