Convertible M3 Dead Battery Conundrum

[bmckeeM3]

I have a manual transmission, 2008 M3 Convertible in Juarez Black that I named Jezabel and have owned since new and have put approximately 20,000 miles on. I moved to Denver and put the car in an enclosed car trailer that I own and parked the trailer in a rented storage garage given that my new home did not have enough garage space to keep all of my cars indoors -- and I didn't want this car outside. My intention was to find a permanent/conditioned storage home for the car over the next year so that I could easily get to the car and take it out for a spin now and again. Importantly the car was parked (stupidly upon reflection) with the top down. When I went to the car to fire it up after a few months in the trailer, the battery was dead. Not a big deal, it has happened before. I went home, retrieved my battery tender, went back down and plugged it in. Upon my return visit several weeks later, the battery was still dead...not a sign of life. I figured I didnt have a good connection, played with the clamps, made sure the Tender had power and left again...next return visit, same thing....no sign of life. I then began digging -what next???? I found that using the smaller of my battery tenders, i may not be providing enough juice to recover the dead battery/overcome the draw on the battery from all of the M3 electronics, which are apparently known to kill batteries. Fine, let's replace the battery....which happens to be in the trunk...under the convertible hard top that is neatly folded into the trunk. I slowly begin to recognize just how stupid i was to park the car with the top down. I travel a LOT for work and have limited time, limited auto repair skills and even more limited garage space. My research has yielded that getting to the battery and getting the top up without power is a rather involved process, and one that I cant do outside with any risk of weather. I have checked with a number of area shops to see if there is anywhere I can take the car in the trailer, back the trailer up to a garage and roll the car straight into and inside work bay where it can live until they (an experienced professional can do what needs to be done to get the top up, battery replaced, and now a thorough scouring of the car and all its components given that it has been sitting for a year + without running in an environment that is very dry/low humidity). That search has proven fruitless....everyone thus far has suggested i come unload the car in their lot and they will get to it when they can...that is a non-starter with the top down. I have continued to look for a permanent storage solution where I could unload the car and have time to work on it...or hire someone to come work on it and that has proven equally as challenging. I am scratching my head as I have a beautiful car that I love, want to drive and that I am paying dearly to store. Does anyone have any ideas, thoughts or suggestions relative to mechanics, storage places, or other approaches I should be thinking about to help me get Jezabel back on the road and part of my driving life?

[Pheonix]

Can you open the hood?
Did you try to jump start the car? If you can't get the jumper cable to the car then get one of those Portable Lithium Battery starter and should work. The positive terminal is in the front.

[cloumeM]

Originally Posted by Pheonix

Can you open the hood?
Did you try to jump start the car? If you can't get the jumper cable to the car then get one of those Portable Lithium Battery starter and should work. The positive terminal is in the front.

Yes, this should do the trick. Positive terminal near the passenger side strut mount with a red cap under the hood.

[bmckeeM3]

I did try to jump the car as well via the remote posts under the hood....nothing (apologies-
I should have included that in my overview).

[bmckeeM3]

Quick note: when i tried to jump the car, i used a small battery jump box. I have heard that some of the bigger more 'industrial' jump boxes are much more effective for VERY dead batteries. Any experience with this? I would be willing to invest in (or rent) a bigger jump box if i thought it would work.

[Pheonix]

I would definitely want to try a larger battery pack.
Hopefully it was a matter if giving it enough juice. If not then you might have some other issues?

[bmckeeM3]

Thanks Pheonix. Will see if I can find one and try it this weekend. Fingers crossed.

[cloumeM]

Definitely try the more potent jump source. Also, for leaving the car stored long-term, consider using the battery tender/charge unit. Some use the OEM one, but I found one from autozone and it worked great for me.

Here's the link to the tender: https://www.google.com/search?sca_es...=1132&dpr=1.31

[Pheonix]

Not sure how emptied the OP battery is but I had good experiences bringing half death battery back to life with NOCO battery charger.

