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cgi2099 asked

24v (12v Series) Smartshunt 12v charging setup help please

I have x2 12v 100AH batteries hooked in series for a 24v trolling motor.

I talked to Victron support and they told me that I would need two smartshunts for my system using the NOCO GEN5x3 12v 3 bank charger. Or I would need to buy a dual voltage 24v / 12v charger, cheapest I can find is the Iconic for $369.00. It is way cheaper to buy another $115 shunt. Also it is a lot easier job to just install another shunt vs changing my charging setup.

I am unsure on how to wire this up correctly and how to set it up in the app.

Below is a diagram of what I am thinking but would one of the batteries read 24v and the other 12v? I would like to configure it to where the smartshunts only monitor each battery and not the system as a whole.


To complicate this even more I also have a minn kota alternator that charges the battery while running, which is another reason I don't want to switch to a 24v charger because the shunts would be thrown off by the charge coming from it. It is a 2 bank DC-DC charger, 12v @ 10 amp each wired to the same spots as the NOCO minus the starter battery. This isn't on the diagram because it cluttered things up pretty bad.battery-diagram.png


Also what would a single shunt monitor, if I remove the shunt to the right and leave a single shunt in the middle? Would that monitor the battery to the left? If so could I then just do a DC meter function on the AUX/midpoint wire for the battery to the right?


Thank you in advanced for help :)

battery chargingSmartShuntwiring diagramsetup
battery-diagram.png (26.9 KiB)
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cgi2099 avatar image
cgi2099 answered ·

Anyone with any thoughts or ideas on this? Is there another forum I need to be posting this too?

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Alexandra avatar image
Alexandra answered ·

@cgi2099

I have not tried it, but it should work and give the correct SOC for both banks.

You could just have one monitor on one battery. Technically the soc will remain the same for both batteries and the bank balanced as each one is being charged by one charger.

Is your charger an isolated charger? Thats the only thing i am not sure about there. Sometimes a dual bank charger means a totally separate batteries.

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cgi2099 avatar image cgi2099 commented ·
On both the NOCO charger and Minn Kota alternator each bank is isolate and puts out 12v. (NOCO 5 amp each, Minn Kota 10 amp each.)


When I contacted Victron they said that using one Shunt for the whole system wouldn't work because the whole system is 24v but I would be charging each battery individually at 12v. They didn't elaborated on this for me though. They did say I would either need another Shunt, one for each battery or change to all 24v charging to use one Shunt.

Without thinking I just ordered another Shunt because it was way less of a headache but especially a lot cheaper.

But now that I have the second shunt and ready to install, I'm not sure on the wiring.

I am new to this and my understanding is limited but my thoughts are the Shunt hooked to the negative side of the trolling motor (24v) would auto detect at 24v during use but when charging would only be at 12v and confuse the Shunt/app.

The shunt in-between the batteries I would think would be okay and detect 12v during use and charging (maybe not?). If I could use the Volt meter option on this in-between shunt to monitor the other battery I think I could get away with just the one. But the manual says the negative of the remote battery needs to be hooked up to the negative of the system. But I can't do this because they are already in series and would create a short.

I am new to all of this and really don't know how it all works. My logic and understanding could be 100% wrong.

I did reach back out to Victron for help with the wiring and they said I needed to reach out to an installer/supplier for more info.


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cgi2099 avatar image
cgi2099 answered ·

So I got in touch with a Victron engineer and they said the shunt will not work correctly like I want it to and would never give a correct soc automatically like designed. Only advice they had was to get a 24v charger and use one shunt or reset the soc on the shunt manually every time I charge.

So I am going this route, they did confirm this will work if I get all the voltages dialed in:

https://community.victronenergy.com/questions/186859/victron-energy-blue-smart-ip67-12v-17a-to-orion-tr.html



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Alexandra avatar image Alexandra ♦ commented ·

The 24v is the simpler route to take and definitely more reliable.

The shunt is designed to measure an entire bank, it should have all chargers and loads on one side of the shunt.

With your battery interlink one, the charger and the second battery would be on the load side. It does break the brain a little, and it not really how the shunt is designed to be used. I have two shunts but not 2x 12v chargers to try it.

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