Unexpected result of "Battery Tenders"

[Speeddog]

Not meant to be specific to the actual product model, though that was the product model used.
Edit: It was a Deltran Battery Tender Junior, 12V @ 750mA Model 021-0123.
Bike is '05 S2R800.
Battery is Yuasa YT12B-BS, installed 11/04/2012.
OEM original voltage regulator.
No electrical accessories other than grip heaters, which are relay-protected.

Always on the tender when not out riding.
Ridden ~3x per month, 2k miles per year.
Every ride at least one stop, sometimes 3 or 4.
In nearly 7 years, never a problem starting.

Bike sat from Sunday night until Wednesday evening, *not* on a tender.
First crank, bike started, but stalled due to not enough fast-idle lever.
Second crank, click.
Third, click.
Click.
Nope!
Bike did not sit with the parking lites lit.

30 minutes later, it did crank and start.

Battery shows 12.8V no load.
Load checked the battery today with Motobatt MBT unit.
Failed miserably with 8.5V result; lowest values on their chart are 9V = 50CCA, so it's got nearly zero power.

Morals of the story....
Battery tenders are good, the battery lasted nearly 7 years.

Buuuuut......
If you're absolutely fanatical about keeping it on the tender, check it every year at least by letting it sit for a week and starting it a couple times in quick succession.
Or do a legit load check.

[herm]

I only put my batteries on the tender over the winter (no riding and damn cold....)

They last about as long as I would expect. I think I'm on the 2nd for my 06 S2R1k, but it's probably time to think about a new one...

[stopintime]

I killed one almost every year with the alarm armed during the autumn when longer rides became few.  Five ~ years ago I started charging it once or twice in this period and the battery is strong. 13.4 - 13.6 after a ride. 13.2 - 13.4 the morning after. 13.0 two/three days after. Still on the original RR (185,000 km)

[ute]

Interesting ..thanks for the tips and ideas

[Charlie98]

I had the old model Battery Tender... I didn't keep my batteries on it all the time, just every so often, switching it between bikes.  Then a few years later I started frying batteries... having to replace them every year.  I'm like... what gives?  Well, that's when I found out the old model BT wasn't kind to AGM batteries... I was literally burning them up with the tender.

Now I have the Yuasa (I think) compact tender, no problems so far...  I still don't leave it hooked up all the time, just every so often for a few days.  I replaced both batteries this spring... the XR's battery was 5 years old, and the 796 was the OEM from 2013.  Pretty good service life I'd say...

[koko64]

I distrust battery tenders, because I have the opinion based on a poorly evidenced (small sample) that they hurt as many batteries as they save. I would rather deep cycle charge a battery once a month than have it on a constant trickle charge.

[Howie]

Battery maintenance chargers can go wonky like any other electronically controlled device.  It is a good idea to occasionally check the voltage with a meter in series with the battery.. 

[Charlie98]

I distrust battery tenders, because I have the opinion based on a poorly evidenced (small sample) that they hurt as many batteries as they save. I would rather deep cycle charge a battery once a month than have it on a constant trickle charge.

Well... and that echoes my experience as well.  Further, after that whole deal with the original battery tender, I replaced my car charger with a multi-mode Schaurer (sp?) which works very well and has a low-amp setting for smaller batteries.  Because the battery on the Monster is all but inaccessible, I went ahead and bought the tender, too.

[koko64]

I just picked up the factory Ducati charger for my Evo that plugs into the diag port plug under the seat for the same reason. It appears to just be a regular type AGM charger which I like. Removing the seat and plugging it into the oem harness beats removing the tank thats for sure. The owners manual says to use this particular charger to avoid damage to the electrics and voiding warranty.  A false claim or an element of truth? Maybe some cheap aftermarket chargers which have the pigtail directly connected to the battery bypass any oem electronics protection in the loom? I dont honestly know. Anyway I snapped it up as I got a great deal and it didnt require me to remove the bloody tank again to fit the pigtail.

I count 21 bolts/nuts, 1 harness connector and 2 fuel quick disconnects to remove the tank.

[Howie]

I just picked up the factory Ducati charger for my Evo that plugs into the diag port plug under the seat for the same reason. It appears to just be a regular type AGM charger which I like. Removing the seat and plugging it into the oem harness beats removing the tank thats for sure. The owners manual says to use this particular charger to avoid damage to the electrics and voiding warranty.  A false claim or an element of truth? Maybe some cheap aftermarket chargers which have the pigtail directly connected to the battery bypass any oem electronics protection in the loom? I dont honestly know. Anyway I snapped it up as I got a great deal and it didnt require me to remove the bloody tank again to fit the pigtail.

I count 21 bolts/nuts, 1 harness connector and 2 fuel quick disconnects to remove the tank.

My guess is probably half bullshit half truth.  I doubt any quality smart chargers would hurt anything, but there is some crap out there.  Woth the convenience anyway IMO.

[Heath]

Thanks for the reminder. You made me actually look up how old my battery is and its already at 4 years. Didn't realize it had been that long already.

[ute]

Well I upluged the tender on the 19th of Sept ..and started the bike today with no issue .

I leave my bike on the tender 24/7 , and inside in the winter as well ..never off a tender

The battery is 6 years old the tender is 13 years old ( Deltran Junior )

So who knows what is good or bad

[koko64]

How long is your winter? Let me rephrase that, how long is the off season?

[herm]

How long is your winter? Let me rephrase that, how long is the off season?

<----Me?

Winter in Maine (defined here as too unpleasant to ride) starts mid to late October and lasts until late March - early April 

[koko64]

Wow.
Keeping the bike inside and battery charged is a big deal then.
People from my part of the world don't know what real cold is.