Idea about a simple USB charging mod for flashlight

Flashlight Modding and DIY Parts
1

I have seen people who mod their flashlights to make them USB rechargeable, however all of them tried to put in their flashlight an USB-charging circuit and these modifications are difficult and not all flashlight can be modded.
I have an idea, not sure if this already exist, to create a simple connection/plug (like Miro-USB or USB-C, or even a more simple connection with two polarities) at the outer of the flashlight that directly connect to the batteries. The charging circuit will be outside of the flashlight, this charging circuit can be in form of an small adaptor for USB cable.

So basically instead of integrating charging circuit into the flashlight, we can keep the circuit outside and simply create a simple connection directly to the battery.
Without the battery slots, the charging adaptor can be made very small. In addition, the charging cable and adaptor are mostly kept at home so the size would not be a problem. So we have the convenience of charging battery without taking them out while keeping the flashlight circuit simple.

I think this should not only for modding but it should be a standard, where all flashlights can be USB-rechargeable and have a same connection. So instead of trying putting tiny low quality circuit into every flashlight, we only need a high quality adaptor to charge all our flashlights. This is easy to mod and cheap to produce.
What do you think about this idea? Please discuss all the advantages and drawbacks associated with this idea.
The only problem i can think of now for modding is how the charging circuit interact with flashlight driver.
Thanks

2

It’s a good idea, I have considered it before and think some have already used this method but for me partly the reason I mod some lights with an integrated charging circuit is so I can charge it almost anywhere with access to a USB outlet and not have to carry any extra peripherals or cells when I’m out and about, the mods would sure be a lot easier just incorporating a micro USB socket though :slight_smile:

You would need to be careful about exposed external battery contacts too, don’t want them shorting out on your keys or any wire wool in your pockets :smiley:

3

If your light does not have a tail switch, a modified tail could be sold to match the tube, with a connector built in. A docking station then becomes a possibility as well, which won’t affect the function of the light, it can be used for ceiling bounce while charging.

4

An integrated charging circuit in the flashlight is more versatile for sure, but the main benefit of USB chargeable flash (for me) is the ability to charge without taking out batteries, not the ability charge with any USB port anywhere. (with the integrated charging circuit you still need to bring the USB cable, right? :smiley: )
Also a separate charging adaptor with be higher quality than a tiny charging circuit in the flashlight. And i really i like the idea of an magnetic connection.
A problem is the risk of short circuit the battery, but i think (not sure) a simple diode or something similar can prevent that

5

No, I expect other people to have USB cables with their chargers too :smiley:

VWpieces did a build with a magnetic adapter, internal charging unit though.

But yeah you should mod lights to suit your needs.

6

I think this should be brought to a next level, not just for modding. Hopefully I will see a next BLF flashlight with this type of charging and a BLF charging adaptor. Would be greater if all new flashlight can be charged without taking the battery out. In this age not many devices need to take batteries out for charging anymore, except DSLR camera because their batteries are small relative to the cameras.

A magnetic charging connector is nice but an usb-c or micro-usb connector with the ability to update firmware is also great

7

This is how pretty much all rechargeable lights used to work. And you are correct about shorting. It is a major issue but very easy to fix. All it needs is a blocking diode. Of course some people skip that.

8

Technically, your idea already exists.

However, it either needs a special IC to actually accept the 4.2V, or a specifically engineered solution.

Also, your solution does not respect USB standards, so making one of your own would be kind of dangerous.

That is because what would happen if you were to connect the USB-C plug inside of a regular 5V USB-C plug?

You would get massive overcharging of the cell.

Your idea is good, but its foundations are lacking.

9

I think you misunderstood me. It’s not about charging batteries directly from USB power source, the USB source supply power for a charger (in form of an adapter). It’s basically same as how we normally charge batteries, but instead of taking battery out, we have a connection from charger to batteries(still inside flashlight)

10

I know.

But what happened if you forgot the adapter and plugging in directly?

11

I simply wouldn’t do that, i will have a cable just for charging flashlight. If you are worrying about safety for normal consumers: i think manufacturers can have solution for this

12

“I simply wouldn’t do that”

Users/customers actually believe that. Experienced designers/engineers are more circumspect. :smiling_imp:

13

I’m going to create a connection from battery to the outer of flashlight. The only risk i can think of is shorting the battery, i’m not expert in electronic.
Could anyone please let me know what specific diodes should I use in this case. Thanks

14

There are such teeny-tiny charging boards out there that frankly it’d be silly to try connecting the cell(s) to the outside world without one.

Just search AX. There are boards where practically half the board is the micro-usb socket. That’s how small they are.

15

How about the quality of those tiny boards, i want to be really careful because batteries are dangerous

16

Pfft. They should be fine. I’d just try one outside (ie, before mounting) and see if it works. If it does, you’re good to go.

17

this is what olight has been doing, but it’s not safe