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chaucer avatar image
chaucer asked

Smart shunt install in a RV

Hi,

Looking for some advice to help me get a Victron smart shunt installed in an RV. I have two 12V batteries in parallel. See attached for wire diagram. There are 3 wires to the negative terminal on battery #1, one from the battery switch, one from the jumper to battery #2 and one from that goes into the RV somewhere (I'm guessing the solar panel). Battery #2 has two wires on the negative terminal, one from the jumper to battery #1 and one from an external solar panel plug.

I believe the shunt gets connected directly to the negative of battery #1, but I'm not sure if all 3 (or just the one from the switch) negative wires get connected to the other side of the shunt? Does anything happen to the negative wires on battery #2?

Also, do both positives wires for the shunt get attached or just the one to battery #1

Thank you

shunt.jpg



SmartShunt
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4 Answers
Kevin Windrem avatar image
Kevin Windrem answered ·

All loads and charging sources need to connect to the system side of the shunt. Only the two batteries connect to the battery side of the shunt.

You didn't say if these are house batteries or if they double as starter batteries. Starter current flowing through the shunt needs to be factored in. You may need a 1000 amp shunt (or more??).

You'll need to trace all the negative leads to make sure you know where they are going. I've never seen a negative lead going to the battery switch so be sure to figure that out.

You should take the negative battery connection from one battery and the positive connection from the other battery. This helps balance the loads between the two batteries.

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chaucer avatar image
chaucer answered ·

Hi, Thank you for the answer.

Not used for starting, only power to run RV when not plugged in.

Yes, I'm trying to figure out why the one negative goes to the switch. Could it be just a pass through to the main ground of the RV?

The positive to battery 2 , from the switch, also seems like a jumper?

Having the negative from the external solar panel plug (not used) does not seem like a problem.

Can you better explain; You should take the negative battery connection from one battery and the positive connection from the other battery

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Kevin Windrem avatar image Kevin Windrem commented ·

Wiring the batteries this way is the best insurance that equal energy will be pulled from each battery


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Jumpers will have equal current flowing through them so the battery voltages will be equal as well.

Taking positive and negative off the same battery will draw more energy from the that battery than from the second.

If you have lots of connections, consider a busbar or stud to connect all wires to. Then run equal length wires from both batteries to the bus bar.

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chaucer avatar image
chaucer answered ·

Understood. Thank you...one more question

Would a positive wire from my switch to the second battery act the same as a jumper between the two positives on each battery (see sketch). Assuming they are tied together at the switch.

On my RV, from the switch, there are two red wires going to the positive terminal on each battery. I can't take the switch off to look behind it, but I'm thinking if they are tied into the same connection on the switch.


img-1617.jpg



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Kevin Windrem avatar image Kevin Windrem commented ·
It depends on the switch. If it is just an on/off, then yes. If it is an off / 1 / 2 / both switch then it provides the capability of running your RV on just one of the two batteries. If you are going to install a shunt, then you would NEVER run on just one battery or the shunt will make incorrect calculations (it would assume there's twice as much battery capacity than there is at the moment so SOC would drop 1/2 as fast as is the actual case.

You would also NOT want to jumper the battery negatives. You should wire the batteries with equal length cables from each battery positive to the switch. And also run equal length negative cables from each battery to the shunt's battery connection.

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chaucer answered ·

Yes, it's just an on off switch. So I'm good. Thank you for the help.switch-back.jpgimg-1618.jpg


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