Car batteries are built for delivering short high Amp bursts (ie starting your motor) and beeing recharged constantly. Applying a constant load (recharging your RC batteries) for a rather long period of time and maybe depleting your battery over half its capacity will degrade its capacity and cycle life in a short amount of time. Running your engine while recharging is the better option (when you don't want to degrade your cars battery).

As _paralyzed_ has already mentioned
-> A marine or RV battery is your best bet

should i replace my car battery with a marine or RV battery? and then charge my lipos off of that while it is idling , is that better? my car has no overheat issues, it warms up and than it stays at perfect operating temp. but this carbon build up thing, should i be concerned?

thank you for your advice and suggestions

Ok, D8, I'll say it again. Dont run your car while charging. It's just NOT needed. The draw from your charger is low enough that it will not drain your battery to a point that you will cause any damage to it. If you feel you must do something, buy a set of jumper cables just in case you do draw it down enough so that it doesn't start. If your drive home is 1/2 hour or so, your car will charge the battery enough so it will start again in the morning. IF then you have more issues with your battery, buy a new battery for it. I've charged lipos for three days straight without starting my truck, and it fired up fine.

i can give it a try, i need to bring so jumper cables and a volt tester to be safe. this battery has some years (about 5-6) on it,

Might be time for a new battery either way then!

what brand of deep cycle battery should i go with?, seventy to ninety bucks is what some people toll me they are priced at.

These are the best, but cost a lot:
http://www.1st-optima-batteries.com/index.html

Ditto:mdr: it seems to me its time for a new battery if it is over 5yrs old, especially if u have cold winters

The optimas are the best but interstate has the greatest, if u really feel u need a large amp hour battery just buy the biggest one u can fit in your battery tray. I use my battery in my jeep just a stock interstate 850cca and never have drawn it down unless i leave my head lights on over night and a charger doesnt use near as much juice as them and i charge 6s at 5amps

i think i understand what all of you guys that are helping me out are saying, that if i get a great quality marine or RV battery and replace it with my car battery, and then when i go to the track to charge my lipos, i should have the car turned off. what voltage is the bear minimal to start the car successfully, i am going to charge up my slash packs a few times and several 4s lipos for my xb808e, i guess these (deep cycle)batteries can handle it no problem.

thank you for your input.

u can buy a load tester from harbor harbor freight they are a great way of seeing how low your battery is under load.
http://www.harborfreight.com/cpi/cta...emnumber=90636

we usually go the the local tip...think it's called the dump in America.
and gave the man $2 to pick up a "dead" marine battery that was showing 12.6v
took it home, fresh electrolyte and charged it and now that battery serves as our field battery as well as starting the old tractor every now and again.

marine batteries get thrown after a year as the warranty usually only lasts a year here in Australia.

i am so concious of my milage and battery life on my van i actually push start it every morning. it only takes one compression to bump off the diesel even w/o the glow warmers, so this keeps my milage good and saves the battery from a hard cold start.

That voltage really depends on too many variables for us to answer. Based on the usage you just stated, you wont even know that you've been charging on it.

:lol: Wow - that's really going to take a toll on your tire life....not to mention your shoe replacement plan...

in other words you really dont need anything special, if u have a good battery in your car u should have no problems charging at the track without having to start your engine or worrying if your car will start afterwords. chargers do not drain as much power as u may think

I'm not real sure if it's all batterys chargers or a select few but if the power source gets below 10-1/2 volts the charger will shut down. It did with my Multiplex charger ???

If the battery cant keep up with the amps drawn the charger will show error or stop. but the battery has to be pretty dead to do that