Pylontech x Sofar - battery in standby mode far too early

[ducabi]

I've noticed (using solarman app) that my inverter (HYD3600ES) moves to standby mode when the batteries' SOC is way over the limit. I've updated software (Sofar), so it now allows me to set DOD to 90%. Depending on a day it moves to standby mode between 22% and 31% (31 is actually today, first time so high). Before the update it was actually very similar with DOD set to 80%. it makes me think it's not related to how batteries are unbalanced, even though I think they are because one day i switched them around and also charged couple days to 100%.
Yesterday when it moved to standby, I disconnected everything and checked the voltage. Each of them reported 48.4V.

Any idea what it can be? Shall i buy some cable to connect to batteries and see all parameters?

[Tinbum]

Their's a thread on here about connecting to Pylontech- do a search. try batteryview.

edit https://camelot-forum.co.uk/phpBB3/view ... =14&t=1459

[nowty]

I would suggest you check all the battery parameter settings on the Sofar as one of them might be overriding the DOD parameter.

[Caesium]

Could be a weak cell in one of the Pylontechs is forcing the BMS to shut off the discharging MOSFET prematurely? Not sure of the exact voltage limit but if a cell falls below a safe limit then it'll disconnect the cells from the front terminals to protect itself.

I'm not sure how that would interact with the rest of the stack; I would have expected only one pack to shut down in that way but its possible that the master tells all packs to shut down if it sees that sort of alarm perhaps.

As has been mentioned, Batteryview will tell you that sort of thing, the Pylontechs have a log of alarms/faults and you'd be able to inspect each cell voltage when they go into standby.

[ducabi]

I would suggest you check all the battery parameter settings on the Sofar as one of them might be overriding the DOD parameter.

Can't see anything there that could overwrite it but it kind of seems related to SOC. Last night I set it to 100% and it did discharge batteries to 19% ( couldn't see if it can go lower because charging kicked in after 23:30). I will keep charging to 100% for couple 2 more days and see how it behaves although I did it before (without checking min DOD). Before updating inverter it was stopping at around same SOC even though at that time DOD was set to 80% rather than 90%.
In the meantime I'm ordering cables to connect them to batteryview.

[nowty]

I would suggest you check all the battery parameter settings on the Sofar as one of them might be overriding the DOD parameter.

Can't see anything there that could overwrite it but it kind of seems related to SOC. Last night I set it to 100% and it did discharge batteries to 19% ( couldn't see if it can go lower because charging kicked in after 23:30). I will keep charging to 100% for couple 2 more days and see how it behaves although I did it before (without checking min DOD). Before updating inverter it was stopping at around same SOC even though at that time DOD was set to 80% rather than 90%.
In the meantime I'm ordering cables to connect them to batteryview.

There is min discharge voltage and min protect voltage setting but I've just checked the manual and its only if you use the DEFAULT battery type, i.e. a non BMS type battery.

Saying that I thought I was able to change the settings with my Pylontechs on the Sofar but it was a few years ago. It may have also been on a very early version of the Sofar firmware.

Re-installing the Pylontechs is another course of action.

[Oldgreybeard]

I tried adjusting the settings on the Sofar, but they seem to get ignored when the batteries are connected and get over-ridden by the Pylontech setting profile, so my gut feeling is that you can't adjust individual battery parameters when the Pylontech BMS is communicating with the Sofar. I may be wrong, as I only tried to do this once.

[dangermouse]

As I said in the other thread I've been having a similar experience. I have a theory about what's going on now. I reckon the individual battery packs are not balanced with each other.

Here's what I did:

Turn everything off, and connect a single battery to the inverter. Turn it on, and force it to charge to a set level (say 80%). You can do this by programming a rule in "time of use" mode. Wait until it finishes charging (check the battery status screen), the charge power should drop to a trickle, about 30W (it never seems to stop altogether).

Then turn everything off again, and connect your next battery. Repeat the above - charge that one to 80%.

Repeat for each battery in turn.

