Battery for Locost

[tibimakai]

I'm about to buy my battery, and I'm not sure which one should I get.
A 12V 30Ah would be enough? How about a lithium battery?
2.5L Duratec, 100A Mazda alternator.

[RTz]

I use an AGM battery from Braille in my 1.8L. Weighs 18.5lbs. I have no doubt it would be fine for a 2.5L. Spec's here... https://braillebattery.com/batteries/b2 ... g-battery/

I'm happy with it, does it's job well. My understanding is AGM's don't like to be abused. I keep it on a battery maintainer anytime the car is garaged. Always.

I hear lithium batteries work well, but there is concern about fragility and fires. Do some research before jumping into one.

[KB58]

I used an Odyssey AGM16L (PC680), 15.4 lbs. It worked great and never failed, though I kept it on a tender when parked. It was marginal when everything was on for too long, like when in stopped traffic with the lights and fan on. It never left me stranded but I could tell that it was getting iffy. You can answer your own question by creating a power budget list. List everything that consumes power and the current each requires. Add that up and compare it to how much current the alternator generates at idle. The size (AH) of the battery will dictate how long it can power everything without help from the alternator.

(Some alternators are incapable of powering everything in a Locost when a modified (high rpm) engine is installed. The alternator pulley must be sized to not over-speed it, which often means that it's running too slow at idle to power everything.)

Or admit to yourself that you don't have a race car and put in a sensibly sized battery and be done with it...

[tibimakai]

It will be a street car only, so weight is not an issue. Rear is already heaver than the front.
Not looking for expensive batteries, something on the locost price budget.

[SkinnyG]

For cheap...

I used to run garden tractor batteries, but I only got 2 years out of them before they died.

I now run a Miata battery. It's small, but not cheap. You can, however, pick up a replacement at any auto parts store anywhere on earth.

I also keep a battery tender on it.

[davew]

I'm also using a garden tractor battery which is only 12 or 13 lbs and only about 40% of the cost of your typical auto battery. I'm having much better luck then skinnyG. My current battery is almost 5yrs old and is still going strong. I think I may even get another couple yrs of service. The battery is an Advance Auto Craft U1-3 425 CCA, P/N 2050013, which is for a LH negative terminal. I top off all the cells once a yr and put a battery tender, on for 3 or 4 months during the winter. My Seven does have a relatively small 44 amp rated alternator, which probably prevents some high-rate over charging, which could reduce the life of the battery.

[tibimakai]

Thank you guys.
There is a relation between alternator amps and battery amps?
My alternator is a 100 amp Mazda 6 battery, if I can make it work properly(I may have to go the old school route if I can't)
I will try a board, that I have posted about in another thread, to see, if it will work first.
I'm looking at Walmart batteries, like the 51R Everstart, in my wife's CRV is the same size battery.
https://www.walmart.com/ip/EverStart-Va ... om=/search