[REKIII]

I got the car out of storage the other day. The battery was dead, not real surprising but I thought it was odd that it was completely dead, not enough juice for the interior lights or trunk release. Also, about a month ago I checked the car and all was good. I didn't start it but the previous mentioned items worked great.
So, I charged the battery and drove it the whopping 8 miles home. 2 days later it is dead. Understandable, but completely dead?
I hook it up to a v8 truck. Wont start. Rev the truck for awhile. Still wont start. Eff it, I now hate this car. Take the batter to autozone, after 45 mins it tests bad.

Battery history of the car :

Oct 07 - buy the car with a brand new bmw battery
march 08 - battery dies and is tested bad. Buy new bmw battery
July 08 - battery dies. Determined its the hvac issue. Battery ok
sept 08 - battery dies. Determined bad. Replace wth an old optima redtop.
May 10 - optima almost explodes on the side of the hwy in Ohio. Savior friends of timmay77 bring me a brand new oreillys lead acid battery
and that brings us to today.

I really don't know what do do. Brand new batteries, old batteries, cheap batteries, expensive batteries, they all die in this car.

I think im done putting batteries in it. I was violently angry this morning. Im still fairly certain this car is the biggest piece of garbage ever made.

Sorry guys. Pretty sure im done.

 

[jfoj]

Not sure how long you "store" your car, but any BMW, E39 M5 or even newer ones cannot sit forever without draining the battery.

If the car will sit for more than 1-2 weeks at a time, you need a Battery Tender/trickle charger. Bottom line is all batteries will drain over time.

Every time the battery is drained flat, you cut its life span significantly.


Amazon.com: Battery Tender 021-0128 Battery Tender Plus 12V Battery Charger: Automotive


Amazon.com: Battery Tender 021-0123 Battery Tender Junior 12V Battery Charger: Automotive

BTW, I do not think I would run an Optima in these cars. They have a large battery with a lot of reserve power due to the behavior of the cars electronics, parking lights, automatic fan and standby heater.

 

[tradin1]

final stage resistor? or was that your HVAC solution?

 

[REKIII]

final stage resistor? or was that your HVAC solution?

Yes. I can never remember what that thing is called.

 

[gsfent]

I second the battery maintanier. I have an inexpensive one, it is a "schumacher". Easy to find on ebay, it has a smart circuit to float the charge when the battery is nearly full. It comes with 2 connectors, clips for the battery, or you can hard wire. There are a multitude of good little battery maintainers, I think there is one called "mini" sold by BMW and another, I think c-tek or similar, that is well regarded (about $100 or so IIRC).

Tough to blame the car on the battery, but hey, if it doesn't start, it can be pretty aggravating. I use an Odyssey, way too expensive, but it holds up well. About 3 weeks is the limit of non use without a charger if I want to start the car. It has enough juice for everything else, but our cars need a lot of juice to crank over.

So, if you don't drive the car off of a cliff, get a good battery, a good battery charger, and give it a fair chance. You are looking at about $250-$300 and you can certainly change a battery yourself. And I always have a portable jumper pack at the house for all of my cars, another good investment for under $100.

Regards,
Jerry

 

[REKIII]

On my second jumper pack. Kids destroyed the first one with a soccer ball.

Your logic isperfectly sound. I'm still very angry. Haha.

 

[herrubermensch]

Bob, dude, hang in there. I know how you feel, but the battery tender is critical for these cars when stored, even with a relatively new battery. I sprang for just about the most expensive battery in E39 M5 history when I grew tired of jumping my car, and I haven't had a problem since. Short of that insane level of investment, you need to run a tender. Unless you have a drain somewhere, the battery tender will do the trick. I have a lightweight Braille battery that I've never used and probably needs charging, but you are welcome to it for the shipping. Let me know.

Best,

Peter

 

[DDSLT5]

Have you replaced the under hood switch for the alarm?

 

[Jacob_Seattle]

Not sure how long you "store" your car, but any BMW, E39 M5 or even newer ones cannot sit forever without draining the battery.

If the car will sit for more than 1-2 weeks at a time, you need a Battery Tender/trickle charger. Bottom line is all batteries will drain over time.

Every time the battery is drained flat, you cut its life span significantly.


Amazon.com: Battery Tender 021-0128 Battery Tender Plus 12V Battery Charger: Automotive


Amazon.com: Battery Tender 021-0123 Battery Tender Junior 12V Battery Charger: Automotive

BTW, I do not think I would run an Optima in these cars. They have a large battery with a lot of reserve power due to the behavior of the cars electronics, parking lights, automatic fan and standby heater.

I think Jfoj is dead on. I store my car for 4-6 months at a time and I must use the trickle charger. Use this and you will never have any further problems, of course after you drop some more money on a new one. I do this with all my cars. My M5 will go flat in 5 days sitting, my Q7 will go flat in 3-4 days. Trickle chargers are the key. I hope this advice helps. Jacob

 

[reekoon]

Have you replaced the under hood switch for the alarm?

