i have used the samlex running three chargers all day with no problems. charging at 5 amps. i dont knoe if i would try four. you would be running at max. rating.
the rivergate 30 amp may be a better choice. www.rivergatedist.com you can order direct. its cheaper
it won't run four chargers but for the price you can easily buy two and run 6 chargers if your were so inclined. The pyramid psv-200 is a 20 amp switching power supply it is very small (7"X7"X2") and very light at 3lbs and is stackable with no top vents. The best part is that its $55 pretty much every where.
i got a 28 amp power supply for sale from Integy/SHE. i used it before to power two pulsars, motor break in, pitbull and GFX at a race with no problems. (all four chargers going at once charging at 6amps) while running my lathe at 5volts. check my signature.