EPEVER Charge Controller Settings

Understanding EPEVER Charge Controller Settings

If you do a search on EPEVER charge controller settings you will see there is general confusion about them.  I attribute this to:

• Chinese to English translation problems.
• Differences in naming conventions of the different stages of battery charging.
• Confusion as to whether a setting refers to battery charging vs power to the load terminals on the charge controller.
• Slight differences in voltage measured by
  • The charge controller
  • The MT50 monitor.
  • A multimeter
  • A shunt battery monitor

Let me preface this article with the fact that I am not an electrician, electrical engineer, or solar energy expert.  I am just an ordinary end user like many of you.  The information here is derived from reading the EPEVER documentation, web searches, and careful observation and monitoring of the behavior of my 2 EPEVER 4210 charge controllers using the EPEVER charge controller screen, the MT50 monitor, and the EPEVER software with the controller connected to a PC.  Using a PC was the only way the controller would specify if it were in Raise/Boost vs Float mode.  Please comment if you think anything stated in this article is incorrect.

I don’t use the load terminals on my charge controllers.  I will limit my comments about them to the following list of settings that apply only to the load terminals (not the battery charging).

Load Terminal Settings:

• OVCutOff
• OVRcv
• LVRcv
• WarnRcv
• LVWarn
• LVCutOff
• DischaLmt

I am also going to limit the discussion to lithium iron phosphate batteries, since that is what I use and from which my observations were made.

EquilDur:

Since LiFePO4 batteries don’t need the Equalization function, the Equalization Duration should be set to zero to disable it.

Charging a LiPO4 Battery:

Most Solar Charge Controllers use a 3-stage process.  The 3^rd stage (FLOAT) is not technically required because, in contrast to lead acid batteries, their spontaneous discharge rate is relatively slow. However, since the discharge rate is not zero, a FLOAT is generally implemented.

• 1^st STAGE = Constant Current (Bulk) – The charger supplies the maximum current until a target voltage (RaisV) is reached.
• 2^nd STAGE = Constant Voltage (Absorption) – The charger varies (generally decreasing) the current to maintain a constant target voltage (RaisV).

Now pay attention here!  What EPEVER variously calls “Boost” or “Raise” refers to the 2-stage process above.  That is, when in “Boost/Raise” mode, it does 2 stages; constant maximum current until “RaisV” is reached followed by Constant Voltage for “RaiseDur” (Raise Duration) minutes. This constant voltage portion of the “Boost/Raise” mode corresponds to what everybody else calls the “Absorption” phase. After that it enters Float Mode.

• FLOAT

Fortunately, float means float. It is a constant voltage algorithm like the 2^nd stage/absorption portion of “boost/raise”, however, this is set to a lower voltage (FloCharg).

• RaisRcv

If at any time while in FLOAT mode the battery voltage drops to RaisRcv (Raise Reconnect Voltage), the charge controller switches back to RAISE/BOOST mode and the process starts all over again.

As of the time of this writing, if the battery type is set to LiFePO4, then many of the above parameters cannot be changed.  If you need to change those parameters, you need to set the battery type to “USER”.

My setup consists of:

• 2 EPEVER Tracer4210AN charge controllers in parallel
• 4 – 100ah 12V LiTime LiFePO4 batteries in a 2S2P configuration (24V 200ah)
• Giandel 3000W 24V inverter

I had to tweak my settings because I was getting voltage surges into the 30s (exceeding “ChrgLmt” which would cause my Giandel inverter, charge controllers, and battery BMSs to repeatedly go into overvoltage protection mode.

I believe this resulted from the following factors:

1. Differing voltage readings of the batteries from different devices
2. The EPEVER charge controllers could not respond fast enough to rapid changes in solar output (sun emerging from under a cloud) when in Boost/Raise mode and the batteries were full.  (e.g. Web search results suggest that Victron Controllers do not have this problem)
3. Slight differences in the batteries in the battery bank.

As of this writing, I am using the following settings which seem to have eliminated (or at least greatly mitigated) the problem:

• ChargLmt = 27.7
• EquilV = 27.7
• RaiseV = 27.7
• FloCharg (voltage) = 27.2
• RaisRcv = 26.4
• RaisDur = 120

Thanks for reading.  Please leave your comments and suggestions below.