The 18650 batteries remain a popular choice for many of the best e cig devices, and with good reason. They’re generally powerful, durable, long-lasting, and about as reliable as batteries come these days. Still, it is also important to remember that not all batteries are the same. And sometimes, you aren’t really sure what battery you’re really getting, since some companies just re-wrap other products. Moreover, even within the 18650 range of batteries, there are different capabilities and sub-types. Take Efest’s 18650 options, for example. They offer a variety of battery options with different energy capacities and different performance capabilities. Let’s just examine two to get a better idea of how different two batteries can be: the Efest 18650 Battery (2600 MAh) 40A Vs (3500 MAh) 20A.

The Efest 18650 Battery 2600 mAh 40A

In our tests of the 2600 mAh 40A, we found that it offers some great performance, depending upon the amps you choose. The best performance seemed to occur at around 10A, and we were able to get the battery to come pretty close to that 2600 mAh rating that it advertises. That performance was maintained as we increased to 20A, but things got a little shaky as we went over that limit. The battery temperature was a little too high for our liking and suggests that the 40A rating may be a little bit of wishful thinking.

In fact, when we operated at that 40A, we experienced voltage variances that indicate that this particular battery is overrated at the 40 mark. These estimations seem to have been confirmed by some other reviewers online, so I don’t think we’re being too harsh in the evaluation. Overall, this is not a bad battery. It is, in fact, an efficient power source if you know what to expect from it. Our advice, though, is to buy it under the assumption that it’s not really the 40A advertised, but a 20A battery under normal operating conditions. At that level, you can pretty much rely on it being efficient and safe.

Efest 18650 Battery 3500 mAh 20A

With the Efest 18650 3500 mAh battery, it seemed safe to assume that it too would test out at something less than its given rating. As we noted, the 40A struggled mightily at its maximum capacity, but performed admirably at half that rating. If that same result held true for the 20A, then we figured that we would be looking at a battery that would perform best at around 10A. So, were we correct? Sadly, yes.

At 10A, the battery tests out at about 3100 mAh- with steady use. That’s typically what you see with any power source that’s rated at 3200-3300 mAh, so that’s about what you can figure you’ll get with this battery. That’s fairly close to the manufacturer’s rating, so we can’t really complain. Plus, when you consider how the 2600 mAh version compared to its given rating, this is about what you would expect for the 20A model.

The higher ratings don’t seem to be accurate, however. We started experiencing overheating at around 15A, and the rated 20A just seems out of the question. For continuous discharge, we think that 12A is about right for this battery. Anything lower and you’re well in the comfort range. Anything higher and you’re taking on the kind of risk that we would advise against. Overall, it seems pretty clear that this is not what you should expect from a 20A battery. However, it is a real star at the 10-12A range, and should provide plenty of life.

Why the Disparities?

Some other reviewers have suggested that these are re-wraps rather than original designs created to meet the designated rating specs. That would certainly explain the wide disparities between the advertised ratings and the actual performance discovered in testing. This is not necessarily a knock on the company, because they certainly wouldn’t be the first to re-wrap other battery models. However, its things like that that gives regulators talking points to use when they want to clamp down on the industry.

Image from torchythebatteryboy.com

One thing’s for sure, though: these batteries certainly didn’t live up to expectations in our testing. The thing is that most moderate vapers probably wouldn’t ever notice. By the time the battery gave out on them, they would simply move on to something different without worrying about why these failed. And make no mistake – if you’re vaping exceeds the actual performance rating of any battery, that power source won’t survive long with continuous use.

The bottom line is that we just feel that both of these batteries are being rated outside their actual safe performance range. That doesn’t mean that they’ll explode or anything like that, but it does mean that you’re not exactly getting what you think you’re getting when you buy one. Are they effective? Yes, but only when used with the understanding that their true rating is half that advertised.