RX-8 Draining Battery While Off?
 

Yes, it's happening I don't know how. I've bought 2 car batteries the past 2 years. The car has just completely died. Clicking sound; dead. The first one I thought well, bad battery. The second was confusing, another bad battery? I took my car to Advanced Auto Parts to see if my alternator was messed up or something and no. The battery was just dead-dead. The issue is, the car is still using power while it's off. There's something that is wasting the battery, every day/night it's off.

I just bought a battery 2 days ago. And it still tends to start sometimes on the 2nd try.

I don't have any aftermarket installs or anything. The only thing I use is a radar detector but well, I unplug that overnight and it still drains battery. So that isn't the problem.

I'm lost. I'm going to take it to a dealer probably next week after this storm passes by.. Anyone ever heard of this? Couldn't find anything on search.

is your trunk light on when its closed and you look at the trunk through the rear seat tunnel?

Real common, do an advanced search on Dark Current

I checked. It's off.

Thanks I did. I mean, people have had the same issue but no help in getting it fixed? Or what the problem is.. :dunno:

You need to isolate the problem by checking for draw, 1 circuit at a time. Try this: BATTERY INSPECTION

One mechanic told me that if you live in a hot and humid environment, your battery will drain faster than usual, I don't know. Anyway, I've noticed that my battery only last for less than 3 years, and I live in Las Vegas...very hot and sometimes humid. :dunno:

Well, for sure it isn't the battery. I just bought a new one the other day. The past 2 batteries have died within the year.

Maybe. But mine hasn't lasted 2. I got a new warranty exchanged Interstate battery last June. It died this month. The past battery lasted about the same.

Haven't had time to take the 8 in but will have to soon.

What you need to do is to test it the correct way.
First thing you should do is clean up the other ends of the battery wires.
The positive connects to the starter, and the negative connects to the frame.
Find those points, and clean them up.

Then, put an meter between the positive cable and the battery post, and read how many amps its drawing while off. Then start pulling fuses from the fuse box one at a time, and watching if there is a large decrease in the draw with one specific fuse.

When you find it, you need to trace that circuit down, and find the culprit.
Maybe its a frayed wire that's grounding out.
Maybe its corrosion in a connector.

The easiest thing is to start with any parts of your car that you know stay hot after you turn off the car. Then go from there. Chances are, a burnt out tail light bulb is not going to drain your battery while the car is off, but if there was a problem in the hazard circuit, or the brake light switch, that might cause an issue.

BC.

^^^ What he said.

Make sure to take note of the most important part of BC's statement here : when off. Do NOT try turning on the car with the circuit set up this way unless you have some industrial ammeter or you will find your meter blow sky high lol.

So how long does it have to sit unstarted, before it won't crank?

I had same issue, and i realized the problem was that my brake light stayed lit. when i checked everything related to it, I saw that my sensor on the brake pedal was hanging off. check that because that will definitely drain the battery quickly like yours.

Battery Drain
 

This is a design aspect of this car
The dealer has tested it yet again with no fault found--nothing to pay sir [good?]
I am told "Modern cars are made to be driven not left"
"You cannot leave it for more than a week or so without it losing enough charge to prevent starting" [In 30 years I've never owned another car that ran down in a week!]
"That's a bit difficult if you bought it to use mainly at weekends" [Wasn't warned on sale that it was not suitable for that purpose!]
"Its the security and other background systems that run it down" [Ironic as it is pretty theft proof with no charge!]
"You cannot turn off the background systems"[So extra technology is killing basic functionality]
"You could always disconnect the battery or charge it up the night before"[Every week!]
So my advice is buy a charger and accept the inevitable...they cannot fix it beyond other contributing faults.

Hi my name is tony , i saw u writed in 2006 about baterry life in mazdarx8 i have the same problem what did u do then , how did u fix it pls tell me at my Email artonkamberi@hotmail.com

Im passing by the same issue. :(

If you don't drive it the battery will die....nothing secret about that.

