First off I'm a retired Master Electrician. I got my Masters licence in 1970. This said so you guys won't think I'm blowing smoke.
Almost all chargers (not all you have to look), have an input for 12v, even the charger that comes with the LB, (look on the bottom). The MAHA C-9000 has a 12v input.
As for myself I have a Stanley 300 amp jump start battery, that has a 12v outlet, (cigarette lighter), and a USB outlet. You can charge it by 120v, or 12v, as well as jump start your car. Most people do not realize batteries charge faster on DC than on an AC adapter. Mainly because you don't get pure DC from an AC adapter. You get pulsing DC, (one reason the PA pulses on max when on the AC adapter). To get pure DC from a wall-wart is asking a lot in such a small space. I use my PA on DC. It never pulses on the jsb. I use the jsb to charge my cell phone. It's about a 1/2 to 3/4 hour faster.
The MFLB is not that complicated. There is less than a dollar in parts in this thing. Ohms law says if you know the voltage and the resistance, then you can calculate how much heat you will get. The spot welding of the screen can be different from box to box, so there is no set way to use them all. Just remember to shake between sips. The herbs need to touch the screen to be heated properly.
Ok I've said my piece. Be easy on me I'm an old man. I can just turn my deaf ear. ;-}