I'm ditching the 30Q - You should too


Photo credit: Jacob - @Movation

I have switched my "go-to" 18650 for esk8 batteries to the Molicel P26A. I'm going to stop blindly recommending the 30Q, and I wont be keeping them in stock anymore. Here's why I think you should too:

1. Real-world energy delivery VS “rated capacity”

Because simply looking at the Amp-hour rating of a cell gives an incomplete picture of how much range we will get out of our batteries.


(Figure 1 & Figure 2)

Delivered energy explanation and data

The capacity ratings that manufacturers give to their cells are measured at very, very low discharge currents (often well below 1A), and therefore are basically useless for our application where we often draw 10, 20, sometimes even 30 Amps per cell in our high-performance battery packs. Capacity measured in Amp-hours also doesn’t take into account voltage sag at high load, or how hot the cell gets, or how much it ages/reduces it’s cycle life when it is discharged in that way.

A much better way to compare the energy delivery of two different cells at a certain load is to look at how many watt-hours it can deliver down to a specific voltage. (For a more clear breakdown of what Watt-hours are, check out episode 5 of Mooch’s youtube series “Minding your mAhs” where he goes into this topic.)

See the ratings graphics that Mooch made for his tests of the 30Q and the P26A (Figures 1 & 2 above). Take note of the section circled in red. In this portion of the graphic we can see that the P26A actually delivers more Watt-hours than the 30Q at 10A of discharge down to 3.2V (which is pretty close to the default VESC tool discharge cutoff of 3.1V/cell) and delivers nearly the same Watt-hours at 20A discharge than the 30Q delivers at 15A!

What I conclude from the data in this section is that the P26A runs more efficiently and delivers more energy at the Amp levels that we see normally in an esk8.

2. Voltage sag and real-world performance

That’s true. Unlike a lot of other applications for lithium-ion cells, we dont draw constant current. Our current level varies depending on acceleration/hills/duty cycle/etc. So I asked @Battery_Mooch if he could simulate the load that a single cell in a high-performance DIY esk8 battery would see on an average ride.

Turns out, this is kind of a difficult question. What is an “average ride?” Average for who? What kind of riding? What terrain? Weight of rider? Etc.

I'll let Mooch take it away with the explanation of our test, and the data:

What we settled on was a discharge profile that I think approximates a rider who is pushing their board to the limits of their battery, which I feel is valuable because we oftentimes are looking to get the largest performance out of the smallest battery. And as we can see, the P26A runs longer, with more energy delivered, and stayed cooler. It also had less initial voltage sag.

3. Price/availability

As I am writing this in March of 2021, you may or may not have heard that there is a global shortage of many of the big-name lithium-ion cells.

This is due to three factors (that I have heard about, anyway).
  • COVID-19. The pandemic (hello to anyone from the distant future who hopefully isn’t living this hell anymore) has caused global manufacturing disruptions in all kinds of markets, including in the battery market.

  • Increasing demand for electric vehicles globally. The massive cell orders that EV makers are placing for cylinder cells is eating up the production capabilities of these cell manufacturers, leaving fewer cells to trickle down the market to hobbyists and small businesses like us.

  • All of the round cells we buy from the big manufacturers are excess inventory sold on a “gray market” by customers of the big manufacturers, unauthorized sales, or diverted shipments. None of the round cells we use were ever meant to be used outside of a fully protected battery pack (looking at you, mech-mod vapers).
    The big manufacturers (Samsung, LG, etc.) are working harder now to get their cells off the gray market because of all the lawsuits by people who set themselves on fire.

What this means is that the Samsung 30Q (as well as many other Samsung cells) are either not available, or only available for massively inflated prices. At the time of writing this, the only reputable cell supplier that I could find who has 30Q’s in stock wants $6.25/cell for 50 cells. That’s nearly double what the P26A is going for.

For my business, I need consistency in both price and availability. Samsung cells simply do not have that right now, and the situation seems to be getting worse, not better. There are several authorized/approved resellers of Molicel batteries in the USA (18650BatteryStore.com, LiionWholesale.com, etc.), meaning they have been able to keep their Molicel cells largely in stock and at a fair price, even through the height of this pandemic.

