Renogy charge controller battery over-voltage alarm

[Tomthumb62]

Well, the overvoltage problem with my Renogy charge controller damaged some of my LiFePO4 cells even with a BMS. I ended up getting my money back from Renogy.

Did they give you money for your battery or just the charge controller?

 

[12VoltInstalls]

17V is like the programming was done by a waitress that moonlights as an electrical engineer to make ends meet, or something!

 

[Tomthumb62]

17V is like the programming was done by a waitress that moonlights as an electrical engineer to make ends meet, or something!

Angry face because an angry laughing face isn’t an emoji option lol ? ??‍

 

[Texas-Mark]

Long story short, it looks like the Renogy Rover has a DEFAULT setting of 17v for “High Voltage Disconnect".

My rover 40's user default is 16V. However, I think people may be looking at this setting wrong. There is a separate charge limit voltage that should stop charging at that point. I believe the "high voltage disconnect" is for a situation (failsafe) where you blow a battery fuse, BMS cuts out, etc. which would cause the CC's output to jump high since there is no load.

 

[Tomthumb62]

My rover 40's user default is 16V. However, I think people may be looking at this setting wrong. There is a separate charge limit voltage that should stop charging at that point. I believe the "high voltage disconnect" is for a situation (failsafe) where you blow a battery fuse, BMS cuts out, etc. which would cause the CC's output to jump high since there is no load.

I wish that were the case. I have screenshots that show that the Rover 30A was overcharging the battery.

 

[Texas-Mark]

I wish that were the case. I have screenshots that show that the Rover 30A was overcharging the battery.

You have shots of what the CC was seeing on it's outputs. May not be the same as the battery. That looks to be too short of a time span for a battery to go from 13.5 to 16.7 without something opening (like the BMS). There have been several threads (not just about Renogy controllers) of voltage spiking when the BMS opens. Most often from unbalanced cells and one going into OV before the charge cutoff voltage is reached

 

[Tomthumb62]

You have shots of what the CC was seeing on it's outputs. May not be the same as the battery. That looks to be too short of a time span for a battery to go from 13.5 to 16.7 without something opening (like the BMS). There have been several threads (not just about Renogy controllers) of voltage spiking when the BMS opens. Most often from unbalanced cells and one going into OV before the charge cutoff voltage is reached

Perhaps that’s all it is. Except the default USER setting for “high voltage disconnect” for the Rover series is set to 17v. This setting is invisible to the consumer, UNLESS they have the Bluetooth dongle installed and use the now outdated RENOGY BT app. The manual buttons on the device do not allow viewing or changing this parameter, nor does the newest DC HOME app.

I’m waiting to hear back from Renogy tech support about this issue.

When this last happened, my battery’s BMS wigged out. With or without a load, the voltage was jumping all over the place, from 12.8v to 14.0v. I removed the battery from the system and waited about 20 minutes before adding it back in. All seems normal now. I’ve also changed the pesky parameter from 17.0v to 14.6v.

 

[Texas-Mark]

Except the default USER setting for “high voltage disconnect” for the Rover series is set to 17v.

Not that it matters, but as I said, my Rover's default setting is 16v for that USER setting. Hidden or not, it really should never come into play if the charge cuttoff voltage is set correctly and the cells are balanced as to not cut off the BMS before the charge voltage limit is reached.

 

[Tomthumb62]

Not that it matters, but as I said, my Rover's default setting is 16v for that USER setting. Hidden or not, it really should never come into play if the charge cuttoff voltage is set correctly and the cells are balanced as to not cut off the BMS before the charge voltage limit is reached.

If I load the RENOGY BT app, the default USER setting for cutoff is 17v. I’ve changed it to 14.6v. If I load the DC HOME app and then immediately close it and open the RENOGY BT app, the cutoff parameter now reads 16.0v. If I click the READ button, it then shows the stored number of 14.6v.

Renogy tech support suggested this is a glitch in the BT app.

 

[Texas-Mark]

default USER setting for cutoff is 17v. I’ve changed it to 14.6v.

Both voltages are too high for a lifepo4 battery to be at. That is why I said it more of a failsafe for having too high a voltage on the line (if something opens), than for protecting the battery.

FWIW, I set charge cutoff to 14.3v and HV disconnect to 14.4. that way nothing higher than 14.4V will ever reach anything else on the "line".

 

[Tomthumb62]

Both voltages are too high for a lifepo4 battery to be at. That is why I said it more of a failsafe for having too high a voltage on the line (if something opens), than for protecting the battery.

FWIW, I set charge cutoff to 14.3v and HV disconnect to 14.4. that way nothing higher than 14.4V will ever reach anything else on the "line".

My understanding is there’sa phenomenon where passing clouds can cause a momentary spike that the charge controller might pass along to the battery if the cutoff is set too high.