Originally Posted by bsloop
Step up to an installed charger like Guest /Marinco and maintain your batteries properly though out the entire year.
Another option either installed or mobile is the CTEK 7002 or others in their line. http://smartercharger.com/battery-chargers/
More advanced charging and desulfation capabilities.
Battery Tender / trickle chargers are old technology and low power.
Batteries are a big investment and while something is better than nothing, there are better products that can significantly increase battery life.
Hmm, not sure about the battery life comment, My current interstate battery is close to 4 yrs old and is always plugged into a battery tender jr. never has any issues.