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Ive been away for 9 months and returned a few days back. I tried to start my BMW 1 series 2007 118D and it wouldn't start.

The car was completely dead as the fob wouldn't do a thing, so I tried to jump start it from the jump points under the hood. The dash all lights up, radio comes on fine, lights, etc. but the ignition dies when I press the start button.

I'm presuming the battery is stone cold dead. I tried to keep it on the jump start from the other car for over half an hour but it doesn't seem to be getting much better (charged). Will a standard trickle battery charger be OK with an e87?

Cheers.

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    You can try to charge the battery, but when the remote key didn't work and no dash light went on, be prepared to buy a new battery. It could be deep discharged and so have lost most of its capacity. Even if you manage to charge it to a point where the motor starts, you could get problems in the winter or when driving short distances.
    – sweber
    Sep 21, 2016 at 8:45
  • Battery is dead... so recharge it.
    – cory
    Sep 21, 2016 at 18:44

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Yes, a standard trickle charger will be fine. You need to make sure you give it plenty of time on charge, circa 16 hours; cranking a diesel engine takes around 700 Cold Cranking Amps. You may also find that, being diesel, it takes some time to prime the fuel system.

I know it sounds obvious, but disconnect the charger before you attempt to start it. Don't be tempted to try and start it after it's been on charge a couple of hours either or you'll be back to square one.

Good luck.

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A lead acid battery will self discharge about 5% every month. Assuming your battery was 100% charged, and there is no parasitic draw, that gives us a charge of ~55% after 9 months.

Realistically, your battery is more likely at about 40-45% charge, so a very slow trickle charge of about 2A (as others have mentioned, 16 to 24 hours) should bring the battery up to a decent state. The slower the better, as a fast charge is ok for topping off a lead acid battery but not really good if you want to recover a battery from a deep discharge state.

I'd also be prepared to buy a new battery. You've not said how old the battery is, so I'll assume it's the original battery from 2007. If this is the case, your battery will most likely be on it's last legs anyway - Lead batteries have a lifespan of 4-6 years.

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  • I'm not sure that his battery isn't even lower than that, in view of the fact that the electrical systems aren't coming on.
    – anonymous2
    Sep 21, 2016 at 11:45
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You can try leaving it on a trickle charger overnight - as Steve says, 16 hours at least. However, if the battery has been left discharged for that long, I suspect it will have lost much of it's ability to hold charge, so you may well have to consider buying a new one...

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  • Thanks for the info. I have read it can be a bit tricky to just replace a BMW e87 battery. Apparently it needs to be re-programmed (smart sensor board) etc. Is this correct or is it just as easy as take out the old battery and replace it with a new?
    – s cro
    Sep 21, 2016 at 11:42
  • That's true, @scro. You should get your battery registered at a dealer, to prevent issues with your IBS.
    – anonymous2
    Sep 21, 2016 at 11:44

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