electricity flow through blue sea acr?

first, can we get an electrical sub-forum?

the truck is getting driven much these days. voltage on my secondary odyssey has dropped below readable for the blue sea volt meter in the cab. i think it's been that way for a few days.

headed out this morning for an errand. truck started fine. drove for 15 min. parked, ran into store to pick something up, came back out. truck did not start. not even a click. deader than dead.

grabbed my jump pack. hooked it up. first try got a click but no start. second try truck started then died like it usually does when you disconnect the battery. third try, it started.

got home, shut the truck off. for giggles, i tried to start it. nada. nothing. zilch. not even a click.

my understanding is that when the truck is on, the electrical flow through the blue sea ACR is one direction, main to secondary. if the truck is off, there should be no flow. if the switch is set to disconnected, there should be no flow. if the switch is set to jump, flow goes from secondary to main. what i'm not sure of is if the secondary pulls power even when the truck is off. does it do that?

my assumption is that the secondary, because it's dead, is pulling so much power from the main right now, that it's draining the main to the point where it can't start the truck. is that valid?

i'm also guessing that making short 5-10 min drives after the truck sits for days isn't enough to get a proper charge to the secondary.

does anyone else have this issue with their dual battery setups? i feel like i'm missing something basic.

right now, i've pulled the batteries and they are sitting on the charger. tomorrow i will be running all the connections for the solar hook-up. i'm using renogy's DC-DC MPPT controller that will send a solar charge to both the secondary battery under the hood and the house battery in the bed when the truck is not running. when it is running, the truck will be able to send a charge to the house battery.