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Victron BMV 702 Wiring Question


Mark
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Hi All

 

I have taken the plunge and will be getting one from Ontrack in Cape Town... Few suppliers stock the 702 which I think is strange.

 

In prep I am looking at the installation manual and find something that worries me...(a newby)

 

The linking of the 3 string midpoints (via the Negative terminals) and then the Victron is connected (see +B2) in diagram (Figure 12).  I have 2 strings but the question still holds.

 

Comments and an explaination would be great...

 

Regards

Mark

 

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In prep I am looking at the installation manual and find something that worries me...(a newby)

 

The linking of the 3 string midpoints (via the Negative terminals) and then the Victron is connected (see +B2) in diagram (Figure 12).  I have 2 strings but the question still holds.

 

Comments and an explaination would be great...

 

I'm not sure what your question is, does the linking of the negatives bother you? Since they've linked the negatives in the drawing (as opposed to the positives) it might cause confusion, but the negatives of those batteries are connected to the positives of the batteries right next to them and that is the mid point between the negative of the battery bank and the positive of the battery bank.  You connect that "mid-point" to the BM in order to measure the upper and lower parts of the battery bank.

 

You have to connect the mid-points of all strings together in order to measure any difference in mid-point voltage accurately - if you only connect the mid-point of one string to the BM, and there is a problem in another string the BM will not detect a problem.

 

Traditionally you should have one fuse in series with each parallel string of batteries - does not really matter exactly where the fuse is located.  By connecting the the mid-points of all strings together, you actually need to have a fuse in series with each string on each side of the mid-point e.g. between the positive of each string and the positive bus-bar and between the negative of each string and the negative bus-bar, just in case something goes wrong in any one of the parallel strings on either side of the connected mid-points.

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  • 3 years later...
On 2015/11/09 at 9:27 AM, superdiy said:

You have to connect the mid-points of all strings together in order to measure any difference in mid-point voltage accurately - if you only connect the mid-point of one string to the BM, and there is a problem in another string the BM will not detect a problem.

Morning Superdiy,

So if i understand this correct, I need to run a cable from the midpoint +B2 to bank 1 and then from bank 1 to bank 2 or can I run a separate cable from bank 2 directly to the +B2 on the bmv

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