I have that very same tender that I leave on my truck since I don't drive it very often. Has worked great over the last year.

well i can tell you guy'* that i have owned all major kinds of batteries! but the only one that has held up to 8yrs now and still starts like new in the winter is the red top optima. i have had this battery for over 8 yrs, been in 4 cars, and now it sit'* in my son'* gtp. and it is still going strong. never had a trickle charger on it either.
Optima batteries are not like the conventional batteries like all you guy'* are speaking about, the optima has six seperate batteries. and each little battery has it'* own secure space, that it why they last so long. you can run this battery up side down, or on it'* side. beat it up and you will still have the same battery you had when you bought it. And there is not another battery that will operate up side down and last.
the optima will cost you double what a regulator battery will cost, but the optima will out last it hands down. i ran this battery for 3 yr in my 69 chevy p/u, then 3 yr in my 04 gto, 1 yr in my son'* honda, and now in the gtp for a year or over. And when it does decide to die i am going to buy another one, even if they are like 160.00$. The absolute best battery ever made. and just think that the red top is the cheapest one made. the yellow and i think it is the blue top are made heavier and better.
So you guy'* can go run your interstate and autozone and wallyworld batteries. I have the best that has been made. OPTIMA BATTERIES!!!!!!