The Bosch 1.3, 2.0??, 2.6, 4.0 & 4.5 AH batteries in 36 v format will fit Mafell's 36v range. As is the standard 36v charger & AL 3680 super fast multi charger seamlessly compatible.
The Bosch Professional 36v, 6.0 AH batteries and charger range are, unfortunately I suspect, incompatible.
Metabo's AIR COOLED ONLY 18v batteries in 1.3, 1.5, 2.0, 2.6, 3.0 4.0 & 5.2 AH will fit & work well on the 2 18v drills, but only the biggest 5.2 is advisable on the KSS 40 saw due to its consistently higher current draw.
Metabo's 18v Li-HD range: 3.1, 5.5 & 6.2 AH are an ideal fit for all, but the 5.5 & 6.2 in particular are significantly bigger & heavier.
Rothenberger's new 18v Romax 4000 batteries & charger will (being made by Metabo) fit seamlessly too.
Rothenberger's Romax 3000 230v/18v mains battery eliminator is I suspect unfortunately incompatible, as is the rest of the Romax 3000 range of batteries & chargers.
Metabo's 10.8v 1.5, 2.0, 4.0 & 5.2 AH batteries are compatible with Mafell's A10 Drill.
Metabo's 36v 4.0 & 6.2 AH batteries are incompatible.