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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...

This is from the SOC OCV charge curve from EVE for the LF230. I shared it on this thread as well as an excel that helps with interpolation. I’m not sure who is preventing you from being in a position to say anything. You describe in your method a FCV value for the LF230. I’m simply asking what...

Heres a nifty excel sheet from lithium balance. just adjust number of datasets to 3.

Would need to interpolate as they provide for only three setpoints. Have a nifty excel sheet from lithium balance but it wont let me share it:rolleyes:

Cheers,

Spot on. The aggressive charge current is a big contributor to imbalance.

Thank you. I’m interested in your thoughts. Perhaps I’m just not grasping your method. In my mind this will affect the gradient of the regression line and I’m concerned about setting a fixed value that should vary with temperature. Using your example. Could you give us an example of the FCV...

Sorry. Always sketchy sending large sums to China when you’re on another continent. PayPal is by far the safest route. Especially for the first engagement. Now I’d happily buy directly from Gobel. Check out Offgrid garage videos.

Have bought BMS’s from Gobel in bulk after discovering them on Outback garage’s recommendation. They are reputable and deliver. Have dealt with Ellie and Jessie. Very pleasant experience. Always sketchy sending large sums of money through PayPal but it arrived and work perfectly. Hope to...

Hi All. I’m about 5 pages in out of 11. Apologies if this is addressed later. Thought I’d add my 5c commentary. I am a BSc engineer specialising in building lithium ion batteries. I own a company that builds batteries and consult for large telecommunication operators in South Africa where the...

Very interesting. I’ve seen this before on SOC OCV curves from some manufacturers (even Eve). Thought it was a typo but maybe it is true. Never had to privilege to try it. Thanks for sharing.

Ignore everyone saying this is pointless and you should get a shunt. The SOC OCV curve is essential for mapping the performance of a cell. Most high end BMS platforms will incorporate it as a backup plan to calculate SOC if coulomb counting (shunt) reference point fails. This is typically...