[m5 bol]

hi, my battery on my m5(e34) has a slow drain so every other week when i go away for work i have to disconnect the battery, which involves lifting up the back seat everytime and im sick of keep recharging the same battery,
i was just wondering if theres any other way i can cut the power so it saves me lifting out the back seat!!

 

[///Manuel]

You can install a cut-off switch if you'd like. However you'd lose your radio, clock and computer settings each time.
If you have time, I would try troubleshooting the drain by pulling fuses out and checking the drain.

You can also use a battery tender when you know you won't be driving for a while, it's always good to
keep the battery fully charged anyway, it will last longer.

Automatic Battery Float Charger

1.5 Watt Solar Battery Charger
.

 

[JohnR]

I agree with ///Manuel. I use a battery tender in the winter on mine and it keep my battery fully charge all winter.
JohnR:byebye:

 

[TurboXpress]

You know there's a negative battery disconnect you can access without removing the rear seat, right?

It's located on the passenger side rear seat on the bottom (in the footwell area)...there's a small plastic access panel (about 4"X2") that pops out and the negative cable is right there.

 

[Blitzkrieg Bob]

My recommendation is to find the source of the power drain.

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Get a multimeter and use the amp function to search for the source by setting up the meter in series to the battery and note the amps being drawn. A few miliamps are okay, this powers the memory in the OBC, radio and DME. Begin pulling each fuse/relay and watch to see if the meter drops, this will lead you to the suspect accessory.
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Last time I experienced this was when a 4 amp draw was killing a battery on an E34 over a few days. It took several searches checking things that remain powered when the key is off. The trunk and glove box lights, alternator diodes, climate control, door lock heater etc are all suspects here.<o></o>

 

[TurboXpress]

and yes, get a battery tender...I got one as well and it works great when my car sits during the winter months.

*edit: or just do what Blitzkrieg Bob is stating...that's the proper way of doing it

 

[m5 bol]

whats a battery tender and how does it work??

 

[Blitzkrieg Bob]

whats a battery tender and how does it work??

low amp battery charger used to keep a battery fully charged during storage.

 

[AliveM5]

Also known as a battery conditioner in the UK.

Battery conditioners | Products | Auto Express

 

[rick]

I have the same problem with mine and I have had it for years....

Been to an auto-electrician who couldnt find the cause of the problem so I have grown to live with it, after about two weeks it loses power (to start) and requires either a jump or 15 mins on a charger.

You could try a solar powered charger - apparently they are very good and keep the battery topped up (for free) - they can be plugged into the cig lighter or plumbed into the main wiring loom. Even though they are called 'solar powered' they only rely on daylight and not sunlight. I am sure that the cig lighter has a permanent live feed so it is good to plug this in even when the keys are removed.

They are sold everywhere - try Fleabay (£15-35)

 

[Rob130]

Had a similar problem on a different car. It turned out to be a diode on the voltage regulator went bad. Found it the way Bob described. Isolate the draw. Disconnect the alternator wires and check amp draw on each one.

 

[m5 bol]

i think ill get one of them battery tenders, sounds like a good little kit, it will do me for now until i diagnose the problem

 

[corneredge]

My 94 Euro has this problem as well. My top notch mechanic was able to trace it for me with an ammeter and a very careful technique of putting the ammeter in-line with the ground on the batter AFTER the high-amperage events have occured.... then remove fuses and watch the draw. He found the draw in my car in the "general module" which for me is a $450 part... so I chose to use a trickle charger instead. I can make it a week or two outside without a problem, and I tested the ALT to ensure that was ok... the car is good to go for road trips and that's what counts.

Cheers,

Russ

 

[Blitzkrieg Bob]

My 94 Euro has this problem as well. My top notch mechanic was able to trace it for me with an ammeter and a very careful technique of putting the ammeter in-line with the ground on the batter AFTER the high-amperage events have occured.... then remove fuses and watch the draw. He found the draw in my car in the "general module" which for me is a $450 part... so I chose to use a trickle charger instead. I can make it a week or two outside without a problem, and I tested the ALT to ensure that was ok... the car is good to go for road trips and that's what counts.

Cheers,

Russ

a good GM can be found on Ebay or at the junkyard from any e34 for a few bucks

 

[Josco010]

Hi i have the same problem come winter time, so what i do is this, back seats notably behind the drivers runyour hands to the bottom there is a plack plastic you can pry open with your hands or flat screw carefully you use a 8mm bolt undo the nut and the a 13m bolt undo that and disconnects the battery end off, only downer is you loose time etc but thats it, this works for me because i don't have a switch in my garage to connect a trickle charger to. Tedoius but works for me.