If you are leaving it for more than a week...just disconnect the neg battery cable...that way Battery just needs to be reconnected when you want to start it

Mine does the same thing. I traced it to the security and keyless entry systems. It takes about 2 weeks to drain the battery to the point of not having enough juice to start the car. I normally just drive the car on weekends and track days, so it has a battery tender on it most of the time. Problem solved.

Keep in mind that little things like an ODB connected device draws power even when the engine is off as well. All those things add up to suck it out more, especially if your battery is already getting old.

I believe I saw on here somewhere too that one of the AC/Car Charger ports is always hot, maybe the front one below the radio? So that could be doing it if you leave a GPS or phone charger plugged in.

I have the same issue, if my car is locked. If I leave my car unlocked, I can leave it for months. So I would agree that it is the security system causing the drain.

I don't know about months unlocked, I don't lock mine in the garage and it will die after a week or so with my odyssey battery and before the battery relocation and smaller battery, maybe two weeks with a decent Group 35 battery. The RX-8 has a draw of about 160-170Ma when off, that is high, most cars are in the 50Ma range depending on the car. Mine sits at 177Ma or so but I made a lot of wiring changes to the car. But I have a charging port in my car so it is always hooked up to a float charger during the week when it is not driven.

Yea I learned that early on in 2008 when I first bought my RX8 and left it during a two-week vacation and I was driving my Mazdaspeed3 GT for more luggage space for my group. Mazda replaced one factory battery under warranty. The charging system was fine. I cleaned the grounds and installed the RX8 battery post kit long ago so that wouldn't be another battery issue and I keep it driven every week now since it is my DD. As others have said, the standalone systems on this car will drain the battery if not driven regularly.

Have had my 8 over nine years now. Weekend car, regularly sits undriven a couple of weeks; occasionally for a month or so.

Always fires right up.

Hey that is great New Yorker, but many have had issues with battery draining when left sitting. The alarm system or other electric accessories hooked up, even the trunk lid ajar, will drain the battery if not driven and kept charged. And a lot of that also depends on if it is garaged or kept in colder weather which will lower the available juice when needed. Not a constant problem for most with strong batteries, but the OEM battery in my Series 1 was weak when I bought it new. I guess the few people that had test driven it coupled with sitting on the dealer's lot and folks going in and out, before I bought it , helped make the battery drained. Mazda replaced that under warranty. Since it became my daily driver I have not had a problem .

Good points, all. I'm in NYC and my '05 is always garaged, so sits parked underground all year at around 60ºF. Plus I had the Mazda upgrade to a stronger starter shortly after I bought the car. And I usually do highway driving with few stops, so that helps, too.

I did drain the battery once; I had left the trunk like ajar. And I had to replace the original battery about 5 or 6 years ago. (Bosch 35-640B great replacement, came out on top of all 35 series batteries in their tests. But that was over 5 years ago).

But still, my 8 usually gets driven only once every few weeks.

Completely normal its a parasitic draw due to keyless system being on all the time. Had a Corvette if not driven for 10 days the battery would be dead. My RX8 is about 15 to 20 days before dying. If the car is going to sit just hook up a GOOD maintenance charger to keep the battery in top sharp.

What happens to an electric car and you don't drive it very often? Like a Tesla?

They will die!

It's two weeks for me when I don't drive it, then dead battery.

Bose 6CD changer causing excess current draw killing the battery in days.
 

I have a 2007 RX8 and had the same issue. I noticed current draw to be ~250mA when locked and with everything off. Obviously this is too high. I have isolated the issue to electrical circuits associated with the Room Fuse. I further isolated it to the Bose factory unit (I have a 6 CD changer). Without the Bose unit the current draw drops to 70mA and after a few min to 35mA.
What is disturbing is that so many people have this problem with most having an electrical issue with various systems.
Has anyone else isolated the current draw to there Bose factory unit?

Parasitic draw 2.8 amps!
 

