Question.. i have a 27 ft '' Chase '' just put two new batteries in it.... I'll prob. be using it once ever two weeks or so... do i need a battery tender ???? I'ts in So Cal........ do you have a recommendation on a solar powered one or all they all pretty much the same on Amazon or at West Marine ?? , and here's the key question, do i need 2 of them or can i just hook one up to the so called'' starting '' battery.. the batteries are joined by a negative jumper. Thx