I recently picked up an Icharger 406duo and am having a hard time deciding on a power supply. I want to charge 6 6s 1300s on each channel at about 1c. Do I need a 24v supply or will 12v work and any recommendations would be awesome.
To take full advantage of the charger you will need a 55 amp 24v supply or a 100 amp 12v supply.
To charge 2 6s batteries at 1.3 amps, you will need a 65 watt power supply. So either a 6 amp 12v supply or a 3 amp 24v supply.
Your cheapest option is an old PC power supply. they are cheap and most can deliver 10-15 amps (120-180 watts) at 12 volts.
There are also pretty common Chinese units that can output some power. Here's one on Amazon, but you can find them all over the place. The 24v/15a model will do 360 watts, which will charge a 6s at around 16 amps.
If you can solder and read/research, you can convert retired (used) server power supplies. They are pulled from service before failure to ensure full system reliability, have plenty of life left in them for our needs, and are easily found on eBay. (Link as a representative example only.) Steady 12v and roughly 50A to 75A output depending on model chosen. They can easily be wired in series to get 24v output at same amps. There are guides on RC Groups and elsewhere showing what brands/models are good, and how to convert them for our needs.
If you don't feel up to doing the conversion yourself, there are vendors on eBay & elsewhere that sell them already converted and with bullet outputs installed to allow for connecting your charger.
This is an example of one already converted, not a recommendation as I have no idea if seller/price is good or bad . . . just the 1st one that came up in the search for an example.