[quote=“Maxid, post:1, topic:74424”]
The obvious choice is 30Q cells but I am wondering if a VTC6 might be the better solution (or other types - I am open to recommendations).
[/quote]
Q 30 are not capable of 30A discharge VTC6 and VTC5A are
Personaly Id only use Q30 in a 4P or more config below there’s better options IMO.
You’re looking at and comparing incomplete data. Henrik stopped the test for 30Q cells at 75C but lets the VTC6 reach a higher temperature (into the 80s) before he stopped the test.
As I’ve stated before, with appropriate cooling, 30A per cell can be achieved on both 30Q and VTC6.
Besides, continuous rates at that current is irrelevant to esk8. Running continuously at 30A per cell means that you would discharge your entire battery in under 6 minutes. We normally don’t do bursts longer than 10 seconds, very few do bursts longer than 30 seconds. I haven’t been around here in a while so I may be wrong there but unless something drastically changed in the past 6 months, we are nowhere reaching the limits of 30Q yet.
You’re still my go to guy when it comes to batteries - so far your advice has been invaluable.
I calculated the volume and capacity in the spreadsheet above and to me it looks like the energy density is actually higher for the 50E (even though only slightly) with a usable capacity at 111% that of a GA pack and only a 108% in size. I used the data from lygte to get the actual dimensions and usable capacities.
Also the voltage sag seems to be lower on the 50E (I compared the lygte data for 7A for the 3P 50E pack and 5A for the 4P GA pack to get comparable currents for the individual cells) which should make for a very energy dense but still powerful ebike pack.
@Maxid I’ve looking a lot at 50E, Padja at endless sphere has some good insights, not only for the 50E, really recommend reading all his posts
They should perform really good, better than the 30Q if you consider the cycle life, even if it doest matter for most people
The GA still my cell of preference with larger packs
That is correct, but when assembling a pack, you lose space between cells. If you take this into account, the 50E is no longer more energy dense.
Assume they are rectangular or hexagonal in cross section. Rectangular is worst case, hexagonal is best case.
Did you also compensate for different discharge capacity? If you compare vertically in the graphs, you are catching both cells at different stages of the discharge cycle which will make the difference more pronounced than it actually is. For an appropriate comparison you have to shift to the right 40% as well. For example, the voltage sag at 5A when the GA cell has discharged 1Ah should be compared to the voltage sag at 7A when the 50E cell has discharged 1.4Ah.
When looking at those two in Henrik’s charts, they match.
Even befor the test stoped both of them VTC maintain less volt drop for longer.
well I don’t know about you but I easily pull over 30amp up a hill sustained so for a 1p group that was originally asked about max discharge is hugely relevant IMO as that be the limiting factor 6 min discharge fine for a 5 minute journey.
As for cooling I’m sure if you cooled any battery enough you could get the desired output but doesn’t mean there’s not other better suited options out there.
Q30 are a very good middle ground but depending on you priority cost, discharge, charge, kWh density life span. Thay can always be beaten because thay are a compromise.
@Darkie02 You are correct in that VTC6s are slightly better as far as voltage sag goes, but not by much.
My point with the cooling statement was that they both require cooling and about the same amount
The same argument can be applied the other way the 30Q are not that much cheaper. 24 cent let’s say it’s a standard 10s4p you save €9.60 on a €1000+ euro build.
8 months ago, that was not the case =) VTC6s were about twice as expensive.
this I did not - thank you!
hm so looks like I will go for the GA pack - even though I thought I am super clever and the 50E is the way to go 
True but things move on and need re assessing.
My first build I kept reading old posts and built a 25r pack because I believed things that were said with out evidence and opinions that were not updated. Combine that with manufactures stats and later realised the hard way I was wrong.
I think the 30Q is soon to be replaced by some thing same way the 25R was just unsure what will be the next standard we compare every thing against but o think it be very soon.
