and it caused me so much grief that I went back to two 100 amp. The 150 loaded the water pump and the main crank to the point that I kept loosing the front seal on the engine. The second time I had to replace the front seal I got the message. The drive belts for the two 100 amp pull almost 180 degrees from one another which helps (I think) spread the load even better then just one alternator. I haven't had the problem sense I changed back. I carry a spare fresh water pumps and two spare salt water pumps and believe it or not, used both spare salt water pumps in one day. The first "rebuilt" pump I replaced my leaking salt water pump with had the seal pressed in wrong and as soon as I installed it, it was leaking. It was lucky that I had a spare, spare pump as I was a hundred miles into a 700 mile trip at the time.