David,
I do not know if my last note helped you. The net of it is if the green light is on and not blinking and the fuses and connections are good then the echo charger basically is a switch that allows current flow from the main battery bank to flow to the starting battery bank but not in reverse. The prerequesite for charging is that the house bank has to be up at 13,8V so that when the banks are tied through the circuitry, that enough voltage is available after circuitry losses of about .5V to enable charging at about 13.3V.
Assuming the main bank of batteries and main charging system is in good shape (voltage at approx 13.8V) then the next requirement, in order to maintain the chassis batteries charged, is that the current supply from the echo charger of 15 amps is not exceeded. That requires that all cells in the starting batteries be in good shape and that the coach is pulling less than 15 amps from the chassis battery bank. If you put a small external charger, with an ammeter built in, on the chassis batteries and they take a charge and the current tapers from the small charger amp capacity down to a couple of amps and you measure over 13V on the chassis batteries then that would indicate that the echo charger is not doing its job and is defective. If the external charger is continually pulling 10-15amps or more and does not taper down then you need to find the source of the current draw and eliminate it and then verify that the echo charger maintains the chassis battery bank at 13.3V or so. Hope this helps.
Later Ed
