Could somebody to me (as newbie) explain how to ''graph'' the capacity points (''pockets'') for my battery?
I've got Sony VTC 4
Cells are: 6 in serial, 4 in parallel configuration (24cells total) [6S4P]
So far - not fully
- depleted battery I've charged till about 1900mah per cell, this is not taking the charge till 4.2v but only till 4.1v, so the ''left 100-200mah'' is in upper and lower region of capacity, if I can trust what my turnigy charger tells me on the screen.
I also suspect that cell can take in 2000-2100 mah as that is in the datasheets, where 2050mah is ''typical'', but for simplicity, I count 1900-2000mah as usable capacity per cell, part of reason - I never discharge too much nor charge till 4.2v)
I made a ''charge'' test of individual cell and it only showed 1973mah when brought up till 4.1, it was at something like 3.2v (no load) when I started charging.
I assume there easly might be these 150mah somewhere in there, If I did charge it till 4.2v..
Load for discharging was flashlight with cree ''XM-L''
Led-diode, so I assume about 1-2A discharge but it seems this is not as important here.
[Details about when in use and the ''low-end'' point of capacity - discharge
What I've experienced so far is - Below 3.5v (3.45v) no load voltage there is very little ''practical'' capacity left.. IT is in 100-200mah range as my load typically consists of drawing 10-20A (2.5-5A per cell)..
So after these 3.4v.. the voltage drop becomes quite extreme.. Today when my no-load voltage bounced backed up to 3.2v.. during load, some of the time cells stayed in 2.7-2.8v range.. that was about 15.5-16v total, so when divided, I get to ~2.60v or even a bit lower.. I couldnt make it out what was the lovest value as my watt meter / power analyzer only showd up 17v+ as lowest voltage point it has recorded (not sure how it records it).. I assume this was a bit normal behavour, as the cells tend to sag more heavily when on their ''low side''..
[The ''Big Story'' short -
I would like to ''map'' the discharge capacity in the 3.5-4.1v Region.. how much Ah do I have left at, let''s say 3.7v - 3.8v - 3.9v points.. it looks like most energy is stored in this region but im not sure how much..
Throw in some ideas.. then I will tell how I imagine doing this but I still have a bit uncertainities in my head..
One of them - from what I saw @DrkAngel posted, it looks like discharge/charge capacity ''curves'' are inversed.. so I wont get ''the same picture'' for discharge and charge.. this suggests I might need an accurate way of measuring capacity/watthours when battery is discharged.. to do this, I probably need a fancy wattmeter / current sensor, as I dont own a Vesc (speed controller) which would be capable to 'store / measure' this data for me..
VTC 4 datasheet:
https://docs.google.com/file/d/0Bx9io5Z ... dSZG8/edit
Discussion with a lot of charts about VTC 4:
https://endless-sphere.com/forums/viewt ... 14&t=53992