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    Right so Iv a got a flat battery and car wont start. My question is if I jump start the car and rev it up and drive for a while, is it true that the battery will still have very little power? (albeit enough to turn the engine over everytime) and if so, is it possible to charge the whole battery by just keeping the car running for say 3hours or so? (basically, would the alternator charge the whole battery over time?)

    Basically, I cant be bothered to take the battery out and charge it ... thanks
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    You dont need to take the battery out - trickle charge it in the car.

    It depends why your battery is flat, if you've left radio on or something then jump start it and run her, and the battery will be fine.

    If your battery is knackered then jumping it and running it wont put enough charge into it to start the car next time.

    Way to check is run it and then turn it off and see what voltage the car is putting out, should be about 14.4 or at the very least something above 12.2.
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    Cool!! One more question, Im considering buying something like this; http://www.maplin.co.uk/Module.aspx?ModuleNo=224828 it looks pretty nifty, however am I right in thinking that I can just connect it to the ciggerette light socket and get the car started without plugging in this portable battery thing into the mains etc??

    thanks immensely
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    You wont need to take the battery out, but you will need to disconect it if you're usign a beefy charger.

    I charge batterys with a massive electric generator that used to be used to charge tanks of chemical solutions for chrome plating. So er... my tools are a little bit more hard core than what you buy of the shelf in halfrauds.
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    You'll ideally need to leave it to charge on a trickle charger overnight or something. IIRC an alternator won't charge a battery from flat. A dynamo on the other hand, will.
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    (Original post by Sver)
    Cool!! One more question, Im considering buying something like this; http://www.maplin.co.uk/Module.aspx?ModuleNo=224828 it looks pretty nifty, however am I right in thinking that I can just connect it to the ciggerette light socket and get the car started without plugging in this portable battery thing into the mains etc??

    thanks immensely
    Yes, just plug in. However I have heard mixed things about those cheap portable jump starters. Mainly that if you have anything but a very small engine in your car it doesn't have the kick needed to get it turning over properly. I would say though honestly not worth much having it, having a battery go flat is not exactly a weekly occurrence (Although saying that I did due to not having a working alternator for 7 weeks so had to remove the battery and charge it up via the mains every few days) and even then it is relatively easy to bump start the car down a hill or with the help of a passer by to get it charging again.
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    the little starting packs are rubbish ...

    a previous ops support manager brought one becasue ambulances have a habit of going flat if not isolated etc etc etc due to quiescent load ...

    no one used it instead prefering to use as their jump starter the LR discovery used to pull the 23 ft trailed treatment post as although it was lit + noised it had simple electrics or the merc minibus that quite literally has a lorry battery ...

    shorelines and 'battery conditioners' ftw in vehicles with high quiescent load ...

    the biggest problem is that 'starting' batteries don't like being deeply discharged

    the other thing to consider with starting packs is the power they can hold given a 'professional' starting pack is 2 lorry batteries on a trolley or a generator with 12 / 24 v output
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    those portable ones are useless if you're battery is anything mroe than 'a bit tired'. Also in maplin but the packs for £40-70, big yellow boxes with a carry handle seem to work relatively well though, it was as essential as the tyres in my granddad's Granada when it started to discharge after every other journey due to a knackered altenator..
 
 
 
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