Hi All,
I have a new setup and just starting out.
I'd like to setup my inverter & battery to only 'operate' within 10% - 95% of its capacity (hopefully to maximize battery lifespan). My aim is the following:
1. Charge from solar panel until battery reach 95% and start grid export/consume
2. Not going below 10% when on battery -> Start pulling from grid at night time when battery level is at 10%
Under 'Quick settings' on the app, System Min SOC is already at 10% but when I tried to set the System Max SOC to 95% (from 100%) , I'm getting 'Write Failed' error.
Note that I haven't touch mode scheduler yet. Work mode is set to 'Self use', with nothing custom scheduled.
Going (physically) on the inverter itself, there is a 'Max SOC Battery on Grid' settings under Settings -> Battery that I can adjust (there is no 'Max SOC' option!) . Is this the same thing?
Am I completely going the wrong route to achieve this?
Thank you
I wouldn't recommend limiting it to 95%, the BMS inside does need to calibrate the end points to know how much power it has stored. I have used 10% & 100% for over a year, and have 100% SoH (State of Health) remaining.
There are some new firmwares being baked (depending on device) that should allow you to have better control over your scheduling, once these are ready, then you could limit charge rates better during the different seasons as needed.
There are some new firmwares being baked (depending on device) that should allow you to have better control over your scheduling, once these are ready, then you could limit charge rates better during the different seasons as needed.
Interested to see this. I've been wondering the same thing as the OP.
I did have maxSOC limited to 95% based on ideas read elsewhere, not personal expertise, that this should extend battery life, but having read on this forum that the BMS could be unhappy with this strategy I put it back to 100%.
My current strategy, based again on web search not expertise, is to run it at 95% routinely to try to protect battery, but let it go to 100% once a week or so to try to keep the BMS happy.
Any advice on the wisdom of this appreciated.
I did have maxSOC limited to 95% based on ideas read elsewhere, not personal expertise, that this should extend battery life, but having read on this forum that the BMS could be unhappy with this strategy I put it back to 100%.
My current strategy, based again on web search not expertise, is to run it at 95% routinely to try to protect battery, but let it go to 100% once a week or so to try to keep the BMS happy.
Any advice on the wisdom of this appreciated.
User Wyndstryke recommends 100% SoC at least weekly, and to reach 10% once a month to keep the BMS calibration fairly accurate.
I figured that as long as I don't abuse the battery cycles, or high/low heat extremes then it should be fine.
I figured that as long as I don't abuse the battery cycles, or high/low heat extremes then it should be fine.
I normally leave it in self-use and never get anywhere near 10%. I guess I'll have to make an effort.
LFP batteries have a very flat voltage curve, making it very difficult to read state of charge (SOC) based on its voltage reading, so the BMS needs to take the cells to 100%, so it is starting from a known point, then it monitors power flow to calculate a battery's SOC.
For example, if you have a 10kWh battery and it's charged to 100% and it monitors power flow of 5kWh then the SOC will calculate 10 - 5 = 50% SOC
The same happens when charging; it's a calculation based on how much power it monitors going in.
The monitoring is not 100% accurate and will slowly drift out over use/charge cycles if not taken to 100% SOC.
By taking it to 100% the BMS resets the starting point to battery maximum, in our example, 10kWh.
The battery will indeed last longer if not at 100% all the time, but if you are using it every day it won't be at 100% for very long, so the shortening of it's life is small and not worth worrying about.
If it were to sit at 100% for months, then it would have a noticeable effect on its life, and more so if it's hot weather.
NMC or similar chemistries read the battery voltage to get the SOC; it's not trying to monitor power flow. So you can charge these batteries to 90%, or whatever, with no problems.
Apart from the Tesla Powerwall 2, all the home batteries will be LFP these days, including the Tesla Powerwall 3.
LFP is safer than NMC types.
I have my battery set to 100%
For example, if you have a 10kWh battery and it's charged to 100% and it monitors power flow of 5kWh then the SOC will calculate 10 - 5 = 50% SOC
The same happens when charging; it's a calculation based on how much power it monitors going in.
The monitoring is not 100% accurate and will slowly drift out over use/charge cycles if not taken to 100% SOC.
By taking it to 100% the BMS resets the starting point to battery maximum, in our example, 10kWh.
The battery will indeed last longer if not at 100% all the time, but if you are using it every day it won't be at 100% for very long, so the shortening of it's life is small and not worth worrying about.
If it were to sit at 100% for months, then it would have a noticeable effect on its life, and more so if it's hot weather.
NMC or similar chemistries read the battery voltage to get the SOC; it's not trying to monitor power flow. So you can charge these batteries to 90%, or whatever, with no problems.
Apart from the Tesla Powerwall 2, all the home batteries will be LFP these days, including the Tesla Powerwall 3.
LFP is safer than NMC types.
I have my battery set to 100%
Thanks for the information - that's helpful.
My use case is perhaps unusual (and last summer here was probably unusual).
Power use during the day is typically very low, and last summer was often below solar input all day for long periods in hot weather. Hence the battery did stay pretty much at 100% and hot until start of cooking at 7pm.
My use case is perhaps unusual (and last summer here was probably unusual).
Power use during the day is typically very low, and last summer was often below solar input all day for long periods in hot weather. Hence the battery did stay pretty much at 100% and hot until start of cooking at 7pm.