AOLITHIUM 100AH 4S SETTINGS

[Captain Hook]

So I have a new 100 4s 12v and on the app settings for each cell voltage / capacity% do not seem like they are correct. Computation shows for example that 13.01 volts is 20%. 10% is 12.84. Is this correct? What chart to use to guide setting the capacity voltages?

 

[mptx]

So I have a new 100 4s 12v and on the app settings for each cell voltage / capacity% do not seem like they are correct. Computation shows for example that 13.01 volts is 20%. 10% is 12.84. Is this correct? What chart to use to guide setting the capacity voltages?

My AOLithium provided app does not show these values…. Where are you getting them? The 3rd-party app I use does have DoC percentages per cell and represented in mV…. Cell empty is stated as 2500 mV, 20% is stated as 3266 mV, 40% is stated as 3291 mV, and so on.

 

[Captain Hook]

On the app settings it shows what you wrote. 3.291 is 40 percent. Makes 13.2 volts. Is that correct voltage for 40%?

 

[mptx]

It’s what my 3 batteries are set at, so I would say it is good. Also, it is pretty hard to determine SoC using voltage on these since the charge curve is rather flat. The shunt on the internal BMS will monitor amps in & out and use that to estimate SoC. As long as you fully charge and discharge as the manual instructs it will be calibrated and give you a good idea where the battery charge sits.

 

[Captain Hook]

OK. The weize went from 14.2 to 13.4in 30minutes. It has stayed at 13.3-4 all night. So I get the flat voltage as I should but it is not at 13.8. What does this mean? Lowered capacity? Or is it just what the settings are on this battery?

 

[mptx]

If resting at 13.6 V (3.4 V per cell x 4) I think the battery is 100%. What voltage are you looking for?

I seem to get a better result by reducing the charge current for the topping-off phase (absorption). Something like 2-5 Amps at a voltage of 14-14.2 seems to help it charge without so many BMS cell overvoltage errors that stop the charging. If you want that last .5 V per cell this might help.

 

[Captain Hook]

I am not really schooled on what voltage it should rest at. I have read 13.8 a lot but it rests at 13.4. Now I just charged my new aolithium to 14.6 and it is resting at 13.4. So I guess that is the number I should be looking for. And stop listening to everyone's personal comments on specs instead of studying the science behind it. I am learning

 

[mptx]

We all learn. Just to be clear - 14.6 is the Maximum voltage where the BMS steps in to protect the battery by stopping charging. You can charge at a lower voltage as long as that voltage is higher than where you want the battery to end up. If that target is 13.8 V then a charge voltage of 14.0 will eventually get you there.

 

[Captain Hook]

Yep. I understand that. This aolithium is 100% 13.35v perfectly balanced to 3.335 on every cell. That was with 14.6 charged to controller cutoff.

 

[Captain Hook]

That is 3.335

 

[mikefitz]

It's difficult to relate voltage to SOC, measurement resolution, accuracy and temperature will have an effect, since the voltage change for a 4 cell battery between 30% and 90% is only around 0.30 volts, (rested battery).

These numbers seem to be considered useful as a guide,
100% 3.42 cell 13.68 battery
90% 3.345 cell 13.38 battery
80% 3.34 cell 13.36 battery
60% 3.31 cell 13.24 battery
40% 3.30 cell 13.20 battery
20% 3.25 cell 13.00 battery
10% 3.20 cell 12.80 battery
Note there is a significant increase above 97%, at 97% SOC, 3.35 cell, 13.40 battery.

Thus even when charging to 100% once there is a small load,. the volts very quickly fall to 13.40 volts. It's also possible due to cell inbalance, the BMS stops charge before all cells are completly full.