Hi all,

I have a new one of these, rated at 14.3kwh: https://dyness.com/powerbrick-low-voltage-storage-batteries-for-household-use

I monitor discharge via rs485 on inverter modbus to home assistant.

Inverter is the sun-12k-SG02LP1-EU-AM3 deye. (Modbus address 190, register type: holding). This should be the watt in/out of the battery. I filter all negative values (charge) so that I can see only discharge.

Battery configured for BMS (dip switches 0010) and the inverter confirms dyness BMS.

If I charge the battery to 100% then drain it to 16%, (having used 84%) I should have gotten 12kwh from that 84%. My inverter measures the power output over that cycle to be 9.6kwh.

If I charge the battery to 100% then drain it to 5% (max rated battery discharge per battery spec), I have then used 95% and should have gotten 13.6kwh from it, but the inverter has measured output of 11.0kwh from that cycle.

Even looking generally for every 10% of battery use, where I should have gotten 1.4kwh, the reading shows it is much less.

I know all batteries have some variance, but is the above expected? Seems too off the target?

I contacted @Dyness support, they offered to do a load test for me, but that involves disconnecting the battery and taking it to midrand etc (a huge pain). So I figured let me ask here to see if the above is expected before I go through the pain of a load test on it.

Does anyone else have a power brick I can compare output with to find out what is normal and expected output of this product?

Thanks.

Some searching shows people saying the deye inverter watt values for the battery charge/discharge can be wrong.

Also on the deye inverter app, the battery power draw watt value is lower than the ups-load watt value (at night with no solar and no grid pull) which makes no sense. There's no grid use and no solar at night so I'm quite sure the ups-load is running fully off the battery. I image the battery power draw should be larger than the ups-load given the inverter itself must use some power. So the app showing battery power draw slightly less than ups-load value, leads me to think the inverter is reporting the battery power draw wrong.

I'm going to see if there is a firmware update for my inverter that maybe fixes the issue, if not, I'll probably try engage deye support on the issue. @Deye

13 hours ago, H1771 said:

Some searching shows people saying the deye inverter watt values for the battery charge/discharge can be wrong.

Also on the deye inverter app, the battery power draw watt value is lower than the ups-load watt value (at night with no solar and no grid pull) which makes no sense. There's no grid use and no solar at night so I'm quite sure the ups-load is running fully off the battery. I image the battery power draw should be larger than the ups-load given the inverter itself must use some power. So the app showing battery power draw slightly less than ups-load value, leads me to think the inverter is reporting the battery power draw wrong.

I'm going to see if there is a firmware update for my inverter that maybe fixes the issue, if not, I'll probably try engage deye support on the issue. @Deye

Interesting on your inverter. On my Deye the UPS shows zero when no PV and no grid used. The battery draw is close to identical to the consumption. Part of the consumption is self use by the inverter.

So after a firmware update to the inverter, my discharge power and consumption power align very closely, with battery discharge very slightly higher (which is what I expect, not the other way around as it was before the update).

But from https://github.com/slipx06/Sunsynk-Home-Assistant-Dash/blob/main/ESPHome%20Configs/ESPHome-1P-Sunsynk-Deye.yaml

If I use these:

Then I see what kwh was discharged from the battery over certain hours, the kwh used does not match the battery % used per battery capacity.

Eg. I ran the battery from 100% to 17% (used 83% of the battery), then check the kwh from those same timestamps, it worked out to 10.0kwh. But the battery is a 14.3kwh dyness power brick, which means 83% of the stated capacity should be 11.86kwh. Does not seem like I get the kwh from the battery per the capacity.