Jimmy,
I just paralleled my house battery with another battery to boost my amp hour capacity. Both are new Interstate batteries. When I have my VHF, GPS, Fishfinder, and radar turned on and I try to run my washdown pump, the radar will shut off. Everything else stays on. I have the radar on standby not transmit. Shouldn't adding the additional battery prevent this? Could the high amp draw of the washdown pump cause a sudden drop in volts and that causes the radar to turn off? All my wiring and battery switches are new. Should I isolate the washdown pump on a differnt circuit? Thanks.