Have a potential supplier of the new Samsung 30T 21700 cells

ESK8 Electronics
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I have a question that has probably been asked but I’d like some fresh responses since we have some new much better performing cells available now.

So as it was pointed out earlier, some cells are good for a small pack, other for a large pack, some for their high discharge ability, others for their range, and so on… SO… is it possible to create day a pack with equal quantities of battery cells? Like a 12s2p Samsung 30T +12s2p Samsung 30Q +12s2p Sanyo 20700A/B

12s6p with mixed mAh, discharge rates, Amps, etc…

I’m sure this is probably possible, but it’s it practical or a good idea at all?

I imagine it is much simpler using the pack than charging it since some of the batteries have different capacities etc, but if you were to wire each type of battery as it’s own so each one can be charged individually, and then be able to combine them to make a 12s6 battery so you have all the positive benefits from each, and then hopefully where each battery is lacking, another battery pack would be able to cover that area, thus creating a battery pack with only pros and the only con being the extra work you’d have to do to charge them separately and then reconnecting them back up, which really would not be difficult at all… So is this a good idea, had anyone tried anything like this before? Or is there something I’m missing that makes this is not impossible, nearly impossible?

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Have you tested any of these cells??? Please don’t make suggestions based on datasheets of cells you’ve never used. That’s how esk8 ended up with using 25Rs in the first place.

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I suggest looking up why it’s a bad idea to mix cells

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Bad idea man and there’s quite a few reasons but simply put some cells have different capacity and discharge so imagine having a 3000 mah and 2500mah cell of course you will run the 2500mah cell down before the 3000mah, that’s not including potential problems with cell chemistry and other reasons

1 Like
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Got it, thanks for the explanation!

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Nope; research for my own purposes. Currently in the process of testing it. I’d appreciate if you offered constructive criticism instead of destructive criticism. I could just as easily not say a word and keep this information to myself. Please let us know your test results!

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I cannot share my test results as they are work related. I can tell you that reading datasheets wrong can lead to big issues…:

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Official specifications: Standard discharge capacity: min. 3000mAh (1.5A charge 0.1A cut-off, 0.6A discharge, 2.5V cut-off) Rated discharge capacity: min. 2650mAh (4A charge 0.1A cut-off, 10A discharge, 2.5V cut-off) Nominal voltage: 3.6V Charge voltage: 4.2V Standard charge: 1.5A charge 0.1A cut-off Rated charge: 4A charge 0.1A cut-off Max. continuoys discharge: 35A at 25°C Discharge cut-off voltage: 2.5V Cycle life: 250 cycles to 60% at 35A discharge. Cell weight: 69.0g max Cell dimension: Height: Max: 70.40mm, Diamter: max. 21.22mm Operating temperature (surface): Charge 0°C ~ 50°C (Recommended <45°C), Discharge -20C° ~ 80°C (Recommended <60°C) Storage temperature: 1 month: -20°C ~ 60°C, 3 months: -20°C ~ 45°C, 1 year: -20°C ~ 25°C

I’m always looking at charge cycles (for true cost calculations) and max charge rate, for brakes (hub motors…). Weird numbers! I guess the spec’ed cycle life is at a bananas discharge rate, probably quite a bit better at 10-20a.

If these 2 numbers were better, it’d sit nicely between 30q and A123.

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That’s the problem, they don’t… At least, not with out sagging from 4.2 down to 3.2 volts…

These cells are good because unlike at only 15 amps per cell, the 30q goes to 2.65 Ah, while the 30T still goes to 3 Ah.

30t vs 30q.png1652×1122 131 KB

I don’t use 18650’s cause I can’t get enough power from them. Unless I do a 12s6p, 18650s don’t deliver enough power for my 4wd boards. And my board is already 25 pounds with a lipo equivalent to a 12s3p.

So in my case, this cell is much needed.

Also, if you wanted a small, lightweight board with some power still, you can do 12s1p and 12s2p configs and still deliver ok acceleration.

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Everything as pretty much been said about this cell so next step is being able to confirm availability and prices ?

30T and 40T are a good compromise for small packs, and powerful with good capacity btw. It’s all about each max power needs too (take in account ESC and motor limitations).

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Again can’t get 120 amps from the 30Q without a lot of sag unless it’s a 6p config. More sag leads to more amps, which leads to more sag, which leads to more amps, and so on.

