Chins 200 amp hour battery at 99% SOC but only 13.4 volts

[waygonewilco]

Hi all, thanks for this forum and all of your knowledge.
I just upgraded my deep cycle batteries to a Chins 200 amp hour LiFePo4 battery with bms and low temp shutoff. My question is that using the EE-BMS app, I see that the battery is at 99% SOC at 13.4 volts, but Chins advises setting charge limit to 14.6 volts. Do I have a bad battery or am I missing something?

I have about ~350 watts coming into a Renogy Rover 40 amp controller. Have had serious issues with the controller and will be replacing with an Epever in the next few days

 

[Derka181]

Hi all, thanks for this forum and all of your knowledge.
I just upgraded my deep cycle batteries to a Chins 200 amp hour LiFePo4 battery with bms and low temp shutoff. My question is that using the EE-BMS app, I see that the battery is at 99% SOC at 13.4 volts, but Chins advises setting charge limit to 14.6 volts. Do I have a bad battery or am I missing something?

I have about ~350 watts coming into a Renogy Rover 40 amp controller. Have had serious issues with the controller and will be replacing with an Epever in the next few days

It no load or charge on it it should be around 13.4-13.6. Meaning it’s full. 14.6 is boost charge I believe

 

[Derka181]

It no load or charge on it it should be around 13.4-13.6. Meaning it’s full. 14.6 is boost charge I believe

 

[Derka181]

Charge state

 

[waygonewilco]

Thank you! That chart is very helpful.
Another noob question, is there a danger to the battery if the controller is still in mppt mode while battery is at 99 or 100%?
My understanding is that that is the job of the bms to shut off charging

 

[MisterSandals]

My understanding is that that is the job of the bms to shut off charging

No it is the job of the charge controller to control the charging.
It is the job of the BMS to disconnect the battery when the settings are out of bounds (voltage too high or low, current exceeds limits, temp, …).

 

[740GLE]

also a fully charge battery can then sit and rest at a much lower voltage 13.6v that the peak charge voltage 14.4v

That’s why the strict Voltage == SOC is a wrong way to look at SOC.

 

[Derka181]

Thank you! That chart is very helpful.
Another noob question, is there a danger to the battery if the controller is still in mppt mode while battery is at 99 or 100%?
My understanding is that that is the job of the bms to shut off charging

The mppt will do all the work. Don’t worry about the battery and the controller . You can also overpanel on most mppt controllers. Just don’t go over the VDC volts on the controller. Remember volts kill electronics not the amps.

 

[Derka181]

The mppt will do all the work. Don’t worry about the battery and the charger. You can also over panel on most mppt controllers. Just don’t over the volts. Remember volts kill electronics not the amps. And amps kiill people haha

 

[Derka181]

The mppt will do all the work. Don’t worry about the battery and the charger. You can also over panel on most mppt controllers. Just don’t over the volts. Remember volts kill electronics not the amps.

Another thing to remember is that the solar panels don’t push power to the batteries/ controller . The controller/ batteries pull power from the panels.

 

[waygonewilco]

Thanks all for the info, it has been very helpful. My concerns are moot then

 

[StuartV]

Charge state

You cant really go by that charge graph.

My battery (24v) is currently on 17.3% charge, but showing a voltage of 26.34V. My battery is made up of 4 x 100ah batteries. I use a Victron smart shunt to monitor solar production & usage.

 

[mikefitz]

The voltage on charge will always be higher that a resting ( no load or charge) voltage.
Regard Chins charge voltage of 14.6 as the maximum voltage you should consider. It's probable that if the charger is set to this voltage, cell mismatch will cause cell overvolts and BMS shutdown of the charge path.
Almost all the low cost batteries have this issue. For less stressful charging and avoidance of secondary effects, ( like voltage surges shutting down Inverters), a lower charge voltage in the range 14.0 to 14.4 could be used. ( Victron default absorbtion charge voltage for lithium in all their chargers is 14.2 volts).

Note on the graph ( thanks to upnorthandpersonal), under low charge currents, any battery volts over 14.0 volts ( 3.5v per cell) is for practical purpose full. Under initial discharge or at rest, any voltage over 13.4 volts, ( 3.35v per cell) is full.

Other than for testing it's not necessary to charge the last 1% of capacity.

Mike

 

[waygonewilco]

Thanks for that info Mike. I was wondering why Chins had their voltage so much higher than most other specs I've seen. I'll adjust mine to 14.2v and see how it does

 

[HRTKD]

The mppt will do all the work. Don’t worry about the battery and the controller . You can also overpanel on most mppt controllers. Just don’t go over the VDC volts on the controller. Remember volts kill electronics not the amps.

You can edit your post instead of quoting yourself and editing the quoted section. One of your posts looks like you quoted yourself and didn't provide any reply text.

 

[Derka181]

You can edit your post instead of quoting yourself and editing the quoted section. One of your posts looks like you quoted yourself and didn't provide any reply text.

Thanks for the info

 

[Derka181]

Thanks for the info

Actually I didn’t know I quoted myself. Don’t know what happened