Need suggestions: Battery drain issue - good battery and good charge

My XJ650 Maxim has a voltage problem - just showed up a month ago. All suggestions are welcome, even from Polock

Okay, here is the behavior: With everything on the bike working nearly perfectly as intended, almost 100% of the time, it will start cold without even a moment of hesitation - the kind of demo you expect in a showroom. (Giving me a sh*t-eating grin every time I ride it from how well it stays in tune all season!)

However, with 24 hours of sitting, I lose a little off the top of the battery (12.45 to 12.35). At this level it won't kick the motor up immediately, sluggishly cranks the starter, then loses all its cranking amps after a handful of starter rotations. But... if I kill all the power, then try again, it kinda comes back to life and starts her up, but not with a spirited effort.

The battery is fine - one year old Auto Craft lead acid, and confirmed okay by Advance Auto's load tester.

So with a lot of forum searching already, I managed to determine the following:
The alternator seems fine. At 3000 rpm I measure 14.75. After an hour or two of riding, I can kill the power and she will crank right back up like a brand new bike.

I confirmed there is no parasitic drain. Did the amp test on the negative terminal.

What I did right before this started: New rear tire and rear brakes. Topped off battery with distilled (second time of the season - typical for my usage). I thought I killed the battery until the AAP test.

What do you think?

 

HOw good is your starter? Could it be a short in the armature that drains current sometimes when you turn the ignition key (in addition to the current needed to turn it I mean), and sometimes not?

 

No parasitic drain and the battery discharges below a normal resting voltage overnight? I don't care what the load test says, you have a bad cell in that battery.

 

the true test of your battery is the voltage drop when you press the starter button , what does your battery drop to?

a bad cell can charge fully then drop off quickly it holds the charge but when left to sit falls off..

batterys can last years or months or fail right off the shelf.


I do not know if the auto parts store can test your starter accuratly maybe a bike shop.

I would get a new battery and check acid levels more often,not wait so long between checks
the term battery boiler comes to mind
how low does your fluid level get ? do you run it below min line?

 

a year old battery, so last year you put water in it twice and this year twice. i wonder if maybe the acid is diluted. if it took a lot of water four times, that's a lot of water.
get one of those hydrometers with the pastel balls and check it before you ride it, before you charge it
i've seen batteries that looked good to a meter but couldn't get that last ball to float

 

Water level has never been below minimum. Everything I have heard about old yamahas and batteries usually comes around to the issue of frequent topoffs. I think even Rick or Fitz had a write up about it once.

Sounds like I definitely need to give it the voltage test when I try to start - I read that in another thread today, too. K-moe, I agree that a bad battery isn't ruled out yet. Before spending more bucks on another battery I wanted to rule out some dumb wiring thing. The next battery will be sealed though.

My starter isn't perfect, but I never had issues with it until the day this battery thing started

 

as Polock suggested pick up a battery gravity tester its about 3$ they look just like an antifreeze tester and do work

sometimes you do loose acid through the overflow tube

 

I think the acid test is a good option here, so thanks for that suggestion, polock, and xj550h for the +1.
Ive never used a hydrometer, so thats a stop on the way home today.

 

Quebecois, the starter is also a possibilty but thats my last resort. I'd rather not tear into the starter if i dont need to. Could be part of the problem, but i feel like the issue is directly connected to the battery sitting for a length of time

 

Unless there is a leak in the case, adding water to the fill line won't dilute the acid. Adding water just brings the acid concentration back to where it should be by replacing th evaporated water.

 

Simple things first, I agree.

 

^^^^+1 That is the biggest problem trouble shooting 101...over looking the simple problems...agree replace battery

 

+1

I do understand some of the basics of lead battery maintenance. Plus I was very anal when I got this battery prepped for use. I filled the battery with acid then brought back to Advance Auto to fully charge.

This makes me at least believe Advance Auto when they said the battery tested fine but then a defect can always show up

 

+2

 

Did you do the voltage drop crank test?

 

under normal circumstances, yes. but there's a lot of damaged chrome mufflers from having evaporated water on them, some acid gets out and gets replaced by water.
over charging, sloshing, over fill, who knows? for 4$ it's worth a try to save a year old battery.
if the hydrometer says it's low but the meter says it's good, which one do you believe?

 

Update: I also ran a couple overnight drain tests, one night with the battery connected, one without, and both nights I seemed to lose a tenth of a volt. However, earlier in the month when I tried that test, after it was a tenth low, there was no change either way.

So today, at 12.34V, I gave it the crank test. With the key switched on it dropped to 12.10, then the start button kicked it down to 6.5!

Thanks for the help. I am shopping for a new battery now.

 

Just ordered a MotoBatt from Amazon. At least I can use the old battery for a few days - expecting a beautiful fall weekend in CO.