Battery drain, read the FAQs

[DeadheadNM]

Working with the dual battery system in my 99 diesel Suburban ex-fire truck. I’ve had a battery drain that I chocked up to a parasitic draw but now not so sure.

I’ve charged the batteries in the truck to full with a trickle charger (connected w an in-series cable that’s OEM) while the batteries are isolated from the system w use of quick disconnects affixed to the negative terminals. A week after sitting the charge isn’t enough to crank the engine sufficiently despite the use of the disconnectors and no apparent power to the system.

Therefore I’m suspicious that one of the batteries isn’t holding a charge. I’ll remove these and have them tested (dated 11/20 generic Fleet Farm brand).

Any chance that despite the use of these disconnects and no apparent power to the truck a parasitic draw could still occur?

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