I have searched around and noticed a lot of posts about the batteries in the rx8. I have a 2004 and replaced the stock battery a little over a year ago. It was giving me trouble in the cold weather and when I got back from a trip last year I decided to just get it replaced. I am having the same problem now. But it started in August and if I don't drive my car for more than 2 days the battery dies and I can't get it to start, longer than 7 days and the car won't do anything. And once I jump it I have to run it for about an hour to get it charged up so after I turn it off I can start it again the next day. I drove it last friday and tried to start it on Monday and no dice. I have a 500w jl audio amp hooked up but the light for power is off when the car is off so I don't think that is using any power when not on. The light in the trunk is off as well. Anyone got any clues on what it might be? I am going to replace the battery too but would anyone recommend the red top optima or the yellow top for my situation (500w amp and living in the cold winters of the north east). Thanks for your help.

 

The Optima Yellow Top (deep cycle) is better when you have added audio options, as you do. Deep cycle batteries better accomodate the repetitive deep depletions and recharges required.

But to get back to your base issue, you really shouldn't be seeing that kind of battery depletion after only a week of non-use, even in the cold. Something is drawing power somewhere. Make sure your audio amp is truly off and not actually in some sleep-standby mode.

 

your battery is draining AWFULLY quick. I've got a 1400 watt amp in my car and don't have that issue.

How old is your battery? Have you tried charging the battery to see how well it takes a charge? I didn't drive mine for almost 3 weeks and it fired right up on Monday.

+1 to the Optima Yellow Top. I've had it in my car for about 3 years now and never had issues. It really can take the abuse

 

See if you can get someone who knows what they're doing to test your battery. If it checks out OK, try measuring the current drain when the car is off. I don't know what the acceptable value is, but I know it's been discussed here and should be findable with a search.

A battery in good condition should hold its charge for a couple of weeks.

Ken

 

^^The maximum allowable "dark current" is 50 milliamps. Note that even that rate can drain a battery in a couple, three weeks. But a couple of days is way out of line. Agreed the first place to start here is to get an actual measurement of the car's dark current useage.

Whatever the problem turns out to be, this battery is probably quite weak from being depleted regularly. I like AGM (type) batteries with deep-cycle capability. Optima Yellow-top is one, but there are many reports of recent quality decline for that brand. A great option is Odyssey. As it turns out, Sears DieHard Platinum is a re-branded Odyssey battery. The group35 version of that battery is what I went with when I replaced the battery recently.

But of course, any battery will eventually have problems if there is excessive drain while parked, or if the charging system is faulty. So you have to solve this from both ends.

 

^ +1

 

Nubo is dead on.

50mA is max current in sleep mode. Sounds like you have a parasitic drain.
Hook up a DVOM in series with your battery. Let the car go the "sleep", should take around 5 minutes, then start pulling fuses till the amps drop. Whatever is connected to the fuse is your problem.

 

^.........if of course he's drawing more than 50mA at that time......else, it's his battery and too many depletions is most likely culprit.

 

If his new battery is drained in 2 days of no driving he has a drain. I can go 2 weeks without driving mine and itll start right up. Unless the battery he got was bad from the get go.

 

I am going to get a new battery this weekend because the battery can't hold a charge for more than a day. I drove it on everyday last week and to and from work then didn't start it until sat night and it barely started. Then I didn't drive it sunday and tried to start it this morning and it was dead. Where would anyone suggest I go to see if there is a drain on the battery? And is yellow top the general consensus for what kind is best for my situation?