Lithium batteries and new solar charger
I am replacing my 4 6V batteries I think 2 lithium, have never been impressed by the 30A PWM charger for my 600W solar, probably my fault for using 8 avg wire on a 9m run. Thinking if I get a Victron ...
Forum Discussion
Good points but missed my question (badly put maybe) so trying again:
Does the LFP voltage/SOC table in the BB blurb linked above apply to all capacity sizes of LFP that use the same type of cell?
If so, then the voltage of a 100AH batt down 80AH will be lower than for a 120AH batt down 80AH.
If the table is for a 100AH batt where zero is 10v like it says, and it is also 10v for zero with the 120AH batt, then when the 120AH batt is down 100AH its voltage will be 12 instead of 10.
So the table would be wrong for the "100AH" batt that is actually 120AH.
Nothing to do with the BMS as such. However, they could fudge the BMS settings and not use the "real" voltages.
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OK capacity testing has the same problem. You use the 50% voltage as your marker. You think you have a 100AH batt. You draw it down at a steady 5 amps for 10 hrs and you should be at 50%. You look at the resting voltage and confirm it is at the correct voltage for 50% and note the AH you got--50AH. So it is indeed a 100AH batt.
Now if it were really a 120AH batt and you took it down to the resting voltage of 50% you would have got 60AH.
The key is that the resting voltage for 50% is the same for any size capacity batt, so you can do that.
If the voltage /SOC table is fake/fudged you can't.
Does the LFP voltage/SOC table in the BB blurb linked above apply to all capacity sizes of LFP that use the same type of cell?
If so, then the voltage of a 100AH batt down 80AH will be lower than for a 120AH batt down 80AH.
If the table is for a 100AH batt where zero is 10v like it says, and it is also 10v for zero with the 120AH batt, then when the 120AH batt is down 100AH its voltage will be 12 instead of 10.
So the table would be wrong for the "100AH" batt that is actually 120AH.
Nothing to do with the BMS as such. However, they could fudge the BMS settings and not use the "real" voltages.
-------------
OK capacity testing has the same problem. You use the 50% voltage as your marker. You think you have a 100AH batt. You draw it down at a steady 5 amps for 10 hrs and you should be at 50%. You look at the resting voltage and confirm it is at the correct voltage for 50% and note the AH you got--50AH. So it is indeed a 100AH batt.
Now if it were really a 120AH batt and you took it down to the resting voltage of 50% you would have got 60AH.
The key is that the resting voltage for 50% is the same for any size capacity batt, so you can do that.
If the voltage /SOC table is fake/fudged you can't.
