B2b charging set ups

Discussion in 'Tech/Mech General' started by Jaws, Mar 3, 2016.

  1. Jaws

    Jaws Funster Life Member

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    Odd question.. But I bet a lot of you will know where I am coming from ;)

    A good many people have fitted decent B2B charging units
    But I have seen a few ties reports of alternator and or alternator reg rec units failing

    At no time has anyone correlated the two things but it strikes me an alternator will be working a lot harder than usual with a b2B fitted.

    Of course all this is little more than mind meandering but how many of you have had an alternator failure after fitting. B2B, and at what mileage
    How many have had a failure that have not fitted a B2B and again, at what mileage ?
     
  2. Techno

    Techno Funster Life Member

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    When my alternator failed googling found that its quite common whether a B2B is involved or not and not even especially related to mileage but there does seem to be an age connection. Mine failed at just over 7.5 years

    EDIT my original B2B was fitted may 2008 so always been on from new.

    It has only cost me £12 plus postage for a replacement regulator and that has fixed the alternator
     
  3. Don Quixote

    Don Quixote Funster

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    If the B2B is "bluffing" the alternator via the vehicle battery (which it connect to) into thinking the vehicle battery needs charging, I cannot see why it would make it fail. I agree with Techno I think it's only done to age of the alternator and nothing else.
     
  4. Techno

    Techno Funster Life Member

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    Thanks to Jock we also now know where to get a brand new and 150 amp uprated alternator for sub £100 so I'd not have any trepidation about a B2B
     
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  5. tonyidle

    tonyidle Funster

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    There's no question the alternator is working hard when charging via a B2B. Alternators are sized not according to charging needs (which are minimal) but in line with the vehicle electrical load. The only time an alternator works hard is at night, when it's cold and raining (to operate lights, wipers, heater blowers, HRW, etc). Otherwise it does very little. The B2B will force it to perhaps 50% to 75% of its rated output which although higher (and probably for longer) than when it's supplying vehicle services is still well within its capacity.
     
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  6. Jaws

    Jaws Funster Life Member

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    I agree Tony well within its ability but...
    Also as you say it would normally only work hard for maybe 15% of its expected life..
    So hooking up a B2B will mean it is working harder for longer and for a greater % of the time.
    Given that alternators rarely fail due to mechanical issues, but rather electrical ones, i think we must take it there is a finite amount of amps ( putting it crudely ) an alternator will deliver before failure...

    And so far no one has actually answered the op question ! :)
     
  7. Techno

    Techno Funster Life Member

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    A commercially used van will drive day in day out all winter with lights heater wipers etc .
    A B2B on a motorhome that does low mileages doesn't compare to that hammering
     
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  8. Techno

    Techno Funster Life Member

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  9. Techno

    Techno Funster Life Member

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    deleted
     
    Last edited: Mar 3, 2016
  10. dave newell lvs

    dave newell lvs Trader-Vehicle Services

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    Alternator failure is a more common occurrence than it should be on late model Ducatos, I have one to replace for a customer next week and no B2B fitted.

    In edit, the last time I saw such a high frequency of alternator failures was in the 70s on Vauxhall Vivas where the alternator was mounted right under the exhaust manifold. Perhaps with the higher output of modern alternators and the mounting position of at the rear of the engine not far from the turbo and exhaust downpipe the regs are failing due to heat build up?

    D.
     
  11. Jaws

    Jaws Funster Life Member

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    Ok.. Let's break that down.
    Headlights .. Two at 55 w, 110w,
    Side and tail lights 4x5w, 20w
    Intermittent brake lights, 2x21w, 42w
    Indicators 2x21w, 42w
    Heater fan approx 50w
    Wipers approx 50w
    Odds and sods 30w

    Total 386 w or about 30 amps tops
    Note I have allowed zero to battery charge as with the above figures all draw is from the alternator and nowt from the battery.. Apart from replacing the current drawn by starting the battery is, for the sake of this discussion, not worth adding

    Now then.. The same stuff will be in the average motorhome
    With a b2b hooked up to a couple of 110aH batteries that have been brought a bit low after a few days of use as a bonus

    You start the motor.. After say 10 minutes the cab battery is back up, but the Hab batteries are gonna be sucking in as much as the alternator is willing to or able to deliver..
    So let's put a realistic figure on the running draw of say a max of 20 amps..
    That leaves about 45 amps to feed a couple of hungry half dead batteries
    Which basically means the alternator will be absolutely flat chat for a while.
     
  12. Techno

    Techno Funster Life Member

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    My alternator in common with many other vehicles is 110amp. A 50 amp b2b is not going to stress it as evidenced by it lasting nearly 8 years
     
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  13. Don Quixote

    Don Quixote Funster

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    At the end of the day there are 1000's of B2B sold and very few reports that it kills an alternator. So in my case I'm happy enough the run a B2B in my MH. What others do is up to them.
     
  14. Jaws

    Jaws Funster Life Member

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    Ok.. So lots of happy users :)

    So wi anyone answer my origina questions ?
     
  15. Techno

    Techno Funster Life Member

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    What do you want to hear that you haven't already. You might have a long wait for someone to claim theirs failed as a result of a B2B
     
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  16. JockandRita

    JockandRita Funster Life Member

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  17. Jaws

    Jaws Funster Life Member

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    I asked at what mileage alternator failed with a unit fitted, and what mileage alternator failed without ..

    Quoting ages is not really helpful as the mileages folk do varies so much
     
  18. Techno

    Techno Funster Life Member

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    Oh sorry, mine was over 47k all with B2B
     
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  19. Jaws

    Jaws Funster Life Member

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    Cheers Andy.
    I fully expect zero correlation between b2b and failure but if I can get enough data it would be good to lay fears to rest
     
  20. thehutchies

    thehutchies Funster

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    The rectifier failed on ours at 10 years and 25000 miles. No B2B but 440Ah of heavily used batteries to charge.
     
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