Sony VTC 4 18650 for 10s3p pack

Hey guys,

Thinking of building a 10s3p pack with these li ion batteries. What do you think? Anyone have any experience with them?

Thanks!

Marcus

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I don’t have experience with these cells in particular however at 30A you will not have much voltage sag and in 10s3p these will probably get you a decent 9-10 miles. As for lithiumionwholesale they are not always bulletproof… I got a weak 26650 cell with them in an order of 12 so quality check can be hit and miss (from my experience, others have had good experiences with them)

Thanks for the info. This pack would have a theoretical 222amp hour size, so I’m thinking range will be be a bit farther than 10 for a 150-60 pound rider. The general consensus is it is about 10 amp hours per kilometer

I have 2 packs of VTC5 cells, they are nearly the same except that the vtc5 has 2500 mAh. One is 8s3p and the other one is 10s3p. With a 200 kv motor I get nearly 18-20 miles with a rider weight of 170 pounds.

I can fully recommend those cells :slight_smile:

I think you mean watt hours no amp hours :wink:.

I thought Sony had discontinued the VTC cells. If Li-ion Wholesale has them, I’d believe they’re legit (I and many others have purchased cells from them before). Many in the electic bicycle community love those cells. I’d say look at the discharge curves of them vs the 30Q and then go for the best one vs. their respective price.

Oop, watt hours…aha

Can I ask why you need the 90A other then to reduce voltage sag? Because if range in important to you you can go with the samsung 30q cells that have 3000 mah but only 15A? Or the LE2 cells that have 3000mah and 20A?

Cost and goal. I want to keep my setup to 3p and the Sony cells at 30 cells are only 4.10 a pop. Howeve, most other cells with higher capacities are only 20amps and three of those in parallel is only 60 amps, a bit too low of a max for the board (correct me if I’m wrong). Otherwise I would have to build a 4p cell to make it a max of 80 amp pull.

The Sony VTC cells are 30 amp max draw which only Three of those will nicely put me at 90amps

ratings mean nothing. Look at the actual discharge test http://lygte-info.dk/review/batteries2012/Common18650comparator.php

I used the VTC5 to compare the 30Q to - VTC4 should be even worse than the VTC5 since they are older generation. Less sag is better!

You are not going to be drawing 90A constantly - that would be a constant 90A*36V=3240W and your ESC and motor would die. A VESC can do like 50A continously - but even that is ridiculously high for a standard esk8. If you want to climb the mount everest in one go at 50km/h on an esk8 you should probably look into a larger battery anyway :wink:

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Ok, what do you think about the Samsung 25R? 2500mah and 20 amp continuous

Again: the rating means nothing. Look at the discharge curves. The 25R is clearly worse than a 30Q. They are not bad - but there are better alternatives out there. You could also look into HE2 and HE4 but best bang for buck IMO is the 30Q right now. It is basically the same cell as a HG2 just with a more conservative rating.

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That’s interesting. When i took a look at official datasheets for each cell (30q 25r) the 25r’s had better sag performance

Yeah, that’s why I would look at the real performance tests and not datasheets as @Maxid linked to.

That site makes it a bit difficult because I think the test equipment they used on the 30Q was different (not sure if it’s better. see the notes on their site). The tests on that site show that the 30Q is a little better than the 25R in voltage sag, even though they are rated ratings are the opposite. It’s possible that the 30Q gets hotter, as they note that the 30Q hits a cutoff temperature while the 25R didn’t (or maybe the test equipment didn’t account for that, not sure).

yeah they used an older test station for the 25R (and other older cells like HE2 and so on) - However I doubt that this has such a large impact. 30Q are not just a little better IMO in terms of voltage sag. You are right with the temperature increase in 30Qs but then we have to keep in mind that this was for constant discharge - we are not draining our batteries that way so they always have time to cool down to moderate levels when used in eks8s. Anybody that would be draining a battery so hard constantly should not build a 3P battery pack but look into either A123 cells or Lipo pouches

Here is a good comparison of VTC5, 25R and 30Q in one graph at 20A discharge (on hopefully equal test equipment performed by Mountainprophet)

You can see the 25R having the largest voltage sag while the 30Q (even though discharged at an overspecced 20A) performs better than a VTC5. Temperature increase is not considered though.

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I saw the comparison graphs for the 30q. Considering amp vs sag there is no game: 30q outperforms any li ion cell except vtc6.

I believe though that if a company advertises 30% less power ,thus damaging sales by a significant percentage, there are VERY good reasons to do it.

We are in fact just considering amp vs sag. There are many more graphs that could prove that more than 15amp continuous is TOXIC for the cell. Could be : amp vs cell life ; amp vs temperature; temperature vs insulation failure ; temperature vs adhesives failure …

Samsung is telling you :“we guarantee 15amp continuous because in some of our graphs (non available to the public) this cell performs shit at 20amps and could fail miserably”

But I just showed you a graph for 20A :confused:

And again: we are not draining the cells constantly at 20A. The typical usage is 10Wh per Km. That is 300mAh at 10S per Km. With say 30km/h you get 9A that you are discharging - in total - not per cell. Per cell in a 3P config this is just 3A.

But what you want to be prepared for is spikes in current when you go uphill or accelerate. So voltage sag is the most important thing to consider because it indicates how well your cell can cope with this

I also think that the reason for the underspecced 30Q is just liability issues. It is not hurting sales because every informed guy will know whats going on but you can’t blame them if something happens while you used them at 20A instead.

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I repeat: sag-wise 30Q is the winner on any amp vs sag graph. Lets just not talk esk8 for a second and focus on the battery as a product. My point is: there is one or more variable (temperature, cell life…) that samsung found out to be consistently damaged after 15amp continuous. There is no graph on the internet containg that precise weak variable.

A good analogy would be : 25r is a car that goes 10 kmph; 30q is an e-bike that can go 20kmph. The seller obviuosly tells you not to go more than 5kmph with the ebike. Problem with the cells is that they seem similar and hide weaknesses

VTC6 looks great on sag, but i like the VTC5A for high discharge - hopefully not really stressing the cell to max. A few more cells in parallel to help with sag and a solid performing option!

Yes capacity is less but in a 3/4p being realistically able to do 20-30A per cell and not exceed his threshold of 78c = a true 90-120A capable 3/4p pack! the VTC6 is great for range, but i don’t need 9/12Ah 3/4p pack. a 3p VTC5a pack at 10s (2.6Ah * 3 * 42v) = 327Wh. 12s (7.8Ah * 50.4v) = 393Wh. 10Wh = 1km… 32km/19mi and 39km/24mi.

I’m less concerned with range/mAh of cells and more ability to provide amps when needed while minimizing heat which = less pack life.

nkon order in for some VTC5A’s around $4 per cell!

Mooch:

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