Yeah they put the two in series so you are limited to chargers that will take the 24V. Not to mention dont ever let the ground on the two cases touch, the magic smoke will get out. They have an insulating barrier installed between them in that wrap Im sure, otherwise it wouldnt work. One supply is actually grounded at the neg terminal, the other is floating, not even a case ground. Otherwise connecting the positive of one to the negative of the other would result in a dead short.