Another bad AGM battery? More likely it's my bike - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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Old 09-02-2018, 10:14 AM Thread Starter
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Another bad AGM battery? More likely it's my bike

One gap in my knowledge about batteries and how they get recharged, I guess, has to do with cranking volts. Just 3 weeks ago, I had trouble starting my bike, and the one thing I didn't suspect was the AGM battery, because it was only a month old.

It had over 13 volts, but the cranking volts dropped way down below the magic 9.6 number. So I figured -- what the heck, I'll just take it into AutoZone and have them check it out. They condemned it and handed me a new one. We called it a fluke.

Now, three weeks later, it's happened again. Yes, I probably should have a voltmeter installed by now (preferably digital), so I could be observing my cranking volts over time. Maybe this happens gradually and not suddenly.

However, I certainly did not observe the bike hesitating to start, until this morning, when suddenly I'm right back to where I was 3 weeks ago, and it won't start at all.

I'm reasonably confident that AutoZone will see that this battery is bad in the same way (is it? Or does it just need to be charged back up in a certain way. There is where my knowledge of cranking volts falls short). And I'm reasonably confident they will honor the warranty again.

BUT, I assume that they will eventually start wondering (as I am) what in the world my bike is doing to these batteries to cause them to go bad in this way. I'm certainly asking that question, since I own a VN750, which has a notorious electrical system.

Oh, speaking of things I should have done by now: I still haven't done the full suite of electrical testing that I know I should have. I always have a stack of priorities that have to be done, and that's just never been at the top of it. Today I'm re-roofing my porch, so I didn't really have time to ride anyway. I was literally just going to ride over to Home Depot to pick up a hand tool. (my highest priority on my bike is still replacing that front tire, which I tell myself I'm waiting for a rainy day to do).

So, any insight on this, while I'm re-roofing my porch? What's the most likely cause of an AGM battery that keeps getting charged back up to 13 volts, but the cranking voltage of which is dragged below the lower limit in 3-4 weeks?

1986 Vulcan 750
Purchased June 2018, as a first bike.
Put 1,300 miles on it so far.
Location: Murfreesboro, TN

AGM Battery, Iridium Plugs
SeaFoam does wonders, and I'm protected by Ride-On
Back tire: Dunlop Challenger.
Front tire: Dunlop Challenger, but about to replace it with a Kenda Cruiser.

Last edited by readparse; 09-02-2018 at 10:16 AM.
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Old 09-02-2018, 10:21 AM
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#1 - Make sure the charging volts are up to par.

2 - Could be the starter pulling too many amps. Parts store should be able to check that if you ride the bike in when they check the battery.

3 - Could be a shelf full of outdated batteries in the store. Check date code on yours.

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Old 09-02-2018, 11:15 AM Thread Starter
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Quote:
Originally Posted by Spockster View Post
Could be a shelf full of outdated batteries in the store. Check date code on yours.
What's the acceptable date range I'm looking for?

1986 Vulcan 750
Purchased June 2018, as a first bike.
Put 1,300 miles on it so far.
Location: Murfreesboro, TN

AGM Battery, Iridium Plugs
SeaFoam does wonders, and I'm protected by Ride-On
Back tire: Dunlop Challenger.
Front tire: Dunlop Challenger, but about to replace it with a Kenda Cruiser.
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Old 09-02-2018, 11:49 AM
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I would take less than a year old.

I have seen batteries at autozone that where already 3-4 yrs old sitting on the shelf.. and they only warranty power sports batteries for like 90 (or is it 60?) days for a reason. they sit on store shelves and wharehouse shelves for eternity

2005 VN750

Sold 11-27-17
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Old 09-02-2018, 02:28 PM Thread Starter
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The sticker on the side says 6/18. The date that's stamped into the bottom has "18" in the center of a circle (for the year), and the arrow is pointing to 4. That's a two-month discrepancy, but whatever. I can't make the case that the battery is too old.

I'll get going on the electrical testing, hopefully sometime this weekend, amid all the roofing and guttering work that I'm also trying to get done.

I broke down and bought some overalls today First pair since I was a kid.

1986 Vulcan 750
Purchased June 2018, as a first bike.
Put 1,300 miles on it so far.
Location: Murfreesboro, TN

AGM Battery, Iridium Plugs
SeaFoam does wonders, and I'm protected by Ride-On
Back tire: Dunlop Challenger.
Front tire: Dunlop Challenger, but about to replace it with a Kenda Cruiser.
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Old 09-02-2018, 06:47 PM
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6/18 is definately not old stock. the date on the bottom of the case is probably the date code for the molding of the case, but not battery assembly

2005 VN750

Sold 11-27-17
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Old 09-03-2018, 12:13 AM Thread Starter
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I had to run out to Home Depot tonight (OK, it ended up being Lowe's, on a technicality). I figured I would take the battery with me and hit up AutoZone with the full truth to see if they would hook me up with a second warranty replacement, even though I am pretty sure the problem is something with my bike.

Fortunately, the guy I spoke with used to have a Vulcan 750, of all the luck. "Say no more," he basically said. He ended up getting rid of his bike because of the electrical issues. He said his horn used to beep when he turned on his turn signal

It turns out that AutoZone's system will allow a second warranty replacement, but not a third. So this is it, no matter what. This guy said the same thing that the last guy said, that this particular battery is not one that people ever report a problem with.

So this battery will be a band-aid until I have a little time to run through the testing that I obviously need to do. Hopefully next weekend, if not sooner. As I said this morning, I still have some roofing stuff to get through first (and I'm behind on that. It's been monstrously hot today. I literally came down off the roof today and vomited. That sounds like quittin' time to me, so that's what I did).

1986 Vulcan 750
Purchased June 2018, as a first bike.
Put 1,300 miles on it so far.
Location: Murfreesboro, TN

AGM Battery, Iridium Plugs
SeaFoam does wonders, and I'm protected by Ride-On
Back tire: Dunlop Challenger.
Front tire: Dunlop Challenger, but about to replace it with a Kenda Cruiser.
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Old 09-04-2018, 01:41 PM
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When you check your charging voltage set the meter to AC volts as well as DC volts, should be NO AC getting past the R/R. When mr R/R went south it let AC through but my DC voltmeter only showed a slight increase in DC voltage! That killed the battery after roughly 75 miles.

'99 Vulcan "Victoria"
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Old 09-05-2018, 12:44 AM Thread Starter
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Quote:
Originally Posted by TonyO View Post
When you check your charging voltage set the meter to AC volts as well as DC volts, should be NO AC getting past the R/R. When mr R/R went south it let AC through but my DC voltmeter only showed a slight increase in DC voltage! That killed the battery after roughly 75 miles.
Good point. I'll keep an eye on that. I've ridden probably at least 400 miles in the three weeks I've had the battery. Maybe more. I guess I probably should have noted the mileage when I put in that battery, but... you know... hindsight.

1986 Vulcan 750
Purchased June 2018, as a first bike.
Put 1,300 miles on it so far.
Location: Murfreesboro, TN

AGM Battery, Iridium Plugs
SeaFoam does wonders, and I'm protected by Ride-On
Back tire: Dunlop Challenger.
Front tire: Dunlop Challenger, but about to replace it with a Kenda Cruiser.
readparse is offline  
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