Does it matter what type of cable/charger you use for a flashlight charged via USB?

Flashlights with integrated USB charging always seem to come with a cable, but not with a charger.

Does it at all matter what kind of charger you use? Does it at all matter whether you use the supplied cable or any other? Or will anything that's USB do?

My charger is an old charger from an old smartphone, it says 5V & 2A.
The cable I normally use to charge my phone and plan to use for my new flashlight is a standard Micro-USB cable from Amazon: https://www.amazon.com/dp/B0711PVX6Z/?tag=cpf0b6-20
Will these do?

I've tested a number of lights, and most charge at 5V and under 1 amp. Your charger will be perfectly adequate.
A few newer Nitecore's I've tested will quick charge when paired with the correct charger, but a less capable setup would just fall back to standard charging rates - so you're still fine.

So the worst that could happen is that it charges slower? That would even be better for the battery, right? Just want to make sure that it doesn't charge too fast or something.

And can a USB cable ever affect the charging speed of flashlights or phones? Or only the charger itself?

Latest gen 3.1 USB A > Micro USB on light can deliver at least 1amp vs 500mv of the older standard, i charge many lights from the desktop pc and i know it puts out that 1amp. 3.1 USB A maybe more than 1amp i'll have to look it up. What the cable can support is another matter, you wont know unless its tested.

Prof.Dr.FlashlightNewbie said:

So the worst that could happen is that it charges slower? That would even be better for the battery, right? Just want to make sure that it doesn't charge too fast or something.

And can a USB cable ever affect the charging speed of flashlights or phones? Or only the charger itself?

Click to expand...

Yes a cable can affect the charging speed of things. I have a phone that supports fast charging (QC2.0) that some cables it won't fast charge at all and some it will fast charge. Better cables have thicker wire and can handle more current (power). Fast charging on my phone is about 18 watts (9v@2A) while slow charging is about 10 watts (5V@2A) so with a better cable my phone can charge almost twice as fast. Sad thing is the expensive cables sometimes are not as good as cheap ones. I have a name brand cable that won't allow fast charging but all the cheap cables from Dollar Tree work fine.

Prof.Dr.FlashlightNewbie said:

So the worst that could happen is that it charges slower? That would even be better for the battery, right? Just want to make sure that it doesn't charge too fast or something.

And can a USB cable ever affect the charging speed of flashlights or phones? Or only the charger itself?

Click to expand...

First off, the factor coming into play here is voltage drop. Any conductor will have some resistance per foot. The higher the resistance the more the voltage drop, which has a direct effect on the charging time. The following is a very good explanation.

One can see the resistance in a circuit increases, the current flow decreases.
In a cable, resistance depends on the gauge, or wire size of the wiring. First off, remember that the higher the gauge number of a wire, the smaller the diameter, and the more resistance per foot. So a two foot cable will have twice the overall resistance of a one foot cable.

With a short cable (3 ft and under) you really won't notice any difference between cables unless you are using a REALLY cheap cable. For longer runs the size of the wire in the cable will make a difference. Basically, the larger the gauge number (and the smaller the diameter of each wire) the greater the resistance per foot. Using a longer cable has already upped the resistance of the total cable just because there is more wire.

In my experience, the wire gauge in the cables runs from 26 gauge to 22 gauge. It is usually hard to determine the gauge of the wire used from the description. I always look for the cables that claim 22 gauge wire. Unless you make your own or have a cable specially made, you won[t find any with thicker wire (remember, as the gauge number goes down, so does the resistance per foot).

I have actually queried the manufacturer when buying a cable. With Amazon, there is almost always a spot where one can ask a question about the product, in this case the particular cable of interest. Usually, they will respond with the wire gauge used. If they don't, or this particular product does not have a way to ask the manufacturer, forget the cable.

I'm surprised to learn that some cables have such small gauge wire that 2 - 3 amps are too much. Jeez, the insulation must cost as much as the tiny wire.

I doubt the insulation cost nearly as much as the wire. Looking at wire charts going 2 gauges larger in wire adds 50% or more in the amount of copper used so not surprising that you find thinner wire on cables as most are made in China and if they can save a penny on each cable in cost they will probably do just that. If you also look at wire charts it takes a decent size wire to carry 2-3A normally, but that is normal and in shorter distances a smaller wire can carry more current without problems than in a longer run where the resistance of the wire keeps adding up more and more to carry an amp current for a foot takes less wire than an amp for a mile at the same voltage.