Charging LFP battery from AC-DC unit
Tried to charge LFP from Meanwell se-200-15. Lynac Lithium 120AH battery marketed as 100AH, you discharge to 80% DOD and get 100AH. Was partially charged already, resting 13.1V. Battery manual sugg...
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"13.2 is the middle of the flat section, so 1536:13.2=116.4 WH. Close enough for me."
Not how it works. If 120AH is the real capacity like they say (probably measured by running it down at 120 amps for an hour) and "full" is 13.6v, then 120 x 13.6 = 1632Wh. However, since 99% is 13.3, it might be better to use 13.3. so 120 x 13.3 = 1596Wh.
But the "middle" is muddled! You have less than half your Wh capacity remaining when you are at 50% SOC by AH. (voltage is lower in the bottom half)
So if you are using a Wh meter to decide how much you have left when deciding whether to recharge today or wait till tomorrow, you have to allow for that.
It is like the gas gauge in your car which might drop faster when it gets below half, so you get nervous as to how much gas you really have left.
I prefer to use AH and have a battery with a straight-forward capacity rating, but you are now in LFP land where ordinary arithmetic is just a "guide" if it can be used at all! :) Have fun!
Not how it works. If 120AH is the real capacity like they say (probably measured by running it down at 120 amps for an hour) and "full" is 13.6v, then 120 x 13.6 = 1632Wh. However, since 99% is 13.3, it might be better to use 13.3. so 120 x 13.3 = 1596Wh.
But the "middle" is muddled! You have less than half your Wh capacity remaining when you are at 50% SOC by AH. (voltage is lower in the bottom half)
So if you are using a Wh meter to decide how much you have left when deciding whether to recharge today or wait till tomorrow, you have to allow for that.
It is like the gas gauge in your car which might drop faster when it gets below half, so you get nervous as to how much gas you really have left.
I prefer to use AH and have a battery with a straight-forward capacity rating, but you are now in LFP land where ordinary arithmetic is just a "guide" if it can be used at all! :) Have fun!
