Battery I have now is 800 CCA and 675 CA seems kinda low and looks small for the spot it's in?

 

The RX-8 battery should be a group 35. Specs will vary depending on price and brand.

 

Should I get one with a high cca. Optima red has 800 cca and 1000 ca. Should be fine

 

Optimas sucks, I went thru two reds in two years before I gave up (even though they were covered under warranty and have known many others with similar issues. They used to be good.


I use an Odyssey PC925 (relocated to the trunk) in my RX-8 but I just got a new Autocraft AGM battery for my BMW and it has a 3 year free replacement warranty. Also if you get one at Advance, use coupon code TRT41 and you will get $40.00 off and online order and then you can just pick the battery up in the store. I saved $60.00 with the $40.00 off and the $20.00 core return of my old battery as a core.

 

You only need enough cca to get the job done. Do you live in a very cold climate?

I agree with 9K. Optima is not what it used to be. I lost about 1 per year until I have up on them.

 

I did some measurement of the Battery compartment and just put in the battery with the best specs that I could afford. I'm in Minnesota which has a sometimes awful winter temp and I decided that I would not subject my new (2004) RX8 to the salt they dump on the roads during the winter months. I do wonder if its better to have a trickle charger on the battery or just to regularly start and idle it? I've done a little bit of both. All I can say is that having just bought the car in late fall I can't wait for Spring...

 

I keep my RX-8 on a Noco trickle charger since I only drive it on the weekends. And it's always good to charge your battery every now and then because the car never fully charges it. I have a brand new AGM (H8 size) in my BMW and still when I hook it up to the charger it takes about an hour to get to 100% and I drive it every day. I have also found this to be true on my Integra which has a year old battery in it.

But keeping my RX-8 with the Odyssey on the trickle charger has insured that the battery remains healthy. Allowing an AGM to fully discharge multiple times will shorten it's life greatly from what I have seen.

 

I have one of those coming for mine , but was going to mount it inside the engine bay. How do you find it for cold starts ?

 

Mine sits all week and never has an issue starting unless I leave it off the charger for more than 5-7 days. Three of us locally have the same battery. Hoss-05 has the larger PC1400. Mine starts with barely a bump of the key with the S2 starter and the PC925 when cold. Now mind you, the coldest it gets here is maybe 32F and that is maybe 2 times a year, generally the coldest month in January and the average at night is only 38F.

My car has also had a higher rate of draw while sitting than other RX-8's we have tested, even before I relocated the battery. But I typically leave it on the trickle charger.

If you use NOCO they also have a few accessories for plugging in the trickle charger that are cool.

This plugs in where the blank is near the DSC button.

 

I also have a charging dongle wired at the battery as well.

 

Definitely use a trickle charger. Idling an RX-8 is not terribly good for it. That just creates more opportunity for carbon to build up in the engine. I use a Battery Tender wall wart. It comes with a pigtail adapter with ring terminals that fit on the battery terminals. When I know I am going to leave the car sitting for more than a few days, I just pop the hood and plug it in.

 

As far as the trickle charger goes, how many amps do you guys have running to the batteries if your leaving them plugged in all week?

 

My NOCO trickle charger is 0.75A.

 

Awesome. I have a VR4 that sits until the weekends and through the winter. Going to look into ordering one.

 

If you want an overall good charger I recommend the G7200 from NOCO, if you have AGM batteries the boost function is nice. The only down side to the trickle charger is that it takes forever to charge a low battery so having a quicker charger is nice.

 

There should be a mode that actually does trickle charge it. I bought this silly expensive on that (hard) charges it at 10 amp (or you can set the thing to start the car with the battery dead and its like 40? 50 Amps?) But you really want to have a smart charger thats low current when it needs it. The "hard" amp mode is more for when you try starting the car and it groan and doesn't kick over and you want to charge it in an hour. If you leave a battery being charged with high current all week thats not healthy for the battery. And YES letting a battery die totally will screw it up. I can't remember what the shop teacher told us (Because it was long ago) but I think it had to do with the plates of the battery getting screwed up an ruining the battery to let it totally go to zero.

I'm a little surprised how much current my RX8 takes when its parked (And btw thanks. I will not start it and idle for 20 minutes. That makes sense that this is not good for it)
I was seriously considering pulling the battery but I started looking at some of things that happen when the car has been left without power for a long time. Engine relearning, crank the steering wheel all the way left and right etc. I'm trying to get all the info on that. Having been in the computer world a little too long and seeing the crap that programmers produce it makes me a tad nervous driving any car that "flies by wire" *Thinking of the Airbus at the Airshow that "autolanded" in a forest.

 

I'm not sure why you posted a pic of a plane crash but yeah the NOCO uses a smart technology so it charges based on what it detects from the battery. There are a few good chargers out there, it depends on what you need and can afford.

 

My Battery Tender is also 0.75 Amp/Hr. I think I paid $15 for it on sale. There are a lot of 'intelligent' chargers on the market now. Any of them should suit your needs.