Bench Test Results: Molicel P45B - 50A 4500mAh 21700

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Mooch
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Bench Test Results: Molicel P45B - 50A 4500mAh 21700

I tested these cells in January for my Patreon supporters and have been torture testing them along with the Molicel P42A and the Samsung 40T since then. With the release of the Molicel P45B hopefully coming soon it’s finally time to post some test results. The cycle life torture test results will remain patron-only though.

The Molicel P45B is an extraordinary cell, matching or outperforming almost every other round cell I have tested at all current levels. The official word is that it will be available before the end of the year but there have been a couple of rumors that some vendors will have it by Summer. I can’t predict who will have it or when.

Compared to the Molicel P42A, the P45B is supposed to have about 7% more capacity, 22% lower DC internal resistance (DC IR), and a higher charge rate. Its main competitor is supposed to be the Samsung 50S.

In my testing the P45B was a better performer in every way over the Molicel P42A:

  • The P45B had almost 9% higher capacity.
  • The P45B had about 33% lower DC IR (at 100% charge).
  • The P45B’s charge rates are 4.5A standard/13.5A max (70°C cutoff) and the P42A’s are 4.2A standard/8.4A max (60°C cutoff).
  • The P45B had longer run times at all discharge current levels.
    The P42A is still a great cell! It’s just that in the four years or so we’ve been using it battery tech has improved and the P45B is a perfect example of that.

Compared to the Samsung 50S…

  • The P45B has about 7%-8% less run time at 5A and 10A.
  • The P45B runs for longer though at about 15A and higher.
  • The P45B has a 26% lower DC IR (at 100% charge).
  • The P45B runs MUCH cooler at moderate to high current levels.
  • The P45B has a higher standard and max charge rating (2.5A/6A for the Samsung 50S).

So while the Samsung 50S had slightly longer run times at 10A or lower, due to its higher capacity, the Molicel P45B beats it in every other way in my opinion. The P45B will easily be my choice for best all-around performing round cell and also my #1 choice for moderate to high power applications.

The preliminary datasheet only lists a “temperature-limited” rating of 50A. Molicel says you can run this cell at 50A but only if it never reaches a temperature of 80°C (hot!).

You cannot run the P45B at 50A continuously until it is empty! This non-continuous rating is set by Molicel for this cell’s intended applications; power tools, electric vacuum cleaners, and similar devices where the cell is used really hard for short periods of time.

While you can run this cell at 50A for a while I recommend staying below about 35A to help reduce voltage sag, improve performance, extend cell life, and reduce risk. Especially if the cells are in a battery pack where they heat each other up. Use a 35A rating for comparing this cell to other cells with true continuous current ratings.

The two cells I tested delivered 4477mAh and 4488mAh. This is great consistency and is typical of cells from the big manufacturers. The cells I tested exceeded Molicel’s 4400mAh minimum capacity rating but didn’t quite meet the 4500mAh “typical” rating. I’m not worried about this at all, especially since it’s only a tiny difference and I tested these cells in January and tweaks to the capacity can be made. I’ll retest these cells once they become widely available.

Here are the discharge graph, performance graphic and a table showing the delivered energy (Wh) and max temperatures the P45B, P42A, and 50S reached in testing: https://imgur.com/a/DrRAOG0

See my 21700 Ratings and E-Scores table (link below) to see how this cell performed against others.

Four cells were sent to me for testing by N-Power Energy, global distributors for Molicels (https://www.npecell.com). Thank you!

18650 Ratings and E-Scores Table:
https://www.e-cigarette-forum.com/blog-entry/18650-battery-ratings-table...

20700/21700 Ratings and E-Scores Table:
https://www.e-cigarette-forum.com/blog-entry/20700-21700-battery-ratings...

To see how other cells have tested check out this link: https://www.e-cigarette-forum.com/forum/blog-entry/list-of-battery-tests...

Edited by: Mooch on 05/17/2022 - 16:46
stephenk
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Thanks for the review!

Sirstinky
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Nice! The question is whre can you buy these or will they be as unontanium as the 50S?

Mooch
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As mentioned above, I don’t know. Smile I’m confident that quite a few vendors will eventually stock this cell.

Samsung actively works to keep their cells out of the hands of end users. E-One Moli supports the use of their cells by individuals and I think these cells will (eventually) be widely available.

