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Powering the Batrium and shunt trip
Hi guys,
I started drawing some schematics for my setup and ran into a little (?) issue...

The batrium can be powered from the battery bank itself, which is the ideal, since running it off grid power may cause the watchmon to stop working if the grid goes out.
My battery setup is 14S (44,8 to 56,7V), which should be no problem for the batrium power input.

However, I have a shunt trip that works with 24 to 30 V AC or DC. I bought a 24V DC power supply to solve this, but now I checked the batrium website and saw this page:
How to connect a breaker to WatchMon4

It uses the negative from it's power supply to trigger the shunt, so in a normal setup it would use the 14S voltage from the batteries to the shunt.
That's too much for the auxiliary contact.

Can I still use the 24V DC power supply, when I connect the negative of the 24V supply to the negative of the battery bank so they share a 'common ground' ?

Thanks for your insights!
Batteries harvested: 2500+ / Cells tested: 2266 (Average: 2357 mAh)
Usable 1800+ mAh batteries: 1943 (78 %) / Cells in production: 14S 60P -> soon 1680 =14S 2x60P

If you ask me:
DO NOT add any extra electronics between the BMS and the shunt trip. That is just adding another level that can fail...
The simplest method is either
* Use the relay output and just take power from half the pack. No it wont cause balance issues... Its for disconecting only
* Use a resistor in series with the shunt trip. For most ABB breakers a 10Ohm 10w resistor is more than enough and will cope with the load fine
* Use the breaker directly on 48V. Atleast ABB breakers will function just fine on 48VDC for 100s of flips if needed. It wont burn up on such a short break but it will be a non compliant setup so its better to use the resistor in series

I run the resistor here and have done 100s and 100s of trips when doing all my video tests as example!
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The Schneider shunt on Batriums site is a 48v device, a few volts more and they fail, so no use for a fully charged pack, unless you have a 48v fixed source. The ABB ones have a much wider input voltage range, and are a more sensible price.

This is for AC load shedding, not DC feeding the inverter.
I have Batrium Watchmon 4 + Expansion board. I turn my AIMS inverter on/off by lowpower 12v relay triggered by Midnite Solar Classic Aux1 ... by voltage. E.g. when Classic detects 52v the relay is powered/closes and enables the AIMS inverter "On switch" thru the remote port. When 48v is hit, the relay opens and turns the Inverter OFF the same way.

In other words it functions as a low voltage shunt trip based on voltage.

My thought is to add one of the Expansion board relays in series so that both Batrium and Classic must say 'OK' for inverter to stay on. The Classic puts out max of 12v @ 200ma to trigger my relay - so voltage/amps should be no problem for expansion board relay if I add it in series.

From what I can tell - Relay 1 of Expansion board opens/closes to "Cricital Events" in Batrium settings - is this true?.

Can anyone advise if I'm on the right track?

(05-05-2019, 09:44 PM)OffGridInTheCity Wrote: From what I can tell - Relay 1 of Expansion board opens/closes to "Cricital Events" in Batrium settings - is this true?.

Can anyone advise if I'm on the right track?


Your plan seems overly complicated.

Any of the WM4 outputs can be triggered by a critical event.
I see - for example, I can assign "Critical Fault" to any of the 4 relays.

But let me clarify. Ideally, I would like a NC relay that would open at a critical event and break the circuit - e.g. turn off the inverter. I just don't see that.. and the examples of shunt trip etc look complicated and foreign to me (I'm not very educated with electrical circuits). The only 'simply relay'(s) I see are the 4 relays on the Expansion board but they are all NO. I can convert a NO to NC by adding additional hardware... but maybe there's something that someone could explain that would serve as NC that I'm just not recognizing the Batrium literature / specs.

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