So there's a new Efest 38A 2100 mAh battery on the block, I thought I'd do a comparison between it and the older 30A version from Efest, along with the VTC4 which is our current most recommended battery for the cloud chaser or someone that needs high current in the 20-35A range. We're going to have to do some work to show some bigger charts on our site so I apologize, but for now you can click the picture to see it enlarged.
EDIT: The effects of shaking on the curves in this post have been found to be mostly due to equipment issues. The conclusions of the article are correct and the "shaking" lines are the ones that are valid, but shaking doesn't have nearly the amount of effect shown in the graphs. We're going to revisit this and redo the graphs soon but some quick testing with fixed equipment shows the overall conclusions were correct.
Let's see some pics of these, and also unwrap them.
As you can see the new Efest 38A has a different darker purpler wrapper with little Efest watermarks. Definitely looks more attractive. According to Efest it is much more heat resistant and durable than the wrapper on their other batteries so that's a plus as well. In my testing all the cells got pretty hot at some points but no wrapper degradation was seen.
Unwrapped Batteries: Are the Efests original cells?
I also unwrapped all the batteries, but it's not very interesting because both Efests are completely blank underneath, no markings at all. It looks like Efest is having them privately made just for Efest, they're not rewrapping a major cell. The VTC4 has the normal Sony markings that you can see through the green wrapper. So I don't see a point in posting those pics.
An interesting point is that at one point the 2100mAh 30A Efest was a rewrapped VTC4, but it is clearly not anymore.
Now onto the testing!
Volts vs Amps
This is always the first test we do. It shows at a glance how much power the battery puts out at different current levels going all the way to 40A. This chart shows that really the VTC4, and both EFest 2100mAh batteries, are not very much different. At lower currents below 10A or so they're right on top of each other. At higher currents you can see the VTC4 is a little bit better than the Efests. As for the Efests specifically, they're within margin of error to each other but the 30A is actually coming out just slightly better than the 38A. Again if you can't read the chart click it for a bigger version.
20 amps, or around 75W per cell, is a pretty common current in applications that need high current cells like vaping and high power lights. Here you can see the constant discharge curve starting the battery at full charge and running 20A until it gets to 2.5V. In our tests we will shake the batteries at random intervals, this is shown in the graphs when the voltage increases. This is because the batteries can become limited and shaking them again refreshes them.
This test comes out similar to the volts vs amps test, The VTC4 is on top although not by a lot, then the 30A Efest is about the same as the 38A but maybe just a hair better. At 20A the Efests do 1.9-2 Ah capacity, while the VTC4 lasts slightly longer at 2-2.1Ah.
Similar to the 20A above, this is 30 amps, or about 110W, constant discharge from full all the way down to 2.5V. Interestingly in this test the batteries all show similar performance. The 38A Efest takes a little while to really start hitting hard, at lower charge levels becomes better than the other batteries and it outlasts the VTC4 and 30A by a significant margin, putting out around 1.9-2 Ah whereas the VTC4 and 30A put out closer to 1.8 Ah. This might be a test we should re run in the future to see if the results are consistent. Overall there's not a big difference between the 3 batteries, all seem to be able to handle 30A without much issue.
2.1A results after a couple weeks of sitting
Now for a lower current test just to see how the mAh capacity changes after letting the battery sit fully charged for a couple weeks (this is hard on batteries). We see that generally they all take it just fine, although the VTC4 loses a little bit of its capacity and drops to 1.9-2Ah to match the Efests. The 30A Efest also showed low performance for a couple seconds at the start of the test, but on a retest later it did not show this behavior, so I wouldn't worry about that too much. I consider all the batteries to be equal in this test.
35A Pulse Test
This is what we call our vaping test. The battery is pulsed on for 2 seconds, then turned off for 10 seconds. This is done at very high current, 35 amps, which would be around 130W per cell. Again the batteries are shaken lightly a few times during the test to make sure they're well mixed.
The higher the voltage stays during the pulse, and the longer the battery lasts, the better the cell. The test is broken up into three graphs so you can see the lines up close.
Here we see a little bit of cell to cell variability in the beginning with one of the 30A cells being a bit worse than the other, but by the middle of the test they equalize. The other 30A and the two 38A Efests are very good from start to finish, but the VTC4 really shines in this test being very consistent cell to cell.
In terms of capacity the 38A Efests are the first to run out of juice, followed by Efest 30A, with the VTC4 winning the capacity test. But, we're not talking a huge difference here. You can see below how many pulses you get at this super high current level if you go to 2.5V loaded (which ends up being around 3.35V unloaded).
Efest 38A battery 2 (orange): 93 pulses
Efest 38A battery 1 (dark green): 95 pulses
Efest 30A battery 2 (purple): 96 pulses
Efest 30A battery 1 (blue): 97 pulses
Sony VTC4 battery 2 (light green): 99 pulses
Sony VTC4 battery 1 (red): 100 pulses
In summary, the VTC4 wins, as one would expect, but the Efests are very close to it and aren't very different from each other. They all can handle very high levels of current and would be much better for cloud chasers than most other batteries.
If you believe Efest that the 38A has a better more heat resistant wrapper, then you may want to consider the 38A over the 30A, but otherwise they're pretty equal. Since the VTC4 can be scarce at times, you might consider going with Efests if that's an issue. Also the VTC4 is a bit more expensive, but not much usually. Finally, the VTC4 is VERY highly counterfeited, and the fakes are getting very convincing so you won't be able to tell by looking at them, so always buy your VTC4s from a trusted battery source like LiionWholesale.
If you liked this article, consider supporting further testing by buying your batteries from Liion Wholesale! Here are links to the batteries reviewed here: