EPEVER MPPT Tracer4210AN Help

Sangeroth

I'm trying to set my charging parameters for my setup.  I have 4 - 100 Watt panels, 2000 Watt Pure Sine Wave Inverter, 20 Amp DC-DC Charger, 2 - 100 Ah SOK batteries, and this EPEVER as my MPPT.  I went into the MT50 and changed the battery type to USER and was able to change everything except three parameters.  The problems I have are as follows:


1. SOK said they want the Boost Charge Voltage to be 14.6 but the MPPT manual says it has to be equal to the Equalize Charging Voltage which SOK wants to be 14.4.

2. The MPPT manual says the Low Voltage Reconnect has to be greater than the Low Voltage Disconnect and SOK wants the Low Voltage Reconnect to be 10 while the Low Voltage Disconnect should be 11.

3. The Under Voltage Reconnect Voltage stays at 11.6 and won't go to SOK's requirements of 11.5.  This is because the Under Voltage Reconnect Voltage has to be greater than the Under Voltage Warning and SOK says both need to be 11.5.



Below are the charging parameters directly given from SOK (I am putting a * next to the parameter for each issue, so for example - the charging parameters for issue 1 will each have one * next to it, Issue two will have two ** and Issue 3 will have *** next to them):

Over Voltage Disconnect 14.7 V
Charging Limit Voltage 14.6 V
Over Voltage Reconnect 14.6 V
*Equalize Charging Voltage shut off or 14.4 V
*Boost Charging Voltage 14.6 V
Float Charging Voltage 13.6 V
Boost Reconnect 13.3 V
**Low Voltage Reconnect 10
***Under Voltage Warning Reconnect Voltage 11.5
***Under Voltage Warning 11.5
**Low Voltage Disconnect 11.0
Discharging Limit Voltage 10.5
Equalize Duration 0
Boost Duration 180 minutes



EPEVER Manual:

https://www.epever.com/wp-content/uploads/2021/05/Tracer-AN-SMS-EL-V1.0.pdf

Please see page 18-19 for the charging parameters rules.

BB.

Found a website that lists the battery's specifications (via: https://diysolarforum.com/threads/sok-battery-manual.29664/SC):

https://www.currentconnected.com/product/sok

1) I would not set boost voltage to 14.6 volts--That is the BMS cutoff voltage... In normal operation, I would not want to trip the BMS battery cutoff (high/low temperature, high current, etc.). I highly suggest that the BMS cutoff be used as a last ditch protection for the battery bank. If you trip the protection circuit (battery disconnect), that can cause damage to the rest of your solar system and loads (i.e, battery cutoff at 14.6 volts, then the solar charge controller could raise the battery bus voltage >>14.6 volts and damage your loads/AC inverter's input and such).

Also, did you set the temperature compensation to 0.0 Volts/C? Lithium Ion batteries do not need temperature compensation, and you don' want to hit >14.6 volts during cold weather (typically for lead acid batteries, charging voltage is raised as the batteries get colder).

2) The specs in link above are different for battery low voltage settings:

Recommended external Low-voltage disconnect	11.2v
BMS Low-Voltage disconnect	>10.4v
BMS Low-Voltage recover	>11.6v

3) I would not worry too much about 11.5 or 11.6 reconnect/warning voltages... There is nothing "electrical" the BMS will do until 10.4 volt disconnect...

For reconnect--With most solar charge controllers, you may have to connect to a "jumper battery" to get the system charging again... Solar charge contorllers (some, many, most?) require >~9 volts to "boot" and turn on... If the BMS trips and truly cuts off the Li Ion battery bank, then the solar charge controller will not turn on (and for solar charge controllers, they use the battery bus voltage to figure out if the battery bank is 12 or 24 of 48 VDC battery bank)...

Again, you want your system "warnings" and "shutdowns" to normally happen before the BMS "trips". Your system will shutdown and recover "gracefully", whereas BMS trips will probably need manual recovery (such as a jumper battery). 

And have you "addressed" battery operation below 32F (low temperature charging limit for BMS)? Lithium rechargeable batteries generally don't like charging below freezing (battery kept warm in box, home, RV) or not exposed/used in subfreezing conditions during operation.

-Bill

Sangeroth

Thanks for the info. Very helpful!

I found out that the MPPT wouldn't turn on because the batteries were below 8 volts so I had to charge them with a foldable solar panel.

Knowing that the BMS trips are more "hard" than the system being a more "graceful" trip is helpful.  I made sure to have a foldable solar panel of my own that can charge the batteries to make sure this wouldn't happen again.

The batteries I purchased have a heater in them and can go down to -20 Celsius while working.

BB.

You are very welcome...

Let us know how the system works out for you.

-Bill