diy solar

diy solar

Float charge for LiFePo

DASH said:
Correct me if I'm wrong, but I thought You could run two independent systems (solar panels and controller) to charge the same battery (providing the charge settings are the same).
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You can .. but both of them will act independent .. if they are in series then one is the Master and one slave ...
 
Electric Personality said:
It depends on what you are talking about, of which I am still wondering. PV input? Charger output? What?
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I'm under the impression you were talking about connecting two separate SCC.. I have two connected to my battery bank.. they are set up for 12v, in parallel. As for solar input, that is up to your SCC and what it can handle, wire size and optimizing based on that. On the solar input side, you can do a combination of parallel and serial.. parallel increases current, series increases voltage. The higher current, the larger gauge wires you need but less suseptable to shadows. Solar input and battery is two different animals.
 
DASH said:
Correct me if I'm wrong, but I thought You could run two independent systems (solar panels and controller) to charge the same battery (providing the charge settings are the same).
Click to expand...

I have done this for the past 2 years without any problem.
 
Fallingaway, the last pic of your project - do you have insulation for your battery tops?
 
Michael B Caro said:
I have done this for the past 2 years without any problem.
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I'm also running two SCCs in parallel and their setting are not the same on purpose. I want the second SCC to back off when the batteries are near full and let the larger SCC manage the final spike over 14v. My point is they don't have to be same, they both will act independently as a power source.
 
Fallingaway said:
I’ve got balancing problems with it and can’t keep them in balance. Running .8a load and after 8 hours I’m .3v out of balance. Driving me nuts!
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The higher the voltage is, the more out of balance they will become as well as nuts you will be driven.. if you wait for the BMS, charge them as a pack with the BMS balance, you will discover all will be well.

My attempt to balance cells also drove me loony. It's nice to have the orderly path but with patients, all cells, especially new will eventually balance with cycles.. if you try to force them, you can actually reduce their calendar life while you wait for the BMS.
 
mandrews44 said:
The higher the voltage is, the more out of balance they will become as well as nuts you will be driven.. if you wait for the BMS, charge them as a pack with the BMS balance, you will discover all will be well.

My attempt to balance cells also drove me loony. It's nice to have the orderly path but with patients, all cells, especially new will eventually balance with cycles.. if you try to force them, you can actually reduce their calendar life while you wait for the BMS.
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I finally bought a bench top charger so I can put a steady current/voltage to them but I was using a lipo charger that did life. The problem is it will only charge at preset voltages. The highest being 3.3v which it stops at 3.2. I’m guessing since it stops at 3.2/3 that it’s the top of the discharge knee so I’m missing out on 60-70% of my potential capacity when using this charger. I have solar but I’m not confident on the charging values I’ve set(which is why I came here) people keep pointing me to a sticky will left but it only defines like 3 values, boost,float, and something else. The epever has like 20 values I need to set and I can’t seem to get assistance with it. These cells where expensive so trial and error are not an option for me.
 
mandrews44 said:
The higher the voltage is, the more out of balance they will become as well as nuts you will be driven.. if you wait for the BMS, charge them as a pack with the BMS balance, you will discover all will be well.

My attempt to balance cells also drove me loony. It's nice to have the orderly path but with patients, all cells, especially new will eventually balance with cycles.. if you try to force them, you can actually reduce their calendar life while you wait for the BMS.
Click to expand...
What do you mean “wait” for the bms? I’m using the bms when I discharge and it’s still getting way out of whack and that’s with a tiny load .8a. 1 3p pack is barely dropping in V and the rest are all over. I’m hoping with a bench top charger and a CC I can actually charge them and top balance. If you find a lifepo4 cell stuck in your windshield in the morning it was probably me.....
 
Fallingaway said:
What do you mean “wait” for the bms? I’m using the bms when I discharge and it’s still getting way out of whack and that’s with a tiny load .8a. 1 3p pack is barely dropping in V and the rest are all over. I’m hoping with a bench top charger and a CC I can actually charge them and top balance. If you find a lifepo4 cell stuck in your windshield in the morning it was probably me.....
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I was thinking you were waiting for a BMS to arrive, maybe it was another thread? EPEver has LiFePo4 settings, you have to use the Control Settings -> LI Product menu option. Your settings seem low to me. BTW, do you have anything isolating the bus bars from a screw driver coming loose? Storing tools in the battery box isn't somthing that is advisable unless the bus bars are covered.

BTW, LiFePo4 batteries are not explosive. I question now matched those cells are and if they are new. You will need to let the pack charge to 14.2 and enable charge balancing on the BMS if you have that option.
 
Here are my settings for EPever SCC. My battery capacity is 1200Ah, it will only accept 999. :) If you use these settings, I think they just might balance eventually. Charging to 3.2v per cell can not balance because 3.2v covers a wide range of SOC, something like 70% to 40%.. To begin to charge and it mean something, the cells need to be upwards of 3.4v or higher. 3.3v is just the beginning of the knee. You can go as high as 3.65v per cell to balance if they are that far out of wack. You can charge each cell bank to 3.5v but with 3p, it might take a while.. It might be better to charge the pack to 13.6 volts and wait for one of the cells to hit 3.5v before starting your manual top balance.

1593396613131.png
 
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mandrews44 said:
Here are my settings for EPever SCC. My battery capacity is 1200Ah, it will only accept 999. :) If you use these settings, I think they just might balance eventually. Charging to 3.2v per cell can not balance because 3.2v covers a wide range of SOC, something like 70% to 40%.. To begin to charge and it mean something, the cells need to be upwards of 3.4v or higher. 3.3v is just the beginning of the knee. You can go as high as 3.65v per cell to balance if they are that far out of wack. You can charge each cell bank to 3.5v but with 3p, it might take a while.. It might be better to charge the pack to 13.6 volts and wait for one of the cells to hit 3.5v before starting your manual top balance.

View attachment 16408
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Sorry for asking but is there any reason you did not set the equalization voltage to 0 ?
 
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