Charge Profile Setup for SOK 12V 206AH

[kazuaki]

I'm new to LiFePO4, so just want to make sure I get my Magnum Energy inverter charger setup correctly for these batteries. This is all installed in a large 5th wheel.

Setup
Magnum Energy MS2000 (2000w inverter and up to 100A charger)
ME-ARC Remote
ME-BMK battery monitoring kit (shunt)
A pair of SOK 12V 206 AH batteries in parallel
All 4/0 power wiring
Shore power and generator power only (no solar)

Based on some videos I found during my research, I've selected the battery type as "CC/CV". The ME-ARC does not have a lithium-specific profile preprogrammed. Here are the settings I'm using within the CC/CV profile:

Max Charge Amps - 80A
CV Charge Volts - 14.4
CV Charge Done - I have the choice of "Time" or "Amps" here. I've set it to "Time" and 1.5 hours.
Max CC/CV Time - 8 hours
Recharge Volts - 13.2

So, questions:
1) Most of these settings are a guess, so I'm looking for any advice you have. I want to get the most from my new batteries, but also need to take care f them.
2) How do I know for sure when the batteries are fully charged? The inverter charger tells me they are, but is there a way to actually verify that manually? Something like disconnecting them, then checking voltage? It would just be nice to somehow verify if I'm getting a full charge (or whatever SOC is best) when the charger tells me I am.
3) I have the inverter low-voltage cutoff set at 11.0V. Is this safe for the batteries?
4) Any other advice or input I should consider?

Thank you so much for the help!!

 

[kazuaki]

Any input? Did I post in the wrong forum?

 

[MisterSandals]

1) Most of these settings are a guess, so I'm looking for any advice you have.

CV Charge Volts - 14.4

14.4V is 3.6V per cell. Is there a reason you need to charge so aggressively?
Do you know what the manufacturer of the battery recommends? Thats what most folks stick to over general settings for LiFePO4.

I do not have a Magnum. Have you tried to search for "Magnum" or "SOK"? There are dozens of threads and discussions about exactly what you are asking.

Search results for query: Magnum

diysolarforum.com

Search results for query: SOK

diysolarforum.com

 

[kazuaki]

14.4V is 3.6V per cell. Is there a reason you need to charge so aggressively?

Because I don't know what I'm doing Thats why I'm asking. SOK's website says "recommended charge voltage" is 14.6V. But that may not translate to setting the CV charge volts. I have in fact searched and found several threads, but not the exact answer I'm looking for. I'll revisit the old threads again to see if I missed something.

 

[chup]

Because I don't know what I'm doing Thats why I'm asking. SOK's website says "recommended charge voltage" is 14.6V. But that may not translate to setting the CV charge volts. I have in fact searched and found several threads, but not the exact answer I'm looking for. I'll revisit the old threads again to see if I missed something.

I have the exact same questions. Can somebody help us?

 

[MisterSandals]

I have the exact same questions. Can somebody help us?

Is there a reason that you think that SOK's recommendations are not correct for your situation?

Personally, i am pretty conservative with my charging. I charge to 13.8V and at that voltage my cells are all pretty even. When i get to a high Soc, over 14.0V, the cells diverge. I don't think there is much added capacity in my LiFePO4 prismatic batteries over 13.8V. Heck, my cells settle to 3.35V within minutes so i consider that 100% full.

After a full charge, where do your batteries settle? Or even with a minor load for a couple minutes? That is what i would consider 100% if you don't want to bang them off the ceiling everyday.

 

[chup]

Is there a reason that you think that SOK's recommendations are not correct for your situation?

Personally, i am pretty conservative with my charging. I charge to 13.8V and at that voltage my cells are all pretty even. When i get to a high Soc, over 14.0V, the cells diverge. I don't think there is much added capacity in my LiFePO4 prismatic batteries over 13.8V. Heck, my cells settle to 3.35V within minutes so i consider that 100% full.

After a full charge, where do your batteries settle? Or even with a minor load for a couple minutes? That is what i would consider 100% if you don't want to bang them off the ceiling everyday.

Yeah I think that some of SOK's specs are....unrealistic for long life (I am a novice here, so I am not really qualified to assert such a thing, but I digress). Here's an example: SOK Specifies Charge Voltage: 14.6V for their 206a 12v battery.

Basically, I want to get as many cycles as a I can while still having usable batteries, so somewhere between maybe 15%-85% SOC seems reasonable...I have no idea what settings to select for this but I'm pretty sure that 14.6x2=29.2 Charge Voltage is not a smart way to maintain my batteries for long life.

Screenshot of my (probably wrong) specs:

 

[rmaddy]

I have two SOK 12V 206Ah batteries in series for 24V. My SCC is setup to bulk charge at 28.4V and float charge at 27.0V. Cut those in half if you have a 12V setup. I've only been doing this for about a month or so so I can't speak to the longevity. 29.2V just seems too high to me but it is what the SOK data sheet states.

 

[chup]

Do you have a "back to charge voltage" and a "Back to discharge voltage" setting in your system— if so, what are yours set to?

The amount of helpful people on this forum and the speed at which my questions get responses never ceases to amaze me. Thanks a bunch.

 

[rmaddy]

Do you have a "back to charge voltage" and a "Back to discharge voltage" setting in your system— if so, what are yours set to?

I don't have anything like those that I can see. It's a Victron 150/45. There is a "re-bulk voltage offset" that is set to 0.2V but that was the default and I have no idea what that actually does.

I did set the absorption duration to 15 minutes. Any longer seems to cause the voltage between my two batteries to start to diverge slightly but they always equalize in about 30 minutes after the absorption phase is done.