How are you going to find out which 5 are sub par?
No idea, but I do not have an ABN (Australian business number) so the company that is willing make the packs cannot purchase the batteries for me. Just wanted a few extraās in case there is issues with one or two instead of being stuck at not being able to have the pack done.
Also if that is not necessary, then I will just use the five of them as spare rechargeable batteries for whatever!
Was going to wait till VESC 6 and JTAGās BMS goes gold, but Iām already fed up with Evolveās voltage sagging on hills and short range, so gonna bite the bullet and do my DIY by the end of the month, hence asking about VTC6.
Iām doing about the same thing. After doing way too much battery research I ended up going with the cheapest 20 amp battery I could get he2 and getting enough for a 10S8P
VTC6 is the best power cell out there. Thereās about 5-10% improvement over 30Q. If you have an rc charger that can measure internal resistance then that would be the way to match them. You want the spread to be as little as possible and on the lower side. The low spread will determine how balanced your cells remain over their life, and the low ir will make them sag less.
If you want to spend less then buy 30Q from nkon. I bought 70 for $230 including shipping ($3.30 per cell). Itās significantly cheaper than VTC6 which cost $5-6 per cell (in the us at least).
I only use VTC6 when cost is a non issue and I want the absolute best power output. Otherwise I use 30Q for marginally worse power output but a lot less $$$. If you want a high range pack then Sanyo GA is the cell you want, again a little pricey $5-6 a cell but it has 16% more capacity than 30Q and VTC6 and has a power output thatās just as good as 25R cells. Which is about half as much as VTC6 and 30Q unless you let it sag significantly.
I currently have 2 battery packs, one out of 30Qs and one out of GA cells. My gf usually rides the GA pack as she wants long range and doesnāt really do high speeds or crazy hills on her way to school, while I like to ride the 30Q because of the sheer power it can output.
Thanks for your reply.
Pretty much what I thought, although it is the first that I have heard of Sanyo GA. ( Is that the Tesla battery? )
Sag is what I want to kill off. Range should be acceptable in six parallel.
80 cells? What board are you using? Iām thinking you are going AT, right?
@Gromok, Yep, it is the updated version of the Panasonic B cell which is the Tesla cell. @smurf, what was the purpose of your large pack? Sorry to be a party pooper but Iām afraid you could have gotten 66 30Q cells for the same range and more power output than HE2 cells.
Voltage sag for 30Q vs HE2. outputting 15A per cell, the 30Q sags as much as the HE2 outputting 7A past the 1Ah mark. Outputting 7A with the 30Q has slightly more voltage sag than the HE2 at 0.2Aā¦ A 10S8P HE2 would have a total of 720Wh, while a 11S6P would have 712Wh, when you adjust for sag, the HE2 has 641Wh when outputting 7A/cell and the 30Q has 617Wh at 15A/cell.
Also you can buy 30Qs for $2.75ea + shipping from Nkon
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@PXSS Are you in the US or Europe? Iām looking at ordering some 30Q from Nkon and wondering what the shipping time is like to the US. They say at least 2 weeks.
@TheImmortalJew Iām in the US. I gotta check my email for how long they took, but I want to say it was 2 weeks from ordering to my doorstep, maybe 3.
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Rough asphalt and big hills. This is where crazy people go to build crazy electric skateboards right. @PXSS at the time Samsung anything was substantially higher in price. Black Friday sale
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Iām guessing Liion wholesale? I wish I had bought more stuff on their Black Friday sale. 
I got a great deal on a handful of protected cells for flashlights and I almost went nuts and got the Sonyās with the special sauce but there so expensive. I wish money wasnāt a factor but in the real world it is.
The real question is still Unanswered. so you get a few extra batteryās how do you sort out the good from the less than ideal batteries?
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iām still using Samsung INR18650-25R cells. 20amp continuous, 2500mAh, 100amp burst. Theyāre older tech, but they take a fair amount of abuse. Iāve even been able to tear off tabs and re-weld them without an issue. We just repacked 60 of them from two different older series space cells into a 12S5P triangular cell layout for shits and giggles and it is behaving as expected. Better, actually, as we sort of thought those original packs were nearing cycle life.
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Do you test every cell or do you just trust them?
I test them, I have 4 icharger 308 duos, which have 2 channels with up to 8S balance port. http://www.progressiverc.com/icharger-308duo.html
I wired 2 of these in series to form 8S battery holders: https://www.amazon.com/Battery-Case-Holder-4x3-7V-18650/dp/B01FSDKXRI/ref=sr_1_2?ie=UTF8&qid=1489095715&sr=8-2&keywords=18650+battery+holder+4
So I can test up to 16 cells per charger at a time. The charger has a test internal resistance feature that runs in about 10 seconds and tells me the internal resistance of each individual cell. I then group the cells from lowest to highest IR, and try to choose the ones that are closest to each other. I rather choose cells that are in the middle of the IR range but that have a smaller spread as this means I have to worry less about them going out of balance. Eventually, we get enough cells in inventory to do a pack with a low spread and low internal resistance. These packs are usually reserved for high profile projects while the high internal resistance packs I usually only use for bench testing.
That said Iāve never had any cells that were out of spec according to the manufacturers datasheet
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Huh I have never looked into the actual data. Thanks for the link really appreciate it. Wish I had known this before I build my pack.