Any vendors stocking them will sell out instantly though. It will take a while before enough demand has been met for the vendors to actually keep stock on hand.

Sirstinky
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Thanks. Probably keep an eye out for them, but you’re right…will probably be sold out quick like P42A. I hope they don’t cost $25 each like the Vapcell 50S.

Mooch
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Don’t think so. I’m sure the P45B will cost more than the P42A but I’ve seen reasonable wholesale price quotes so I’m hopeful they are priced kind of reasonably at retail. Well…eventually.

Sirstinky
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Thumbs Up I hope so. These seem like awesome cells. I have some P42A, but I am liking the 40T better in my high performance flashlights. Hits harder at start and maintains higher output for 15 minutes or so at high current.
Correllux
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Hey Mooch, good to see you! These sound like little powerhouses. Maybe when the e-bike folks eat their fill, maybe some tool manufacturers, they’ll trickle down to where we can buy them easily.

Side note…your review on the QB 26800 was great and a lot of us here and on reddit have been very pleased with them. There were restocking/supply issues for awhile, and during that time more of the green/blue wrapped 26800 mystery cells were sold and/or included with some lights. Still some questions but we know enough about the QB to be satisfied. Do you know anything about those green or blue cells? Any chance you’ll have those in the test queue? (Heck, for that matter, do you know the actual manufacturer of the QB cell or those others? Wondering if they’re the same cells/same manufacturer.)

Big thanks for all the time you spend testing for us. You and HKJ keep us going!

Sirstinky
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The blue/green (I have a green from Nealsgadgets) are shorter than the QB by 1.5 mm or so and have a higher current rating possibly. The Ni03 I tested on the green cell pulls 28 amps, but the QB gold one only about 24 amps. Maybe because it was new vs the green having about 4 cycles on it, but the green seems to be a higher drain cell.

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Hmm, interesting…so not the same cells then. This could be a good thing in the end. Thanks, Sirstinky.

Mooch
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Correllux wrote:
Do you know anything about those green or blue cells? Any chance you’ll have those in the test queue? (Heck, for that matter, do you know the actual manufacturer of the QB cell or those others? Wondering if they’re the same cells/same manufacturer.)

Sorry, I don’t know anything about those other 26800’s and none are in the queue (no requests yet). I’d take the time to test them though if anyone wanted to send me two of each.

Correllux
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Cost might be problematic just due to shipping them individually (i.e. not inside a device) from Asia, but if something can be worked out I’d sure chip in. I’ll put a post in our main 26800 thread here, maybe it can happen.

These new 21700 are really impressive. Cells seem to have plateaued for the most part and then boom, driven by industry we suddenly see some real gains!

Sidney Stratton
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Correllux wrote:
Side note…your review on the QB 26800 was great and a lot of us here and on reddit have been very pleased with them.

I’d be very interested in this review. Would you have a link?
‘r/mooch’ shows nothing, ‘QB26800’ has many hits, none regarding his review.

Mooch
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I can’t guarantee they haven’t changed what cell they are wrapping but here’s my test report:

https://www.e-cigarette-forum.com/threads/bench-test-results-queen-batte...

Sidney Stratton
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After much digging (“mooch315”), and finding your review some umpteen pages (been over a year), finally got to that linked forum.

Many thanks, I’ll dive in…

Mooch
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Yea, I reallllly need to get my web site up and centralize everything, indexed, with search, etc. LOL…in my copious spare time.

Sidney Stratton
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As I have your attention, perhaps enlighten me. I’m into designing my own builds and balancing cell discharge to LED current demand. The newer LEDs are power-hungry.
Trying to interpret those current graphs, they are in Amp-hours (capacity). I’m looking for sustainability (my preferred would be 3 minutes) and at no less than 3.6 volts (battery sag). These LEDs don’t perform at their peak below 3.6 volts, many at 3.8 volts (I’m disregarding those above as inconceivable to attain such with 20+ amps draw).

So how do I calculate or interpret those graphs?

Mooch
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Choose the discharge current level closest to that at which you are operating. Then follow the discharge curve plot line down to your cutoff voltage, 3.6V or 3.8V or whatever you choose. Whichever cell(s) deliver the highest capacity at that cutoff voltage will be the cells that give you the longest run time.

