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Charging from a jump point?

  • 18-06-2020 12:38pm
    #1
    eamonnq
    Registered Users, Registered Users 2 Posts: 4,012 ✭✭✭


    Have a 00 Mercedes C180 with a flat battery, battery is in the boot but can't open the boot as the battery is flat and the actual key won't open the boot either.

    There is a jump point under the bonnet, but am wondering if it is possible to stick a battery charger onto the jump point in the hope of charging the battery or is it the jump point only useful for jump starting the car ?

    Car is in an awkward position to even use jump leads just to start it too.


Comments

  • #2
    ironclaw
    Registered Users, Registered Users 2 Posts: 8,004 ✭✭✭ironclaw


    It should be no problem. Just check your manual for the correct jump start/charge procedure as some cars have weird and wonderful points for jumping versus charging. Pretty sure some VW's had points under the seat / in the boot at one point.


  • #3
    Isambard
    Registered Users, Registered Users 2 Posts: 5,795 ✭✭✭Isambard


    charger starter ftw to suitable connections or just use the battery out of another car and jump leads. Will be qjuicker than trying to charge what may be a scrap battery


  • #4
    Voodoomelon
    Registered Users, Registered Users 2 Posts: 9,661 ✭✭✭Voodoomelon


    On the contrary, many modern cars should never be charged or jumped directly to the battery. If there is a jump point, absolutely use that to charge.


  • #5
    eamonnq
    Registered Users, Registered Users 2 Posts: 4,012 ✭✭✭eamonnq


    Thanks for the replies, will give it a go and hopefully get it going. Hasn't moved since lockdown began. Tax is a few months behind now, so probably won't take it out for another while either!!


  • #6
    listermint
    Registered Users, Registered Users 2 Posts: 34,217 ✭✭✭✭listermint


    Voodoomelon wrote: »
    On the contrary, many modern cars should never be charged or jumped directly to the battery. If there is a jump point, absolutely use that to charge.

    Why


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  • #7
    galwaytt
    Registered Users, Registered Users 2 Posts: 12,823 ✭✭✭✭galwaytt


    listermint wrote: »
    Why

    Not 100% sure, but I believe it's capacitance of the new batteries and the effect on electronic control systems - including of the charging battery/charging circuit.

    In fact, the only 'official' way I've ever seen to jumpstart is:
    Earth clamp off charged vehicle to Earth POINT (not battery earth terminal) of dead vehicle.
    Live clamp off charged vehicle to Live terminal of dead vehicle.

    In real life, for most, they go Earth terminal-Earth terminal, and Live Terminal-Live Terminal purely for convenience and with std charging systems and lead acid batteries its tolerant of that.

    Newer stuff and coded batteries I'm not so sure.

    In the OP's case, on my 996 if the battery goes awol - and it does - the procedure to open the bonnet is: open car door, remove fuseboard cover, pull out the RED jumper 'plug' and connect the + of your new battery to it, and connect the - to the door hinge. This puts enough juice in it for you to open the bonnet (electric lock).

    To actually jumpstart the car you go the the back of the car and there's a jumping + and a negative to use. Which, of course, you need the electric lock to open.............


    Try connecting your battery to the jump point and just pressing the button to open the boot and forget about charging via the jumping posts, and then connect your charger as normal.

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    “And my existence, while grotesque and incomprehensible to you, generates funds to the exchequer. You don't want to acknowledge that as truth because, deep down in places you don't talk about at the Green Party, you want me on that road, you need me on that road. We use words like freedom, enjoyment, sport and community. We use these words as the backbone of a life spent instilling those values in our families and loved ones. You use them as a punch line. I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the tax revenue and the very freedom to spend it that I provide, and then questions the manner in which I provide it. I would rather you just said "thank you" and went on your way. Otherwise I suggest you pick up a bus pass and get the ********* ********* off the road” 



  • #8
    R.O.R
    Registered Users, Registered Users 2 Posts: 12,712 ✭✭✭✭R.O.R


    In the past I tried trickle charging an E90 3 Series from the jump points under the bonnet (easier than trying to get at the battery in the boot) and it didn't work.

