Any testing done on lights with built-in chargers?

Someone asked on the LED forum about the safety of the built-in charger systems (sometimes coupled to an external charging mount) that we're starting to see on more and more lights. The replies back were essentially, "eh, they are good companies, you should be fine", which seems a bit incongruous with some of the dangers of this technology, documented on CPF. Back in the bad old days, we saw many mistakes, like chargers that did not terminate properly (that is, they trickle charged at "termination"). I have not been able to find any reviews specifically of the integrated USB-based charging systems being used by Fenix, Klarus, Olight, etc. Do such reviews exist, or are we all just guessing that the integrated USB charging systems just behave themselves?

+1

I'd like to know as well.

As a longtime eneloop user I steered away from LiIon chemistry a few years ago because it felt like the wild west. Enelops in a smart charger are about as foolproof as a battery can get.

But with newer batteries, better chargers, and protection circuits, I have seriously considered a USB rechargeable 18650 light, but don't know anything about the relative safety to standalone solutions.

For instance, can I leave an Olight S30r charging overnight, or is it going to blow up if I don't manually check the temperature and voltage every 30 minutes? :devil:

Curious too. Especially the Acebeams. I am not comfortable using them. Plus I already have several external chargers.

I'm tempted by the Fenix UC35, which would be my first Li-Ion light. I really like the idea of an integrated charger, but I feel a bit nervous about not having the kind of test data that people like HKJ very kindly provide for standalone chargers.

Glad other people are interested. I think the testers here have done the community an immeasurable service, I almost wonder if to some extent the manufacturers have increased their quality specifically because they risk bad reviews here. For any reviewers looking to make a big impact in an area that's had no attention whatsoever, and has big financial implications to the flashlight makers, I assert that this would be a great area to look!

Good points, I am on the market for one of those torches.

I have always assumed that the built in chargers had a very low voltage charge. Like sub 500mA for single cell lights - 1+amp for multi cell light charging. Something low that would not heat up the cells. Of course it would take several hours to fully charge. When I use my Xstar charger in the low mode the cells barely get warm and 2 weak 18650's can take several hours. Then they would also have to address those folks who like to keep the light "on charger" all the time. I read that its not good to keep cells on the charger once they are charged. So I wonder if these built in chargers turn off once the cells are full? Or do they trickle?
I like the 12 volt car lighter adapter that the Acebeam comes with. Never opened it, but it would be good to know if that was a safe thing to use (properly). Could you imagine plugging this in to charge in the summer, on your seat in the sun, in a closed vehicle! kabooooom! lol

Of course, I check all my cells prior to using the light. I guess I could do the same thing prior to charging. I could pull them, check voltages, make sure they are all close to the same, then charge. As long as the charge voltage is low, and the light is not in a hot, closed up car in the summer sun, it should be safe.

Str8stroke said:

Curious too. Especially the Acebeams. I am not comfortable using them. Plus I already have several external chargers.

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I think selfbuilt covered the charging system for the K50 pretty well in his review. Seems like a reliable charger in my usage.

I have been wondering the same thing, and it would be great if someone knowledgable tested them. These lights seem to be so convenient for particular usage scenarios, and I'm tempted to try one out myself sometime.

Add another interested party.... particularly given the sealed tube/pipe bomb nature of a flashlight charger, and the ability to use poor quality or inappropriate batteries in them.

+1 on this, total noob wanting to dabble with lithium....

KelDG said:

+1 on this, total noob wanting to dabble with lithium....

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You may want to check with your primary care physician first!

I've got no idea what circuitry that Nitecore uses in their lights that have built in charging circuits, but the power supply for the Tiny Monsters are limited to 1 amp. One amp between 4 cells isn't much of a charge rate. Nitecore does however recommend the use of protected batteries, so that there are additional protections afforded by these cells.

I wouldn't want to internal charge batteries that didn't have the protection trip inside a light body.

I think it is not difficult to test built-in charger function....
Actually the issue is if the proper C/CV is followed....

This can be done with taking tailcap measurements

That depends on the light. For example, I don't have a Fenix UC35, but it seems that the charging system is in the head, so the tailcap would only give access to the negative terminal.

I presume that you'd need to take the head off, crocodile-clip to the spring for the positive contact and somehow connect to the negative ring (using a big spring clamp like the ones people use to temporarily connect to a lead acid battery, perhaps?) The battery for the test would need to be in a separate battery holder and wired into the test arrangement.

Unfortunately, I don't have access to an auto-logging test system, or I'd be sorely tempted to buy a UC35 and try it for myself (despite being wholly standardised on AA / AAA cells at the moment!)

maybe crocodile clip on the threads, and have a magnet soldered to the other end of the cable ,to fix on the battery bottom.