12V Car Batteries, what cell construction are they?

[Marvin]

Are 12V car batteries Lead Acid? I'm after a battery for charging 'in the field' and would prefer to use my normal charger for charging it up. Are only certain car batteries lead acid?

[jhammond]

http://en.wikipedia.org/wiki/Lead-acid_battery

I've always known all car batteries to be lead-acid, but apparently some of the new hybrid cars just use NI-MH and Lithium-ion.

[Marvin]

Thanks, I didn't see that article when I searched for 'car batteries' on Wikipedia.

[MatJohnson]

Remembering a car battery isn't designed to be deep dischared (as in its only there to give the car an initial kick, not drop to a lower voltage). A leisure battery would be a better option.

[Marvin]

It looks like I'll be going for a leisure battery then, they are still Lead-Acid presumeably?

[jhammond]

Yes, leisure batteries are still lead-acid. Even the "gel batteries" (Or VRLA) are still lead-acid. The differences are mainly capacity and maintenance requirements.

As "Toadeh" mentioned; Car batteries are not designed for deep-cycling however leisure batteries are.

Julius.

[Alfonzo]

But if you are only running one charger off it, and doing 4 - 8 heats during the race meet you'll find a car battery fine, and lots cheaper than a leisure battery. At least, that's my experience to date.

[PaulRotheram]

Originally Posted by Alfonzo

But if you are only running one charger off it, and doing 4 - 8 heats during the race meet you'll find a car battery fine, and lots cheaper than a leisure battery. At least, that's my experience to date.

but more expensive in the long run as the car battery will quickly loose its charge hold. leisure batterys will last a lot longer as already said they are designed for deep discharging.

[Alfonzo]

I know you're right. But my (second hand) Ford Fiesta 12v has done 3 seasons now, no problems. Just making the point if anyone is getting a downer on the cost of leisure batteries, etc etc.

[Marvin]

I'm fine with the extra expenditure. I only need to charge one battery, once at a race day. Having said that though, it will be a 5500mAh 18.5V Lipo at ~3-4C . What capacity would people suggest? I was thinking about 85Ah with 50% depth of discharge.

[peetbee]

85mah should be fine, easily does a days racing, a 110mah will even doa weekend of charging at a national (assuming you need to do a bit of soldering too!)

[Marvin]

Thanks!