Settings for a Dyness PowerBox or B4850? Does Absorption, Float and Equalisation Voltage settings apply even with BMS?
I have a PowerBox F10, which is basically 4x B4850 in a wall mounted box. It's in the list of supported batteries, but the applicability of some settings is unclear.
The dyness install manual has spec data that mentions a charge voltage range of 40.5V to 54V, max continuous charge and discharge of 1C, and recommended charge rate of 0.5C.
Dyness doesn't supply any clear info about Bulk V, Absorption V, Equalisation V and Float V in their F10 install manual or B4850 user manual. These settings typically apply more to lead acid without BMS where the inverter is controlling charge, or Lithium without BMS? But even with BMS configured for the Dyness, these settings on SynSynk remain editable and are not disabled/greyed out by the UI (firmware updated in September). So I'm unsure if Dyness via BMS does it's own battery cell equalisation (I'd assume this), etc, or if the inverter has to manage it (that would be odd - why have BMS with access to internal cell state/gravity, etc but not manage it via BMS). So my installer set it up with BOTH BMS successfully connected AND various settings for voltages are also set. It's unclear what applies or overrides between these. E.g. do any of the settings compliment or override BMS settings? Does Absorption V, Equalisation V and Float V apply or is it just the case that installers set this for other batteries and got confused not knowing it doesn't apply if BMS configured?
The current manual shows BMS is to be setup with CAN and protocol option 0.
Batt type This is what my installer did (he also set capacity to 180Ah, which is incorrect I think, so I changed it to nominal 200Ah).
So far, so good? Technically, I should be able set discharge Amps to 120A since that's the max for the inverter and the powerbox can handle up to 200A for 3s (peak current). But left it at 100A (4800W) to be nice to the battery.
Batt charge
This was set and I'm unclear if/how it's applicable instead of BMS or not. The applicability and correctness of Float V, Absorption V and Equalization settings is in question. And they're not greyed out or disabled, so I'd assume they do apply somehow? Or is it just the UI failing to disable not-applicable settings?
By the way, I think the 40A setting means my installer limited grid charge 40A which I assume applies to the DC side and AC side, so at 48V DC for the battery, this would be 1920W, and ~8.3A load on the grid side (given 1920W / 230V). I can tell the BMS overrides this setting since I see the battery does charge at over 1920W when enough PV power is available.
Shut Down
This was set. Again, this is inverter control, not BMS control. It overides BMS? So okay to have higher than spec settings?
Note, according to the Dyness manuals:
Max DoD is 90%, so ShutDown should be 10%?
Low Batt alarm: 10%<SOC<30%. so Low Batt should be 30%?
Nothing noted about restart.
LI Bms
When I check "LI BMS" output, BMS reports currenet, voltage, temp, SOC as expected. But some questions:
What does LiBms: 03 mean?
It also specifies the charge voltage to use, and charge discharge limits. So does this BMS control supersede whatever is set in the "Batt charge" settings?
Here are conflicting sources on the matter showing the amount of confusion between charge voltage settings and BMS for Dyness SOL-ARK 8K INSTALL GUIDE & OWNER’S MANUAL: https://www.sol-ark.com/wp-content/uploads/2020/10/8KOD-Manual-10-14-2020-.pdf
Tends to show higher V limits compared to others.
Dyness Powerbox With Victron --> Settings Found: https://powerforum.co.za/topic/5547-dyness-powerbox-with-victron-settings-found/
Provided nice table showing charge and discharge limits per SoC and per temperature range.
Noted CAN-bus BMS (500 kbit/s).
solaradvice.co.za: Dyness and Deye Setup: https://solaradvice.co.za/wp-content/uploads/2019/09/Dyness-Deye_Sunsynk-Setup-startshut-down.pdf
I tried to compare the above and here's a table showing various sources have notably different recommendations. Many don't define the PowerBox max charge/discharge, just <num batteries> X B4850 module.
Here's a screemshot of what I found in the Sol-Ark 8K manual, and Sol-Ark looks like the USA equivalent of SunSynk / Deye.
Update here. Asked the above via email and Dyness support were very quick to reply. Firstly, they shared these settings, but also said that the slightly lower settings of 51V absorption and 52V float my installer had was okay:
Incidentally, the above matches up with the compatibility note victron has about pylontech (https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom#after_charging_the_battery_the_charge_current_often_changes_between_0a_and_25a), where they say:
Note however, SunSynk doesn't override the BMS settings like Victron.
Float and Absorption only apply if BMS is not connected.
Equalisation settings should not apply since BMS has its own internal equalization.
Ideally, SunSynk should grey out equalisation options for Dyness!
The one setting that did apply/override as a lower threshold is the charge limit setting. E.g. I limited to 40A which means even if BMS communicated 100A max charge, the inverter should only use 40A.
Again, I think the SunSynk manual could do a better job clarifying all the above nuances.