Thread: Low battery - 6.5 - 8.5V

Originally Posted by Disco-tastic

My next step is to totally disconnect the battery overnight and measure the voltage drop.
If the battery comes up good from that, does anyone have any ideas what could be drawing the current?

If the alternator is disconnected I still think the battery is your issue Dan.
The normal small drain from ECU checks every few hours overnight could be causing the voltage drop you're reading if the battery is cactus.
Remember the battery measured at very low voltage in your initial post.
The battery taken out of vehicle without any load on it may not show symptoms.
Perhaps a proper battery test is the go.

Cheers,
Scott

Doesn't leaving it unlocked mean the electronics are still active and doing periodic checks, draining power?

Originally Posted by DiscoMick

Doesn't leaving it unlocked mean the electronics are still active and doing periodic checks, draining power?

Locked or unlocked makes no difference to the periodic checks, which draw very little power anyway.
Older models take longer to go to sleep initially after stopping when left unlocked (approx 30min versus 3min).

Scott

Hi Dan, charge everything back up and then disconnect your cranking battery’s NEGATIVE ( - ) terminal and then see if the battery’s voltage drops over night again.

Originally Posted by drivesafe

Hi Dan, charge everything back up and then disconnect your cranking battery’s NEGATIVE ( - ) terminal and then see if the battery’s voltage drops over night again.

Thanks Tim. Should i disconnect the second battery before?

Can you please explain the logic so i have a better understanding of whats going on? I'm assuming you're checking foe an earth leak or something, but I dont really know.

Cheers. Dan

If you fully charge the cranking battery then disconnect the earth lead overnight you will be able to tell if the battery is RS If the voltage has dropped overnight

well, I unplugged the negative terminal of the main battery (and disconnected the secondary battery). I first unplugged the battery completely and it measured 12.5V. An hour later I reattached the positive terminal at it measured 12.53V. This morning it measured 12.5V again (about 12 hrs total)

Previous measurements were 0.3V and 0.7V loss over 17hrs, so i take this to mean the battery is not the cause of the problem (even if it may be damaged).

My next step will be to disconnect the SC80 overnight and measure voltage drop.

If anyone with more knowledge than me has any further opinions please let me know!

Cheers
Dan