60 amps is too weak for me :slight_smile:

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Define small packs? According to @b264, it’s a 2p. I’d argue that it’s useful in a 3p and 4p config also. Above that, doesn’t make as much sense.

Everyone assuming that it’s only useful for small configs are ignore the less sag and less wear and tear of the cell. It’s not good to pull 20 amps for a 30Q cell for much time. That will shorten their life cycles.

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Not saying it’s not useful for bigger packs (keep in mind ESC and motor limitations), if you got the rig it is a beast for a cell.

But to me @b264 said something relevant : I’d literally run them in 1P or 2P packs because of space and weight constraints.

It totally fits my bill as 2x12S1P if I were to replace my current 2x8S2P, as far as power rating goes and I save some space while raising max speed.

Though comparing 32x 18650 cells and 24x 21700 cells, the 21700 comes heavier. It’s all about different needs IMHO.

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Not sure, but boosted might using these cells in a 13s2p configuration on the new extended battery.

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Lets consider some board options:

4wd, with VESC6, capable of 80 amps per motor, means 240 amps possible.

30Q pack needed: 12s16p, 9216g total 30T pack needed: 12s4p, 3312g total

Another setup:

4wd, with VESC4.12, capable of 30 amps con with bad heatsinks (way more if good heatsinks), that’s 120 amps.

30Q pack needed: 12s6p, 3456g total 30T pack needed: 12s3p, 2484g total

A 12s6p board needs to be almost twice as large. Space wise, the 12s6p 18650 is much larger than a 12s3p 21700.

So for me, as someone designing hollow core decks, my latest design that I hope to have samples in hand for in a few weeks, fits a 12s3p of 18650 or 21700 with space for 4x vescs and a bms. I don’t need much more space for the 21700 cells. So being able to shrink the number of cells I need is huge for me.

That’s not a good comparison though. A good comparison would be 2 packs that are the same amp rating (and watthour) numbers, 32x 20Q 18650 cells vs 16x 30T 21700 cells. In this case, 1536g vs 1104g.

So if your after performance with less weight, the 30T is the winner.

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If your after range, than yes, this is a different story. Weight to range ratio on the 30T cell is higher.

But 6-20 miles (depending on weight and how you ride) is enough for most people, especially in a city.

12s4p is big enough for most people in terms of range. 60-80 amps though, is not enough if you want real power.

The other place I see these cells being used is in mountain boards. They need huge amp discharge rates, just like my 4wd boards need, and they will also benefit largely from these cells.

And again, even if 80 amps is enough for you, your 30Q cells are going to last a fraction of the life cycle of the 21700 30t cell in the same config. So even if you don’t need 160 amps, and only 80 amps, your cells will last much longer than the 30Q cells.

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If you want a weak performing board, stick with the 30Q, it’ll do fine for you. But if you actually want to increase performance and the life cycle of your cells, the 30T is better.

I’m ignoring cost aspects, so I know that will come up.

Lets add up the costs of these packs.

Lets assume the 30Q cell is $3 per cell and the 30T cell is $7 per cell.

The 12s16p 30Q pack costs $597. The 12s4p 30T pack costs $336.

So performance for your buck here, the 30T is cheaper.

Now we look at my second example, which is more practical.

The 12s6p 30Q pack costs $216. The 12s3p 30T pack costs $252.

So in this case, performance for your buck, the 30Q is cheaper, but not by that much…

Now yes, again, I’m ignoring range. Lets assume at these higher amp draws, the 30Q dies at 2.65 Ah and 30T dies at 3 Ah (As the graph I posted above).

12s16p 30Q is 42.4 consumable Ah. 12s4p 30T is 12 consumable Ah.

And the second example.

12s6p 30Q is 15.9 consumable Ah. 12s3p 30T is 9 consumable Ah.

So yes, if your after range with these high amp ratings, the 30Q yields better results. But these larger 30Q packs need more space and take up more weight than the equivalent amp rated 30T pack to get this range.

If you want high performance with long lasting cells and range, the 12s5p or 12s6p of the 30T pack will be the winner. Long range, high amp rating, and a longer life cycle.

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That was my opinion also with the 30T cells for a 12s6p configuration.

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So I have these people contacting me asking if I was still in need of the cells. Should I ask for a sample first then?

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How about comparing 2 wheel drive boards? Because frankly, I don’t pay any attention to 4WD needs. If you’re making a 4WD board, you can fend for yourself LoL

The vast, vast, vast majority of boards are 1WD or 2WD

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