ABOUT MY 2020 KW990 BATTERIES

Batteries are 12v so when the truck or apu cuts off it dropping down to 12.6-12.8v quickly is normal. Batteries are definitely bad when it’s dropping to 11v quickly with no or light load. Even then voltage alone isn’t enough to know if it’s bad. You’re batteries around 2 years old if you’ve had to boost them before cause you got them too low one or more times maybe it’s time to change them. That and also maybe the apu ran them down I’ve heard you need certain type of batteries when you got an apu equipped on the truck or the truck will run them down quickly from all the charging and uncharging I’m not too knowledgeable on that end though.

 

I believe, you’re thinking of deep-cycle batteries, where they’re designed for huge swings in voltage, such as a total-loss system like used in trolling motors on boats. In that scenario, the battery starts out fully charged, then, is subjected to hours of use in a slow, discharging state, until it’s dead. That’s incredibly hard on a battery. Trucks with bunk heaters and/or drivers using battery power in the bunk create a similar scenario, as well.

The great thing with an APU is it monitors voltage and starts up when a minimum is reached, which keeps the truck’s battery voltage in a fairly narrow window. It’s exactly what you want.

 

Road service in the truck stop parking lot season is just around the corner. Battery life span and fuel gelling mysteries will soon be getting solved.

 

NOTHING is wrong with the batteries. The resting voltage is about 12. 6 volts DC and it sounds like they are doing their job.

HOWEVER the APU controller may be seeing the lower voltage because of a bad connection or it is going out or out of adjustment. It should be kicking on when the voltage hits 12.3 or about there.

 

His forward battery is awful warm to the touch the remaining 3 are cool..if that tells you anything.

Small world but I’m parked beside the op, lol.

 

When battery plates sulfate or break apart from vibration, they short out against one another, creating that heat. I’m taking a wild guess either situation is what’s happening.

 

#### small world. Ha Ha

 

Just talked to him and it was the warm battery that was junk.

 

Cool, glad you helped him out, just going on his first post, nothing else.