Tripac APU (legacy model) not charging batteries

Hello,

For the last several trips I have been home when I arm the APU (turn it on with nothing on like the heat or ac) so it will charge the batteries it seems to just be letting the batteries die. Its an old legacy model APU according to the guys at TK. I read on some answer forum where someone had this issue, the tech answering his question said the 200amp fuse sometimes doesn't let all the voltage through. Does that sound accurate?

I replaced the 200amp fuse in the black box that tech referred to as a "conditioner", and set the ac at 50 degrees and its ran since then with the ac on. It will run as long as I let it with it set on ac, but wouldn't charge the batteries before. I am kind of skeptic now of just going and turning it to just arming it to see if it lets the batteries die again.

Any truth to the 200amp not being "good enough"? It had continuity still, the old 200amp fuse I took off. The copper ends were a little dirty but other than that appeared and tested ok.

 

It gets control power on AC, when the fan is in without the AC going, and sometimes starts if or when the bunk heater is going. The heaters been messed up for a year now. Sometimes comes on, most of the time doesn't. I had the apu turned on, but not started, with my sleeper lights on and when it did fire up the apu to charge the batteries I heard this kind of long beep for about 5 seconds before the apu started.

The only way it will stay on constantly with the apu running is if I set the AC temp to 50 degrees. It will then run until I either turn it off or it runs the truck out of fuel.

All I know is when the beep happens before the apu starts, that's my tell tale to start the trucks engine and let it run a bit to charge the batteries.

The wiring is old, the ends, both the one that connect to the battery post and the end that connects to the 200 amp fuse in the battery box for the apu are bent a bit. There's some little nicks and stuff in the wire casing. Maybe I just need to replace that wire. And maybe adjust a ground somewhere. It did spark once when I had to wiggle the 200amp fuse wire to get the apu to start. The spark came from the negative post though. Before that it intermittently would when the apu would go to start just tick like the battery was dead.

 

I took the truck to TK in Dallas, they wouldn't work on any of it. They said they "tightened connections" on the batteries of the truck. It did the same thing when I got it home Friday. It kicked on a couple of times presumably when it needed to charge the batteries. Went out yesterday to check, and the batteries (Sunday) were again low. Alarms going off in the truck, but still had enough power to start the truck. So I started the truck, then turned on the APU in a/c mode, with it set to 50 degrees. Went out last night and the APU was off with just the fan blowing for the a/c. I have heard the APU run though several times since I have had it set on a/c. TK insists that the wiring is "old" but offered nothing whatsoever to remedy it at all other than suggesting buying a new APU, or a new bunk heater. The bunk heater is what I took it in for to begin with. The service manager insisted I had the old D4 Espar heater, which it isn't. It is a D2, says so right on the dang label on the cover of it. But attempted to try to sell me a "new" D2 heater to the tune of nearly $1,900.00. The service manager claimed by the time they pulled out the heater to replace the atomizer screen, and put in what he kept referring to as a rebuild kit, I would be a couple hundred shy of buying a new heater anyway. And then claimed they didn't have any parts for the D4 heater, which again I don't even have. Almost like they just didn't want to do anything with it cause it is old, and has some dirt on the wires.

 

I am telling you man, they just don't want to get dirty. For mechanics, the guys at that TK shop look like the cleanest mechanics I have ever seen in my life. I think they really just didn't want to do anything. They ended up not charging me anything at all for what they say was tightening battery cables on the batteries. They weren't loose. They moved some cables around.

 

I started to think alternator, but when I have it on ac mode and it runs like it is now, the batteries stay charged. It seems to be if I have the apu set to on, with no heat or ac on it will kick on when it needs to until the batteries lose charge. The code is keeps showing on the HMI is BAT. I guess I will just have to follow the ground wire or the sense wire and see if its rubbing something and shorting out. I am not sure what the deal is with it, but know I cannot count on TK in Dallas to find or fix it either.

 

I am really beginning to think I just have a bad battery. Or maybe all 3 are bad. I bought the cheapo $75 each reman batteries from a freightliner dealer a year ago. They will go dead on their own inside of eight hours, if I don't have the apu running constantly. I think the apu will kick on, until the battery just gets so depleted the apu can't keep up with it, essentially just running the batteries dead faster. Dead battery cell maybe, or possibly a dead cell in all 3 batteries?