12v battery powered desk lamp

[Moomooman]

Hello all,
I recently set up a small scale solar powered system. It includes a 4.5 watt panel that connects up to a charge controller, and then a 12 amp hour 12v agm battery. It originally set up this system to power my desk lamp and maybe charge my phone using only the power of the sun. So far the battery is charging and I have been able to use it to charge my phone, but I'm having trouble with my led desk lamp. I opened up the bottom of the lamp, and disconected the ac adapter (which says it outputs 12v at 300ma). Using a voltage regulator, I stepped down the voltage, and using resistors, stepped the amperage down to 300ma. I hooked it all up, but the lamp won't power! For the life of me I can't figure out why. Sorry about the long explanation, but can someone please point out my mistake? Thanks in advance!

 

[ronv]

If your ac adapter puts out 12 volts all you need to do is plug your battery in. No regulators or resistors needed. The lamp will only take the current it needs, just like the lights in the car.

 

[Moomooman]

OK, so because this is a cheap lamp made in China, the positive and negative leads were actually reversed ( that's what you get for buying cheap stuff I guess). Sorry to have wasted your time with something I should have tested, but thank you for your speedy response nonetheless.