APU Tri-pac not charging batteries

The APU on my truck is not keeping my batteries charged, even when it is running all night. I do have a lot of electronics (2500 watt inverter, home stereo, 22"LCDtv, microwave, laptop, etc.).

But I have run the engine and charged the batteries up to where it reads "14.1 volts" on the dash, and then turn off the engine, and have the APU kick on almost immediately. Then I turn off all my electronics and go to sleep. After about 3 hours I'm awakened to the sound of the low-battery alarm and then the auxiliary circuits are cut off.

I took it to Thermo King and they tested it saying that the alternator on the APU is charging and they don't know what's wrong.

I am on the way back now to my home terminal to have our mechanics look at it. I'm thinking that if it's not the APU, maybe I have a dead battery. But the truck only has 84,000 miles on it. But that's all I can figure. Unless the APU has to run for a couple of hours before the alternator stops working. At Thermo King they only tested it after it had been running for a few minutes.

Two different drivers at my company have had to have the alternator on their APU replaced or rewired.

 

I will mention it to them. I haven't heard of that either.

When I was posting this, the low battery alarm came on and I had to turn the engine on.

 

All the terminals are clean and tight. I'm hoping it is a battery, though, they still look new.

After further reading, it turns out the alternators on these APU's are a big problem for people like me who run a lot of electronics. Thermo King doesn't make a high enough amperage alternator to handle it. The one they install is only 65 amps.

So hopefully it is a battery, but from what I'm reading, I'm going to have problems with the alternator sooner or later. I read in another forum where a driver rigged a higher amp alternator on his, but I don't know if I could convince my company to go for that.

 

It's in the shop now. Maintenance said they would check it all out and see if they could find the problem. I didn't even bring up the subject of a larger alternator. I'll see what they can do first.

The truck is an 09' Frgtlnr Columbia. Thermo King only makes a 65 amp alternator though there is rumored to be an 85amp. The Delco Remy is 160 amps! That's definitely what I would like to have. If I continue to have problems, that's what I'm going to push for. I'll send you a PM as to what company it is.