Recently did a amp draw test, pulled 2.8amps, as you probably know this the kills battery within hrs. The fuses/ relays associated are room(15a) and accessories relay. When I pull the room fuse the amps drop to (0.13 amp) once I remove the the accessories relay it drops to (0.0amp). The [U]room fuse[/U] is drawing the most from the battery, however when I install the accessory relay I hear a click on that exact relay. The items that stay on are(radio, gps, rear dvd player[unsure if factory or not], also hear actuators power up on all four doors but not enough to move door locks) believe this vehichle is also fully equipped meaning... bose system, nav, power seats, heated seats etc etc

Items checked....
#ignition switch....disconnected,#all fuses good,#rear dvd unit disconnected, #bose amp disconnected

Items I plan to disconnect....
Radio, nav, keyless entry module,

A few key notes....
the data link connection is reading error no codes just error this must all correlation in some way. Previous owner replaced a 15amp fuse with a 30amp. Pulled the brake light switch down by the trans(it was completely fried) car no longer blows the 15amp ignition fuse, I believe the previous owner used the 30amp to keep car running. Hoping they didnt fry something pricy any advice or schematics would be nice. Have pdf manuals on it aswell if anyone wants to help or just wants the pdf

Can you please send me the PDFs. Also, I believe the keyless entry module is under (behind) the glove compartment correct?
Send a picture if you can. I was able to reduce the current draw mostly by unplugging the Bose car stereo unit.
None of the other fuses made any noticeable difference in the draw.

Send me your email in a p.m. or I.m. and I'll shoot you the pdf tomorrow...intelneo.

I was going to pull the radio a GPS tomorrow as well I'll post the outcome....

Yes behind the glove box, should be two bolts or screws on the side and then just disconnect the strings that keep the box uprigh. I will be checking that module as well

Me too
 

Okay so my battery also drains while it's off and now my alternator belt is seized up and won't turn so I am guessing it's the alternator?

Could be, it's kind of hard to guess over the internet. Pull the belt and see if the alternator is seized.

Doubt it a the alternator due to it draining over night it's probably a parasitic draw... Google parasitic drain look for one with Eric the car guy he's very knowledgeable and explains things simply

The DVD in the trunk is not stock.
Find the connection at the radio and disconnect it.
If you disconnect it in the trunk you could still have a draw as the wires may be grounded.

It's the factory navigation DVD player. Problem is something is telling the accessories relay to power up when key isn't present. Also it's not the ignition switch, nor the keyless control module. Another symptom is the obd2 port is not communicating with the code reader it's pulling up "error" message and the scanner works on my Honda Subaru and Chevy.... Any ideas or suggestions are appreciated. Car will start up just cant pass smog due to the lack of communication

I have a 500ma battery tender and it can hold fully charged battery means when turned off, the car draws less than 500ma total.

I found a white connector on the negative cable located in between the battery and the filter box to be the culprit. I replaced it with a 10-12 yellow barrel splice and its been 2 weeks of flawless ignition. I had this problem for close to a year. Battery would go dead over the weekend. Drove me nuts. The connector would create a parasitic draw because of the male and female terminals not making good contact.

Just replaced my Mazda 60-month high performance battery which was going after about six years of service. Got the same battery. which performed great year-round through six winters and summers. Only the second battery I have needed for my RX8. I again made sure that I had Mazda's battery Service kit BGK-BST installed. It features super stout terminal connections and covers and ground connector. Service kit is only $12.95 .

How did you manage to fix this? My 8 has the brake sensor hanging and battery dies really quick. Some mechanic fixed my clutch pedal aince it was broken and left the sensor hanging.

I was responding to Street rx8 race, he stated his belt was seized.

About the dead battery problem,I had 3 beautiful rx7s at one time,a 79,an 80,and a 91 widebody,and the trick to keeping your battery juiced while it's not being driven is to hook up an extra ground strap from you strut tower bolt to your engine block,it wouldn't hurt if you wanted to hook one up to each strut tower,take my advice,newer cars have multiple ground points ,I'm surprised that Mazda never did this,but it does fix the problem

I recently did a parasitic loss test and found I had a 1.5A loss associated with the "BTN 30A" fuse (pulling the fuse left me with no parasitic loss).
I took it to the dealer and they said I just needed a new alternator, and that this 1.5A loss is normal. Seems insanely high to me.

