Battery Question

We recently parted with our 2005 Miata. The battery was about 5" x 8", stood about 7" tall, had 300+ cold crank amps. That's a pretty small footprint. The car had an 80 amp alt, same as my 2005 Scion Xb. They are neither very large alternators, either.

You can Google "automotive battery group numbers" and find out more about batteries than you really want to know. A .9 L engine only needs a 16 to 18 AH battery. That's a battery only about the size two fists together. Anything physically larger or more AH is overkill.

skygazer6033 said:

You can Google "automotive battery group numbers" and find out more about batteries than you really want to know. A .9 L engine only needs a 16 to 18 AH battery. That's a battery only about the size two fists together. Anything physically larger or more AH is overkill.

Click to expand...

I would prefer over kill! The battery in my polaris rzr had to be changed every three years, along with all my other small battery's in the cold/hot climate I live in. All my bigger battery's last longer.

Keith, if those are ordinary flooded-cell batteries that is a little short of a life, but not shockingly so. If they are AGM (VRLA) batteries, then I think something is wrong. I assume you keep either type charged during the off-season either via a smart-maintainer or periodic charging, and regularly check and fill the cells if they are flooded-cells.

I use "small" AGM batteries from Odyssey and more-recently Deka "Power Sports"* in my cars and they last for about a decade even in my daily driver. If the vehicle isn't in use, I put $20 smart maintainers made by Schumacher on them. (Deka power sports batteries are re-branded by Braille and others and sold as "racing" batteries for twice as much.)

I do not recommend Optimas as they are heavy, expensive, and do not tolerate deep discharges well.

* http://www.eastpennmanufacturing.com/applications/power-sports/

StuartGrant said:

The P4 at least uses a standard automotive battery located at the top left of the engine compartment.

Here it's seen next to a small power inverter used to keep the lights running all day at indoor events, which will not be in the production version.

Click to expand...

Remember that the P4 does NOT have the production engine. While it IS cool to see under the hood, the final setup will undoubtedly look completely different.

Keith Stone said:

I would prefer over kill! The battery in my polaris rzr had to be changed every three years, along with all my other small battery's in the cold/hot climate I live in. All my bigger battery's last longer.

Click to expand...

Over the years here in Florida I've bought new vehicle batteries every 2-3 years, usually end of summer but my lawn mower battery is 6 years old and still going!

trock59 said:

Over the years here in Florida I've bought new vehicle batteries every 2-3 years, usually end of summer but my lawn mower battery is 6 years old and still going!

Click to expand...

I think battery life has to do with short trips. My daily driver (2002 Ranger) is still on the original battery. I rarely drive less than 20 miles each time I start it.

BrianRosenthal said:

I think battery life has to do with short trips. My daily driver (2002 Ranger) is still on the original battery. I rarely drive less than 20 miles each time I start it.

Click to expand...

And the average temperature. For me. batteries did not last as long here in AZ as they do in Washington State at the lower altitudes. And they always quit at the change of weather, going into or out of Summer or Winter, but Summer mostly.
There are some standards for battery size that the manufacturers recommend via cold-cranking power. You would need to know what your cold-crank requirement would be. What the Geo Metro used is likely very close.

BrianRosenthal said:

I think battery life has to do with short trips. My daily driver (2002 Ranger) is still on the original battery. I rarely drive less than 20 miles each time I start it.

Click to expand...

That is impressive! I wonder if engine heat has much to do with battery life, I have seen some vehicles with insulation for there batteries. I have never been past the five year mark myself, I have also tried many different brands, glad my newest ones from autozone are guaranteed for five years which is double what napa offers...I only got 37 months on my last napa premium 84 month batteries...(I say batteries because I drive a diesel pickup)

It will nice to get beyond the 1 year mark which is what I get in my Grand Prix regardless of the battery I purchase from autozone.