Is their a difference in charging batteries between a charger that is plug via wall outlet (AC) and power supply (DC)??? Can anybody give me the pros and cons between the two ways of powering the charger. TIA

The chargers that have integrated power supplies have limitations because you can only have so big a PS inside the case design. Most I have seen with built in supplies have a 10 amp max charge rate, and that is only for the 1-3s batteries, maybe 4S max. The power available is no different, just one method uses a supply internal to the charger and one external. In fact, an external one may be more efficient and or better quality.

the pros of having the supply internal to the charger... convenience of plugging in one unit.
the cons... if the supply goes bad, you lose everything. you are limited by the internal supply to available power.

if you go with an external supply, you can select proper voltages for optimal operation. You can get a large one and use multiple chargers on it. You can upgrade your charger and keep using the same supply for years and years. They are super cheap to make yourself! Chargers are cheaper without built in supplies. Chargers without built in supplies can have higher charge amperage. High quality supplies from servers are relatively cheap and if you build one yourself will give you good, regulated output for multiple chargers for not much $$. You can easily build them for $20 each or less for a 40+ amp 12V supply

-just ordered the 400w Duo from SKy RC., but you can get a PL6 or PL8 for awesome fast charging. Don't forget newer batteries can take super high charge currents. my new Nano-techs can do 10C charging.

You have a link to a schematic for something like this? Of all the schematics I've seen, the transformer alone would be $20+ for a 12v 40+ amp supply.

Just search something like server power supply conversion. Server power supplies are available cheap on eBay. all you need to do is wire it up so the unit starts when you plug it in or switch it on. Then you solder on the wires to the 12v outputs and connect to your charger.

Server power supplies are better than regular PC supplies because server supplies have gobs of 12v availability and ver little 5v and 3.3v. Normal supplies have a lot of 5v and less 12v.

Any PC PSU from the last ten years will have plenty of amps on the 12V rail. I wired one up from a PC PSU that I would have otherwise thrown away. If you're trying to power multiple chargers you may need a PSU from the last 5 years that has multiple 20A+ 12V rails. I have a relatively cheap one in my PC right now and it looks like it has three 12V rails that are above 30A each. That would run a half a dozen decent chargers with room to spare.

Or you could contact this guy: http://feathermerchantrc.com/ He has excellent feedback..