It is insanely high. My normal draw with car off is 0.028amp.

Who is this dealer so we know never to go there?

If I remember well, the tail lights are on the BTN fuse, so if you have the common broken 3rd brakelight harness problem, that could easily be it. Less sure, but the trunk light staying on would be right around 1.5 amp.

Fremont Mazda. Ticket for new alternator was $800.

They also literally left something in my dash that rolls around during hard cornering. Would not recommend going there.

Same Problem
 

I have a 2005 RX8 and have been experiencing the same problem. Have replaced the battery twice in the last year, took it to my mechanic, who is normally very good, and he told me to just buy a better battery and that one of the wires was loose and nothing wrong with it. I have read all of the other explanations offered in this forum regarding the security system, trunk light, etc. draining the battery. My only question is this: if that was the case, why did it just start to happen now? (BTW, I disconnected my trunk light years ago so that would NEVER happen.) This seems to be a legit problem happening to lots of other people, but just like gulf war syndrome, nobody seems to care or want to recognize it because it would probably cost too much money. I should also mention that my check engine light and radiator have been going off for about 2 years now, but have had everything checked out and car runs fine, as long I can get it to start. I miss the days when cars did not have computer systems, which are simply not designed to last more than 10 years in anything, especially a car.

Welcome.

A couple of things may explain 'why now'.
It's possible your battery terminals are stretched.
Even though the bolts are completely tight, they can stretch and not tight enough to make good contact.
You could have a loose or corroded ground wire.
Your alternator could be failing.
Btw, I'm on my 3rd battery in less than 7 years.

In addition, the coolant light probably means your coolant tank sensor is bad.
A new tank would fix it, around $125.
Personally, I don't like not having it functional in case it actually loses coolant due to a leak in the system, especially since the temp. gauge is borderline useless.
By the time you notice it, it could be already be overheated and damage or destroy your engine
Lots of people say unplug it, I wouldn't.

Also, NEVER ignore a CEL.
Get it scanned if you haven't already.
It could be misfires, that causes the catalytic converter to fail.
It could also be a code for a bad cat.
Probably the No.1 reason for Renesis failure.

Misfires kill cats, bad cats kill engines.

Listen to BigCajun here, he spokes the truth. The battery even if all connections are tight will lose juice over just a week or two from the drain of the alarm system and other systems that stay on in your car. leave the trunk open and the trunk light will take down a good battery very quickly. Buy the best battery you can after checking all your wires and connections and don't leave the car undriven for too long unless you use a trickle charger hooked up to the battery. I use this one for two of my cars ,including my 2008 40th Anniversary Edition RX8 and it works flawlessly.

I left my car undriven for 2 weeks once and it fired right up. I doubt the alarm drains that much juice unless you have a low capacity battery, which some people use for weight reduction.

Do you have anything aftermarket like a subwoofer? I'd start looking there.

Honestly, I think the RX-8 doesn't have too much electronics. It's not a BMW or some German overengineered BS.

Don't tell me you like old cars because there is no CEL and you can pretend there isn't a problem...

The last time cars didn't have computers, warranties were 3 years or 30,000 miles max. I don't think anyone misses those days.

Get a multimeter out and check for fantom current at each fuse. I have something in my headlight washer circut that draws about 100mA and runs the battery down when sitting for a long time. So I just pulled that fuse until I figure it out.

You shouldn't see more than 0.025 amp draw from the battery with the car off.
​​​​​​
This has been a thing as long as motor vehicles have existed.

Believe it or not Jinx it is a bigger issue then your experince with many RX8s, even with NO aftermarket parts . They do drain batteries even when in excellent health. Dealers and rotary specialist and tuners will verify that. It is also a factor depending on where you live. A cold winter can drain a battery faster and then any other normal drain while sitting can drop the battery below the ideal cranking power. Cheers