Autocross racecar battery dilemma/?/conformation

[URY914]

I have an autocross racecar battery dilemma/question that I need some feedback on.

My 914-4 is a dedicated bare-bones autocross car. When I say it is bare bones I mean if doesn’t make it GO or STOP it is not on the car. This includes the alternator which I removed years ago. Problem is I don’t use the car as much as I used to, so I’ve been going through batteries because they don’t get cycled enough and they die an early death. Over the years I’ve used different types of batteries including everything from little ATV batteries to used car batteries bought at junk yards. Recently battery “management” has become my biggest PITA. Also my old “dumb” charger isn’t able to keep them charged properly and with the car being use less, they die early even when kept charged.

Now I’m thinking I need to take a new course of action. I want to buy a new marine battery of the dual purpose starting/deep cycle type and get a new high-tech trickle charger to maintain it. I need something that has the CCA to turn the engine over, plus the long discharge capacity of a deep cycle battery in order to be able to make several runs and keep it running while waiting in line between runs. I’m thinking the dual purpose battery is the way to go.

So I asking for your thoughts, comments and concerns? I'm really looking for some validation that is the right thing to do.

I found this to have a good explanation of battery types:
Selecting a Marine Storage Battery | West Marine

[Flieger]

Why not put the alternator back on and use a lithium iron phosphate battery?

[John Rogers]

Well it seems to me that the battery/starter/charging system are meant to make the car "go" which is 50% of your goals. I would suggest getting one such as one of these: Lightweight High Performance, One-Wire Alternators & Accessories and under drive it as much as possible such as off an axle so it is only working at speed. For starting I'd get a "starter cart" like I used to see a lot of vintage race cars have with a pair of huge batteries and one of those nice plugs to run power in the pits. If used with a small battery that can get you started in case of a spin and engine stall it will solve your issues.

Several years ago Ron Mistak in the famous number 22 Wayne Baker 914 IMSA was at a vintage race, got the car started okay but stalled it when pulling out of the pits and the battery was too small and pretty much dead and he could not get it running until several laps into the race. Remember to win you first have to get started and that requires some power.

[asphaltgambler]

Originally Posted by john rogers

........................... was at a vintage race, got the car started okay but stalled it when pulling out of the pits and the battery was too small and pretty much dead and he could not get it running until several laps into the race. Remember to win you first have to get started and that requires some power.

THIS - I can comment because I have raced cars and motorcycles. Unless you are campaigning a top fuel bike or car, it should be self starting with some sort of charging system. You might be surprised at how many top sportsman and pro category cars (drag) run starters and charging systems.

Look into light weight aftermarket gear reduction starters, small - current generation alternators producing 60-70 amps will be enough and then Lithium-Ion batteries.

[J P Stein]

I bought one of them hi-tech chargers this week.
I bought it at NAPA .....Charge IT is the make/model?......go figure.
It was the only one at NAPA that specifically mentioned AGM capability......and it was the cheapest @ about 60 bucks......Those AGM batteries will change everything you thought you knew about charging.

It works fine for the AGM battery and claims to do the job on any type automotive battery. Sure, the name is funky, it looks funky, & weighs about 1/3 of my old charger......but it works.....it's got all them hi-tech flashing lights, LEDs, and buttons to push.

The deep cycle battery ain't a bad idea and you could probably shut the car down in the lanes, then restart without a problem.....you'd have to find the limit. I always shut down but I had an alternator keeping the PC680 up to snuff....

Adding 30 odd lbs to the overall weight goes against the grain for both of us. An alternator and fixens' weighs less than that, me thinks. A lot more work tho.
Just make sure the beast is tied down well....if you can find something solid on your car.....that battery would tear your car apart if it decided to leave the building.

[URY914]

Thanks for the replies so far but I'm asking about selecting a battery.

Originally Posted by Flieger

Why not put the alternator back on and use a lithium iron phosphate battery?

I don't want an alternator. I want a battery.

Originally Posted by john rogers

Well it seems to me that the battery/starter/charging system are meant to make the car "go" which is 50% of your goals. I would suggest getting one such as one of these: Lightweight High Performance, One-Wire Alternators & Accessories and under drive it as much as possible such as off an axle so it is only working at speed. For starting I'd get a "starter cart" like I used to see a lot of vintage race cars have with a pair of huge batteries and one of those nice plugs to run power in the pits. If used with a small battery that can get you started in case of a spin and engine stall it will solve your issues.

Several years ago Ron Mistak in the famous number 22 Wayne Baker 914 IMSA was at a vintage race, got the car started okay but stalled it when pulling out of the pits and the battery was too small and pretty much dead and he could not get it running until several laps into the race. Remember to win you first have to get started and that requires some power.

This is an a/x car. I spend more time idling in line than driving it. So an alternator driven off an axle that not turning most of the time won't help much. As far as a starter battery, I'm trying to make this simple; one battery and charger only.

Originally Posted by asphaltgambler

THIS - I can comment because I have raced cars and motorcycles. Unless you are campaigning a top fuel bike or car, it should be self starting with some sort of charging system. You might be surprised at how many top sportsman and pro category cars (drag) run starters and charging systems.

Look into light weight aftermarket gear reduction starters, small - current generation alternators producing 60-70 amps will be enough and then Lithium-Ion batteries.

This is not about the starter. I HAVE a gear reduction starter and it is self starting.

Originally Posted by J P Stein

I bought one of them hi-tech chargers this week.
I bought it at NAPA .....Charge IT is the make/model?......go figure.
It was the only one at NAPA that specifically mentioned AGM capability......and it was the cheapest @ about 60 bucks......Those AGM batteries will change everything you thought you knew about charging.

It works fine for the AGM battery and claims to do the job on any type automotive battery. Sure, the name is funky, it looks funky, & weighs about 1/3 of my old charger......but it works.....it's got all them hi-tech flashing lights, LEDs, and buttons to push.

The deep cycle battery ain't a bad idea and you could probably shut the car down in the lanes, then restart without a problem.....you'd have to find the limit. I always shut down but I had an alternator keeping the PC680 up to snuff....

Adding 30 odd lbs to the overall weight goes against the grain for both of us. An alternator and fixens' weighs less than that, me thinks. A lot more work tho.
Just make sure the beast is tied down well....if you can find something solid on your car.....that battery would tear your car apart if it decided to leave the building.

Thanks J.P. for staying on topic. Adding a few pounds to have a reliable battery to start the beast is not a problem. I've bolted all my batteries down and passed tech with no problems.

[J P Stein]

Idling in the lanes was not my cup of tea. My car would idle OK but for an extended period (like 5-10 min), it would load up & the plugs would foul (beyond the gas it up to clear the crud point.). Fouled plugs happened often enough. I got real good at isolating the dead hole when this happened but it was a PITA.
Heat never was a problem, but it wasn't a T-4 motor.

[campbellcj]

FWIW I use the little PC680 in my car, although I do have an alternator, and in between usage I simply turn-off the cutoff switch and it holds a charge just fine for weeks/months. I wonder if you could use one of these, charge it prior to storage and then disconnect it. If needed, charge again prior to use.