TPCeLL Replacement Batteries for Dewalt Power Tools

This time a short(ish) post with some technical data about replacement batteries for power tools from AliExpress. After years of being reluctant to try any after-market batteries for my Dewalt tools, mainly due to quality/safety concerns, I final gave these a try. I opted for a slim (single stack of 21700 cells) 4Ah battery from TPCeLL (TP-cell). The capacity is what I typically use (3-5Ah normally), the form factor is quite compact, and the price was too low to resist. So is it any good? Lets have a look.

First things first, the look and feel. I have an original Dewalt 3Ah battery with 21700 cells, which I can compare to. From a quick look, they look and feel almost identical. The stickers are different obviously, but other than that they are surprisingly similar. The one most annoying thing I noticed was the charge-state LED’s. while the original Dewalt battery is more than bright enough, the TPCell battery shines so bright its uncomfortable to look at the LED’s. Not a major issue at all, but visually quite noticeable.

Figure 1. Batteries Visual Comparison
Figure 1. Batteries Visual Comparison

Next I wanted to check the capacity of the battery, versus the advertised 4Ah. I’ve used the BK8500 with the control program posted on the blog in the past for these measurements. 4-wire connection was used with remote sense to minimize cable effects. I chose a 5A constant current discharge curve, with a minimum voltage value set to 15V as the discharge stop.

As a comparison, I’ve used an original Dewalt battery of similar dimensions, but with only 3Ah advertised capacity (as I don’t have a 4Ah variant with 21700 cells). The results were quite satisfactory, with both batteries logging exactly 90% of the advertised capacity.

So for the Dewalt DCB230 (2021 date code) the reading was:
2.69Ah, 48.74Wh, 32min to test finish
For the TPCeLL DCB204, this was:
3.60Ah, 65.01Wh, 43min to test finish
Overall a good result, which is close enough to the 4Ah rated capacity, which most likely assumes a lower discharge current. During the test I didn’t see any elevated temperatures.

Figure 2. Dewalt Discharge Curve vs. Time
Figure 2. Dewalt Discharge Curve vs. Time

I’ve measured one additional parameter from the log, that is the equivalent resistance of the battery, when the load current starts at the start of the discharge curve. For the Dewalt battery this was 82mOhm, while for the newer and higher capacity TPCell it was 88mOhm. So not quite as good as the Dewalt (which is 3 years old), but very similar results which shouldn’t cause any issues.

For these interested, I’ve repeated the TPCell discharge test at a reduced 1A current, and the results were:
3.67Ah, 67.39Wh, 220min to test finish

Figure 3. TPCell Discharge Curve at 1A
Figure 3. TPCell Discharge Curve at 1A

However, as I’ve stated at the beginning of this post, the main concern I have with these batteries is the reliability and safety of these, especially in the long run. In this regard, not only do we have to wait some time to see how they will hold up, I actually have some bad news already. I’ve  ordered 2 identical batteries in the same order. One of these, wouldn’t charge at all in either of the chargers I’ve tried. After checking with the DMM, the issues seems to be a missing contact for C1 (first cell in the stack) which means the charger cant measure the cell voltage.

After verifying there’s no need to send the problematic battery back to China, I took it apart to check what’s wrong there. Indeed there was a cold soldering joint to the charging connector. A quick and easy fix, and the battery is now charging as expected. However, this isn’t something I expect most users would want/be willing to do.

I don’t want to add any “conclusions” about the battery here, I think there’s enough data here for every reader to draw his/her own conclusions. I will update in the future in this post if there’s anything worth noting about these batteries. Hopefully, they will just keep working with no issues, in which case, I will have nothing to add 🙂

Leave a Reply

Your email address will not be published. Required fields are marked *