portable LED floodlight , power source ?

Evening gents . A couple of years ago i bought 2 of those yellow portable rechargeable led work lights . A cheap one from Screwfix , and a fifty quid one from the newly opened Led lighting shop.. Guess which one still works ? Yep ,the cheap one !! The other one doesn't charge properly , or runs out of juice quickly anyway.. So rather than chucking it away , and assuming the "bulb" is ok , I thought maybe i could run it on a cable, to another battery ..but what voltage ? About 3v innit for leds ?? After a little dismantling , there's a circuit board in it too.

There's a red wire and a black going to the "bulb" , but connecting them to two AA cells doesn't make it work !! ? Does it need "special electric" from that board bit ? I'll take some photos in a minute .

Edited By Hacksaw on 24/10/2019 21:15:46

If possible I would put it back together with the original electronics and measure the operating voltage. Alternatively connect a variable voltage power supply and increase the voltage to an acceptable level of brightness, taking care not to cook it. Michael

What is the voltage of the rechargeable battery ? Or what is the rechargeable battery ?

Roy

Having opened the thing up, does the battery not tell you the voltage on its own label?

Closer to 4V for white leds, so three AAs. I've found a 4.2V lithium battery pack from an old phone works OK and has excess discharge protection.

Neil

I took it apart a while ago..having had a rummage i've found the battery ..cells are 3.7v ,i don,t know if they are in parallel or series ...and it unwrapping it reveals yet another i.c.!

And the other end !   

Edited By Hacksaw on 24/10/2019 22:17:22

Edited By Hacksaw on 24/10/2019 22:24:58

Lidl have recently had two of these for sale, one battery and one mains, I bought the mains one, it was £14.99, I think the battery one was more. The mains one has 1500 lumens@ 20W and is intended for a security light, it comes with a remote control programmer. I intend to use it as a light for the mill, on an adjustable arm.

Those 18650 lithium cells are easy to get hold of if you need some.

Edited By old mart on 24/10/2019 22:18:34

Looks like series connection to me so you have 4*3.7 = 14.8v. The circuit board(s) probably deliver a constant (switch mode) current, connecting 14.8v direct to an LED without a series dropper resistor would release the magic smoke. You could try connecting the wires which now go to the batteries to a car battery, if it then works you have duff batteries, if not you have a duff circuit board. Both are repairable, but is it worth it? Make sure it is connected the right way round

They are bright , no doubt about it , but it's a horrible cold light .. The warm white gu10 led in my kitchen is a much nicer light . I want ideally , to have it on a lead , with croc clips to attach to a 12v lead acid , Just not sure what voltage the bulb would be ..I didn't want to pop it trying !

Those are 18650 cells. eBay job, but buy the best ones you can. Should be an easy repair

The light looks similar to the one which I have. Label on the back says that it has a 8800 maH, Lithium-ion battery and the charging input is 8.4VDC, 1000mA

Paul

But the light only runs for an hour or so on the cells and then it's 8 hrs charge ! A 12 v lead acid would run it for ages..

M.B , D.W . and F .I. thanks for the info on the constant current requirement ..

I have , (by re - using the circuit board bit ) and reconnecting the wires , hooked it up to a 16v drill battery ....And it works !! .. And the drill battery recharges in only an hour !

I've chucked the old battery pack on the bonfire...as its nearly Guy Fawkes night anyway

Edited By Hacksaw on 24/10/2019 23:11:17

Edited By Hacksaw on 24/10/2019 23:12:21

Glad it's fixed, but i'd take the old ones off the bonfire if I were you, one of those going off with a bang could take your eye out, and the contents are probably most unpleasant

+1 and while the 'nominal working voltage" is 3.7V (minimum discharge voltage ) the fully charged voltage is 4.2V
DaveD

Edited By Meunier on 25/10/2019 20:05:32

Thanks chaps , i know you'd have milled out a perfect flange to slide and lock the battery pack on .

I'm a cowboy, so i made it from wood, polymorph ,banana skins and bogies...but it works