Sunsynk (Deye) inverter not charging battery to 100% .... can anyone help please

[MisterB1959]

My Sunsynk 5.5kw inverter isnt charging my battery overnight using grid power at a cheap rate as it should. The inverter recognises the battery and does charge it but its not getting it to 100% - today it was down to around 51% !

i think it might either be be an issue with the BMS on the battery not resetting - i think the issue was shown on the off grid garage a while back, my battery is a Seplos 280L (14.3kw) with a Seplos BMS with bluetooth, or its a problem with the inverter, though that all seems to be working fine.

i have only recently had the sunsynk installed, prior to that i had a Sofar ME 3000SP, which didnt have any problems and always charged to 100% and i havent made any changes to it

can anyone point me in the right direction please?

 

[houseofancients]

Sure,

Please provide your BMS settings and inverter setting.
Have you top balanced your cells before charging ?
Is communication setup and working correctly ?

The BMS will do a reset to 100% if amps are less than 7% of set max capacity for 30 minutes , so make sure your BMS is properly calibrated, and you have set the correct values in the inverter and bms

I usually don't charge any values, beside setting max charge voltage to 56.8

Make very sure to double check the Time of Use settings

 

[MisterB1959]

time of use settings









where do you set max charge to 56.8? if its on the inverter, i thought you only change those settings on a LA or AGM battery?

i will sort bms settings tomorrow, thanks

cells were all properly top balanced before assembly, i recently had a sofar me3000sp inverter removed and replaced with the sunsynk. the battery charged fully with the sofar inverter and no settings were changed on the bms when the new inverter was fitted. i am using the aux load - micro inverter tab as i have an existing PV system.

comms are working correctly and give me readings as they should




- thanks for taking the time to respond.

 

[houseofancients]

time of use settings

View attachment 173467

View attachment 173468

View attachment 173469

View attachment 173470

where do you set max charge to 56.8? if its on the inverter, i thought you only change those settings on a LA or AGM battery?

i will sort bms settings tomorrow, thanks

cells were all properly top balanced before assembly, i recently had a sofar me3000sp inverter removed and replaced with the sunsynk. the battery charged fully with the sofar inverter and no settings were changed on the bms when the new inverter was fitted. i am using the aux load - micro inverter tab as i have an existing PV system.

comms are working correctly and give me readings as they should

View attachment 173471


- thanks for taking the time to respond.

Your setting on the inverter seem just fine..
Do wonder if the timeslot is long enough, but that is maybe something you to need to experiment with...
If your cells are far out of balance , the time slot may be too short for the balancer to do it's work.
Also.. you can help the BMS a bit.
Once the cells hit 3.6 , it will micro cycle default between 96% and 100% .
You could try and this to 98% so it cycles more often and stays above the balance voltage..

As your comms are working just fine as far as I can see, you need to focus on the BMS setting, as they override the inverter settings when comms are running.

The setting you are looking for is in the BMS, there only 1 setting set to 57.6.
Change that to 56.8.

 

[MisterB1959]

Your setting on the inverter seem just fine..
Do wonder if the timeslot is long enough, but that is maybe something you to need to experiment with...
If your cells are far out of balance , the time slot may be too short for the balancer to do it's work.
Also.. you can help the BMS a bit.
Once the cells hit 3.6 , it will micro cycle default between 96% and 100% .
You could try and this to 98% so it cycles more often and stays above the balance voltage..

As your comms are working just fine as far as I can see, you need to focus on the BMS setting, as they override the inverter settings when comms are running.

The setting you are looking for is in the BMS, there only 1 setting set to 57.6.
Change that to 56.8.

Thanks, as it happens the battery charged fully last night !! Yesterday was the first day that the battery had actually gone down to 15% which is the level at which it stops providing energy to the household. Is that just coincidence?

I need to monitor more closely what is happening. I will try to reconnect to the BMS today and look for that particular setting though aswell. Thanks for taking the time to respond.

 

[houseofancients]

Thanks, as it happens the battery charged fully last night !! Yesterday was the first day that the battery had actually gone down to 15% which is the level at which it stops providing energy to the household. Is that just coincidence?

I need to monitor more closely what is happening. I will try to reconnect to the BMS today and look for that particular setting though aswell. Thanks for taking the time to respond.

That 15% is a setting in your inverter, so wouldn't call in coincidence
Btw seplos defaults to 10% for shutdown

Btw you are aware that there's no need to connect your PC, as it is very likely your BMS has Bluetooth and an Android/iphone app

And you're welcome !

 

[MisterB1959]

PS sorry to anyone not from the UK, some of the points i am raising may have no relevance, other than idle curiosity, so definitely keep your cats away from reading this ... LOL

@houseofancients - thanks for your help !


thanks, would you advise then setting shutdown on the inverter to 9% to let the bms to do its job, or to 11% to let the inverter do its job? either way there would be a back up shut down- i found it easier to use the cable connection than then use the bluetooth app android app, might be to do with a bigger screen LOL

i just want to get everything fully up and running before investing in another battery - though after using the sunsynk for a short while, i am beginning to wonder is the additional investment of @£2400 for another 14.3kw battery actually a cost effective purchase. if i can get the setup working as i hope, charging to full every night (we are on an octopus tariff for cheap electricity 1230 - 0430 - just 4 hours which is why i changed the 3kw inverter for a 5.5kw inverter) then it will meet my daytime energy consumption throughout most of the year, allowing me to buy electricity at 15.15 pence and use it during the peak period when it is 36.12p - so i am using energy at half price effectively.

