@makia2023 I hooked up the cell monitoring lines before connecting the B+ cable (circled red) from the pack to the BMS. After about 2 mins I noticed the telltale smell of hot conformal coating coming from the area around the balance resistors (circled green).

Seplos V3 has the shunts in the -ve bus, unlike V2 which had a separate shunt onboard in the +ve bus, hence the need for a bat+ sense wire.

The BMS powers up fine but it reads 0mV for all the cell voltages. It reads the pack voltage correctly however.

I think I'll order a replacement from fogstar, I could swap my batrium over from my 9.6kWh pack, but it's very much not reliable, and it would be some work to make it all fit.

@hughf - balance resistors ... in an active balancer model?

What are they doing there?

@transparent The seplos v3 is the standard passive balancing BMS, their 'active balancer' is a separate unit that connects via an additional harness, directly to the cells. It is non-programmable, and works at any cell voltage >3V, when there is a 50mV delta.

It's generally considered to be 'a bit junk', as it's not programmable and can't be enabled only at >3.45V/cell.

@misterb Ive got a 60w tube heater hooked up to a temp control plug. I will insulate and keep at around 18 C over winter.

@Transparent - as it will be set low AND should be fed using the electricity from the battery, then i thought it was a reasonable option, especially if i insulated the heating pad and rear of the Seplos with a couple of inches of celotex or similar.

@Makia2023 - i did consider something similar but decided against it as i wanted to stop the battery from dropping below charging levels, as opposed to heating the immediate are its in.

New bms delivered today from fogstar, all installed and up and running 👍

Now to find that 3kW charger I’ve got somewhere….

Installed and working.....but CT clamp isn't registering !!!!

Expand that comment please @makia2023

The full SunSynk diagram of all possible configurations has three CTs on it. 🙄 

I'm going to assume that you're referring to the one which connects to positions 5 & 6 on the Inverter, and has the clamp/transformer around the live feed wire between the inverter and its mcb-trip in your consumer unit.
In the manual, you probably have this diagram, and will have read the comments below and to the right:

See also the table at the bottom of the following page.
Although it's beneath the diagram which covers installation in the USA, it's still relevant.

What reading do you get if you disconnect the CT-clamp wires from the inverter, and use a multimeter set to ohms?

@transparent i appear to have put my multimeter somewhere safe.......

Having more than one multimeter would seem a prudent investment for someone who's just imported 64 lithium cells from China!

I have three multimeters, one 'mains tester' box and an assortment of dedicated current/voltage meters.
And yes, I have needed to use all of them simultaneously on one occasion!

I've just checked online, and Amazon have at least 50 multimeter models, auto-ranging, at less than £30 and available for delivery on Saturday!
Give yourself an 'essential' Christmas present.

I have a spare. I'm getting no reading from either my old or new ct clamp with it. Any thoughts?

I'm tempted to run another cat 6 cable separately and see if that works. But will be a tomorrow thing. I'm stumped.

It should definitely see the grid load regardless of battery system/solar right?