[Johnny E92]

Hi I was away with work for 5 months and my E92 was dead as a door nail when I returned, not unexpected. I live in an apartment complex so a trickle charger is not an option unfortunately due to no power outlet in the parking bays in the complex.

It was that ‘dead’ that I had to use the manual key to open the door and the car wouldn’t even power up, even the interior light was very very dim.

However I did get one of the lithium battery jump packs and used that on the terminals under the bonnet (hood) and it fired up almost instantly. The battery is only 18 months old and is an AC Delco battery and seem to have recovered and the car starts and runs fine now.

I’m not sure if the jump pack I got is available in North America as I’m in Australia, but if so I can highly recommend the one in the photos. If not just get a decent one and biggest one you can afford.

Cheers

[Nickco43]

Originally Posted by bmckeeM3

I have a manual transmission, 2008 M3 Convertible in Juarez Black that I named Jezabel and have owned since new and have put approximately 20,000 miles on. I moved to Denver and put the car in an enclosed car trailer that I own and parked the trailer in a rented storage garage given that my new home did not have enough garage space to keep all of my cars indoors -- and I didn't want this car outside. My intention was to find a permanent/conditioned storage home for the car over the next year so that I could easily get to the car and take it out for a spin now and again. Importantly the car was parked (stupidly upon reflection) with the top down. When I went to the car to fire it up after a few months in the trailer, the battery was dead. Not a big deal, it has happened before. I went home, retrieved my battery tender, went back down and plugged it in. Upon my return visit several weeks later, the battery was still dead...not a sign of life. I figured I didnt have a good connection, played with the clamps, made sure the Tender had power and left again...next return visit, same thing....no sign of life. I then began digging -what next???? I found that using the smaller of my battery tenders, i may not be providing enough juice to recover the dead battery/overcome the draw on the battery from all of the M3 electronics, which are apparently known to kill batteries. Fine, let's replace the battery....which happens to be in the trunk...under the convertible hard top that is neatly folded into the trunk. I slowly begin to recognize just how stupid i was to park the car with the top down. I travel a LOT for work and have limited time, limited auto repair skills and even more limited garage space. My research has yielded that getting to the battery and getting the top up without power is a rather involved process, and one that I cant do outside with any risk of weather. I have checked with a number of area shops to see if there is anywhere I can take the car in the trailer, back the trailer up to a garage and roll the car straight into and inside work bay where it can live until they (an experienced professional can do what needs to be done to get the top up, battery replaced, and now a thorough scouring of the car and all its components given that it has been sitting for a year + without running in an environment that is very dry/low humidity). That search has proven fruitless....everyone thus far has suggested i come unload the car in their lot and they will get to it when they can...that is a non-starter with the top down. I have continued to look for a permanent storage solution where I could unload the car and have time to work on it...or hire someone to come work on it and that has proven equally as challenging. I am scratching my head as I have a beautiful car that I love, want to drive and that I am paying dearly to store. Does anyone have any ideas, thoughts or suggestions relative to mechanics, storage places, or other approaches I should be thinking about to help me get Jezabel back on the road and part of my driving life?

A couple of weeks ago I had a very hard time trying to find a shop in Denver to perform a few maintenance items. All the shops I called said they were a month or two out. Only BMW of Denver Downtown said they could get the car in without a loaner fairly quickly. It seems to me like there is just a lack of any kind of good service shops in Denver. My buddy took his E class to Paddock Imports where they ended up improperly filling his transmission twice, messed up his command infotainment with a software update, damaging his center console and leaving fuses on the passenger side footwell.

I ended up taking my M3 to Honest Assembly Garage and I should have my car back tomorrow after about a three week wait (I had to source good used valve covers which was the bulk of the delay). I can't personally speak about the quality of work as I have not received my car back yet but I was very impressed with the attention to detail and knowledge the shop owner had when I dropped my car off. I was told they have 20 something bays and no cars are left outside which is probably the most important thing in your situation.