You have not given quite enough information about your system to fully understand your issue.

However, to fully charge your 25 LFP cells to 100% SOC, your charger should shut off at a voltage of a minimum of ~3.45 volts on all cells.
The full-charged pack voltage should be 87.5 volts, or a bit more.

3.6 to 3.8 volts on the highest cells is where your BMS should be set to reduce the output of your charger. You should not be going over ~3.8 volts on any cell.

Your charger should be controlled by your BMS somehow, hopefully.

Like I said, we need a bit more information on your system to understand exactly what your problem really is.

Bill D.

On 8/7/2017 12:53 AM, Matthew Quitter wrote:
Thanks guys... but if the charger is turning off at a fixed voltage how do I 
get more power into the pack?


On 7 Aug 2017, at 05:02, Bill Dube via EV <ev@lists.evdl.org> wrote:

I agree. Voltage on LFP cells is useless for determining the SOC.
The voltage is very constant except at near 100% SOC and at 0% SOC.
You really need information about the middle, and voltage doesn't give any clue 
about that.

You need to count the amp-hours, like with an E-meter or a Cycle-Analyst.

Bill D.

On 8/6/2017 7:00 PM, Willie via EV wrote:


On 08/06/2017 07:38 PM, Matthew Quitter via EV wrote:
Hi Guys,

My 1238-6501 Curtis controller gives very different SOC % for similar
voltages.

For example I've recorded a pack voltage of 82.2 and had the Curtis show
22%, 31%, 43%.

The pack is made up of 25 Thundersky 160Ah batteries.
With LFP cells, you can't accurately infer SOC from voltages in the middle of 
the range.  The voltage/SOC curve is too flat.
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