Nasa BM1 Battery Monitor

Discussion in 'Tech/Mech General' started by Hellboy, Dec 22, 2013.

  1. Hellboy

    Hellboy Funster

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    I would like to monitor the 2 leisure batteries fitted to our Autotrail :Smile:
    Q. Can you use the Nasa BM1 to monitor 2 x 110ah Elecsol carbon fibre batteries? (BM1 instructions only mention lead-acid)
     
  2. pappajohn

    pappajohn Funster Life Member

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    your two batteries will be linked as one large battery (in parallel), and the BM1 uses a 100amp shunt so you shoud be able to use with any battery type and any number connected together.
    it measures the current passing through the shunt and doesnt care where that power originates.
     
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  3. Hellboy

    Hellboy Funster

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    The 2 batteries on our Autotrail are connected by 2 seperate plug in fly-leads...
    How do I connect the 2 x -ve's to the shunt with just 1 cable supplied?
     
  4. pappajohn

    pappajohn Funster Life Member

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    you cant.....

    both batteries must be connected in parallel...pos to poss and neg to neg....in effect becoming one large battery.

    no reason why you couldnt connect in parallel.
    just link the two batteries and connect both flying leads together to the posts of one of the batteries.

    that has the effect of doubling your ah reserve to 220ah while maintaining 12v

    then connect the BM1 as instructed and calibrate as 220amp hour
     
    Last edited: Dec 22, 2013
  5. gozomike

    gozomike Funster Life Member Life Member

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    Hi

    I fully agree with what Pappajohn is saying on the use and connections, I just wonder if the % left will indicate correctly with non lead acid batteries, is the minimum usable voltage the same?

    Mike
     
  6. pappajohn

    pappajohn Funster Life Member

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    it should do.

    BM1 calculates the known full capacity (110ah @12.6v), if it was programmed for 110ah, minus the present voltage (say 12.3v = approx 50% of available capacity therefore 27.5ah remaining(55ah usable capacity)) and all points between 12.6 full and 12v dead
     
  7. FULL TIMER

    FULL TIMER Read Only Funster

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  8. pappajohn

    pappajohn Funster Life Member

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    effective, but still only a dual scale volt meter with fancy scale markings.
     
    Last edited: Dec 22, 2013
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  9. Hellboy

    Hellboy Funster

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    It would appear Elecsol Batteries are Lead-Acid after all :thumb:
    The Elecsol brand have been around for some years producing high quality unique carbon fibre lead acid leisure batteries.
    The patented carbon fibre technology reinforces the lead plates and helps prevent the plates from shredding the oxide paste.
     
    Last edited: Dec 22, 2013
  10. pappajohn

    pappajohn Funster Life Member

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    do a search on elecsol batteries here on fun or on the web.

    5 year guarantee. ?..maybe on paper but the paper is worth more as they wont accept their batteries can fail early.

    extremely poor customer service.

    obviously, keep/use them but think hard about renewing like for like when the time comes
     
  11. Hellboy

    Hellboy Funster

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    Thanx...yes I have read the posts about problems with the batteries but 'touch wood' ours are 3 1/2 years old and still appear to be okay but will certainly consider other alternatives when the time comes :Wink:
     
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  12. hilldweller

    hilldweller Funster Life Member

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    Our original German leisure battery lasted 8 years !!
     
  13. callumwa

    callumwa Read Only Funster

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    ..... and expensive at that (£60.12)........:Eek!:.....


    ......I only paid £10 more for my NASA BM1
     
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  14. jonandshell

    jonandshell Funster

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    I wouldn't fit the BM1.
    Being able to monitor the fact your batteries aren't charging well from the alternator due to the thin Sargent wiring will just depress you.

    Can I suggest a charging circuit upgrade before fitment?:thumb:
     
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  15. Hellboy

    Hellboy Funster

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    I did think a charging circuit upgrade might be worth doing...we have a 100w solar panel to supplement but what else would you recommend?
     
  16. Larrynwin

    Larrynwin Funster

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    I have a BM1 fitted , always see what's going on , handy bit of kit :thumb:
     
  17. voyagerstan

    voyagerstan Read Only Funster

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    another solar panel :Doh: stan
     
  18. jb0371

    jb0371 Read Only Funster

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    def worth upgrading the charging circuit, I also have the bm1 attached to to 2 traction batteries, with a b2b sterling unit, with extra thick wires as suggested by jon.
     
  19. Hellboy

    Hellboy Funster

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    Okay so we have established that the 2 x fly-leads going to each battery are light weights (Drawing 1)
    So double them up on Battery 1 and then strap across to Battery 2 as per (Drawing 2)
    Then connect the BM1 shunt as (Drawing 3)...I think this is what pappajohn is saying :thumb:
    PS What size cable will I need for the battery straps?
     

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    Last edited: Dec 25, 2013
  20. pappajohn

    pappajohn Funster Life Member

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    looks good to me :thumb:

    dont forget a fuse on the pos terminal and depending how far apart the batteries are and how vulnerabe the link is to damage you need to fit a fuse at both ends of the positive (B2B) link wire.

    fuse size will depend on current draw but I would think a 25/30amp will do.

    Link wire size......i would use a minimum 4mmsq depending on how far apart.
     
    Last edited: Dec 25, 2013
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