i have a Heart interface energy management system in my 1994 Beaver contessa rv, model number 81-2813-12, serial number 50154, date 1292, the problem is the charging is not working, running the test , the input shore power or gen power light comes on, and when checking voltage inside it shows 120 ac in outlets, but no charging to batteries..... i think everything is good except the charging part of it.... can this be repaired , what time frame, and approx cost? thanks