E34: Battery transfer (front to rear seat)

[ktteoh]

moots, there is already an existing heavy gauge wire - no (3) on my diagram - connecting the fuse A and fuse B - albeit it is not as thick vs the ones to the starter motor from the front battery terminal.

yes perhaps the batt will last longer located away from the engine heat but i really am not keen to route a thick gauge wire from the rear seat....tell us how it goes shud u decide to proceed.....me Malaysian too....he he

[ktteoh]

ferret, here's the existing front engine +ve connections and the front main fuse:

Kttroh, snap us a photo of the +ve batt terminal and the leads coming out of it plus where they anchor... I was sure my 525i only had small leads coming off the batt to the fuse point.

[Ferret]

ferret, ok. i will snap that when i get home. meanwhile i would still like to know if the wire no (3) - connecting fuse A to fuse B - can cope with the current load demand of the starter motor.

it looks like a heavy gauge wire but the one (at the front battery) to the starter motor is "thicker".

thoughts?

Hurr, it'd probably kick the engine over happily from a short burst. But, more than a few seconds cranking would cause that wire to heat up badly, and it runs under carpet. I'd hit a scrap yard and rip out the battery wire off something with an underseat battery rather than risk pushing that...

I had a look at my diesel one while I was just out doing the rear brakes, and it's around the 3/4" thick mark. (Though, diesels do take a hell of a lot of current to start and its got a massive battery.)

[Ross]

Yep, that little wire won't handle the starter load. 4 gauge is what you need.

[ktteoh]

what is a 4 gauge - would a battery cable that handles 60A do? or 100A?

Yep, that little wire won't handle the starter load. 4 gauge is what you need.

[BIGRED]

Seems like a lot of work at a fair cost to accomplish something that a month later will be forgotten (of course that is said without having an understanding of what you are experiencing).

Curious as to why this seems to be an important modification? I noted a mention of hot temperatures. Is it killing batteries that warranty won't cover or at such a rate that its a pain?

For myself, I would have preferred to have the battery located under the hood. Not all that keen on having something with acid sitting under my kids. I know of a couple of battery explosions, but trust that BMW knows whats best.

Regards
Don

[Ferret]

Seems like a lot of work at a fair cost to accomplish something that a month later will be forgotten (of course that is said without having an understanding of what you are experiencing).

Curious as to why this seems to be an important modification? I noted a mention of hot temperatures. Is it killing batteries that warranty won't cover or at such a rate that its a pain?

For myself, I would have preferred to have the battery located under the hood. Not all that keen on having something with acid sitting under my kids. I know of a couple of battery explosions, but trust that BMW knows whats best.

Regards
Don

Hmm, as well I've just remembered that the battery should have a heat shield up one side of it as standard fit on an M50 bay...?

Yours gone missing somewhere ktteoh?

[ktteoh]

ferret, the ones in malaysian market somehow doesn't come with the head shield (for the exhaust side) - i asked before. anyway can send me a picture of what the heat shield looks like?

for the wire (3), i notice that fuse B is rated at 80A - would that indicate that wire (3) is sufficient for 80A - if so would 80A be sufficient for all electrical load during starting.

Hmm, as well I've just remembered that the battery should have a heat shield up one side of it as standard fit on an M50 bay...?

Yours gone missing somewhere ktteoh?

[shogun]

item 14?
http://www.realoem.com/bmw/showparts...61&fg=30&hl=92
here is all I found with the search for heat
http://www.realoem.com/bmw/partsearc...1&mospid=47370

[ktteoh]

shogun, what are items 7, 12 & 14 - it is not in the description? i think i'm missing those items in my current setup.

item 14?
http://www.realoem.com/bmw/showparts...61&fg=30&hl=92
here is all I found with the search for heat
http://www.realoem.com/bmw/partsearc...1&mospid=47370