Wiring in a shunt

[DumfriesDik]

I am not an electrician.

I have a bluetooth battery monitor (NASA BM1 BT) that I would like wired in. Thanks Richard n Ann !

I have two 12v leisure batteries and an inverter. The batteries are connected red to red and black to black.

The inverter takes its power via leads to battery A and everything else takes its power from battery B - although as already mentioned they are connected anyway.

Is it best practice to take all the power via (say) battery B as all the negatives have to go through a shunt? Can I take the inverter negative from the shunt??

Does it really matter how the positives are connected, can that come from either battery?

When making changes, what do I need to isolate, what sparks can I expect, do I unplug the solar panel etc? Any hints and tips gratefully received. I suspect, get a professional to do it will be the most sensible!

 

[DumfriesDik]

Here is the wiring just now

 

[Richard n Ann]

Keep the negatives joined... Put the shunt onto one of the negatives and connect all outgoing negatives to the other side of that.

Keep the positives joined... connect all outgoing positives to the diagonally opposite positive to the negative you used for the shunt. If that makes sense

 

[Richard n Ann]

 

[Raul]

Put the negatives from the batteries on the shunt battery side. The other side of the shunt is for all your loads and charging sources. Positives does not mater.
Are those batteries new? You may want to remove the red transport plugs. It says on the sticker as well.

Richard n Ann beat me to it.

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[Manic]

Are those batteries new? You may want to remove the red transport plugs. It says on the sticker as well.

Also if there are lead acid and inside they should have vent pipes to the outside.

 

[DumfriesDik]

Thanks everyone for your replies. I will check for the red transport plugs and vent pipes.

Do I need to somehow (how?) isolate the solar panel whilst working on the batteries? Anything I should avoid??

 

[Manic]

Thanks everyone for your replies. I will check for the red transport plugs and vent pipes.

Do I need to somehow (how?) isolate the solar panel whilst working on the batteries? Anything I should avoid??

Yes don’t disconnect them under load , cover them or disconnect them the night before , that’s what I do.

 

[huck999]

As per Richard n Ann's drawing, ensure that you have the negative load cable on the first battery and the positive load cable on the other. This ensures that both batteries share the load (and charge) and not just the first battery.

 

[Richard n Ann]

Thanks everyone for your replies. I will check for the red transport plugs and vent pipes.

Do I need to somehow (how?) isolate the solar panel whilst working on the batteries? Anything I should avoid??

I put a 100 amp version of one of these on our solar panel positive cable. Just to use to isolate it.

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[Stealaway]

I put a 100 amp version of one of these on our solar panel positive cable. Just to use to isolate it.

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Why did you fit an 100amp breaker?

 

[Raul]

Why did you fit an 100amp breaker?

To use it as a strong switch. Those breakers are not type approved, so can’t rely on its rating, only a reputable fuse or type approved breaker can be relied on for its rating.

 

[Stealaway]

I only fitted a 20 amp because that's all I need. Been trouble free for 6 year's and I test it regularly.

 

[DumfriesDik]

Monitor and shunt installed. Thanks everyone for your help with this.