As mentioned, I had the battery tenders since they first came out and had to change them after a couple years of constant use.

I've had the NoCo chargers for the truck, car, tractor and lawnmower for 5 years and except for the one I had to change when lighting hit my power lines, will never own another brand.

YES, hook up to surge protectors for safety. But you will not regret buying them.

And if there is a possible 2 to 4 days without using any vehicle, I plug them in.