S818A Battery Master Switch Option ?

AseanAero · 5th July 2012, 14:34

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 ?

xsailor · 5th July 2012, 20:21

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.

AseanAero · 5th July 2012, 21:55

Thanks X Sailor,

Yes , I'd be interested in seeing a picture

xsailor · 5th July 2012, 23:47

Here are a couple of pictures of the battery switch

DiegoR · 6th July 2012, 04:31

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.

AseanAero · 6th July 2012, 07:12

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 ?

Fordkoppie · 6th July 2012, 12:09

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.

AseanAero · 6th July 2012, 15:37

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 ?

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