Replacement for Smart Shunt AUX

DIY
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1

If the Smart Shunt is disconnected where the starter battery is connected to the AUX and monitored and replaced with a Cerbo GX and a Smart BMS NG, is it somehow possible to continue to monitor the starter battery voltage via some other type of input?

2

Hi merc_on_the_go,

how did you connect your starter batterie to the Cerbo? Did you manage to have it displayd via the AUX on the shunt or did you use an additional shunt on the starter battery?

3

Hi Martin
The solution was to leave the Smart Shunt as a electricity meter for the entire original electrical system of the motorhome and with that the connection of the starter battery remained on the AUX input, so no direct connection to the Cerbo GX.

4

Okay, so you would suggest to not use two Smart Shunts but use one and connect the starter battery only via the Smart Shunt’s AUX input, right?

But in this case, can we get a SOC reading or is it only currency?

Thank you,
Martin.

5

You can use two shunts but if you don’t plan on installing a Smart BMS then one is enough, in my case I replaced the primary shunt with a Smart BMS and if I hadn’t put the shunt back as a meter for the original system I would have lost the volt input (AUX) for the starter battery.
See the picture, the big blue box at the bottom can be Shunt or Smart BMS, the box to the right of it shows the original system which is now measured via the shunt. The starter battery Volt (via AUX) is not shown in the picture, it is in another menu.

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6

Hi, but if have only one SmartShunt you get only the voltage from the starter batterie via AUX, right? You don’t an acutal reading on the state of charge (SOC).

Is it that we just have to accept that?

Thanks,
Martin.

7

Yes, just voltage from the starter battery, but it’s probably a lead-acid battery (AGM?) and then you can read “SOC” via the voltage “like in the good old days” after it falls in a linear curve.
Lithium batteries basically keep the same voltage all the time and in these cases you have to keep track of the flow in and out to be able to know what the SOC is and for that you have to have a shunt or BMS. Putting a shunt against an AGM leisure battery is just like an extra bonus, it’s not needed but you get refined values ​​and the shunt can calculate how long it will last etc.

8

Yes, that’s true. Thank you.