Well that should be easy to locate. However, I'd start by testing the voltage coming out of the charger - that way you know if the charger is toast. Then test the voltage coming into the battery if there is none at the battery then you're going to have to check and see ihow the PO wired the charger. I have a different charger on my 2005 280 so I'm wondering if the charger was done after. Also while I'm not an expert on chargers the 20 amp charger seems light for three #27's.