Voltage Drop.

Boff

This weekend we were actually on EHU for the first time for ages.  So after I had found the EHU lead luckly we had one in the van and remembered which end plugged in where.   I switched my truma fire on to the supplemental electric heating setting and lets
face it was pretty pants.  So used the gas to help all weekend.  This morning I  got my voltmeter out to see what voltage we were getting and it was about 185V.  To be fair the hot water seemed to be OK on electric but the heater just didn't put out any significant
heat at all.  So what should have expected if I am getting 185v should I be getting 75% of the heat out or am I missing something?