Controller puzzle - Float for LFP on solar (long post)

[Almot]

Preamble - for those who are interested. I'm trying to set EPEVER MPPT controller for LFP battery. Custom charging profile for LFP requires connecting laptop with proprietary cable (not included) and downloading and installing EPEVER software. Procured the cable, installed the software, controller is not recognized. Software Read-me and Help files are in horrible Chinglish. I am not new to controllers but had to read each phrase several times, comparing to interface screens and buttons, going back and forth again and again before could understand what they meant. Had to dig into Win 10 Control Panel and change Port COM number, delete ports, add ports, delete and create custom profile 10 or 12 times, uninstalled and re-installed the entire software a few times - after 5 or 6 hours it works now.

Battery specs:
charge Full to 14.2V, set Absorption to 0-10 minutes, avoid Float or set Float as low as possible 12.8-13.6V.
BMS: LVD= 10V, HVD= 14.6V.

Objective: keeping battery being charged all the time unless it's Full, because this is solar, North Pacific - sun today, gone tomorrow.

Can't set Float to lower than 12.9V.

Custom charging profile that I've set:

Charging limit: 14.2
Over voltage disconnect: 14.4 (why do I even need this when charging stops at 14.2?)
Over voltage reconnect: 14.2 (don't ask me what this is)
Equalize: 14.2V, duration 0.
Boost charging (aka Absorption start): 14.2V, duration 10 minutes (thinking changing to 5 minutes)
Float: 12.9 (can't be set below Boost Reconnect)
Boost Reconnect: 12.8
Low voltage reconnect: 12.7
Under voltage warning reconnect: 12.7 (don't ask me what this is)
LVD: 12.6
Discharging limit: 12.6 (why do I need this when LVD= 12.6?)

As said, Float can't be set below Boost Reconnect, and there are other mandatory relations, ex. LVD>= BMS LVD+0.2, OVD> BMS OVD+0.2 (not sure about the latter, could be a typo). Complete list of requirements below (pain in the ars, told ya :). PCM means BMS, but other than that, controller manual is in good English. Software is not.

I. Over Voltage Disconnect Voltage > Over charging protection voltage(Protection Circuit Modules(PCM))+0.2V;
II. Over Voltage Disconnect Voltage>Over Voltage Reconnect Voltage=Charging Limit Voltage >= Equalize Charging Voltage=Boost Charging Voltage >= Float Charging Voltage>Boost Reconnect Charging Voltage;
III. Low Voltage Reconnect Voltage > Low Voltage Disconnect Voltage >= Discharging Limit Voltage;
IV. Under Voltage Warning Reconnect Voltage > Under Voltage Warning Voltage >= Discharging Limit Voltage;
V. Boost Reconnect Charging voltage > Low Voltage Disconnect Voltage;
VI. Low Voltage Disconnect Voltage >= Over discharging protection voltage (PCM)+0.2V

[StirCrazy]

Almot wrote:

StirCrazy wrote:


I have the renogy rover, all it requires is the bluetooth modual and the app and you can set it up how you want it with your cell phone. you just go to user definded battery type if you dont like the settings they have for Li and pick the value for each setting.

Steve

They sell Rover either without BT dongle, or with (for more money). It looks like RS232 port is there on the unit no matter what, and they are talking about using PC as well. Not sure I understood them correctly.

From the manual: "RS232 port to communicate with BT-1 Bluetooth module and PC". Don't see RS232-USB cable in Renogy Accessories. RS232-USB cables on Amazon have very different monstrous RS232 looking more like a VGA monitor connector.

yes, I bought the bluetooth dongle, for the 40ish bucks, maybe 50... it was well worth it. it showes lots of info and keeps a hystory of charges and such. plus I can edit the setting from my cell phone and not have to have a laptop and cable that I have to access the charger physicly.

Steve

[pianotuna]

Almot wrote:

I tried to set Float low because the battery manual said so - no Float or as low as possible :).

Victron quality is definitely superior to Epever or Renogy, though at a double cost. From what I read, Victron has no display and no interface on the actual unit, you have to use the phone app or again a laptop with cable. Seems like after the defunct Rogue nobody can make a small MPPT with a proper interface on the unit. Don't recall anybody before Rogue, either. Kid by Midnite Solar came the closest, at a higher price and fewer features.

Blue Sky does have an add on box (ipn remote) that allows for full programing rather than the limited settings from the dip switches.

They did, at one time, sell a control chip that you could request the parameters you required--I think for $75.00 I have the unit that displays voltage and amperage flowing into the battery bank.

https://sunforgellc.com/blue-sky-energy/#bse_product_row

[FWC]

A 'float' of around 13.3V is about perfect, won't charge the battery, will carry the load.

