Thanks to the generosity of one of the forum members my 20mt130 is now equipped with one 12v desulfator unit per battery bank and a 50amp anderson plug connection for solar charging (in addition to retention of the on-board mains powered charger). The unit charges via connection to a 200w monocrystalline solar panel and 20 amp solar regulator with the desulfators maintaining all 4 batteries in excellent condition. Fitting of the anderson plug solar charging connection was fast and required only 2 connections to the unit.