New from TPcell: Makita batteries with USB-PD support—not a review

Sometimes, when looking at batteries for power tools, I wondered why not combine one with a power bank. Yes, I’d come across adapters that offered a similar function, though only in one direction: discharging. But recently I saw something in the TPcell store that really caught my interest: a battery with a built-in power bank.

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Previous reviews of TPcell products
5 Ah battery for Makita tools
6 Ah battery for Makita tools
Charger for Makita batteries
7.5 and 9 Ah batteries from TPcell for the Makita system, not a review
New series of batteries from TPcell, with 21700 cells and capacities up to 15 Ah, not a review
TPcell battery for Milwaukee M12 tools


Why was I thinking about a solution like this? Modern power tool batteries often use pretty good cells designed for high current, and they also have a substantial capacity. For example, a two-row 6 Ah battery stores about 108 Wh of energy, comparable to a 30,000 mAh power bank. And with modern chips, you can get not only decent output power, but often charge the same battery through the same connector as well.
I think many of you know the common red boards that run from 3–5S batteries, with a choice of standard lithium-ion or LiFePO4 cells, as well as a choice of charge termination voltage. They can deliver up to 100 W and charge at 60 W, all in a relatively compact package.

The idea was to combine a good, high-capacity power tool battery with one of these boards to make a power bank and a convenient alternative charging option. Suitable chargers are widely available, not just for mains power but also for a car’s electrical system, which opens up even more possibilities.

Anyway, I came across a listing with several versions of these batteries, with capacities of 4, 5, and 6 Ah, priced at around $40, $46, and $60, respectively.


But to me, the 5 and 6 Ah versions are the most interesting: the first because it offers the best price, the second because it has the maximum capacity you can fit in this size. Sure, there are 4 Ah cells, and theoretically you could make an 8 Ah battery, but they aren’t designed for high discharge currents.

By the way, keep in mind that higher-capacity batteries usually allow lower discharge currents. So if you have a very powerful tool, it’s better to look at a 4–5 Ah battery. For a typical cordless drill or something similar, a 6 Ah battery should be fine. Of course, this rule doesn’t always hold, since some unscrupulous manufacturers may make a 3 Ah battery with a low discharge current, but not the other way around.


I was thinking of ordering one to try, but ran into a problem: for some reason, items from this listing aren’t shipped to Ukraine.


What’s interesting is that other listings ship without any problems. Ukrposhta delivers a postcard, while the battery itself is shipped by Meest Express, but that’s not really important.
So I think it’s worth asking the seller about shipping the new batteries, or perhaps they’ll add shipping to Ukraine themselves a little later.
There’s another wrinkle, though: I bought batteries from Valentino Boutique Store, but they don’t have these batteries yet. They are available from tpcell Battry Official Store, and I suspect that once they appear in the first store, shipping to Ukraine will be available too. To be fair, though, I think Valentino Boutique Store is better. I’ve also dealt with the seller there, who is more than reasonable, so that’s the one I recommend.

One more thing: the prices listed above are before discounts. The stores have discount coupons, and coins can be used too, so the actual price is lower.


From the product description, you can tell that the battery’s stated capacity is genuine and that they use tested cells: Chinese cells in some batteries, branded cells in others, usually Samsung. I’ve already written about this in my reviews of their batteries.
The idea is that they take branded cells from disassembled batteries (not used batteries, but new ones taken apart), test them, and assemble new batteries. For example, Nkon sells similar cells and specifies that they come from disassembled batteries. Roughly speaking, they assembled a large battery, then found a defective cell in it. Replacing just one cell isn't cost-effective, so it's easier to dismantle it and sell the parts.



They also include the markings of the cells they use.


Back to the battery.
From the description, it looks like it uses MOSFETs with low on-resistance, rated at 1.2 mΩ. It's not entirely clear what that figure refers to—most likely the total resistance from the cells to the contacts, though I could be wrong.
The battery's positive and negative contacts are copper. The point is that these terminals are narrower than the strips connecting the cells in the pack, so strip resistance matters more here. They used copper instead of nickel, which is good to see.
It's also rated for 65 W input/output through the USB-C port, and the chip is listed as an IP2366. So the output is probably up to 20 V at 3.25 A.



It's a very interesting chip. Judging by the description (as far as I can make out the Chinese and the Arabic numerals), it supports all the common protocols, up to 140 W, including 28 V at 5 A, 2–6S batteries, and a bunch of charge termination voltages, including LiFePO4.


I could be wrong, of course, but this seems to be the chip. The 65 W limit is probably due to cooling constraints, with the power capped in software. That probably wouldn't stop you from unlocking it for higher power, though. Damn, I already want this battery for experiments :)
The power is set by the value of a single resistor.


With an adapter or a compatible cable, you can power laptops at up to 65 W, which covers a pretty large range of computers.
But there's a catch: if you power a laptop through its Type-C port, you may run into trouble. Since both ends support charging and discharging, your laptop might decide to charge the connected battery instead of the other way around. Sometimes unplugging the connector, turning it 180 degrees, and plugging it back in helps; you can also try swapping the ends of the cable.


Another bonus is that they kept the standard Makita connector, so it's claimed to work with the manufacturer's chargers, too.
And there's an indicator. Speaking of the indicator, it's not entirely clear, but it probably estimates the charge level from voltage alone. The IP2366 chip has its own coulomb counter, but it only works on the Type-C output, so it isn't used here—even though it's more accurate.


I found a YouTube video showing an actual photo of the board, and it matches the photos in the store quite well.
The person in the video also tested it under load with a hair dryer. The current came out to about 3C, since the discharge took 20 minutes. That's not much, of course—only about 300 W—and the author measured the case temperature rather than the cells. Still, it's much better than nothing, and we can already tell that this is a decent battery.



Conclusions, as far as we can draw them from the photos and the information available.
It's a great idea: flexible charging, plus the option to use it as a power bank—and a fairly powerful one at that. It may also be possible to increase the power, especially since the battery can handle it.
The cells are decent, though I've said that more than once already.
As for the price, that's up to each person to decide. In my opinion, it's quite reasonable for this feature set and package.

That's all for today. I hope you found it useful.