I put a brand new battery in my 07 Softail last April. I have had it plugged into a Harley supersmart tender since riding season was over in late November. Last week I went out to the garage and noticed the light on tender was completely off. I unplugged it from the wall, plugged back in, still nothing. I checked the outlet- it was fine. I chalked it up to the tender failing after a few years. Just picked up a new tender at the dealer, plugged it in, and it lights up, but the lights would not change color when I plugged the bike into it. Turned the ignition on and absolutely nothing came on at all. No fuel pump, lights, anything. It's like there wasnt a battery even in the bike. I checked all fuses and connections, all looked fine. Just tested the battery with my multimeter, it's showing "0.0".... to make sure there wasn't an issue with the multimeter, I checked the battery on my other bike and it's working fine- not plugged into a tender for the same about of time, reading 11.9. 2 questions here- is it even possible for a battery less than a year old to have absolutely no juice in it at all? And has anyone ever heard of a tender failing and destroying a battery like this? It's all odd and really frustrating. The bike not plugged into a tender has a battery that's really low, but is showing voltage. And the one plugged in is completely dead... bike ran fine all summer with no electrical issues, including sitting for 3 weeks un-tendered while I was on my honeymoon.

Any insight or anyone else have anything like this happen??

 

Is your new battery a flooded type or an AGM?
If flooded, is it cooked dry? I did have one boil a flooded battery dry. Ever since then Iv'e put mine on a timer to charge for a few hours 2-3 times a week.
I'm wondering if your failed tender boiled the battery dry, or did it fail in a way that discharged your battery completely. Does your tender pig tail have a fuse in it?
As a test, you could connect your failed tender up to a good battery and measure the current to see if it's discharging.

 

I have had that happen more than once, I have 2 portable generators, 2 ATV's and 2 Bikes, had it happen with 2 different brand chargers, some of mine sit on the battery maintainer (charger) for months, About a 2 years ago I sold all my chargers at a garage sale, and now only use Genius chargers, more money , but have never had a failure.

 

generally if the battery is completely dead or a bad cell a battery tender wont be able to charge it, it wont even recognize that a battery is connected.

I use battery tenders for the past 5+ years on 6 things (jeep, tractor, riding mower, Fatboy, quad and a generator) Ive never had a problem but I also set a alarm on my phone for 90 days and I disconnect and start everything and let run 10-15 minutes then reconnect bout a week later. I dont know if this schedule does anything but it works for me and i think it allows the batteries to have a load put on them (starting) and a short break from continuous charging.

Im using 2 original "battery tender junior $ 30.00 , a Sears Craftsman $25 and 3 from harbor frieght $ 19 , they all seem to work the same. I do have a Interstate "trickle" charger that has been able to bring back to life a battery that the "tender' would not do anything to.

 

Make sure your hook up sequence is by the book. Hook up the bike first, then plug the tender into the wall. To disconnect, unplug the tender from the the wall first, wait till all the lights go out then unplug from the bike. If you do not do it this way it will fry your battery or damage the battery tender. I have seen this happen a few times.

 

Ive always heard that a battery hooked to an unplugged charger that the charger will drain the battery. Again, I heard this years ago.

 

It shouldn't. It should have a diode in it to prevent drainage..

 

In the OP's case, his tender failed so it's quite likely it drained the battery.

 

Like stated a tender will not charge a dead battery. And i know you said you checked all the fuses, Did you check the 1 in the tender pigtail too?
I'd not use it (the old tender) until I know what happened. If the was a short or heavy draw for the bike, the fuse in the pig tail could blow
once the battery got low enough.