3.7v to 12v?

[TravellerNick]

Hi all. I'm new here and I'm hoping you can help with some simple problems.
I'm trying to add some funky lights to my roller skates. I've had some success by cannibalizing torches and hooking them up to battery packs but I'm trying to upgrade to some 12v led strips. The thing is that I'm trying to run these off a single li-on 3.7v battery. I bought some small step up transformers off eBay but they burnt out straight away.
So, can anyone help with some tech knowledge please?
I'll try and send a picture of my skates too.

 

[Nigel Goodwin]

What do you mean by 'step-up transformers', you can't use transformers on DC.

There are numerous small step-up DC-DC converters available from China (Banggood etc.), what are the specs on your 12V LED's, and do they need external current limiting?.

 

[TravellerNick]

Well I didn't know you couldn't use a transformer for DC, so thank you and how would I find out if it needs external current limiting.
I think I may have been trying to draw 1 amp as I'm looking at the control box now and that says 6 A max. But divide that 2 as I was only using 2 of the 4 lights and divide again by 3 as I was only powering 1 of the 3 coulers.
Am I very wrong?

 

[Nigel Goodwin]

Have you a link to the transformer you used?, so we can see if it's a 'transformer' or what it is.

How many LED's are in the strips?, again do you have a link to them?.

 

[TravellerNick]

I think I may have drawn too much current through but by looking at the wires I would have thought it was milliamps

**broken link removed**
**broken link removed**

Can't seem to post photos though

 

[Nigel Goodwin]

OK, that's NOT a transformer, it's a DC-DC converter - which is the type of thing you need.

At the bottom of that page it gives a link to a 20W version, that should be more suitable. However, you could really do with finding out what power the LED's require, do you have a multimeter you could use to measure it?.

On that same page there's also a link to MT3608, these also might be suitable, but require adjusting to 12V, so you'd need a meter for that as well. I've used a good few for various purposes, and they work quite well.

 

[TravellerNick]

Ok. Thanks for the help. Like I said, I think I might be drawing a hole amp which is more than I first thought. I'll check with rhe multimeter next time.

 

[audioguru]

If the LEDs need 1A at 12V then the voltage converter needs 3.5A or more at 3.7V. If you run the LEDs until the 3.7V battery is dead then the battery will not work properly anymore and might not charge.
3.7V is probably a half-charged Lithium-Ion battery that needs a special charger and a circuit that disconnects it when its voltage has dropped to about 3.2V.