Odds are that the cells running for the longest down to my 2.8V cutoff will also be the ones running the longest down to a higher cutoff. You could use these tables to narrow down your choices:

https://www.e-cigarette-forum.com/blog-entry/20700-21700-battery-ratings...

https://www.e-cigarette-forum.com/blog-entry/18650-battery-ratings-table...

If HKJ has tested any of the cells you’re considering he has a much wider range of discharge current levels you can check for highest delivered capacity at your cutoff voltage.

Sidney Stratton
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That’s what I’ve been doing, but how to translate Amp-Hours to minutes?

Example:

Mooch
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Ah is just amps * hours.
Convert the delivered capacity in mAh to Ah (Ah = mAh / 1000). Then divide the number of Ah by the current (amps) and you’re left with hours. Then you can convert to minutes. Since the discharge is constant-current you can do this.

You can do this directly using mAh and minutes but you need to handle the units carefully. I leave this as an exercise for the reader. Smile

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That’s the maths I’ve been doing. As per the above example:
0.73 AH ÷ ~8 (estimated) ÷ 25 A = 0.004 Hours x 60 = 0.219 minutes (~13 seconds)

I’ll reverse engineer the graph so to what current can be sustained 3 minutes.

With some fiddling, about 18 amps.

Mooch
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I was thinking you could get that number just from the math but I deleted my post on that since I think the difference in voltage sag at lower current levels will have a big enough effect to make the math method not accurate enough.

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It’s ok. I’ve been doing this for a while now and just ballpark figures do give me an insight as to what to expect.

Strange, the West Mountain Radio graphic uses such an awkward AH scale.

Sidney Stratton
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Nevertheless, those QB26800 cells from Aloft (the gold wrapper ones) don’t live up to my expectations. Originally was supposed to be ~10 mΩ IR (1kHz). And they cost me much with the shipping to Canada.
Looking forward to the eventual test with the green and grey wrappers. I would like to contribute but these were above my paygrade ($54 / 2)

Mooch
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Ah is the industry standard so it’s the default for most testing. They allow plotting by run time or Wh though.

Sidney Stratton
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But all this analysis gives you an insight into what we flashlight enthusiasts have as current capacity, that’s to say below ~3.6 volts isn’t worth considering for a power-hungry LED. And they have some at above 30 A !!!

Have to add, I bypass the FET driver for such high demand – hardwired direct drive, single-mode ON.

Mooch
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Sidney Stratton wrote:
Nevertheless, those QB26800 cells from Aloft (the gold wrapper ones) don’t live up to my expectations. Originally was supposed to be ~10 mΩ IR (1kHz). And they cost me much with the shipping to Canada.

Sorry to hear they didn’t work out!

Mooch
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Sidney Stratton wrote:
But all this analysis gives you an insight into what we flashlight enthusiasts have as current capacity, that’s to say below ~3.6 volts isn’t worth considering for a power-hungry LED. And they have some at above 30 A !!!

No good boost regulators to help out with that?
Hmm…actually, there would be a decent chunk of heat to deal with using that regulator and I bet you’re already dealing with a lot of that from the LED.

I like that bypass solution.

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Part of the exploration costs. Others in that build and 100+ sank in. Put aside till I find a better cell or lower Vf emitters.

Just now Simon (Convoy) is developing a power boost driver. I’m in line for a few…

Heat isn’t a problem if there isn’t a thermal cut-out. I live in a cold climate and use work gloves with these lights. I do check on the tube heat – wouldn’t want a runaway battery.

And my builds do consider the wattage. This one is above 1 kg.

Mooch
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Sidney Stratton wrote:
Part of the exploration costs. Others in that build and 100+ sank in. Put aside till I find a better cell or lower Vf emiiters.

I’m thinking Vf is about as low as it will get. At least for remotely affordable ones. The cells will probably be a better option but none will give you want you’re looking for I think. Three minutes at 25A above 3.6V is about 4.5Wh of energy…that’s a LOT.

A super-efficient boost circuit might be the best solution. Anyone working on that?
Oops, you mentioned this while I was composing.

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Perhaps I should be building with multi-cell hosts….

Just tonight was looking into a 3×21700 model from Simon. See if he would sell a hollow shell as a host.

As an end note, that P45B would be a good cell for the aforementioned build. Inferring from your discharge graph, could sustain 25 Amps for 2 1/2 minutes. Looking forward to the availability this autumn.

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