Originally Posted by DrGonzo (Post 3457360)

Labrat - I don't know how well relocating the battery to the boot will work in an RX8 if you want to keep it in a cooler place - I have noticed that the boot area can get quite warm after some driving. I'm sure it won't be as warm as the engine bay, but it's still not ideal IMO.

Originally Posted by Revolver (Post 3455526)

Just registering another stat for the knowledge bank on our car's dodgy ignition engineering.

Car has been running fine. As late as last night started fine and I drove home without a problem. Locked up and no lights on overnight.

This morning, go out, unlock it, key in ignition, dull thud from engine bay then nothing. No starter motor response, no cranking, no warning light except red key. Then interior lights in roof started going on and off and locks sounded like they were clicking in the doors. Bloody thing sounded possessed.

Still nothing. No response from engine at all. After I gave up it wouldn't even lock remotely. Had to use key in door to turn the locks.

Diagnosis - the battery, she is kaput. Don't you love how there's no warning. You'd think for a car with a notorious habit of eating batteries long before other cars they would (retro)fit a low charge sensor or make it a replacement item every 20k or so.

Open to other suggestions as to cause of failure btw. Having a new battery fitted this arvo, so fingers crossed that fixes it. :wallbash:

Originally Posted by labrat (Post 3456903)

Dave, your symptoms pretty much mirror what happened to me last year. Fortunately, it happened at work, and I was able to call on an electronics engineer who is also a certified car nut. It was a collapsed cell. Could the mod. to improve cranking power result in higher current demand on the battery?

I think that the high engine compartment temperature in the RX-8 is at least partly responsible for the problem. My BMW125i has the battery located under the boot floor, to the rear of the axle. As well as improving weight distribution, it provides a cool environment. I just checked mine. It is cool, clean and dry. I don't how how feasible it would be as a mod. to move the battery into the boot of the RX-8, but it would most likely prolong battery life.

Originally Posted by Cromax (Post 3457355)

My original battery died a couple of years ago suddenly, however it was not a collapsed cell that caused it but a whole week of hot & humid days pushed it over the edge.

I don't believe it is just your car though Dave. Without running the numbers, I can say that battery sales from where I work are stronger on hot & humid days than any other type of day. This must be caused by the increased heat transfer caused by the increased moisture content of the air.

Engine @ Operating Temperature + high ambient temperature + >90% Humidity == Battery on death row.

Originally Posted by DrGonzo (Post 3457360)

My wife's Honda Civic had exactly the same thiing happen to it about a year ago, down to the door locks clicking and interior light flickering. It was the result of the battery dying suddenly overnight and we found that the problem was that the air conditioner actually stayed on over night after we turned the car off. There wasn't air coming through the cabin, but the motor stayed on (if that makes any sense?). Maybe your RX8 is experiencing something similar whereby an electrical component isn't switching itself off?

Originally Posted by PeteInLongBeach (Post 3457433)

I don't understand how you equate a dead battery with "dodgy ignition", since you don't state anything about prolonged difficult starting as a source of battery drain.

I don't see much evidence on the forums for "eating batteries", even on the early cars before the upgraded starter and battery specification. Something else is going on with your car....

Originally Posted by Brettus (Post 3459711)

1. Slap a supercharger on it
2. Relocate battery to boot (Improving weight dist.)
3. fit after market muffler to replace that bit heat sink of a muffler

All problems solved ....

Next question

Originally Posted by Revolver (Post 3459728)

The car's an '04 and is yet to crack 65,000kms. Since new it's had 3 new batteries, 1 new set of coils, 6 new plugs and 4 new plug leads. So I was talking ignition generally, not just in relation to this particular battery replacement. I'm sorry but I call the need for those many parts dodgy.

I've read of a number of battery replacements in both the yank forum and our own Aussie forum and have had the problem informally confirmed by Mazda service guys and both of the last two battery replacement guys who came to my home. I appreciate it doesn't affect every car but there's more than enough smoke for there to be some fire on this issue.

Since you think I'm wrong, what's your theory? I'd love to solve it instead of forking out for a new battery every couple of years.

Originally Posted by PeteInLongBeach (Post 3459758)

Have you had a qualified shop check:

• the electrical system for parasitic drain, bad grounds, etc.?
• the charging system for over / under charging?

Since this is a 2004, have you had the starter & battery upgrades done per the TSB?

Originally Posted by Mazurfer (Post 3460538)

Well......make sure your battery air duct channel isn't blocked or you have the battery itself blocking it? ... There really is an air duct channel that runs up into the battery tray for cooling.