Tinbum

I know it was for Victron but Pylons recommendation in the manual and on the battery itself is a range. I was wondering though, how you are supposed to set that, when the battery itself always set's it at 53.2v. Victron do change it in some of their units but if you don't have that and still use CAN or RS485? (I do it by sniffing the CAN messages and then adjusting them and sending them on to my inverters which are not Victron).

Interesting to see the voltage recommendation direct from pylontech.

Have a look at

It doesn't start at that voltage see my last post with the attachment. It's 50.4v

The balancing current in the BMS is very very low and it will take a long time to balance. It also only starts to balance above 30mv. I regard 53.2v as too high and alter the CAN messages down to 52.5v except for one day a week. Pylontech must be happy with their 53.2v though.

I thought the Victron system reduced the max charge voltage to 52.4v or s that just some of their equipment and not all?

That may be the case but it does say in their warranty terms that the batteries may only be used with approved inverters. I would never run them without comms being set up and working.

The thing is the pylontech bms relies on the inverter following it's instructions.

The log is for a single battery and it shows DOCA error.

They don't work like that.

Looking at your logs you seem to have drawn some very large currents from this pack, way above those recommended. Did you have communication set up between the batteries and the inverter?

Has your setup always had the CAN connection working as you mentioned the installer using a standard patch cable?

The BMS link should set the voltages but I have a recollection that someone on here mentioned that the batteries will use the settings if the CAN fails. I think their was a link to a YouTube video about it. (It may have been on another forum that it wa mentioned.) Personally I would expect the inverter to shut down but I don't have your inverter.

I'd personally set it a little bit lower at 52.5v. That's enough for the batteries to balance. (I run mine at 53.2v once a week (until it gets to 100% SOC) and 52.5v for the rest of the week).

I'd change those voltages as well as a precaution.

The bms does not balance the entire stack it only balances the cells in a battery. Balancing between batteries is done by the laws of physics. You need the batteries to be similar SOC (voltages) to stop huge currents between the batteries which could cause the bms to shut batteries down to protect the battery.

Your new battery will come at about 50% SOC. Get your old batteries to about that SOC, check the voltages of old and new are nearly the same and then connect together with as you say the new as the master. Check the manuals regarding the CAN cable pins used on the US3000C.

Their is a post on here showing a strip down of Pylontech batteries. They are different BMS's

Very neat. Looks to be a lot of black cable. From the photo I can't see any markings. Are you certain the + and - haven't got swapped somehow?

Thanks, that shouldn't cause it. Can you post photos of all your set up?

What exactly was done in the minor upgrade?

?? https://cdn.enfsolar.com/z/pp/b9pnq4usr2/SEG-48100H-4U-HESS-PRODUCT-SPECIFICATION.pdf See page 8 items 8 (one RJ45) and 9 (2x RJ45) and page 10.

It looks to be a Seplos BMS in your battery so google that.

Their is a way to reset the SOC on a Seplos BMS but I don't have time to look it up at the moment. It varies between model numbers.

The first post shows them all the same.