What's this thing on my battery?

Discussion in 'Tech/Mech General' started by marksmith, Sep 8, 2013.

  1. marksmith

    marksmith Read Only Funster

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    Hi folks,

    Can anyone tell me what this thing is/does on the positive terminal of my starter battery? (Roller Team on Fiat Ducato, 2004.) The negative terminal has a fairly straightforward terminal block on it - with connections to the chassis earth and leisure battery I presume - but the one above is on the positive terminal and looks much more complex than just a terminal block.

    Does it relate to the split charging system or fridge relay or something like that?

    [​IMG]

    (As an aside, the reason I'm looking at this is that we have just done our first tour with our own motorhome - two weeks in Scotland. On the way up and the way back the van failed to start after a stop of literally about two minutes - symptoms like a flat battery. On both occasions a jump start fixed it and all was well but it was completely unclear what caused it to happen. During the fortnight we must have stopped/started the van 50 times and had no trouble at all. Yesterday I discovered that the negative terminal was very loose - just lifted off - so I hope/suspect that's the problem.)

    Thanks!
    -Mark
     
  2. jb0371

    jb0371 Read Only Funster

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    probably just an adaptor to keep the wires all neat and tidy. Making it easier to connect and disconnect all the bits.

    Just my thoughts, not an expert by any means:BigGrin:
     
  3. hilldweller

    hilldweller Funster Life Member

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    Your main fuses. The + bussbar.
     
  4. pappajohn

    pappajohn Funster Life Member

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    loose neg terminal....definately the problem.

    would work fine powering the vehicles electronics but a very heavy load, like the starter motor, would break what contact there was.
     
  5. marksmith

    marksmith Read Only Funster

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    Thanks hilldweller - that sounds about right.

    Thanks jb0371 - but it's definitely more than just a terminal block.

    It's definitely a problem. Whether it's the problem remains to be seen but I'm hopeful. Exactly how it would behave would depend on what state of bounced-off-ness it was in at a given moment...
     
  6. hilldweller

    hilldweller Funster Life Member

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    Yes, but which one !!

    Our 2003 FIAT did this on us and I eventually traced it to the main engine<->chassis earth bond under the engine on the near side. Fully exposed to road spray, great move FIAT. Corroded joint on the engine, cut a bit off refit, fine. And with a mass of copperslip good for the rest of the life of the vehicle.
     
  7. BwB

    BwB Funster Life Member

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    You're lucky you could get jump leads to stay on the POS side, mine only just catch onto one of the bolts on that plate as you can't get to the battery terminal and will jump off almost every time I let go of the crocodile clip.

    (my newer fiat work van has the battery under the cab floor and two specific jump start terminals under the bonnet which are far easier to use) (hope I've not missed something similar on my motorhome van :Sad: )
     
  8. Merle

    Merle Funster

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    I have the same problem on my Peugeot Bryan, has any one tried the cigar lighter jump starters that are advertised? are they man enough for a diesel?
     
  9. TheBig1

    TheBig1 Funster Life Member

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    absolutely not anywhere near man enough. you are relying on a cigar lighter socket circuit capable of handling just 10amps

    a bad earth strap on the engine or loose terminal on the battery will cause this problem. better to fix the problem before it leaves you stranded. very simple for even a basic diy mechanic

    first check clean and tighten battery terminals. smear with a little vaseline to prevent corrosion

    then check the condition of the earth strap. if it looks frayed or burnt a little at the ends just unbolt both ends, clean the connecting points and bolt a new one in place. the earth strap is a thick wire, as thick as your finger between the engine or gearbox and the vehicle bodywork. its often exposed to the elements under the van where it get road spray and debris on it

    as for the bus bar, keep it clean and prevent anything metallic bridging it to any bodywork
     
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  10. pappajohn

    pappajohn Funster Life Member

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    still cant get my head around these things.

    how can something rated at maybe 2 amps (the battery in the box) provide power, through a 10amp cable (fag lighter supply wire), for a starter motor requiring upwards of maybe 400amps.

    even a car to car type lead would still only be rated at 10amps

    if these things actually work, why do we need such heavy 600amp+ jumpleads
     
  11. vwalan

    vwalan Funster

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    http://www.durite.co.uk/pdf/2013/4/04.5_Cable_and_Wiring-High_current_connectors.pdf
    better to have these fitted .then make a set of jump leads to fit .
    the prison trucks we build on have these as the batteries are hidden behind the cab . makes it easy just plug on then connect to other vehicle . tail lifts etc sometimes use them . but durite have outlets all over the country almost every auto electrician possibly buys off them .
     
  12. duane0001

    duane0001 Read Only Funster

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    Those are anderson lead ends, we use em for powering any ancillary equipment on artic trailers
     
  13. vwalan

    vwalan Funster

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    yes but they make ideal connections for jumping leads if batteries are buried . make the leads to the plug and have the other plug on your jump leads .
     
  14. Curtisden

    Curtisden Read Only Funster

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    Battery conections

    That is the mega fuse.

    Have you checked the electrolyte levels? You will have to remove the mega fuse board first carefully after removing the neg. first.

    Peter
     
  15. marksmith

    marksmith Read Only Funster

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    That was indeed a problem. The positive terminal is so inaccessible under the scuttle that I was worried the croc clip was going to pop off and bridge it to the metal panel right above it. That would have been messy. Why didn't they just put it the other way round - positive at the front?

    I was actually thinking of making a jump start terminal - just 20cm of shaped metal with a hole in one end to attach to a terminal, and heat-shrink sleeving over most of the length of it, and a removable cover over the exposed end.

    The cigar lighter ones I've seen (some time ago) were not jump leads but car-to-car chargers. You'd plug them in for an hour or so (charging at say 10A) and then you'd have 10Ah in your battery, which would hopefully be enough to run the starter for 5 seconds.

    The battery is the mainenance-free type. Anyway I think the loose neg terminal is very likely the cause of all the trouble. The battery is almost brand new - suspect the fitter introduced this problem.

    That's exactly what the AA van had. Quite handy if you are going to use it frequently. I'm hoping not to have to jump start it too often though... plus then your jump leads only work on one vehicle.
     
  16. mitzimad

    mitzimad Funster

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    you might get some charge in via a cigarette lighterif you have plenty of time but no way you could start via it ,wiring much to thin
    as said the photo is the bus bar and some fuses possibly the additional red wire is connected to the split charge relay
     
  17. Steve

    Steve Funster Life Member

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    My 05 2.8 Ducato has this set up handy for adding extra wires but not good to fix a jump lead to. The only time I had to jump I undid the battery and pulled it forward so I could get onto the + in a strong bit.
     
  18. marksmith

    marksmith Read Only Funster

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    Well it turns out the dodgy negative terminal was not the only problem. Shortly after replacing it the alternator stopped charging altogether. Removed the alternator, which tested OK. Battery is almost new.

    After quite a bit of hunting (and disappointing bad advice from a local specialist!) the problem turned out to be poor earthing: connected a jump lead from the alternator bracket to the battery -ve and it started charging perfectly. The bolt connecting the earthing strap to the gearbox was rusted to pieces. In fact it snapped when I tried to undo it.

    New bolt into a conveniently-located and suitably cleaned spare hole on the gearbox and now it's charging properly.

    As a precaution I've ordered a second earthing strap which I'm going to fit it between the alternator bracket and the body.

    It's a bit of a mystery that the van would start (but not charge) because both the starter and the alternator use the same earth. The starter sounds a lot stronger now though, so I think it was struggling too.
     
  19. hilldweller

    hilldweller Funster Life Member

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    Message 5 last month :Wink:
     
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