APU Tri-pac not charging batteries

Thanks I found what happened. The belt came off. I looked in there this morning.

 

That was easy........ now the question is why did the belt come off?

 

Right

 

Make sure the counter clockwise fan is installed to prevent
overheating

 

Belts on these tri pacs do come loose

 

Those wide bare metal bonding cables, one goes from the alternator to the frame on a stack of a bunch of other wires on the same bolt, then another wide bare metal bonding cable goes from there up to another spot on the frame. Those are ground cables, no? In my guitars, if I get a double ground it cuts signal completely, I jiggle wires around till I find what's touching then separate the wires with tape. The bonding cable from up top that comes down was rubbing on a metal exhaust tube, but just barely. Would that mess with the alternator's ability to send juice, or cause the APU to randomly start to shut down but then fire right back up before it shuts down?

 

The cable you are talking about is a ground strap...it will not cause a problem if it touches ground or any part of the motor . Check the ends and make sure there clean and tight also check the battery connections at the altonator,and battery. If your unit has a 50 amp mega fuse on the battery cable coming out of the altonator check that for corrosion last check the belt and make sure its tight

 

what TK location wanted $560 for the upgrade install? Best I've found is at least $1k+ for the upgrade

 

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My alternator connections are pretty corroded, I'm complaining that it's starting to short out somewhere and not get juice to the batteries, but in all actuality, it's been bouncing around back there for going on 2 straight years with not so much as a tightening...I'd say that's pretty good lifespan for copper wires.

It's been lately where the short (wherever it is), will intermittently fix itself, after driving, or after banging all over the alternator with a flashlight.

If the connection is shorted, the Tripac will start to surge (voltage regulator confusion?), the inverter will show 12.2 v at the batteries, and after a few minutes the Tripac shuts down with an alt error.

If it happens to fix itself, the Tripac will run very smoothly, the inverter will show 13.4 at the batteries, and it will run until all its requirements are met (55 degree coolant return, AC thermostat temp held for 10 minutes, batteries above 12.6v, 20 minute minimum run time).

The strangest thing just happened though. I recently got my ignition switch on the truck replaced, and the freightliner tech didn't reconnect the Tripac standby wire to the ignition, so now I have the added flexibly of turning the key switch to "on" without the Tripac turning off, so you can view the truck dash information while the Tripac runs.

The truck low voltage circuit had just cut off, so I went to start the Tripac...inverter showing 12.6v at the batteries, Tripac surging, the usual death rattle. I went to turn the truck ignition to "on" to see what the truck showed at the batteries out of curiosity, and as soon as the Tripac felt the extra electrical load from the truck computers/AC fan/radio, it immediately smoothed out and quit surging, the Tripac alternator started pushing 13.6v at the inverter, and the truck showed a steady 13.2v at the batteries.

If I turn the key to accessory, the same thing happens...Tripac smooths out, inverter shows 13.2v at the batteries, running like new.

If I turn the ignition back to off, the Tripac starts surging again, and the inverter shows 13.2v at the batteries, but will quickly drop back down into 12.5v or 12.6v at the inverter, it might keep running, or it might shut off. Depends on what mood it's in.

I was under the impression the alternator was struggling. It seems like the alternator just needs something hard to push against, otherwise it doesn't know what to do, gets confused, shuts off. Or is it that with corroded connections, it has trouble pushing low amounts of power through the wires, but if it gets asked to push a lot, the higher voltage is enough to bridge the spaces in the corrosion and the electrons can flow freely? The alternator is apparently fine and willing to work, but it's having trouble getting its juice to the batteries unless it's going full throttle.

Could that be an alternator grounding problem, or also possibly a battery sense wire problem? Or does turning the key to "on" or "accessory" inadvertently create the needed (missing) ground connection to get the power to the batteries?