BMS communication issues

[cojmh]

I completely agree .... assume nothing and test everything!

A bit of an update.

I decided to leave the batteries online (I normally turn them of as I don't like the idea of them being on if I don't know they are working properly)

It would seem they are now willing to discharge - the only problem is that the inverter is discharging them to the grid (which is the opposite of what I want to see!)

So I have now seen that the batteries will discharge, but not correctly (and at the maximum discharge rate which seems to have reset itself to 50A)

I will have to see if I can get hold of the manufacturers.

[nowty]

The calibration (i.e the direction) f your grid CT clamp may be wrong.

[cojmh]

I didn't realise there was a direction.

It is very possible - just before I installed the batteries, I had a new smart metre installed by British Gas which included a an isolator switch - so I know they had to disconnect the grid clamp and they might have put it back wrong.

I will have a look at that .... is there any directional markings on the clamp?

Thanks,

[Joeboy]

There should be.

[Joeboy]

Can you post a photo?

[cojmh]

OK,

I have just had a look and referenced the Solax documentation and it is indeed pointing in the wrong direction. There is an arrow on it that is supposed to point to the public grid .... mine points to the consumer units.

Before I start fiddling with the CT sensor do I need to turn off the power or turn off the inverter?

Or can I simply unclip the CT sensor and clip it back on the correct way around without doing anything to the inverter?

Thanks - I would never have thought to look at that!

[Joeboy]

Here's mine, the black one.

[Joeboy]

OK,

I have just had a look and referenced the Solax documentation and it is indeed pointing in the wrong direction. There is an arrow on it that is supposed to point to the public grid .... mine points to the consumer units.

Before I start fiddling with the CT sensor do I need to turn off the power or turn off the inverter?

Or can I simply unclip the CT sensor and clip it back on the correct way around without doing anything to the inverter?

Thanks - I would never have thought to look at that!

Unclip.

[Joeboy]

I sincerely hope it has been a CT clamp and wrongly wired bms lead. Fingers x'd.

[Tinbum]

Your cable certainly seems ok at the battery end and from what you have said the inverter end looks ok.

I would drop the Voltage down to 53.2v as that is the max the battery will every request. Their are many warnings not to over volt the batteries as it can easily lead to a new bms being needed.

I think you are going to have to go back to Solis and ask them to confirm the pinouts and that their protocol is ok for the USx000C and if not they need to bring a new firmware out.

Have you tried using a different one of your batteries as the master, just to rule out a battery fault?