The thing I like about the 2 amp NOCO battery charger is the flat battery charging if you have a battery with only 1 amp showing dead battery it can force charge if you hold the button for 7 seconds on the version I purchased that charges 12 volts and 6 volts and lithium batteries at 2 amps charge. I think your version only charges 12 volts.
The genius 2 is only rated for 40 amp hours a Duramax set of batteries is normally about 120 amp hours total (60ah per battery) You are using way to small a charger is you are only using the genuis2d. You need more like the 5 or 10 to keep up if you discharge the batteries often. I use the 10 and have zero complaints.
