Thread: Can Batteries drain just sitting there?

In a word, yes they can and do. I check all of my non connected lead acid batteries each 3 - 4 months and they all always need a top up. Can't speak for the newer types

Yes all batteries do, both primary and rechargeable. It's the self discharge rate and is generally listed in the full battery specs (although it can be difficult to get these)

For decent lead acid batteries of 100 AH it's typically 30maH. For your situation a 2W 12V solar charger per battery should provide sufficient current to keep already charged up to full charge with the surplus being low enough to avoid overcharging.

yep, its a primary killer of all types of batteries as I had it explained to me the self discharge if left unrectified is what causes the plates to sulphate up.

Thanks guys for your prompt replies.
I'll recharge it again and keep an ey on it. it is a lead acid so I can pop the tops off and see if there is any visiable collapsing of the plates.
Other wise its $500 for 2 new ones last time I checked
Volts: 12
CCA @ -18?c: 730
MCA @ 0?c: 875
RC @ 25?c: 180
AH: 100
Weight (kg): 24.10

Originally Posted by Blknight.aus

yep, its a primary killer of all types of batteries as I had it explained to me the self discharge if left unrectified is what causes the plates to sulphate up.

Eggsakly right,I connect a solar panel on my camper batteries to stop this from happening. Pat

Yep, need regular charging to remain healthy.

Originally Posted by Roverlord off road spares

In my boat I have 2 separate deep cycle batteries.
They are wired up to an isolator switch ( The dial type) off, Battery 1, both batteries and battery 2.
I mainly use battery 1 for starting, running and anchor winch. Battery 2 is just a reserve in case I need power if battery 1 goes low.
But I find that battery 2, the switch off one goes flat after a few weeks end gets crusty at it terminals. It'll charge up overnight again. And will have enough power to tilt the motor and start it. Being quite a few years old I think it's probably past it's use by date?

Regards, Mario

Deep cycle batteries are not designed to handle Starting duties, they are designed to Store power, you may have damaged a cell, have the electrolyte level checked in each cell, Regards Frank.

Thats true Frank but then most marine batteries are deep cycle.