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Converting 12V car cigarette power sorce to external battery

Hey guys,

I got a electric mug recently. Best invention for a hot beverage drinker like myself. The only way to power the mug is with a car cigarette socket. My goal is to build a external battery pack with rechargable battery. I got a few RC car battery(NiMH) laying around for my disposal. The package saids 'Powered by DC 12V in car with cigarette socket adapter cable'. Could I just rewire the connecter of the battery to the mug connecter or do I need some kind of power regulator?


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Your concern here is of current (amperage). Put simply, current (amps) cannot be given, only taken. I.e. your mug (or a motor or a light etc) is going to "suck" whatever current it needs and no more.

Your concern is if the supply has the ability to "dump" that much current (and for how long). The fancy word is "discharge". Sometimes it is stated in a "C" value. Put simply, a 9v battery can not "dump" current worth a darn, where as a car battery probably has 300 amps if you ask it. 

My rough guess would be your RC car packs (if you can add them up to 12v'ish) is probably going to be enough in terms of umpf. That said, probably not for long. You can figure on Amp/hours --I.e if something is rated at 2500 mAh (milli-Amp-hours) it can dump 2.5A for one hour, 1.25A for 2 hours and so on. If you know how much your mug draws, you can quickly do the math.

Finally, if your mug draws less than a couple amps (which it probably does) I would suggest hacking a ATX power supply (full-size PC power supply) and using it's 12v line. Hell, you would get a nice 5v supply outta the deal as well --would be handy on your desk to run robot brains.

You might even consider a "wall wart". Also, like Chris said, you need to know how much current the hot plate is expecting.