Is this why I notice serious loss of power with my vesc, carvon v2, and lg hg2 12s4p pack? @chaka
What cells do you recommend @chaka? I wouldn’t like to go something like 2500mah like the 25R because of the lower range, how drastically do you think the loss of capacity would be in the HG2/30Q? If in 2 years, maybe 400 cycles, i can go the 25km of my daily commute that’s ok, by this time i hope better cells will have hit the market
Coulombic efficiency is a measurement of how much power you charge the cells vs how much you are able to discharge. Ideally this would be a 1:1 ratio but as a pack ages the amount of power you can draw begins to drop. Tighter cells experience more plating vs the lower capacity cells and will have a lower cycle life in comparison if pushed hard.
@Pedrodemio I like the HE4 cells but they are nearly identical to HE2’s. If you go big you can play with HG2’s becuase the pack will not get hot like they do in 10s3p and 10s4p configurations.
Try to remember all my recommendations come from riding at 35mph. An average rider may never heat a pack up as much if riding at 20mph.
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If I wanted better performance and life out of my packs, what would you recommend 12s6p?
If my planned top speed is 35mph with dual belt drive and want to make a 12s4p pack the he4 would be a better choice over the hg2 and last longer/have more capacity over time?
I recommend going as big as physically possible. I personally do not recommend going less than 60 cells, this keeps voltage sag to a min and heat is never a problem. Heat is what kills packs over time.
A 12s4p pack will be under a lot of load if geared to hit 35mph so I would go with a 2500 mAh cell vs high capacity since they will get hot on hills or frequent accelerations and a high capacity cell will be more susceptible to plating.
Another factor not discussed much is you want a pack that can do 35 miles if you plan to do regular 20 mile runs. The reason for this is you do not want to deplete your pack all the way down to 3.3v per cell every time you ride. Heat starts to peak rapidly when you cross the 3.3v “cliff”
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Okashira at “Endlesssphere” tested the 30Q and seemed to say they were a cell that did’nt heat up as much as others ??
The 30Q actually has a higher internal resistance than the HE2, HE4 and HG2. The 25R has the lowest internal resistance, just barely under that of the LG cells.
@chaka How about 30q cells in 10s4p setup for single Carvon hub motor ? Should I be ok with such pack ?
Should be fine as long as you don’t try and break some speed records. 
One reason a favor a digital voltage readout vs a “fuel gauge” is you can see how much your voltage is dropping when you hammer the throttle. If the voltage is sagging severely then you know that you should ease up on the throttle to keep the cells in good health. It is very important on smaller packs to keep an eye on things like this.
Again, I have to keep reminding people, my methods are based on very aggressive riding. What works for most people does not work for me.
@chaka are you sure about these internal resistance numbers? Looking at the data sheet the 30Q is slight lower, but I think the difference is negligible
HG2:
30Q:
My ridding conditions are less severe than yours, geared to 35 km/h and most of the way flat, but I have one or two “hills” of 11% and maybe 100m or so that if I’m on a lower state of charge the board struggle and loses a lot of speed In my calculations, while I this situation (20A battery limit / 37 V / 0,36 ohms IR) i’m loosing 200w of power in heating the battery, not good, and only 500w actually going to the VESC/Motor
The reference I gave above was from my notes, the 30Q was only about 5 milliohms higher then the LG cells when I had tested them. A lot of builders do not realize that pushing these cells hard produces some very high temperatures and the tighter the cells are wound the more they will suffer from plating when hot.
I have been studying the discharge profiles of everything available for a long time and I came to the conclusion a long time ago that we should aim for a 5 amp per cell “max constant discharge” to have a healthy long lasting battery system in the 18650 format. This chart gives a good representation on why this is important.
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One interesting thing - Mooch from E-Cigarette forum has recently lowered LG HG2 discharge rate to 18a, and is keeping Samsung 30q discharge rate at 20a.
Is there a way to calculate this average “max constant discharge” ?
It is said we consume on avr: 10-12 wh… so a (460wh 10s4p pack) would be good for about 40km range.
How much Amp on average would this be for each cell?
In my opinion there is no such thing as burst current in electric vehicles. Everything we do is sustained long enough to be considered constant. Hill climbing and braking to be the times when we abuse our packs the most. These are the scenarios you should be designing for.
I’m asking my EU fellows, whether anyone knows a reliable 18650 source apart from www.nkon.nl?
Totally agree with your 5A max logic, minimum sag = minimal heat = minimal degradation
Unfortunately some compromises have to be made, for a lightweight commuter is simply not possible to reach this 5A per cell while still maintaining a decent performance
I see a lot of people using the maximum discharge rate of the battery as the current limit, maybe if each one find what’s the lowest current limit that still maintain a satisfactory performance we can have batteries that last a little longer
From what i have learned from a member at “Endlessphere” who has ordered before …and has re ordered 1500 cells from “Shenzhen E-fire Technology Development Co.,LTD” on Alibaba .
According to him they are Authentic cells.
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Nkon is the most reliable place to buy batteries in EU. They usually ship within 48h, longest delivery time was 3 days.