Deuce alternator dead

[dozer1]

Recently I had helped a fellow member recover a deuce at Fort McCoy. His 109 had no voltage output from the alternator. One thing I noticed about the truck is that it had a battery disconnect which broke the ground. The batteries were switched off when we got there. Once that was figured out, we jumped the truck and no juice yet. OK here's the question. Would it fry the alt if someone shut off the disconnect while the truck was running? My guess is yes and that is what caused the failure. Any thoughts on that theory and if so, maybe disconnects have a downside on a vehicle that runs without the need for an electrical system.

 

[cranetruck]

...... OK here's the question. Would it fry the alt if someone shut off the disconnect while the truck was running? My guess is yes and that is what caused the failure. Any thoughts on that theory and if so, maybe disconnects have a downside on a vehicle that runs without the need for an electrical system.

The answer is yes. Similar to having a poor battery terminal connection. Many references to the keywords "load dump"...

 

[tie6044]

I learned that the hard way a while back, I used to jump my deuces to move them around and one had no batteries in it, well it didn't take long for that alternator to fry. All that voltage built up with nowhere to go will burn out the alternator. If he is near you and needs a replacement shoot me a PM.

 

[saquishmike]

I had a problem once with the batt on / off switch in the cab being bad and the alt was good just not reading on guage . I still have the new alt in the box .

 

[houdel]

I had a problem once with the batt on / off switch in the cab being bad ....

Did M109s come with a battery disconnect standard or was that added on?

 

[Rustygears]

It's pretty hard to fry an alternator except by short circuit or excessive loading over a long time which wears out the commentator & brushes. The regulator is what fries due to transient load switching.