Recent content by DavidKelly

Hauwei ESM48100AhB1V1 batteries with compression.

So target 3,525V and float at same voltage or float at 3,37V? Merely trying to understand your logic.

From your statement “Then it is a simple matter of applying linear regression to find the desired (voltage, current) pair connecting these two extremes. (FCV, 0 C) and (3.65 V, 0.05 C). There is only one unknown in this statement of which can be solved by simple linear regression…But we’re not...

This is the age old debate hey. Might even elicit a more passionate response than the top end voltages. Technically the Aluminium casing are supposed to provide sufficient resistance (This is advertised on some datasheets). If you’ve ever had a pouch cell go bad and swell you’d realise how...

This is very entertaining…. You are proving the above for me. By doubling the capacity you have halved the internal resistance. So capacity and internal resistance are inversely proportional. Yet you demand citations. I did not say a decrease in internal resistance will change the FCV. An...

GFB SOC OCV for LF206 for reference. Closer to the 3,5V side at 100% on charge.

The impedance thresholds are usually on the datasheet.

Yes. If you ask them they will share it with you on a batch that you have ordered. Certainly with Eve. They are very professional. We once used it to solve an issue we originally thought was caused by bad cells but data proved it to be a faulty BMS. I digress. I currently am involved with a...

Think your method is spot on. Might have to play with the numbers a bit depending on the cells you have but should work well. I agree with your reasoning. I don’t think it will be too high. In many motive applications the charge target voltage is 3,458V. Your set point will be fine on good...

At the factory the cells are graded. This is relative to capacity and is based on internal resistance. The can’t capacity test every cell, it would not be economical (The amount of energy!)… So they determine the cell capacity based on the relationship with internal resistance as mentioned...

This is true on some of the cheap and nasty cell makes a float voltage of 51,8V- 52,5V is not uncommon for a 15S battery.

Full charge being as per datasheet to 3,65V and CV or CP. Then cell rests and lowers voltage to FCV. I think everyone is in agreement with the above. This is the method for the SOC OCV plot supplied by the manufacturer. This test is done at a variety of temperature intervals to form the SOC...

I’m being polite. Your method for determining FCV is not clearly explained, nor will you simply explain it. From my understanding it does not take temperature into account (Which makes it only work at that specific temperature and breaks at all other temperatures) and you refuse to clarify it...

May I ask, what do you mean by 'Convergent balancing'?

The document is from the manufacturer of the cell. It’s quite clear on procedure. Full charge as per datasheet and then discharge in increments, rest period, voltage test and log, Repeat at different temperatures. Done for both Charge and discharge - the same procedure you praised in an earlier...