Connect battery once a month (what I do) or as recommended by manual to top it off every 2 weeks. My OEM batteries last about 8 years. Bought 700 miles 2 years old bike that was always on the tender all the time battery need to be replaced next year after purchase.

 

i don't think the battery tender will help if it needs a charge. I think it's more to maintain a charge. I keep my bikes plugged in when not riding them. And like someone said already, check battery cables. My Heritage was hard to start when I bought it. Guy said he just put a battery in it, so I said it was probably the stator and he took some money off. Got it home, pulled the seat and the cables were loose. For some reason they come loose on this bike once in a while. I should probably try some new bolts but it doesn't bother me enough.

 

One is and I got seven years out of the last one. The other two are agm’s and are year 8.

 

A "Load Test" will tell you what you need to know

 

Good point, YZR.

I have had maintainers go bad. If the 2nd one works, throw out the 1st one.

I have 4 smart chargers, 2 for both bikes and 2 for the 2 batteries on my old boat. Batteries are expensive, And like Keithhu I leave mine on 24/7, tenders are not supposed to "boil" batteries if they're working right.

Someone asked earlier, boat batteries are generally large flooded deep cycle.

 

24/7 vs once every few weeks, might as well start an oil debate here too.

 

Bought my 2016 SGS - had a bad battery right out of the gate. It took 2 visits before it was replaced. If your battery will not fully charge than it is separated at the cells. Replace the battery - it is cheap insurance.
Take the advice of charging the battery to capacity regularly. The bike only maintains the battery, but does not charge it to its full potential.

 

By using the bike as an errand transport, or a lot of stop and go traffic, the battery will get what's called a surface charge. A deep charge will occur after about an hour riding time. Same goes on a bike sitting on the show room floor, how many times do you think that bike is started during a day or two with no charging? I suspect the bike will charge to 12.8-13.9V that's what the regulator does. To use a tender, IMO, is a decision that the owner makes, it's his/her equipment.

Slow starts, evaluate the battery, replace if need to.

 

yuppp... agree totally with this....