Engine jump start

I have thermoking APU but it not prevent from draining batteries

 

This is the time of year you want to clean you batteries and independently charge them, with a regulated charger, clean the conections and cables to the motor. They have fancy computerized testers that work very well. Do that a week after doing the charging, if you have 4 batteries and 1 is bad change them all, it does not work to have old and new batteries mixed. the new ones charge and get hot, the old ones do not charge. We had customers that got over 7 years out of a set of batteries and this is in Canada, I have the original batteries in my Duramax. The right side battery runs a little lower than the left on I use the right one to boost. I am going to charge the batteries in my pick up now.
Just a thought!

 

then you got apu problem or bad batteries.

 

The kind of jump starter you're thinking of does not have the capacity for your truck. If you're in a position where you will be starting a cold truck in cold weather, better to use a block heater or something like a Webasto Thermo 50 that uses your battery to run a pump to circulate coolant and some diesel from your truck to heat the coolant. It can be setup on a 7 day programmable timer and setup to preheat the truck an hour before you arrive to work. There's also some versions that heat a sleeper too. Think they use about 1-2 liters an hour and not much battery juice (maybe a draw of 1-2 amps). A warm block is much easier on your batteries than a cold one, plus when you start your truck it will warm up your cab right away.

 

One bad battery drains other.

To find bad battery disconnect all negative terminals for weekend and monday morning check voltage on every battery with DVOM. Replace bad battery.

Ok. about APU... good idea to have APU with small AGM battery (45-55 Ah). This battery must not be integrated to truck system (easy to do it with diodes and switches). Use APU battery to start APU and APU charges truck batteries

 

I know this one will works fine: check here