Nasa BM1 Battery Monitor (1 Viewer)

Hellboy

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Nov 26, 2009
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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)
 

pappajohn

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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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Hellboy

Hellboy

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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?

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pappajohn

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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?

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
 
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gozomike

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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
 

pappajohn

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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

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

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FULL TIMER

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BEEN BUILDING THEM FOR 32 years

pappajohn

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Last edited:
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Hellboy

Hellboy

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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

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.

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pappajohn

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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
 
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Hellboy

Hellboy

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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

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 :winky:
 

hilldweller

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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 :winky:

Our original German leisure battery lasted 8 years !!

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jonandshell

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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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Hellboy

Hellboy

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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:
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?

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Feb 22, 2008
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I have a BM1 fitted , always see what's going on , handy bit of kit :thumb:
 

jb0371old

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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.

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Hellboy

Hellboy

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Nov 26, 2009
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both batteries must be connected in parallel...pos to pos and neg to neg....in effect becoming one large battery.
no reason why you couldn't 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

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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pappajohn

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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.
 
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Hellboy

Hellboy

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looks good to me :thumb:
Link wire size......i would use a minimum 4mmsq depending on how far apart.

Thanx John...the batteries are in the same compartment so the terminals will be only 200mm apart
Just need to get some cable and connectors to get the job done...early new year I think ::bigsmile:

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jb0371old

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I could be wrong, and I am sure Jon will be on to put me right but I am sure he used 80 amp fuses on my system. He is a battery fork truck engineer, so he knows a thing or two about batteries and wiring.
 

Techno

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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

Elecsol went tits up this year
 
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elecsol batteries

hya do any of you elecsol owners know how to get flat plastic top off to check water level ??
 

pappajohn

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hya do any of you elecsol owners know how to get flat plastic top off to check water level ??

the battery top has a special valve which re-condenses and diverts the evaporated electrolyte back into the cells.

in theory, you should never need to check or top up the levels.

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Hellboy

Hellboy

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Nov 26, 2009
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Could someone please post a picture of the rear of a BM1 monitor
I have not bought mine yet but the instructions say you need a hole in the panel 87mm wide and 67mm deep
Its going to be tight were I have in mind so might have to mount in a component box but I would just like to see what I am dealing with :winky:
 
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Can't help with a picture but if you haven't bought yet maybe it would be worth looking at the BM1 compact?
 

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