Tv : run battery dead

Z

Z4edmo

Member
What a night I have just had. Had to do brownies pickup but arrived 30 mins early so decided to watch the built in tv to pass time. Top gear on Dave :D my fun was soon ruined when I tried to drive off. Dead . A friend offered to jump start me but luckily I decided to phone Aa . He got me going in no time said that I need to use more and that battery was fine.he told me never to jump as the Ecu would blow. £2000 to fix I believe.
Has anybody else experienced this problem ?
 
Z4edmo said:
What a night I have just had. Had to do brownies pickup but arrived 30 mins early so decided to watch the built in tv to pass time. Top gear on Dave :D my fun was soon ruined when I tried to drive off. Dead . A friend offered to jump start me but luckily I decided to phone Aa . He got me going in no time said that I need to use more and that battery was fine.he told me never to jump as the Ecu would blow. £2000 to fix I believe.
Has anybody else experienced this problem ?
Click to expand...

why exactly? maybe if you jumped it with a 24v lorry :? but all you are doing is connecting another 12v battery in parallel giving a total of, err, 12 v?

Never heard of an ECU being blown in such circumstances .....but then I was wrong once before. :thumbsup:
 
Z4edmo said:
What a night I have just had. Had to do brownies pickup but arrived 30 mins early so decided to watch the built in tv to pass time. Top gear on Dave :D my fun was soon ruined when I tried to drive off. Dead . A friend offered to jump start me but luckily I decided to phone Aa . He got me going in no time said that I need to use more and that battery was fine.he told me never to jump as the Ecu would blow. £2000 to fix I believe.
Has anybody else experienced this problem ?
Click to expand...

I would also say that, in my experience, once a battery on this model has died, for whatever technical reason I don't understand, the charging system is sufficiently sophisticated (or the battery sufficiently crap) that it will never return to optimum functionality. If the battery is 3-4 years old and the car under-used, I'd junk it in favour of a new one and get myself a battery conditioner.

And hope it doesn't trip into transport mode......
 
I think the reference is when jumping on the wrong connection points.

Using the dedicated points under the bonnet is fine.
 
lacroupade said:
Z4edmo said:
What a night I have just had. Had to do brownies pickup but arrived 30 mins early so decided to watch the built in tv to pass time. Top gear on Dave :D my fun was soon ruined when I tried to drive off. Dead . A friend offered to jump start me but luckily I decided to phone Aa . He got me going in no time said that I need to use more and that battery was fine.he told me never to jump as the Ecu would blow. £2000 to fix I believe.
Has anybody else experienced this problem ?
Click to expand...

I would also say that, in my experience, once a battery on this model has died, for whatever technical reason I don't understand, the charging system is sufficiently sophisticated (or the battery sufficiently crap) that it will never return to optimum functionality. If the battery is 3-4 years old and the car under-used, I'd junk it in favour of a new one and get myself a battery conditioner.

And hope it doesn't trip into transport mode......
Click to expand...

I guess this is because the batteries on normal road cars don't take kindly to deep cycling and soon die if you keep doing it. If running the TV is enough to kill it then regardless of regular use the battery is likley somewhat tired and in need of replacement.

Really not sure where this myth about no jump starting comes from. Go to any iarport car park and see then jump start dozens of cars a day.
 
I agree with what you all have said, as that was my thinking. However I have spoke to three separate mechanics and they have all said that a standard boaster charge is 12 v and will blow the ECU as on the zed it is only 8v . The Aa me Janice also went on to say that the first thing they check when called out is that the display is on and if not you have to sign to agree that it is off.lots of people seem to try it on. One story he told me about was that he got called out but noticed big tyre marks on the lawn and New they had tried to jump it, the display was out but the customer swore blind that he hadn't done anything. The AA driver then refused to get him started.
In answer to how did he get me going , there boaster charger costs a fortune and is designed differently than the ones we buy.
Regards the battery took it in to BMW dealership who checked and said battery a ok?
I am no mechanic and thought the same as you. This might be m specific I don't know but thought I should share with you all
 
That all sounds crock to me. I think you need to find a decent auto electrician to explain the ins and outs.

The voltages coming out of, or being sensed by, the ECU will vary from 0.5 to 12 volts depending on what sensors its reading data from, and there may well be an 8v supply coming out somewhere to feed something, but its fundamentally a 12v device, so unless BMW has done something very radical for reasons I can't even begin to fathom, and fitted an 8v management device to a 12v system (I mean why???), then your AA man is talking rubbish. I mean the car would then need 8v relays, not 12v, and all sorts of other stuff to boot.

Similarly, the dealer has clearly done a pretty lousy check on the battery, given that the reality is its gone flat in 30 minutes with minimal drain on it....I'd be going somewhere else.

But as CJ says, the jump start 'issue' is a complete myth as far as I am aware.
 
There's loads about this stuff on the internet and as far as I can see the issue seems to come from connecting boosters to dead batteries directly. I guess perhaps they can up the voltage way past the 12.x of a normal battery, or a spiked voltage.

However I see no reason why a jump start car to car, especially if it's using the correct points as opposed to terminal to terminal can have any detrimental effect.

Of course getting the wrong terminal to terminal or not a clean connection might cause a lot more fun
 
Why would connecting to the points under the bonnet make any difference? They're still connected to the battery and therefore the rest if the car such as the ECU...
 
Liam-O said:
Why would connecting to the points under the bonnet make any difference? They're still connected to the battery and therefore the rest if the car such as the ECU...
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I agree with CJ and I'm thinking that maybe the underbonnet connecting points are electrically protected in some way, as opposed to just being a convenience?

Doing a bit of research it seems thats its very common for an alternator charging circuit to 'spike' if an external supply (another battery or booster) is disconnected WHILE THE ENGINE IS RUNNING - bit perverse since presumably you would have trouble re-starting, but fact is, accepted wisdom seems to be that is the case, and you are supposed to leave it running and connected for 5-10 minutes, TURN OFF, disconnect the external source, then restart yourself.

So it sounds like its operator error that can blow an ECU, NOT the mere process of jump starting.

Having said that, how many times have we whipped the jump leads off while the engines running? LOL Guilty as charged, but not any more....as the OP indicated, ECU replacement is fricking expensive!
 
I don't think the cable run from the correct points is protected per se. There may be some benefit in that the main has a long cable run and earth is the chassis, rather than terminal to terminal.

I'm still convinced human error in wrong connections, or not making a smooth and quick connection is half the trouble.

Fact of the matter is jump starting should be a rare event and whne done almost always in a stressed time when sitting around waiting for a charger, the AA, etc. is not an easy option.
 
Was curious to see what the handbook procedure was,donor engine switched off and all consumables off as well, connect positive on the dead car then positive on the donor, negative on the dead car then negative on donor, start donor car and run fast idle for a few mins, start dead car, if wont start leave donor running for several mins and try again, once started leave both running for a few mins then remove leads in reverse order.
Usual procedure as far as i can see.
 
When I cable BMW assist out he happily jumped my car with his booster pack direct from the battery. He would have had trouble trying to get under the bonnet without pushing the car out of the garage a few feet.
 
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