RADAR + BATTERY = BAD
Take a look at your ammeter when the radar is firing, a 4KW radar draws just that, I dont run my radar without the engine on.
Regardless of the age of this discussion, there is apparently a misconception about the rating of radar power as an indication of current draw. The radar power rating (in this case, 4KW) is not an indication of current draw from the battery bank. It's more likely the 4KW radar, when transmitting, is only drawing a few amps. If, as indicated above, the amp meter indicates significantly more, the poster has a real problerm.