I use a 3 battery charging strip that I got and it works great, has a charge rate button for DHI 100 watt power supply or switch to after market power supply up to 300 watt. Mine will charge all 3 batteries from 20% to 100% in about 2 hours, without the PS getting any hotter than it does with one battery. This strip has LED read outs that give voltage and wattage status and balances the load of each battery to ensure they don't pull to much current. I was thinking of wiring my OEM 57 watt charger in parallel to boost available current and get an even faster charge and take some of the load off of the 100 watt PS.