Yes the Victron is a little more expensive, but they are very high quality products and you will be up and running in minutes - the phone app or computer app is extremely easy to use (no futzing with cables, drivers etc). If you want a display/interface there is also one available, but the app is so good I doubt you would end up wanting one.

Almot wrote:

FWC wrote:
I am still not sure why you were trying to set the float so low.

But I think you are on the right track, with the amount of time sunk into this you would be further ahead to just buy a Victron MPPT to begin with and call it good. Skip the Renogy and get one that is easy to program and just works, no laptop required.

I tried to set Float low because the battery manual said so - no Float or as low as possible :).

Victron quality is definitely superior to Epever or Renogy, though at a double cost. From what I read, Victron has no display and no interface on the actual unit, you have to use the phone app or again a laptop with cable. Seems like after the defunct Rogue nobody can make a small MPPT with a proper interface on the unit. Don't recall anybody before Rogue, either. Kid by Midnite Solar came the closest, at a higher price and fewer features.

[Almot]

StirCrazy wrote:


I have the renogy rover, all it requires is the bluetooth modual and the app and you can set it up how you want it with your cell phone. you just go to user definded battery type if you dont like the settings they have for Li and pick the value for each setting.

Steve

They sell Rover either without BT dongle, or with (for more money). It looks like RS232 port is there on the unit no matter what, and they are talking about using PC as well. Not sure I understood them correctly.

From the manual: "RS232 port to communicate with BT-1 Bluetooth module and PC". Don't see RS232-USB cable in Renogy Accessories. RS232-USB cables on Amazon have very different monstrous RS232 looking more like a VGA monitor connector.

[Almot]

FWC wrote:
I am still not sure why you were trying to set the float so low.

But I think you are on the right track, with the amount of time sunk into this you would be further ahead to just buy a Victron MPPT to begin with and call it good. Skip the Renogy and get one that is easy to program and just works, no laptop required.

I tried to set Float low because the battery manual said so - no Float or as low as possible :).

Victron quality is definitely superior to Epever or Renogy, though at a double cost. From what I read, Victron has no display and no interface on the actual unit, you have to use the phone app or again a laptop with cable. Seems like after the defunct Rogue nobody can make a small MPPT with a proper interface on the unit. Don't recall anybody before Rogue, either. Kid by Midnite Solar came the closest, at a higher price and fewer features.

[StirCrazy]

Almot wrote:
More news.

Raised Float to 13.8, also raised Boost Reconnect - don't remember the value because Epever software froze on the laptop. Upon restarting the software it became unruly, stopped recognizing the "station" (in other words, custom profile including data of the controller and solar array). I deleted the "station" and it's now refusing to add a new "station" and configure Port COM - Windows seems to dislike this software.

Whatever settings are in the custom profile, are buried in the controller memory for good. I can't communicate with controller, can't see or change custom profile.

Meanwhile controller itself works, quietly doing Boost at 10A, as I can see on its built-in display. Only I don't remember the latest settings and can't be sure they are still what I set.

Will try and return Epever and get Renogy Rover Li, it can't be much worse. Rover also requires a laptop and software for custom profile BUT at least it has a preset Li profile accessible (though not modifiable) directly through controller interface.

I have the renogy rover, all it requires is the bluetooth modual and the app and you can set it up how you want it with your cell phone. you just go to user definded battery type if you dont like the settings they have for Li and pick the value for each setting.

Steve

[FWC]

I am still not sure why you were trying to set the float so low.

But I think you are on the right track, with the amount of time sunk into this you would be further ahead to just buy a Victron MPPT to begin with and call it good. Skip the Renogy and get one that is easy to program and just works, no laptop required.

[Almot]

More news.

Raised Float to 13.8, also raised Boost Reconnect - don't remember the value because Epever software froze on the laptop. Upon restarting the software it became unruly, stopped recognizing the "station" (in other words, custom profile including data of the controller and solar array). I deleted the "station" and it's now refusing to add a new "station" and configure Port COM - Windows seems to dislike this software.

Whatever settings are in the custom profile, are buried in the controller memory for good. I can't communicate with controller, can't see or change custom profile.

Meanwhile controller itself works, quietly doing Boost at 10A, as I can see on its built-in display. Only I don't remember the latest settings and can't be sure they are still what I set.

Will try and return Epever and get Renogy Rover Li, it can't be much worse. Rover also requires a laptop and software for custom profile BUT at least it has a preset Li profile accessible (though not modifiable) directly through controller interface.

