Very odd sleep issues with Mavericks; battery indicator culprit?

I refurbish MacBooks and MacBook Pros as a hobby and a side source of income. I have run across some very odd issues since installing Mavericks on my machines by default. Specifically, the issues are all related to MacBook Pro models equipped with Mavericks.

I had 3 MacBook Pros that I completed restoring, and the last step was to load Mavericks on each. I did so, and immediately after doing so, each MacBook developed similar but slightly different issues relating to their sleep functions, as well as odd behavior when starting up. Something I noticed they all had in common, however, was that the issues all resolved themselves when I unplugged the battery indicator cable from the logic board in each. I'm not sure why the battery indicator cable has anything to do with the sleep functions of the computer, but it worked in every single case.

One MBP had an issue where the display backlight would actually cut itself off midway through booting. I could see the objects on the screen with a flashlight, etc. It also would not wake up from sleep once booted in Mavericks. Just very odd behavior. After unplugging the battery indicator cable, all was well with not a single issue.

The second MBP had an issue where it would take a long time to boot, and once it got to the desktop, it would go right into sleep mode. Nothing would wake it up, and when I opened the lid, the display would remain black but the sleep light would go off. I grabbed the flashlight again, and sure enough the display was working, just no backlight. I was able to restore the backlight about 1/5 times by pressing the brightness-up key, but this was not reliable, and the backlight would cut itself off again shortly after. Unplugged the battery indicator cable, and all was well with no issues.

The third MBP PRAM would take forever to reset, and once I got into Mavericks, the same issue as number 2. Unplugged the battery indicator, and it was fine.

Just to be sure, I replaced each MBP's battery indicator cable/unit, hdd cable/assembly and even the display on one MBP. Same issues.

What in the world is Mavericks doing to these machines? And why does it seem to be related to the battery indicator module? I need to sell these MacBook Pros, but I don't want to have to say that the battery indicator does not work on each (because I'd have to leave it unplugged in order for the computer to work fine).

Any input would be appreciated. I'm out of ideas, and there are tons of sleep-issue related posts online about Mavericks, but none seem to be related to the battery indicator like I'm experiences. Just curious!

Thanks.