Next, connect all the batteries together as normal, but disconnect the comms lead from the inverter. Isolate the batteries from the inverter, either with your frankenstein switch or by pulling the cables. Turn on the master battery. If the batteries show the charge level LEDs, they are balancing. The battery (or batteries) being charged will flash one of the charge LEDs. Wait until the batteries all go to standby mode - just the power light flashing once every 4s.

Now all the packs are balanced to each other, so turn them off again. Reconnect the inverter and turn everything back on in the usual way. Remember to disable the extra "time of use" rule.

My theory is that the inverter sees the combined SOC of the bank of batteries,and uses this to decide when to stop discharging. Say battery 1 is at 20% and battery 2 is at 10%, the average SOC will be 15%, so at that point the inverter stops discharging. But now battery 2 is at 10% and so asks the inverter for a top up charge. So both batteries start charging, even though the combined SOC (which is displayed on the inverter status screen) is higher than the 15% cut off point. Once B2 gets to 15%, B1 will be at around 25%, giving an average of 20% and so the unexpected charge stops at this point.

Anyway, that was a lot of words to say "perhaps the batteries are not balanced", so I'll stop waffling and report back tomorrow once I've gone through another charge cycle.

[Tinbum]

I'm not sure that is correct. The Battery BMS sends an averaged reading of all the individual batteries to the inverter. The inverter doesn't see individual battery SOC.

The inverter will stop charging at the SOC it is set at and that will be at the average SOC. Your batteries shouldn't get out of balance with each other.

[Oldgreybeard]

As I said in the other thread I've been having a similar experience. I have a theory about what's going on now. I reckon the individual battery packs are not balanced with each other.

Here's what I did:

Turn everything off, and connect a single battery to the inverter. Turn it on, and force it to charge to a set level (say 80%). You can do this by programming a rule in "time of use" mode. Wait until it finishes charging (check the battery status screen), the charge power should drop to a trickle, about 30W (it never seems to stop altogether).

Then turn everything off again, and connect your next battery. Repeat the above - charge that one to 80%.

Repeat for each battery in turn.

Next, connect all the batteries together as normal, but disconnect the comms lead from the inverter. Isolate the batteries from the inverter, either with your frankenstein switch or by pulling the cables. Turn on the master battery. If the batteries show the charge level LEDs, they are balancing. The battery (or batteries) being charged will flash one of the charge LEDs. Wait until the batteries all go to standby mode - just the power light flashing once every 4s.

Now all the packs are balanced to each other, so turn them off again. Reconnect the inverter and turn everything back on in the usual way. Remember to disable the extra "time of use" rule.

My theory is that the inverter sees the combined SOC of the bank of batteries,and uses this to decide when to stop discharging. Say battery 1 is at 20% and battery 2 is at 10%, the average SOC will be 15%, so at that point the inverter stops discharging. But now battery 2 is at 10% and so asks the inverter for a top up charge. So both batteries start charging, even though the combined SOC (which is displayed on the inverter status screen) is higher than the 15% cut off point. Once B2 gets to 15%, B1 will be at around 25%, giving an average of 20% and so the unexpected charge stops at this point.

Anyway, that was a lot of words to say "perhaps the batteries are not balanced", so I'll stop waffling and report back tomorrow once I've gone through another charge cycle.

That sounds plausible, I might try doing the same thing. When I let the pack run out very recently I noticed that the Sofar was reporting 20% and had shut down, yet the battery cut off is supposed to be 15% (I've not updated the software in the Sofar to allow a lower SoC). When I went out to the shed to check, I found one of the six batteries had no LEDs showing, the other five showed a couple of LEDs. Looked to me as if one pack had shut down, and that then shut down the Sofar and so it reverted to grid import. There were no errors showing or logged, though.

The next time we get a sunny day I might try disconnecting them all, then doing as you suggest, charging each to a set level, then connecting them all back up again. I'd not seen this before, but then I've never run the pack as low as I did last night in the two years we've had it.