MPPT Charge Controller Over-voltage

[sjkted]

Hi All,

I have a LiTime battery being charged by a PowMR MPPT solar charge controller. A 3000 Giandel inverter is powering a small residential fridge. Right now, the battery is charged to 100%. I have an intermittent alarm that is going off on the inverter for high voltage. When I check the charge controller, over a 1 minute period, theses are the voltages I see on the SCC: 15.2, 14.2, 13.7, 13.6, 14, 16.1, 17.4, 18, 16.3. It seems like the SCC is looping from a high voltage back to a normal voltage over and over and over again. I have the battery type set to L04 which should be correct on the SCC. My temporary solution is to just turn off the solar as I don't need it right now. Is this normal? Is there a way to program the SCC not to do it? Per the manual a LIPoe4 battery should have the following:

Boost charging voltage: 14.5V
Float charging voltage: 13.8V
Low DC cut-off voltage: 11.2V
Low DC cut-off recovery voltage: 12.8V

I can edit these values as a custom setting but I don't really see the point if it is not respecting what is already in there. Please advise. I already e-mailed the manufacturer.

Thanks,

sjkted

 

[sunshine_eggo]

LiTime battery is imbalanced and cutting off charge causing MPPT voltage to spike as the battery is suddenly removed from the charge circuit. The MPPT can't clamp down on the current fast enough to prevent a spike.

Very common especially with new batteries. Typicaly installed 90+ days since they were last charged and must ship at 30% SoC max due to hazmat regs.

Boost to 13.8V
Float to 13.6V
Boost duration to 4 hours.

Should reduce/eliminate spikes. Leave it this way for about a week.

Once you can charge to 14.4V w/o spikes:
Boost to 14.4V
Float to 13.5V
Boost duration to 30 minutes.

 

[sjkted]

Thanks, I remember seeing this elsewhere on the forum.

Can you explain how that works in a practical sense? Do I need to unplug the inverter and fridge?

Are you saying just to charge once and let it sit for a week?

I have the MPPT SCC, a Litime 40A charger and a generic 10A charger that will do LiPOE4 batteries?

sjkted

 

[sunshine_eggo]

Thanks, I remember seeing this elsewhere on the forum.

Can you explain how that works in a practical sense?

It lowers the absorption voltage to a point that should reduce eliminate spikes (BMS protection events) while still allowing battery to achieve a near full SoC (98%+) over a longer period of time.

Do I need to unplug the inverter and fridge?

If you can eliminate the spikes, it should be unnecessary.

Are you saying just to charge once and let it sit for a week?

No. Let it operate with those settings for a week.

 

[sjkted]

So I have been running on the MPPT SCC for a week:
Boost to 13.8V
Float to 13.6V

If I try to increase those settings at all, I get boosts just like before. Any recommendations? I'm not sure if this is a battery thing or an issue with the SCC.

Thanks,

sjkted

 

[sunshine_eggo]

It's hard to imagine a scenario where this could be the charger. What you are experiencing is extremely common with batteries that are received imbalanced as I described above.

It may be that your batteries will not balance at the lower voltages prescribed. Given that you have not seen any improvement for a couple of weeks, I'm thinking that's the case. Unfortunately your only other option is to take the battery offline and hold it at 14.4 volts for 24 hours to see if there's any improvement.

 

[sjkted]

So, I have the Litime LiPOE4 battery charger and had problems with charging it. I sent an e-mail to Litime and this was their response:

I have a LiTime 12V 230Ah battery with Low-Temp (200A BMS) and a LiTime
14.6V 40A LiFePO4 Battery Charger. Yesterday, when I tried to charge the
battery, the red light would turn on and then click and then the green
light would turn on. When the red light was on, it would show charging
around 14.4V and then various lower voltages with the green light. I
don't think it was charging the battery. Can you tell me how to
troubleshoot this?

Thank you contacting LiTime service , it's Ricket, i will be of your any assistance.
Don't worried, it was the common status when the 14.6V charger charging the battery with low-temp protection. when The red- green lights alternately light up and the relay switches on and off. When the above situation occurs, it means that the battery is fully charged and the charger can be removed. (Note: The above phenomenon will not affect the battery or charger and will not cause safety hazards.

According to them, the battery has already been fully charged. I suppose I could try again, but I am off-grid so I can't really charge anything for 24 hours and the only other charger I have is 4 amps and it says that the battery is fully charged.

sjkted

 

[sunshine_eggo]

They're basically giving you an ESL nonsense answer.

"fully charged" to the chargers means:

1) charger is at peak voltage
2) current has dropped to 0

The above two criteria are met when the battery engages charge protection. If you're able to watch or log the charge, protection is indicated by an abrupt jump to max voltage (and/or a voltage spike), and an immediate drop to 0A.