IMHO, "battery tenders" are not always a good thing.

• Most tenders are made for car batteries, which due to their higher AH rating, have a much higher maintenance charge rate. For a average motorcycle battery the charge rate shouldn't be over 3/4A (750mA). For continuous "maintenance" far less than that.

• Obviously one of the big criteria for continuous maintenance is what controls the 'cutoff limits' of the charger. What are the settings (for both OFF and ON) and how is it implemented. I worked in the phone industry for a decade and learned there's quite a bit of knowledge required for maintenance charging. To start with, every brand of battery had its own prescribed voltage setting. I don't see that level of sophistication with motorcycle chargers, although there is a known difference between flooded cell batteries and AGM batteries.

• Findings from the electric car industry indicate that batteries really don't like to be "fully charged" to achieve their maximum life. So this underscores point number 2 about how the charger is controlled, and what are the limit settings.

I'm not really sure I can advise anyone on this subject since there are so many variables. However, for me the better answer is to simply disconnect the battery from the bike. Without the losses of the clock and rectifier, battery discharge is slowed considerably. Then a much slower maintenance schedule can be manually applied. Something more like 1 hour of charging for every 2 months of non-use. Of course this is based on Georgia storage temperatures, where freezing is not an issue. Someone in Maine would most likely do better to bring the battery into a semi-temp controlled area, like a basement.

This is the one I like.  Schauer CM6A.  I have an Odyssey battery, so I had to get an "approved" charger for that battery, which this is on the list. It has multiple battery type and Amp charging rate controls.  I use it on both my Airhead (AGM) and Valkyrie (wet).  Hasn't killed either of them and voltages are always correct when I run a meter over them.  I also have a Battery Tender brand that seems to be essentially the same.  It hangs out with my ATV.  That being said, I never leave them on for months on end.  I'll throw it on here and there over hibernation for a day or so.  

Posted by: @jnicks01

This is the one I like.  Schauer CM6A.  I use it on both my Airhead (AGM) and Valkyrie (wet).  Hasn't killed either of them and voltages are always correct when I run a meter over them. That being said, I never leave them on for months on end.  I'll throw it on here and there over hibernation for a day or so.  

Chargers rarely "kill" a battery outright so that you can point to it and say 'there's the guilty party'. They generally ruin the battery over time, so that its life is severely shortened.

This almost always happens during extended charging because the "sense" or "charge reduction when battery is full" circuit isn't what the owners think it is. For instance, how many owners actually put a volt AND amp meter on their battery chargers to see what the output really is ? That number of owners is probably near zero.