BMW M5 Forum and M6 Forums banner

1 - 11 of 11 Posts

·
Registered
Joined
·
3,725 Posts
Discussion Starter #1
S818A BATTERIEHAUPTSCHALTER Battery master switch

I know what a battery master switch is (we have them on aircraft) but why is this an option on the M5 , what's the purpose ? How is it controlled ? Why isn't it fitted as standard ?
 

·
Registered
Joined
·
75 Posts
I think the battery master switch is only used during the shipping of the car from germany to the country where it is to be sold .
The master switch is in the middle of a 6ft. cable that is put in series with the - termanal of the battery and ground. So that the power to the car can be switched off during transport.
I was in a dealer's service area when new cars were arriving and the switches were removed as part of the pre delivery inspection. In fact one of the techs gave me one and it is in my basement,I could send you a pic if you want.
 

·
Registered
Joined
·
826 Posts
That's a cool thing! IOD fuse in the Jeep/Dodge vehicles that I sell and do the PDI's can't beat this technology back in the 90's! lol

I wonder if this kill switch was made bu Hella? It looks the same but the ones I bought, fails after some time working, the contact start to corrode or wear I think and loose the current energy.
 

·
Registered
Joined
·
3,725 Posts
Discussion Starter #6
It seems like a lot of effort (install and uninstall) for shipping when they could have disconnected the battery terminal.

Where was the cut off switch located when it was installed ?
 

·
Registered
Joined
·
449 Posts
Mine has this retrofitted.
The car stood for long periods with the previous owner (explaining the 54000km) and he simply located it through the carpet just in front of the battery well.
Very neat and out of sight. I like having it, since it gives some extra piece of mind should you detect a "thermal event" early on and it saves the battery when standing for long periods without having to remove the seat to get to the battery.
I have found however that the car would be full of funnies when it stood without power for a while. For instance the central locking wont work untill i physically locked and unlocked it from outside with the key. And sometimes a rough idle. They do sort themselves out after a minute or 2 and a couple of operations. Of course all your radio and OBC data would be lost.
 

·
Registered
Joined
·
3,725 Posts
Discussion Starter #8 (Edited)
I think a main battery master switch is a good idea , perhaps run a separate supply to the OBC and radio , if you like a low amperage 'avionics' power supply ?







-
 

·
Registered
Joined
·
46 Posts
It seems like a lot of effort (install and uninstall) for shipping when they could have disconnected the battery terminal.

Where was the cut off switch located when it was installed ?
It seems like a lot of effort (install and uninstall) for shipping when they could have disconnected the battery terminal.

Where was the cut off switch located when it was installed ?
They move the cars around all the time. So (dis)connecting the terminal everytime does take time.

With the switch inside, they just get in the car, flip the switch and be done with.

It was routed (maybe differently for each model) to rear seats or to in between the front seats.
 

·
Registered
Joined
·
1,109 Posts
When I worked at the dealership in the early 2000's, very many (but not all) new cars came with these switches and cables attached....we had to remove them during pre-delivery service and inspection, and they were required to be sent back to BMW NA in New Jersey (from Maui). It's been a long time, but I believe that all cars from Germany and South Africa had the cables, X5s from Spartanburg didn't....

One didn't make it back to New Jersey, by the way.....it somehow ended up in my old yellow 533i dirt oval race car... ;)
 

·
Registered
Joined
·
1 Posts
When I worked at the dealership in the early 2000's, very many (but not all) new cars came with these switches and cables attached....we had to remove them during pre-delivery service and inspection, and they were required to be sent back to BMW NA in New Jersey (from Maui). It's been a long time, but I believe that all cars from Germany and South Africa had the cables, X5s from Spartanburg didn't....

One didn't make it back to New Jersey, by the way.....it somehow ended up in my old yellow 533i dirt oval race car... ;)
Chris, Can you provide a picture of where the S818 runs in your E39? I'd like to add one (my own manufacture) to my 2000 M5. Thanks in advance. I would like to access it from the Drivers seat if possible. Maybe on the Rear Seat riser (passenger side)?
 
1 - 11 of 11 Posts
Top