We also have dimplex quantum storage heaters, which recharge during the same period, but as we have a split 3 phase supply - one not used, one for the night storage heaters which is time controlled by the smart meter via octopus and the other a constant 24 hours supply to the rest of the house.
to complete the picture, we have 4kw of PV installed under the FiT scheme so dont want to compromise those payments but the sunsynk gives me the option of adding additional PV to supply just the batteries, (which the sofar me3000sp didnt) so with a longer lifespan it might be the better financial option as there doesnt seem much point in investing £2400 to save £200 per year on bills? it should also reduce the amount of energy i have to buy in, so it seems to be a sensible consideration

re the sofar me3000sp, it really was a very good inverter, it just didnt allow me the flexibilty of making additions and fully utilising the cheap rate periods that the sunsynk does.

 

[MisterB1959]

@houseofancients





im not sure where to make the change ??

i cant get the bluetooth app to connect

 

[houseofancients]

load parameters, however looking at you cell voltages, your cell seem with 15 mV , and thus are in (almost) perfect balance , wouldnt touch the 96%

the value is set to 56.8 = Total Voltage Overvoltage Protection

the rest of them you can leave as they are

 

[Steve_S]

Your battery packs are FULL (100% SOC) once they reach 55.2 Volts (3.450 Volts per cell).
Your EndAmps/TailCurrent is 14A. Once the batteries take only 14A they should transition to Float (Constant Voltage - Variable Current) at 55.1 Volts which will allow the cells to top off & balance out.

Charging beyond 3.450 does NOTHING for you as that is above the working voltage range and voltages above that will settle to 3.400 which is a Chemistry FACT regardless of what some "folk" say. Additionally, the LFP are all calibrated & tested to work within a range, beyond 3.45 the Internal Resistance in the cells WILL deviate with some cells reaching higher voltages before others, resulting in High Volt Disconnects.

Note, that if you continue to charge the pack(s) above 55.2 Volts, there won't be any harm but you will never get the full capacity you wish due to HVD and other factors. In other woords, don't try to pour 2 extra gallons of gas into the tank once the pump kicks off.

 

[houseofancients]

Your battery packs are FULL (100% SOC) once they reach 55.2 Volts (3.450 Volts per cell).
Your EndAmps/TailCurrent is 14A. Once the batteries take only 14A they should transition to Float (Constant Voltage - Variable Current) at 55.1 Volts which will allow the cells to top off & balance out.

Charging beyond 3.450 does NOTHING for you as that is above the working voltage range and voltages above that will settle to 3.400 which is a Chemistry FACT regardless of what some "folk" say. Additionally, the LFP are all calibrated & tested to work within a range, beyond 3.45 the Internal Resistance in the cells WILL deviate with some cells reaching higher voltages before others, resulting in High Volt Disconnects.

Note, that if you continue to charge the pack(s) above 55.2 Volts, there won't be any harm but you will never get the full capacity you wish due to HVD and other factors. In other woords, don't try to pour 2 extra gallons of gas into the tank once the pump kicks off.

if using that voltage, the passive balancer will never be able to keep the cells in balance

 

[Steve_S]

if using that voltage, the passive balancer will never be able to keep the cells in balance

WRONG
Passive only burns off Hi Volt cells !
Float will feed (as it should) whatever the pack will take and replace energy and balance out... Even ANDY on YT proved that ! even though he didn't intend to.

 

[houseofancients]

so for me it is a trade off...
i charge my cells to a little higher voltage to keep my cells in balance, as for me, that takes presidence over maybe a few months of extra life, which won't be a problem because lifetime will be long gone by then

 

[MisterB1959]

so, the answer is, i dont need to do anything other than try to check if i am getting up to 100% charge - even though it means i need to wake up at 0430 hrs (again!!)

 

[houseofancients]

WRONG
Passive only burns off Hi Volt cells !
Float will feed (as it should) whatever the pack will take and replace energy and balance out... Even ANDY on YT proved that ! even though he didn't intend to.

so, the answer is, i dont need to do anything other than try to check if i am getting up to 100% charge - even though it means i need to wake up at 0430 hrs (again!!)

well... that depends...
the BMS by standard uses a charge voltage of 57.6...

again, up to what you do, just be very aware your bms can and shall no balance at 3.450 ( as also proven by andy on YT)

 

[MisterB1959]

all i want to do is to make sure its charging overnight to 100% (or would 95% preserve my battery life substantially?)

 

[houseofancients]

all i want to do is to make sure its charging overnight to 100% (or would 95% preserve my battery life substantially?)

Well, told you what I run, and I get to 100% every night without stressing my cells too much and my reasoning behind it..
Guess it's up to you now