Single Lithium cell COB driver

dermotd

Newly Enlightened
Joined
Dec 21, 2015
Messages
2
I recently picked up a couple of mini work lanterns that have a small COB strip - all leds in parallel, running from 3 x AA cells - and a series resistor.

It has a magnetic base as well as a hanger and was good value at $3 in Ace hardware last week, since it provides an even illumination.

Not wanting to use disposable batteries long term, I'm looking to mod to Lithium. I can fit 2 x 18650 cells in (I've been harvesting, testing and matching dozens from old laptop packs) together with necessary BMS and charging electronics, but am looking for a physically small LED driver.

I can configure the two cells in series or parallel and have BMS/charger from USB input for both. It works, but very inefficiently, with a single Lithium cell to 5V USB boost circuit, but needs a very wasteful dropper resistor, so far, I've not had any luck on Ebay on a small enough PCB, so looking for advice/sources. I only need a few hundred mA, but can only find chunky 5A or so ones there.

cheers,

Dermot
 

lunas

Enlightened
Joined
Apr 18, 2014
Messages
206
humm 4.5v with current limiting resistor direct drive is the old way they were driven what i would do if i was you is i would get one to use as a test subject i would see what the lowest safe voltage is and what the highest is. And depending on answer and configuration options you can get 3.7 v 6v and 12v flashlight pill drivers no reason you can't just solder wires to the outer ring and inner pad https://www.amazon.com/dp/B07JMF3PNR/?tag=cpf0b6-20

https://www.mouser.com/ProductDetai...cH_fUrxfbPJs82sgij4vkR4ibQ1K67m4aAknqEALw_wcB

making one yourself is about the only way to get it smaller.

also these?
https://www.amazon.com/dp/B072WBCBJH/?tag=cpf0b6-20
 
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