...batteries on a daily basis Tom. Granted, they are tiny Vespa batteries but the numbers of batteries we see, both failed in a year and in good shape after 5, are many, many more than you might suspect. The batteries are expensive, tiny lead acid batteries. The failure rate over a winter left uncharged? Close to 100%. Those that are kept on a tender? Very low incidence of failure in 4 or 5 years... My own Vespa is still fine and the battery was installed in late 2007.

The reason I asked if you load test the batteries was that the damage begins showing up there first (forget about an old automotive style load tester, I mean actually testing capacity). Even a Vespa battery has plenty of voltage unloaded when it has essentially failed. They will sit happily at 12.8 or 12.9 volts on the shelf after a charge but they have no life left. It happens very quickly too. You can actually see the sulfating of the plates if you look...

I understand that your batteries are inexpensive and you don't need the capacity of a boat like ours (Esmeralde is a modern day energy hog!) but it might be interesting to see what the actual capacity of the bank is anyway. Maybe your batteries are truly in good shape and I am wrong but I have never done well with batteries of any type until I began paying attention to charge. I fully expect that my agm bank will last, in great shape, for 8 to 10 years. I have tons of voltage as the bank is used, they charge easily and I expect this to continue (hope I haven't jinxed myself now...).

The only other old style lead acid battery I still own is in our 1972 Fiat 500L. It has been abused lately (no tender, just use it once in awhile) and the results are as expected. When I was using a tender, the first battery lasted about 6 years, now that I have stopped, we are getting about 2 years to a battery before it begins showing signs of failure. They are cheap and I am lazy so I have been simply replacing them. No excuse....

In the end, do what makes you happy, as I mentioned earlier, our boat is an energy hog, you can not even flush the head if we loose batteries. I want it to be reliable and I want my head to work. The regimen I subscribe to has easily doubled the life of my batteries over past years and gives me great voltage throughout their use. I keep them charged (easy for is as the boat is kept in a slip when not being used), never routinely discharge them below 50% (except for a capacity test every year or so) and finally I try to get them topped up to 100% at least once a month when we are out cruising.

Don't you love the different routines we subscribe to with our boats? Makes it all the more interesting.....

Bruce