Weak Battery
 

I just got my 8 back from the dealer - with a new battery installed.

This last weekend, as I was ready to go for a fun drive, I tried to start the car and it was completely dead - couldn't even use remote!

Tech told me that I need to crank it every few days - it is not my daily driver. He also said that Mazda knows that the batteries are going to die since they are not strong enough - the 8 needs full battery power to crank. He was explaining how easy it is to remove and install a new one - and this particular dealer has already replace quite a few.

The cold helped me discover this problem - oh well, guess I will have to drive it more!:D

Guh?

I don't know. It's been single digit farenheit here for the past few days, and my car cranked up fine with no hesitation at all. I also leave it sit for up to five days at a time with no noticeable drain to the battery. I guess that I'm just not letting it sit long enough or something, but so far I have had no problems with cranking amps.

Just had a thought. I always leave my car locked. Maybe leaving it unlocked would make the security system use more power than if it were locked? Just an idea.

When I bought my 8 I went with the salesman to go get the car from the storage lot and the battery was dead. We had to go back to get the jumper and it started up and recharged itself and has been ok since. My 8 is my daily driver. But yes, Mazda could have put in a stronger battery in these cars.

It was 3:00 in the morning when I read it but I seem to recall that the manual cautions against jumping the car when the battery is down? It's a vague memory and could well be wrong. Anybody sure?

I also have had my car out for periods of time in the cold and not driven it for as many as 3 days. Car has started fine even in the cold. As far as jumping the car goes I don't see how this could be a problem and I have jumped someone else's car with my RX-8 and had no problems getting them started.

There's this brand of battery that uses "Dry Cell" technology. I forget which brand, but if you call SP Engineering in City of Industry, they'll be able to tell you. The battery is extremely small (smaller than the stock battery on the 8), but it's more powerful and cranks out more amps any another other "Wet Cell" battery that's 2-3 times its size (common auto batteries that uses distill water or gel). Give it a try.

You're talking about Optima. These are also sold under a more common name - can't remember the brand - but they are made by Optima and branded with another name. It actually is still a "wet cell" battery, they are just sealed and the electrolyte is held in a matt. They are also spiral wound, not flat plate type. I don't think they make one that will fit in the RX-8 stock location yet. It's a strange size.

It doesn't take much to start a rotary engine. You can turn it over with one hand on the alternator pulley. My 3rd gen now uses a tiny battery intended for a civic, with no problems. Of course it sleeps all winter for other reasons.

http://www.batterytender.com/

If you store your car for long periods between drives you may want to get one of these. I used it on my z3 and it keeps the battery nicely charged without cooking it.

Great product. You can get it cheaper if you look around.

i left my car out for 13 days without touching it in the freeking cold we experience here in the north east and it started right up whe i tried it last sunday. (we had -30C for 3 days)

I had a nearly dead battery a couple of weeks ago. We did not close the trunk lid all the way and the light stayed on. I was surprised that the RX8 does not have the feature where the interior lights turn off after 20 minutes or so. Also, there is no trunk lid open light to warn of this problem. You might check to see if your lid is completely closed before blaming the battery.

The first thing I thought of was doors and trunk light but all was close and locked!

It was definitely the battery - had a bad/weak cell in it according to the mechanic notes

srm858,

The interior lights do shut off after a period of time but apparently not the truck. And I have to agree that I wish the trunk did have a warning light for when it is open. My wife was putting some stuff in the other day and didn't close it all the way. I didn't notice until I had already driven 10 miles down the freeway to my destination. How irritating.