Batteries - Diesel Trucks

philh wrote:

Camreal wrote:
My 2005 discharges the batteries 24 hours a day. I have read that this is normal draw from the electrical systems. If I let the truck sit idle for a couple months I know to put a charger to keep them up. Batteries dont like being discharged.

Thanks to all the computers :)

well, I disagree. at least 15 years ago mfg solved the long term accy discharge problem with a several stage shutdown of onboard elecronics.

if they are discharging in less than a few months something is likely amis.

Every vehicle I've had with computers and electronics in it has 3 stages of current draw after shutdown

1) immedidately after turning off ignition with everything off may be in the 1A range
2) exiting and closing doors etc. next stage of shutdown draw goes to the 100-300 ma range
3) after a set time often around 20 minutes full shutdown where current draw is close to battery self discharge rate. takes months to discharge even to 50% SOC

in the full shutdown, things like alarm etc. still are operational but don't wake up until something triggers them.

Now if something is preventing (3) from occuring or there is a fault, and you stay is (2) battery will be discharged way to soon if left unattended.