    Charger left overnight and was still dead as a dodo in the morning - charger worked on other vehicles so wasn't that.

    As above, hopefully connecting the charger to the jumping posts will give enough juice to open the boot, then trickle charge the battery directly.


  • #9
    eamonnq
    Registered Users, Registered Users 2 Posts: 4,012 ✭✭✭eamonnq


    galwaytt wrote: »


    Try connecting your battery to the jump point and just pressing the button to open the boot and forget about charging via the jumping posts, and then connect your charger as normal.
    R.O.R wrote: »
    In the past I tried trickle charging an E90 3 Series from the jump points under the bonnet (easier than trying to get at the battery in the boot) and it didn't work.

    Charger left overnight and was still dead as a dodo in the morning - charger worked on other vehicles so wasn't that.

    As above, hopefully connecting the charger to the jumping posts will give enough juice to open the boot, then trickle charge the battery directly.

    Should I try the battery or the charger ?:confused:


  • #10
    teediddlyeye
    Registered Users, Registered Users 2 Posts: 436 ✭✭teediddlyeye


    galwaytt wrote: »

    Newer stuff and coded batteries I'm not so sure.

    There seems to be some confusion even in the trade about that. You don't actually "code" a battery, you tell the battery monitoring that it has had a new battery fitted and enter the capacity, that's really it, once it's the correct type for the car that is.

    You should charge a battery off the jump point so that the control unit can see that there's current flow into the battery and will adjust the charge level.

    For jump starting in work we've a big battery on wheels that's just connected straight to the terminals and that's it. Never a problem on even new cars.

    "I never thought I was normal, never tried to be normal."- Charlie Manson



  • #11
    jimgoose
    Registered Users, Registered Users 2 Posts: 20,195 ✭✭✭✭jimgoose


    R.O.R wrote: »
    In the past I tried trickle charging an E90 3 Series from the jump points under the bonnet (easier than trying to get at the battery in the boot) and it didn't work.

    Charger left overnight and was still dead as a dodo in the morning - charger worked on other vehicles so wasn't that.

    As above, hopefully connecting the charger to the jumping posts will give enough juice to open the boot, then trickle charge the battery directly.

    Hmm. I had a trickle-charger on a 2010 F10 520D belonging to the brother for a couple of years while he was away, connected to the positive jump-point under the bonnet and grounded to chassis via a bolt on top of the shock. Worked fine.


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  • #12
    R.O.R
    Registered Users, Registered Users 2 Posts: 12,712 ✭✭✭✭R.O.R


    eamonnq wrote: »
    Should I try the battery or the charger ?:confused:

    Do you have a spare battery or can you jump it? I'd be trying to get power to the car through the jump points any way you can. Shouldn't need much power to be able to open the boot, then once you are in the boot, connect a trickle charger to the battery.
    jimgoose wrote: »
    Hmm. I had a trickle-charger on a 2010 F10 520D belonging to the brother for a couple of years while he was away, connected to the positive jump-point under the bonnet and grounded to chassis via a bolt on top of the shock. Worked fine.

    Never tried it on anything else after that due to failure on the E90 - think it was an 08 model, so going back quite a while. Can't even remember if there's 2 terminals for the jump points, or if it had to be grounded elsewhere

    Could well have just been a bad ground that meant it didn't charge. Getting harder and harder to find a decent ground point under the bonnet, close enough to the battery, nowadays. Especially if it's a trickle charger with short enough cables.


  • #13
    jimgoose
    Registered Users, Registered Users 2 Posts: 20,195 ✭✭✭✭jimgoose


    R.O.R wrote: »
    ...Never tried it on anything else after that due to failure on the E90 - think it was an 08 model, so going back quite a while. Can't even remember if there's 2 terminals for the jump points, or if it had to be grounded elsewhere

    Could well have just been a bad ground that meant it didn't charge. Getting harder and harder to find a decent ground point under the bonnet, close enough to the battery, nowadays. Especially if it's a trickle charger with short enough cables.

    Only one on that F10 that I could find, the positive. I was able to get a decent ground, via clamp.


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