Voltage concerns from dc to dc charger

[jamesaustin541]

I have a 100 watt panel supplying my renogy dcc50s 12v 50a dc-dc on-board battery charger with mppt rbc50d. When the 2 150 watt hour lithium batteries are at 100 percent, and the panel is still supplying the dc to dc charger, I get a reading of 17 volts at the shunt/Voltage -Current -Meter. as well as the LED read outs on my litium batteries. and any one shed some light on this for me. Can I be doing harm to my batteries?
Thanks

 

[BentleyJ]

17V/4 cells = 4.25V per cell.
Depends on the cell chemistry but both Li-ion and LFP cells are considered to have an upper limit of 4.2V before electrolyte degradation may occur, again depending on the specific chemistry involved.

 

[jamesaustin541]

17V/4 cells = 4.25V per cell.
Depends on the cell chemistry but both Li-ion and LFP cells are considered to have an upper limit of 4.2V before electrolyte degradation may occur, again depending on the specific chemistry involved.

thank you . I have LFPs

 

[Tomthumb62]

I have a 100 watt panel supplying my renogy dcc50s 12v 50a dc-dc on-board battery charger with mppt rbc50d. When the 2 150 watt hour lithium batteries are at 100 percent, and the panel is still supplying the dc to dc charger, I get a reading of 17 volts at the shunt/Voltage -Current -Meter. as well as the LED read outs on my litium batteries. and any one shed some light on this for me. Can I be doing harm to my batteries?
Thanks

I just went through this with a Renogy Rover, which is similar to your device but without the DCDC charger.

You need to use the “Renogy BT” app, go into the USER mode and change the High Voltage Disconnect setting from 17v to 14.4v.

The default setting is 17v. Why, I don’t know. It’s not visible on the device itself, nor from the DC Home app. You must use their older app I mentioned above.

Hopefully you haven’t damaged your battery. What I had to do was to disconnect the panels, then remove the battery completely from the system, wait 25 minutes, then reconnect it to the system and turn the panels back on. It’s been working normally since.

I’m in current communication with Renogy about this issue. I’m hoping to get a refund for the Rover and put that money towards a Victron.

 

[upnorthandpersonal]

LFP cells are considered to have an upper limit of 4.2V before electrolyte degradation may occur

Keep in mind that while this was the case a decade or so ago, nowadays for LFP this is considered below 4V, which is why you never tend to go above 3.65V per cell nowadays. Current cells such as those from EVE and others (the blue prismatic ones) start to swell significantly at 4V. So for OP: stay below 3.65V with LFP.

 

[jamesaustin541]

I just went through this with a Renogy Rover, which is similar to your device but without the DCDC charger.

You need to use the “Renogy BT” app, go into the USER mode and change the High Voltage Disconnect setting from 17v to 14.4v.

The default setting is 17v. Why, I don’t know. It’s not visible on the device itself, nor from the DC Home app. You must use their older app I mentioned above.

Hopefully you haven’t damaged your battery. What I had to do was to disconnect the panels, then remove the battery completely from the system, wait 25 minutes, then reconnect it to the system and turn the panels back on. It’s been working normally since.

I’m in current communication with Renogy about this issue. I’m hoping to get a refund for the Rover and put that money towards a Victron.

Thank you so much