4. Conclusion:

The P26A performs slightly better than the 30Q in a simulated esk8 use-case, delivering more energy with less voltage sag and less heat generated in the cell. It is also rated for a higher discharge level than the 30Q, so a pack of the same size could theoretically provide more current safely than one make of 30Q’s. (For these tests, we looked at the two cells at the same discharge levels to keep the results consistent and comparable.)

The P26A’s are also cheaper and more easily available to US battery builders, meaning our packs can be cheaper and more accessible to builders of any budget!

That’s enough to convince me. I have just ordered a large stock of P26A’s and I will be making lots of batteries with them. I know several other battery builders such as @glyphiks have jumped on the P26A train as well. As more results come in, I will update this post so we can all see exactly how well these cells are doing across a range of different builds :slight_smile:

Disclaimer

This article is my opinions and interpretations of the data presented. My opinions do not necessarily reflect those of @Battery_Mooch or anyone else mentioned or quoted in this article.

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I am really looking forward to hearing people’s experiences with these cells in the wild, so if you have a battery running these cells, or if you have built with them and have some insight, please share it!

This article is my opinions based on the current evidence I have right now. I tried to avoid bashing the 30Q, because it’s a really good cell that has been doing great in many boards for a long time.

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Popped my p26a cherry on the weekend. Putting it in an evolve board, which i have good experience with in terms of equivalent 30q packs. Very excited to see how it goes.

PS. This article made me hard. Well done.

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Really looking forward

Ideally I would like to see two identical board with same weight and fluffy riders, just changing the packs and riding side by side

I still think that for people that ride like me that the average cell current is around 2 A the 30Q would come on top range wise. Actually the 30Q is also a bad choice for that case, but the only thing I had available lol, other cells like the MJ1 start to make sense

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The 50 new 30Qs under my desk would like a word with you.

Great post, Ben.

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Molicel is the new king, wait until P31A hit the market. we might even have a better 18650 cell :rofl:

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Sexy little pack! I’ll definitely be interested to hear how it stacks up against 30Q evolve packs :slightly_smiling_face:

Determining and comparing real world range is really really tough, simply because there are so many variables. For example, the single biggest variable for determining how efficient an esk8 ride is, is how aggressively the rider is pushing the throttle.

Your idea of two riders side by side is interesting, though even then there will be slight differences in their weight/riding style/their boards/etc. Even stuff like belt tension can throw off range calculations a bit.

That’s why I feel that Mooch’s test gives us better data, as they are repeatable and easily comparable. It doesnt necessarily tell us how much range we can expect from each cell - that’s not the point. It just gives us an even playing field to compare both cells on.

If anyone has data for what a different discharge graph should look like, Mooch and I are very interested!

Those are gonna be worth more than gamstop stock here real soon :joy:

Thats my hope! :grin:

The question of price and availability is what really sparked my interest in these cells. Finding out that they perform as well if not better than 30Q’s was just icing on the cake. If Molicel keeps pumping out awesome cells and US distributors keep them in stock at great prices, then they are going to own the market in my opinion.

Maybe I should start pursuing a sponsorship deal :joy:

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that would be dope!

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I sadly bought 200 VTC6 (arriving soon), a week later 18650store had the P26A as the daily special I was kicking myself. This is for my 12Kw bomber ebike build.

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Its happening. Although no time to ride it til friday :expressionless:

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Stock Evolve ESC?

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Yeah totally stock evolve. I consistently get 21-22km on this setup with a 30q battery… if i get the same or better with p26a, i’ll be stoked.

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Kind of a waste that 37 amp combined limit is a real kill joy.

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I see what you did there…

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Yeah but so many people still want these upgrades. If the molicel is a viable replacement for the 30q, its happy days for me.

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Did you hare to print a spacer or is it a GTR, looks like a gtx

Its a bamboo gt. Need to use an 8mm spacer to stack the bms on the motor controller

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You do tidy work mate. Missus is bugging me about upgrading her Evolve GT one, going to grab some P26A, due to clearance I wont be able to use PCB’s (sad face emoji)

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I’m very interested in seeing this as well!

Hmm this may be low enough that the 30Qs have a shot to win out. Will be fun to find out!

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But evolve cuts to eco at 34V. So there is definitely a good chance for p26a, especially for harder riders.

About to charge it up, but still can’t ride til tomorrow :expressionless:

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