Power supply for LED strand

[Buddy919]

Too old to be considered "new" at anything, but have no experience or understanding of electronics.
I built an oak cabinet and put in some LED shelf lighting strips. Lights are listed using 8 watts and run on a 12v dc adapter. They came in a strip of 600 lights that was cuttable to length.
I still have several feet of lights left over. Last week, our leaf blower needed replacing. New ones come with batteries and chargers. So now, I'm just wondering if I can use my old battery/charger (2.0 AH, 20v) to power up those extra lights. I've taken a single LED and lit it up with a 9v battery, but I'm not sure if I plug in too many of the lights I'll kill the battery, or will too few lights cause the battery to burn out the string, or some other god-awful thing might happen.
The lights and battery seem awfully convenient, since they are already available and paid-for. It seems a waste if I can't find another use for them.
I do know there are formulas to determine how much power you might need, but without understanding it I am at a loss to figure it out.
Can someone please let me know if this can work (or if it's dangerous!), and if so, how many lights would I be able to turn on?
Also, if someone has found other uses for these large tool batteries, I would love to hear the ideas. Thank you.

 

[kellys_eye]

Your light strip requires 12V to work regardless of the length of the strip that may be cut from the original. Running off-cuts using 9V will work but with reduced light output.

All you can do by powering 'too many' LEDs is flatten the battery quicker - just recharge it! You can't do any damage by running too few LED's - the battery will just last longer.

 

[danadak]

The 20V charger, thats controlled for charging a battery, so might have shutoff
automatically or not even start up because it thinks battery pack (when used as a
battery charger) is too low a V (in this case 12V) and no longer usable battery.

How many strips do you have to run ? Is it 8W for the total 600 leds ?

I would think easiest way just use a 20W 12V brick (20W to give some margin) would
be easiest way. Current you need is P = I x V or I = P / V = 8W / 12V = ~ 3/4 Amp X the
number strips you have to power.

So buy a brick and use some margin. Example if you have 4 strips, then thats 32W,
but a brick is ~ 80% efficient, so thats 32 W / .8 = 40W

Using a brick they usually have thermal and short circuit protection.

Amazon.com

Or use

DC 12V 1A to 50A Amp 110V 220V Power Supply 5050 LED Strip Light 12 V 220 110 AC | eBay

These power supplies are a high quality and perfectly safe item making them ideal for powering any 12v DC item. Product: 12v DC Power Adapter. Intended Use: Ideal for powering LED Strip Lights. Widely used in Industrial automation, LED display, communications, etc.

www.ebay.com

You could possibly use a buck regulator at the output of the charger, but again the buck charger combo
might not power up right, bit of a crap shoot.

Amazon.com : buck regulator 12v

You need to answer how many 8W strips you need to power.

Computing P, V, I in DC circuits roughly :




Regards, Dana.