Could open this up a little bit?

 

[vantaam5]

Come on man,it is only a battery....


I discovered after my rebuild that my battery is dead as well after 3 years...

get a quality one with warranty on it and call it a day...

 

[gsfent]

I sprang for just about the most expensive battery in E39 M5 history when I grew tired of jumping my car, and I haven't had a problem since.

Peter

Well, don't leave us hanging..........lovelove
Regards,
Jerry

 

[timmay77]

I agree with all of the above. Battery tender all of the way......

As it is linked above, this is the one Chris and I use. (my Christmas gift to him)

Amazon.com: Battery Tender 021-0128 Battery Tender Plus 12V Battery Charger: Automotive

 

[timmay77]

Well, don't leave us hanging..........lovelove
Regards,
Jerry

OF COURSE Peter would buy the most extravagant battery possible. The damn thing as an on/off switch for crying out loud......

How does Peter screw in a light bulb?

That one KILLED me, I was laughing for 10 minutes after I read that.......

 

[ND4SPDLSC]

Have you verified no drains/shorts exist? If none are present, then a battery tender or disconnecting the battery is the way to go for long periods. Look for root cause before throwing parts at a problem.

 

[Hdhntr23]

Have you verified no drains/shorts exist? If none are present, then a battery tender or disconnecting the battery is the way to go for long periods. Look for root cause before throwing parts at a problem.

Why unhook the battery while on a tender? Isnt it a closed loop?

Or, am I misunderstanding you?

 

[ND4SPDLSC]

If you are using a battery tender, you do not need to unhook the battery. It's nice because you don't lose your settings etc. If you don't want to use a tender, unhooking the battery is the next best bet.

 

[REKIII]

well, I was impatient today and actually needed to drive the car to work, so I ran to autozone and bought an optima Yellowtop. I know, it will probably go dead by thursday, but I could not get myself to spend money on another lead acid, and after 2 BMW battery fails I refuse to put one of those in my car as well.

Peter, I am still interested in your Braille, I will buy it from you.

PM me a price shipped.

Thanks guys for the words of advice. I'm still relatively certain I will be buying a battery every year or twice a year, but we will see. Also still fairly certain the car is the biggest piece of garbage ever made. If it doesn't start, it really can't be the ultimate driving machine, now can it.

 

[jfoj]

This is a pretty simple issue.

OEM BMW battery has a 2 year warranty, as do all parts purchased via a BMW dealer. I did not look over your timeframe, however, this may be something to look into.

Again, this does not resolve your issue. If you plan on parking your car for more than 2 weeks, either get a battery tender, a solar charger or disconnect the battery. All cars since about 1980 have some sort of parasitic power draw.

You also need to make sure your car does not have a draw that it should not, like a fan FSR or possibly even bad diodes in the alternator or something simple like a trunk or glovebox light staying on.

I hear you purchased an Optima battery, make sure you have it properly secured in the battery tray.

When I bought my car it did have a BMW battery, not original, just slightly over 2 years old. Had a bad cell due to a leak at the TOP of one cell, due to all the high gforces during turns and acceleration, the battery leaked so 1 cell was a bit low on electrolyte. I decided to replace it with an Interstate lead acid battery, the height & width were correct, however, length was about 2 1/2 to short. I made up some spacers out of scrap wood and this keeps the battery tight in the battery box.

If I had to do it again, I would probably go with an OEM BMW battery for a number of reason.

 

[DDSLT5]

Could open this up a little bit?

Interesting reply! The underhood switch on my car (common on the e39 5s) became defective and was triggering the alarm to go off. I never heard it do it until a warmer day a year ago in spring. I usually don't lock the car at home, but this day the car was on the street, and I had engaged the locks. Every 20 min or so the alarm would be triggered. I turned it off a few times, then moved the car into the garage, and relocked it to test if the car was going mad! The alarm didn't trigger again. I then started reading about the sensor inside the cabin being faulty on some cars, etc etc. I didn't take any action.

Fast forward two weeks: I come back from a trip, and I'm greeted by a completely dead battery in the M5. A quick charge of the battery by an airport truck and she was up and running again. My alternator was new a short time previous, and I didn't want to kill the new one, so off to the local dealership for a new battery. After a FIRM raping for that battery, I drove home. I dropped the old battery off at my mechanic friend's shop - he charged it, and tested it. It tested well within normal limits. The battery was fine.

So - I talked to my local deadership. I had already narrowed down the search to a possible faulty underhood switch for the alarm. I mentioned to my service guy that I had a dead battery recently, and he immediately said "underhood switch for the alarm". So, I ordered a new one from BMW Parts and BMW Accessories | Bavarian Autosport and installed it. Problem solved.cherrsagai