Chargery BMS16

[DaveTM]

Originally Posted by Sergio

DaveTM, percentage of SOC is not the same as percentage of voltage.

A lithium cell does not go from 0v-4.2v so 50% SOC is not 50% of the voltage at 100% SOC.

The SOC graph of Lithium is also not linear, it has a knee and drops pretty quickly at the end of the SOC, so the voltage will drop a lot faster on the last 10-20%SOC.

I don't believe I made such a statement. All I was pointing out is that if the 90% of the top end voltage is 4.1v, then 100% would be 4.6. (If its 90% of something.....then what is that "something"?) Ergo the low of 3.25 is is the low end cutoff.

No different that Lead Acid batt's where 51.1V is 100% and if you drop below (memory here....just a guess) 45.0V you have just killed your LA batts. LA batts also do not go from 0 to 51.1.

Wouldn't the % of SOC be calculated by the "available" volts in the batts?

[Sergio]

All I was pointing out is that if the 90% of the top end voltage is 4.1v, then 100% would be 4.6.

When You hear talks about only charging to 90%, it is referring to 90% SOC not 90% of the maximum voltage.

Since You mentioned Lead Acid batteries:

100% SOC = 50.9v.
90% SOC = 50.5v or 99% of 50.9v fully charged voltage.

Does that make sense now?

[DaveTM]

Originally Posted by Sergio

When You hear talks about only charging to 90%, it is referring to 90% SOC not 90% of the maximum voltage.

Since You mentioned Lead Acid batteries:

100% SOC = 50.9v.
90% SOC = 50.5v or 99% of 50.9v fully charged voltage.

Does that make sense now?

I know your trying to educate me on this, and I don’t wanna come across as a PITA, but I’m not really following you on this. So.., how do you know that the LA batts are at 90% when the volts are at 50.5? Is there a chart or formula? (I know engineers like formulas 😂)

[Sergio]

Yes, You need to look at the capacity discharge level vs Open Cell Voltage.

They have them on sticky threads:

[bronsonj]

Ah, SOC. The SOC on lithium is much more complex as the lithium cells have a point at which the voltage just starts to drop like a rock. That's the 'knee'. Often, the knee is pretty close to the low end of the voltage range for a cell, so when you get the pack voltage close to your bottom end, you may have 1 or 2 cells actually below the safe range. That's why it's important to leave a little extra capacity in the cells or monitor each cell and when any one gets below the cutoff, kill the current.

According to the internet, for Chevy Volt cells
4.2 is 100%
4.1 is 90%
4.05 is 80% (so the discharge isn't really linear as per SOC)
I haven't found a complete chart, but 80% was the lowest SOC i found where multiple sources agreed.

[DaveTM]

Ok... I see it. But, does anyone have a chart for Leaf batts?

[ag4ever]

Evbatterycenter.com has lots of data and links to even more data if you want to get deep into the weeds.

[BBBHC]

Reddawg454, did you end up getting the Chargery 16 BMS? How is it working out for you?

I'm looking at it for my build with a 14 module leaf pack.

[Reddawg454]

I have not purchased anything yet still waiting to hit the lottery lol.

[BBBHC]

Originally Posted by Reddawg454

I have not purchased anything yet still waiting to hit the lottery lol.

Yeah, I hear you on that!

I'm wondering for a 14 module Leaf battery pack, which would be the better/more economical choice:

BMS16T
600 amp charge, 600 amp discharge, with current shunt

BMS16
100 amp charge, 300 amp discharge, with current shunt

I don't know enough to know what the benefits between the two are....