SOK Battery Bank CC - Charging Settings

[solarisland]

Hey Guys! Nice to be a part of this Forum, have been watching Will for a while now.

So after watching the SOK battery review, I decided to go with 16 x SOK 208 AH (832 AH @ 48V) to replace the FLA Trojan Industrial Bank @ 1000AH. which reached the end of useful life after 6.5 years of hard use.

Please note I am new to LIFE PO, would appreciate any advice on configuring the charge controllers, without overstressing the bank.

I have sent SOK various emails they have been great about answering questions even late at night. Min from SOK stated that 57.6V was a good safe 100% Charge value, and would be safe up to 58.4V without any issues.

Setup
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48V OUTBACK RADIAN 7048 @ 230V 7KW ( located in se-asia )
Charge controllers - FM-80 x 2 (Flexmax 80amp)
16 x SOK 208AH (4 strings of 4 @ 48v) Buss Bar combined to Inverter
Panels - 33 LG 300 watt each (oversized for rainy weather)
Midnight Solar Combiner
Outback FLEX-DC Monitor
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Attaching Datasheet for SOK battery 208AH, and the configuration that I came up with after watching the Outback tutorial on LIFE PO config.

*Note I have limited FM-80 CC to ADC 60 AMP per CC, so a total is 120 AMP to the bank, is this too much, too little? My understanding is the bank of this size can take 200 AMP max charge @ 48v.

The bank is on its first full charge cycle and will report back with results.

Any advice on how to configure this would be appreciated.


~solarisland

 

[solarisland]

Sun setting now, here are the results. We reached a max of 54.7V, DC monitor still confused showing 100%, Outback said will take 3-4 days to calibrate to the new bank. the SOK's Absorbed about 35 KWH, with some loss. I'm guessing we need about 5-10 more kwh to reach the top. We will consume about 8kwh tonight and resume tomorrow and see if we can get it topped up.

 

[solarisland]

Still never could reach more than 55V even after a second days full charging with only about 14 KWH removed at night. Trying to figure out why its not reaching 57.6v as recommended by SOK. Give it another try tomorrow.

 

[Huey]

I was just reading the Victron Wiring Unlimited guide and saw this illustration that seems relevant to your situation. Perhaps your bank is not well balanced enough to take a full charge. I don't know, the image just reminded me of your photo.

 

[solarisland]

I was just reading the Victron Wiring Unlimited guide and saw this illustration that seems relevant to your situation. Perhaps your bank is not well balanced enough to take a full charge. I don't know, the image just reminded me of your photo.

Thanks for the reply. After some time the bank actually has balanced itself out. I installed little voltmeters on each SOK, and they are pretty much exactly balanced now. I was able to get them to full charge now, however, it takes a lot to get them there seems very high resistance at the upper voltages. However its not necessary, I set them to charge daily to 56v and it provides way more than enough juice for the loads. They only drop to about 54, after a full night use approx 14-16 kwh. Everything seems to be good.

I am using the figure #2 setup, no midpoint. This would not allow me to use the 4 disconnect switches, in the event i have a bad battery i can cut that string of 4 and keep operating. If things do get out of balance again I might consider the midpoint technique. Do you need a midpoint cable for each verticle, set in my case need 4 midpoints if im correct.

Cheers!