Flat Battery - BMW 316

BombJack

manda1205 wrote: »

the auction uses jumper packs (propper 1's that cost thousands) because its not very professional to push start all these cars and things can break if you do (hands pushing lamps and spoilers etc)

if the battery had a internal fault (left on a car for years untouched) then it may not push start cos the battery is no longer making a circuit but if its a servicable battery it'll start with a push fine, soon as the lumps turning over it'll sort the ignition with power and off she goes, longer pushes needed for efi

as for jump starting frying ecu's its balls, ive heard these stories for years and its never from any1 it ever happened to, jumping is the same as normal starting, managment is protected from such problems by alsorts of jiggery pokery

i pref a good car battery for jumping and some really good jumper cables, a crap battery and wilco jumper cables wont start a moped and jumper packs under a few hundred quid are not worth the space they take up

if you do it alot a lorry battery will start anything, just dont forget to turn your lights off and if you do, beg/borrow some jumper cables from somebody whos handy and off you go again

Ok here's the deal. With respect to frying the electrics, it is possible if you are trying to jump a BMW with a car that uses a different voltage ie Ford, or Vauxhall. the reason being, that BMW use a 12.6 volt system, whereas the Fords use a 14.5 volt system.

It turns out that there shouldn't be a problem as long as the car providing the charge isn't actually ticking over, ie engine running. this would provide to much of a charge and potentially fry the BMW's electrics.

We did try to bump start it, but as a previous poster mentioned, if the battery is completely flat it won't matter how much you try, the engine won't kick in.

Interestingly, we got a neighbour to come round with his leads to provide the initial jump, which appeared to be ok - ie we could start our car. Thing is, as soon as he released the jump leads, the engine would die.

Why is this? Any ideas?

tomstickland

It suggests a totally knackered battery or a wiring fault.

espresso

BombJack wrote: »

Ok here's the deal. With respect to frying the electrics, it is possible if you are trying to jump a BMW with a car that uses a different voltage ie Ford, or Vauxhall. the reason being, that BMW use a 12.6 volt system, whereas the Fords use a 14.5 volt system.

Sorry but that is rubbish as they both use 12V batteries. The output from the alternator may reach 14.5V on both makes of car but the batteries are 12V.

Sounds like you didn't give the battery long enough to take some charge, before disconnecting the donor battery if the engine died. You can't charge a battery in minutes if it is totally flat.

manda1205

BombJack wrote: »

It turns out that there shouldn't be a problem as long as the car providing the charge isn't actually ticking over, ie engine running. this would provide to much of a charge and potentially fry the BMW's electrics.

Surely if you do that you're just taking the donor cars battery power, then gonna leave that one flat, sorry if thats an ignorant thing to say but I thought it had to be running to keep the alternator charging the donor cars battery????? And also agree with above posts, gotta leave it running for a while to give it enough power otherwise it will die(and also going on a long enough run to charge the battery (and turn your radio/lights off)otherwise when you stop again its gonna be flat again), and if you did this then go buy another battery.

misterthrifty

Hi

Interesting reading as my car had a flat battery today, and I only fitted it a month ago. The breakdown bloke says there could be an intermittent problem with the battery being drained. I thought about getting a booster pack just as a back up, are they really no good or do they at least work in an emergency?

Conor_3

BombJack wrote: »

Ok here's the deal. With respect to frying the electrics, it is possible if you are trying to jump a BMW with a car that uses a different voltage ie Ford, or Vauxhall. the reason being, that BMW use a 12.6 volt system, whereas the Fords use a 14.5 volt system.

Utter tosh.

Measure the voltage across the Ford when it's not running and it'll be around 12.6V. Measure it with the engine running, it'll be around 14V. Likewise the BMW.

Conor_3

BombJack wrote: »

Interestingly, we got a neighbour to come round with his leads to provide the initial jump, which appeared to be ok - ie we could start our car. Thing is, as soon as he released the jump leads, the engine would die.

Why is this? Any ideas?

Alternator is knackered and the battery is so flat it can't keep the engine running.

manda1205

ha ha ha, all 12v systems shoudl charge at 14v or a little above


if the car runs while jumped leave it for 5 mins to get some poke in the flat battery, then disconnect the jumpleads, if it still cuts out battery is dead, if it keeps goin for a bit then dies alts not charging, battery could be on its way wount neways if it goes flat over time and if didnt before (if it did before there could be a rain on it like a constantly powered stereo or faulty switch holding something on)