[time2roll]

I don't see any reason to run the voltage up every day. If you are at 95% on LFP you are done. Controller stops at 95% is good.

[Almot]

time2roll wrote:
Why not just charge to 14 volts and let it float at 13.3?
Bulk restart at 13.1 is fine.

What are you expecting from the charging?

I can't charge it to 14 anymore, it won't restart Bulk. With battery resting at 13.2 controller starts with Float - which I set to 12.9. It did Bulk at the beginning of the experiment but not anymore. There wasn't much charging done here, 11A Bulk lasted a few minutes before I disconnected it. Battery is now at the same point where it was.

13.2 (more likely will settle at 13.1 if given some time) = 95% SOC. I don't expect much from charging at this point, but controller should at least try :). Maybe a few amps load will kick it into action, by lowering the voltage. Tomorrow.

[time2roll]

Why not just charge to 14 volts and let it float at 13.3?
Bulk restart at 13.1 is fine.

What are you expecting from the charging?

[time2roll]

Over voltage reconnect is exactly what it says. If the voltage goes too high and there is a disconnect... the controller will wait for the voltage to drop below the re-connect voltage.

This way it does no flip On-off-on-off at exactly the over volt disconnect voltage.

The over voltage disconnect should be set about the same as the BMS protect voltage and the reconnect should be a few tenths below. The charging should not be controlled by this function. This setting is to protect battery and components from over voltage damage.

If you were able to set the reconnect to zero you would have to disconnect the battery for the reset.

[Almot]

Update - simulated morning sunrise.
Hooked up controller to regulated DC supply, battery was resting 13V, setpoints as in the post #1.
MPPT input 15.2V, battery went into Boost/Bulk, current 11A.
Battery voltage went up instantly to 13.4 and dropped back to 13.1 when disconnected again.
So... boost/bulk starts in the morning just fine, despite battery voltage being already higher than Boost Reconnect. This was the only time when things worked - bear with me.

Simulated "battery full":
Disconnected DC supply, changed Boost Charge, Overvolt Reconnect (I wish I knew what it was) and Charge Limit to 13.4. Battery was charging at 13.4 before disconnecting.

Reconnected DC supply - no charging, laptop reads "Boost, SOC 100%" - as it should, because the battery = 13.4, controller thinks it's Full. In 10 minutes it switched to Float 12.9 as per timer, laptop reading "Float", battery resting at 13.2V, current - zero.

Shut the sun down - lowered DC input to to 13.6 - at this point charging stopped, laptop reads "Solar Cut Out, Not Charging".

Turned the sun On again - MPPT input 13.4, still no charging. Alright, I previously set charging limit 13.4 so controller still thinks it is Full.

Changed charging limit to 14.2 as before, set MPPT input to 13.4, 13.6, 14.0 - no charging. Controller wakes up when input is at least 14.2 and goes into Float, current = 0.

Upped MPPT input to 15.2V as at the beginning of the experiment - still Float, zero current. What changed? Battery resting voltage is almost the same as it was at the beginning - 13.2 vs 13.0, Charge Limit = 14.2. I need Boost now, not Float.

Other findings:
Can't set Boost Reconnect to zero, software response: "BR not in the allowed range".
Can't set BR to 11 or 12, software response: "Low Voltage Reconnect must be smaller than BR". (I wish I knew what the Low Voltage Reconnect was).
Can't set Boost timer to less 10 minutes.

What do you think, should I throw this controller out of the window?

[Almot]

I warned that Epever manual is a pain. They don't explain what each parameter means.

I "think" Boost Reconnect (12.8 in my case) is when it resumes bulk/boost when battery drops below 12.9 Float when in use, or when it wakes up below 12.9 in the morning. Would love to hear other explanations before contacting the manufacturer (after their dreaded software the thought of emails in Chinglish scares me).

Charge-discharge curves: https://www.lynaclithium.com/wp-content/uploads/2020/10/12.8V-100Ah-True-Series-Quick-Sheet.pdf. (They assume 0.5C but my charging will be <0.2C and discharge <0.1C).

When bulk/boost hits 14.2, it goes to 12.9 Float, drops to 12.8 BR, resumes bulk/boost.

In the morning it wakes up at, say, 12.5 = 80% DOD, this is below BR 12.8 so it starts bulk/boost. So far so good.

OTH, if I manage keeping it at 12.9 = 45% DOD in the morning, it won't start charging at all - because it's above BR 12.8. Probably won't Float either because Float comes after Boost/Absorb 14.2, this is how other controllers work. My solar is 200W, draw 30-60 AH per 24 hours, a tight fit, don't want to waste any sun.

Maybe should raise BR higher - assuming BR means what I think it means.