Good morning everyone, I need some help please.

I have a 5kw Deye inverter and a 10Kw Revov battery. It's been working perfectly for 4 years, but recently the inverter has been drawing down the battery too much at night. My settings stayed the same with the time of use set to discharge the battery to 40% at night. The inverter still shows 40% in the morning, but the battery is below 20%. The inverter and battery percentages used to be spot-on and I did not change anything.

Any advice would be appreciated.

Usual suspects would be check that comms between inverter and battery is good (LiBMS screen should reflect values for current/temp/etc as they change, in close-to-realtime); and if that's not the issue the battery BMS may simply be mis-reporting it's SOC.

See what happens after you've taken it back to 100% when it starts charging again today. That might re-calibrate the BMS thereafter.

Failing that, a power cycle of the whole system may help, and I've had luck temporarily running my own battery in AGM Voltage mode (using the specifications from the manufacturer) to allow it to get to 100%, then let it drop close to cut-off voltage, which in many cases (including my own) will re-calibrate the BMS to have it corrected when going back to Lithium/BMS.

 

As a side-note, in voltage mode after hitting full capacity (ie when the battery stops accepting any more current at the charging voltage) the inverter will use that as that as the 100% mark, and 'estimate' (with frighteningly good accuracy) SOC thereafter, which can be used to replace voltage mode - by swapping over the 'AGM%' battery mode instead. No comms in this mode, it's just based on Power In/Power Out from the battery bank - the inverter is 'guessing' the real percentage using the capacity captured on the Battery screen and good old fashioned coulomb counting. My testing indicates this is within 4% of the value reported by the BMS.

3 hours ago, JL10 said:

Good morning everyone, I need some help please.

I have a 5kw Deye inverter and a 10Kw Revov battery. It's been working perfectly for 4 years, but recently the inverter has been drawing down the battery too much at night. My settings stayed the same with the time of use set to discharge the battery to 40% at night. The inverter still shows 40% in the morning, but the battery is below 20%. The inverter and battery percentages used to be spot-on and I did not change anything.

Any advice would be appreciated.

 

1 hour ago, JayMardern said:

Usual suspects would be check that comms between inverter and battery is good (LiBMS screen should reflect values for current/temp/etc as they change, in close-to-realtime); and if that's not the issue the battery BMS may simply be mis-reporting it's SOC.

See what happens after you've taken it back to 100% when it starts charging again today. That might re-calibrate the BMS thereafter.

Failing that, a power cycle of the whole system may help, and I've had luck temporarily running my own battery in AGM Voltage mode (using the specifications from the manufacturer) to allow it to get to 100%, then let it drop close to cut-off voltage, which in many cases (including my own) will re-calibrate the BMS to have it corrected when going back to Lithium/BMS.

 

As a side-note, in voltage mode after hitting full capacity (ie when the battery stops accepting any more current at the charging voltage) the inverter will use that as that as the 100% mark, and 'estimate' (with frighteningly good accuracy) SOC thereafter, which can be used to replace voltage mode - by swapping over the 'AGM%' battery mode instead. No comms in this mode, it's just based on Power In/Power Out from the battery bank - the inverter is 'guessing' the real percentage using the capacity captured on the Battery screen and good old fashioned coulomb counting. My testing indicates this is within 4% of the value reported by the BMS.

 

There is no comms between my battery and inverter, running on voltage mode, back when it was installed Revov could not communicate with Deye. I know they can now so maybe it's time to fix that.

I'm letting it sit on 100% the whole day, so hopefully it will recalibrate itself. Thanks for the reply.

Yeah - 100% then let it dip low (down to 15%) and hopefully you're sorted after a full cycle.

2 minutes ago, JL10 said:

There is no comms between my battery and inverter, running on voltage mode, back when it was installed Revov could not communicate with Deye. I know they can now so maybe it's time to fix that.

I'm letting it sit on 100% the whole day, so hopefully it will recalibrate itself. Thanks for the reply.

 

2 hours ago, JL10 said:

There is no comms between my battery and inverter, running on voltage mode, back when it was installed Revov could not communicate with Deye. I know they can now so maybe it's time to fix that.

I'm letting it sit on 100% the whole day, so hopefully it will recalibrate itself. Thanks for the reply.

If there's no comms you should be running it in voltage mode, then the timer settings will be voltage based as well, not % based , which can be way off. 

21 minutes ago, abd7 said:

If there's no comms you should be running it in voltage mode, then the timer settings will be voltage based as well, not % based , which can be way off. 

Yeah he mentions he is. You'll still see a % though when clicking through the info screen, even in V mode (at least on the SS's you do).

My experience with AGM % mode is totally different to yours though: with last month's firmware update, the discrepancy between battery-BMS-reported SOC and inverter-displayed % is consistently under 5%: And this is with two inverters running in parallel and drawing/charging from the battery bank slightly differently (I test by temporarily activating Lithium mode to compare on the BMS screen, at various levels of SOC).

However: this does include a charge to 100% (which re-calibrates the measurement) at least every 2nd or 3rd day though. 

If I didn't have BMS comms this would do the trick for me, though comms is always first prize of course.

V mode doesn't have enough decimal points to be useful for precise night-time targets in my case, I need at least two decimals rather than one (lithium has a rather flat discharge curve!).

Edited April 19, 20242 yr by JayMardern