Battery cut off

[JungleGus]

Does anyone have any pics of a nice tidy installation of a battery cutoff in a 325i? I'm more interested in it for battery saving purposes rather than motorsport.

Although re-setting the clock every single drive is a PITA....

[flybynite]

if you don't specifically want it in reach from the drivers seat I would attach the cut off to one end of the battery lead either under the bonnet or in the boot. Then make a short lead back to the battery or terminal block where it came off.

That way you are not hacking into the original battery wire.

[JungleGus]

The bonnet sounds most appealing in that case since there is a bit more room to play (with the plastic cover in the boot, there's not much room to the terminal).

Does the battery cable go straight from the positive terminal to the RH turret connection and only then connect to the engine/body loom? Makes sense I guess

[flybynite]

The bonnet sounds most appealing in that case since there is a bit more room to play (with the plastic cover in the boot, there's not much room to the terminal).

Does the battery cable go straight from the positive terminal to the RH turret connection and only then connect to the engine/body loom? Makes sense I guess

On mine it looks to go straight, plenty of images of 'battery relocation kits' about. Also this might give you some ideas

https://www.e30zone.net/e30wiki/index.p ... ry_In_Boot



Is this a long-term thing or is the battery draining quickly?

[JungleGus]

Something like this looks about right - also seems to have a cut-off to keep voltage to stereo, although wiring that in may be beyond me

Battery is new and fine, just want to keep it disconnected while in storage for 1-2 months at a time so it doesn't drain - more of a preventative measure

[martauto]

I have one on mine which is very similar but it cuts out everything .If I know I wont be using it for a few days then it gets turned off, also it helps to stop the opertunists having a go.
I would like to see a better one from inside the car.

Mart.

[Satan]

Something like this looks about right - also seems to have a cut-off to keep voltage to stereo, although wiring that in may be beyond me

Battery is new and fine, just want to keep it disconnected while in storage for 1-2 months at a time so it doesn't drain - more of a preventative measure

I have this on my E30, yep it can be a pain to reset the clock and the stereo and for the ECU to get its optimal settings back but at least it stops the battery draining.

I have this on the Lotus it was already fitted to the car and its under the front hood.

[Brianmoooore]

Ideally, any cut off switch should be in the battery negative lead, which with a rear mounted battery, confines it to the boot. The switch with the red handle, above, is suitable. These switches are also used in touring caravans as isolators for remote control movers, and recessed housings are available to mount these switches in for a tidy installation.
The clock, radio memory, SI board, etc., ARE what drains the battery, so little point in fitting a switch with a bypass resistor.
Don't forget that if you have the later type of SI board, the batteries will fail after a year or two of cumulative battery disconnection.

[Satan]

Ideally, any cut off switch should be in the battery negative lead, which with a rear mounted battery, confines it to the boot. The switch with the red handle, above, is suitable. These switches are also used in touring caravans as isolators for remote control movers, and recessed housings are available to mount these switches in for a tidy installation.
The clock, radio memory, SI board, etc., ARE what drains the battery, so little point in fitting a switch with a bypass resistor.
Don't forget that if you have the later type of SI board, the batteries will fail after a year or two of cumulative battery disconnection.

Mine is fitted to the negative lead but my battery is under the bonnet half a turn or so and it's disconnected, the issue in my car apart from the long standing around not being driven bit was a parasitic drain on the battery of a dodgy alarm install.

Most issues with battery drain are either an aftermarket/faulty alarm install or a bodged stereo upgrade.

[Brianmoooore]

Mine is fitted to the negative lead but my battery is under the bonnet half a turn or so and it's disconnected, the issue in my car apart from the long standing around not being driven bit was a parasitic drain on the battery of a dodgy alarm install.

Most issues with battery drain are either an aftermarket/faulty alarm install or a bodged stereo upgrade.

Parasitic drain is a current draw from the battery that is intentional by the designers. It's the current drawn by the radio memory, the clock, the instrument cluster memory, the OBC and a working alarm/immobiliser/remote central locking, plus anything else I've forgotten. In a car in normal use, this drain causes no problems, and the battery is replenished within seconds or minutes of starting the car. It only causes problems with cars that are laid up for long periods of time.
What you are describing is an electrical fault.

[ChrisHC]

I use a maintenance charger when not using the car for any lengthy period, in a garage with power that is no problem, outside you can get a solar powered one and you can put it inside the car and run the cable out of the door and under the bonnet, the rubber seals accommodate it easily. Having wrecked batteries in the past by allowing them to go flat, I am now quite careful to set it up.

[flybynite]

I use a maintenance charger when not using the car for any lengthy period, in a garage with power that is no problem, outside you can get a solar powered one and you can put it inside the car and run the cable out of the door and under the bonnet, the rubber seals accommodate it easily. Having wrecked batteries in the past by allowing them to go flat, I am now quite careful to set it up.

I keep a couple of small Cteks for exactly that and they do very well, but I assume the OP can't leave it connected.

I used to use a solar panel on my E36 M3, it helped but didn't work that well. However, that car was a pig for battery drain and it was a while ago, they should be better now.

Problem is a solar charger tends to advertise the car is parked up and probably won't be missed for a while.

[Satan]

Mine is fitted to the negative lead but my battery is under the bonnet half a turn or so and it's disconnected, the issue in my car apart from the long standing around not being driven bit was a parasitic drain on the battery of a dodgy alarm install.

Most issues with battery drain are either an aftermarket/faulty alarm install or a bodged stereo upgrade.

Parasitic drain is a current draw from the battery that is intentional by the designers. It's the current drawn by the radio memory, the clock, the instrument cluster memory, the OBC and a working alarm/immobiliser/remote central locking, plus anything else I've forgotten. In a car in normal use, this drain causes no problems, and the battery is replenished within seconds or minutes of starting the car. It only causes problems with cars that are laid up for long periods of time.
What you are describing is an electrical fault.

It was fault, a fault with the shite alarm that was draining far too much, I tested and worked out where the train was and eliminated the problem. Was a sparks and network engineer in the past so used to being able to fault find certain things out.

[Satan]

I use a maintenance charger when not using the car for any lengthy period, in a garage with power that is no problem, outside you can get a solar powered one and you can put it inside the car and run the cable out of the door and under the bonnet, the rubber seals accommodate it easily. Having wrecked batteries in the past by allowing them to go flat, I am now quite careful to set it up.

Do not leave the charger in the engine bay of the car or in the car as on a Lotus forum a guy had one left it in the car and it failed, started a fire and totalled the car (a nice low mileage S1) it was written off and damaged the garage and could of burnt the house down.

[ChrisHC]

That's a useful warning. Perhaps also a warning against buying very cheap electrical products, there are a lot of very shoddy items of all sorts about now

[Brianmoooore]

Was a sparks and network engineer in the past so used to being able to fault find certain things out.

I know - we're both on the ElectriciansForums.net . You have a different user name on there, but posted a pic. of your white cab. once, which got my attention.

[Satan]

That's a useful warning. Perhaps also a warning against buying very cheap electrical products, there are a lot of very shoddy items of all sorts about now

It was a Sealey unit.......