Magicshine MJ-808 driver question 12V


Newly Enlightened
Feb 6, 2010

The batterypack has just given up on me, 7,5V when fully charged. And now, instead of buying a new pack, I'm going to make an adapter to use my cordless drill batteries instead. It's a great charger, and the batteries are high C capable. It's the Bosch 10.8V drill batteries:


The original 2S2P liion battery pack has a voltage of 8.4V peak, but these packs measure in at 12.1V at full charge. And I could make a linear voltage regulator with the LM350T, that could step down the voltage to 8.4V. But I was wondering what kind of input voltage the magicshine driver can handle? I've heard that 12V from cars is not recommended due to it's "dirty" nature, spikes and all that. But a constant pure 12.1V feed...Could that damage the driver?

If heat would be an issue, I can dissassemble it and lapp it and apply thermal paste. I will also only use this as a helmet light for my quadriding, so airflow around the head will not be a problem.

rick oz

Newly Enlightened
Aug 23, 2009
The manufacturer states 8.4v MAX input for the MJ-808 lights. I have read of one person trying it on 12v (google 'Magic shine on 12 volt') and states that it gets 'hot' quickly but works fine though i dont know if it was 12v from a battery pack or car. I definately would not be trying mine on automotive 12v as yes it is very 'dirty', generally around 14.4v with 30v+ spikes.

If you do try it on 12v and damage the driver, you may have to buy another complete light head as the driver is not sold separately. Fitting a different driver is possible but will require some modification as the driver is made for the magicshine with switch and status leds all mounted on it.

Stepping down the voltage would be the safest idea, and the light head would not know any difference to the original battery packs. Where did you purchase the light? You might be able to get the pack replaced as part of a recall.

I checked my two, plus a few for riding buddies, and some are good while others are lacking in thermal paste and one even had the screws holding down the star loose! Check it out inside just to be safe and dont forget to drop it down from high when you stop moving as without airflow it really cooks!


Flashlight Enthusiast
Dec 5, 2007
Las Vegas
Using a quality battery pack and charger from a tool battery sounds great, but using a linear regulator to adjust voltage will be horribly in-efficient. If you do go that way, at least buy a switch mode regulator. There is one I have bought off ebay based on the ax2002 IC that is sold by satistronics I like a lot. Also, while there search for LM2596 step down.

Another option of course would be to remove the factory driver from the MJ-808 and use a custom one. Even if it will handle 12.1V and not burn up, if it isn't designed for it, at the very least, efficiency will suffer greatly. There is a new 3A 6-18V circuit board available at DX I am very curious about, but 3A may be a bit much :) It's sku 57779.
You could also take a look at 20330 as a possible replacement if somehow you do burn yours up. It too is only rated at 8.4V, but who knows it may be the same as what you currently have.