I have two tenders (two bikes) One is a Yuasa and the other a Battery Tender. I have the Yuasa for over 12 years and it's going strong. I just had to replace the Battery Tender because it died after about 4-5 years

 

a battery with a tender on it all the time can evaporate the acid/water inside.. thats why they should only be used to put on to completly charge it and take it off

 

I have used a CTEK tender for years. no problems.

 

Isn't that what a "smart" tender does, stop charging without having to physically remove it from the battery?

 

CTEK chargers are designed for AGM batteries, i've been using their chargers for many years and have never had any problems.

 

Yes.

Some in this thread are using some old school thinking and confusing a "Smart Battery Tender" with a charger.

I think everyone will agree that a battery should never be left on a charger any longer than needed to charge the battery.

A battery tender (brand name) or similar "smart charger" can be plugged in for very long periods of time.
However, it sounds like there is something wrong with the OP's battery tender.
He listed it as the Harley brand tender, and they are supposed to be a smart tender.
I would ditch that one and get a new one as someone else mentioned.

 

Nope. That's what they are made for. If so, my batteries should have dried up many years ago. I can see a normal charger doing this but not a tender.

I use the BatteryMINDer:

"The BatteryMINDer has full-time battery monitoring that automatically tests the battery every microsecond, supplying only the current needed to maintain battery at full charge. It does not overcharge, regardless of time connected."

 

Yeah Ive got a few of those....in fact I put dates on mine and Im still running an 07' tender that still works great. Best $20 Ive ever spent!

 

Sounds like you have a defective charger. I have my 05 on a harley smart charger for 3 years with no problems and always charged. I have 2 bikes and cold winters here in NY so it may go 2 months in the winter without riding it but starts right up with the tender.

 

I use my battery tender for about 20 minutes every two or three weeks during the winter. My vintage bikes always show a full charge in minutes. No micro-amp drain as one finds on new bikes. My Road King will take 5-10 minutes if I do it in 2-3 weeks. If I am traveling and it is more than a month that I have been away, the tender will take several hours to turn green.

I have just never trusted leaving electronics on full time all winter. Besides an occassional ride in rare but dry weather, it sits unattended. Yet I find that the few minutes I attach the battery tender and check the tires gives me solace from shoveling snow or listening to the 38F rain pound the roof.

I know of too many fires started by unattended electronics left plugged in. I am not saying battery tenders specifically. Anything from mice chewing the wire, a bad Chinese diode that fries the battery, somebodies foot catches the wire and pulls it away or stretches the cable.