Seeking charging lead (and specs) for generic high power led torch  - Page 1
Forum section: electronics / general

author: eti
author_rank: Super Contributor
timestamp: January 16, 2022, 02:41:24 am
content: 16/1/22 - 21:02 BST - photos added16/1/22 - 21:32 BST - IC name fixed in photoHello.Please note: I know I can, but do not want a solution that spells out the obvious “buy an 18650 battery charger.” Nope, that’s out of the question.I’ve Googled this endlessly. I was given a torch that looks almost identical to this, and which has a barrel jack socket on the side, covered with a rubber flap. There’s no documentation or charging specs - the torch is a “SupWildFire” 3000LM, from what I can ascertain.A Google does show me a very tiny photo of a lead, which appears to be a USB “A” plug wired across to a barrel plug, but … ¯\_(ツ)_/¯This is almost identical, except mine DOES NOT USE USB-C to charge.https://gb.ledsupermall.com/nitebeam-18xcree-xml-t6-4-modes-15000-lumen-rechargeable-usb-type-c-led-flashlight-5602.html?gclid=CjwKCAiA_omPBhBBEiwAcg7smYmuMK_IgnDGAsy4LKr7kpk_I4r13e_TUQTwYUiUJT0GsAXEkF-AQRoCJuAQAvD_BwEDoes anyone know if a straight 5V would do it? I don’t want to charge it unattended if it could overheat. Thanks

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 16, 2022, 04:49:09 am
content: Only sure way to know is to take it apart and reverse engineer it. If that's too difficult, try connecting a bench power supply with a voltage limit of 4.15V and current limit of 1A just in case it's one that relies on the charger to limit the voltage and current.

author: deadlylover
author_rank: Frequent Contributor
timestamp: January 16, 2022, 07:24:44 am
content: Oh man you're really testing my memory here. I think that's a clone of thisUltrafire...which is a clone of something else. I know the "original" previous model was affectionately known as the Sky Ray King or SRK if you want to Google around, but the one you have is an updated version with that barrel jack and display. The even newer ones will have on board USB charging.If the barrel plug wired directly to the battery positive/negative? If so then it's relying on the wall wart to control the charging (kind of meant for you to hook up a hobby charger or make flying leads from a normal charger). The USB variants all use the LTC4056/LTC4057 clones (like the TP4056).Yeah I agree with the other poster, take it easy with the limits because you are probably using questionable cells too.In the flashlight community we used to call these pipe bombs (before the advent of USB charging ICs making their way into flashlights). It's really not worth messing around IMO. Just buy a cheap Liitokala charger and be done with it.

author: eti
author_rank: Super Contributor
timestamp: January 16, 2022, 09:03:57 pm
content: Quote from: deadlylover on January 16, 2022, 07:24:44 amThank you! I have now added photos, with a weird 8 pin IC (and an unmarked one, prob the MCU)

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 16, 2022, 10:33:03 pm
content: Looks like the connector just goes in parallel with the battery, try the bench supply. If it works, a cheap TP4056 board can be used to make a charger for it.

author: deadlylover
author_rank: Frequent Contributor
timestamp: January 16, 2022, 10:41:54 pm
content: Quote from: eti on January 16, 2022, 09:03:57 pmThe 8 pin thingamajig is the 9926A dual mosfet likethis. Very common for flashlights to basically be "direct drive" and use PWM on the mosfet for brightness control. (especially multi emitter lights like that)Ahaha it needs quite a large MCU to drive the 7 segment display.

author: eti
author_rank: Super Contributor
timestamp: January 17, 2022, 01:41:47 am
content: I’ve just remembered that I’ve got an old power bank, inside which is 5x 18650 cells. I suppose I could remove those and use the circuitry as a charger for the flashlight cells, eh?Update: opened power bank, and it’s basically a tiny pcb with micro usb in from the wall or a usb socket, and the charging output goes to 5x 18650, all of which are in parallel. So what I’ll probably do is find a way to see if the jack input at the side of the torch, actually sits directly across the 4x 18650 cells when they’re installed, and send the output from the power bank pcb into this jack

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 17, 2022, 04:27:28 am
content: If the power bank's 18650s are still good, you can just wire them in parallel with the charging cable for the flashlight using a PTC to limit the current if the connection is made with very different charge levels. Now the power bank will also work to extend runtime in addition to operating as a charger.

author: eti
author_rank: Super Contributor
timestamp: January 17, 2022, 04:55:20 am
content: Quote from: NiHaoMike on January 17, 2022, 04:27:28 amGreat idea thanks 😊

author: eti
author_rank: Super Contributor
timestamp: January 17, 2022, 09:10:16 pm
content: This now works perfectly. Thanks for the help chaps.