yeah, some chargers only work off of Direct Current, rather than Alternating Current. In the case of DC chargers, they need to be powered by something that offers DC current as an output. Generally, your options are a power supply (a device than changes AC current to DC current) or a large battery such as a car battery. DC chargers will generally run more expensive since they usually do a lot more and are very programmable. Things that are overkill (IMO) for the average weekend rc'er. Plus you also need something to power it which is even more money. There are however a number of cheaper ac/dc chargers on the market that will do more than just charge and won't break the bank. I've been using a Duratrax Intellipeak Deluxe for a few years now and it has been a pretty decent charger for about $75. It's AC/DC so I can plug it into the wall at home (AC) or hook it up to my car if I'm out and about (DC). It charges both Nimh and Nicd batteries at trickle charge or fast charge with adjustable rate up to 6.5 amps. It also discharges at either 2amps or 10amps, your choice. Add to that, it will even cycle (discharge, charge) a battery once or three times in succession. Pretty good bang for the buck if you ask me. Someday I will upgrade to something nicer but it's still not necessary for me with what I actually need out of it.
