Dear MOby,

My motorcycle is about 4.5 years old, still has its original battery, and lives in an insulated garage. I always connect the battery to a trickle charger/maintainer. When I turn on the electrical system without the motor running, the battery registers 12.3 volts; with the motor running it registers about 14.4 volts at 4000 rpm. I have not had any problem starting the bike. I frequently go on long motorcycle trips, however, and it would be inconvenient to find out I need a new battery while a long way from home.

Should I replace the battery in my motorcycle even though it’s still working well? How do I know when it’s time to change the battery?


John B.

Responsible type, eh? How I wish I were more like you… If your bike’s only 4.5 years new, we’ll assume it’s a newer, sealed type. Yuasa says on its FAQ page:

SEALED AGM BATTERIES (Absorbed Glass Matt) – Last Longer. They are not “open to the air” by way of a vent tube. They do not lose water. They are also packed tighter. Plates do not vibrate causing material to shed from the plates and short out. Or worse yet, simply breaking apart in some high vibration applications. Sealed AGM batteries typically last 3 to 5 years on average. 6 to 8 years is easily obtainable with proper maintenance. Typically sealed AGM batteries will give warning before completely dying. They will start slower, and require more charging. This is your clue to replace the battery. Typically they do not fail all of a sudden. Conventional “acid-filled” batteries have a harder life, for many of the reasons listed above. Conventional batteries typically only last 2 to 3 years on average. Although, 4 to 5 years is possible, in the best environments, and with excellent maintenance.

It also depends where the bike lives: Hot and cold climates are both harder on batteries than temperate climes, and bikes that get ridden regularly are easier on batteries than ones that sit for months – though a good battery tender with a float feature negates much of that. In fact, I was bragging about the Shorai lithium-iron battery in my bike not long ago, which must be seven years old now and has never seen a charger, when my friend Jim said big deal, the original equipment sealed AGM battery in his VFR lasted 9.5 years, and his 21-year old Ducati is only on its second battery. So, sealed batteries can last a long time especially if you’re OCD about maintenance.

According to several sources including, though, your 12.3-volt reading means your battery may be on its way to Nirvana; a fully charged one should read 12.7 volts or above. Since you like to play with your voltmeter, there are instructions to “stress test” your battery at the same page, along with a lot of other battery tidbits that will let you know for certain if it’s time to replace.

Send your moto questions to If we don’t know the answer, we know who does, and if they don’t know we’ll make up something reasonable-sounding. What do you want for free?

Related Reading
What’s up with the Ducati Sixty2?
Why Do OEMs Use Ball Bearings In Steering Heads?
How Can I Get A Smoother Ride From My Motorcycle?
How Much Faster Are New Motorcycles Than Older Ones?

  • Mahatma

    Not sure about the new tech batteries,but old gel batteries and older ones you are somewhat at the mercy of the luck of the draw to a degree.

  • D H

    As an oldtimer, I remember when all motorcycle came with a free Kick Starter.

    • TC

      I had a 1962 BSA 250, and the ignition switch had an “Emergency Run” position, which bypassed the battery and used power directly from the alternator to allow you to kickstart the bike with a dead battery, which was often the case, since it was a British bike with Lucas electrics.

  • azicat

    The numbers provided by John B. aren’t detailed enough to diagnose the health of his battery. 12.3V with the ignition on may or may not be fine as it depends on the current draw (is the headlight and fuel pump on? etc). 14.4V at 4000rpm just tells me his stator and regulator is working.

    My rules of thumb:
    Battery older than 5 years: replace.
    12.4V or less with nothing plugged in, battery charged and left to rest for 24hrs: replace.
    Less than 10V when starter motor is cranking: replace.

  • gunny 2shoes

    and no more scrapping acid corrosion from the battery tray

  • Walter

    The stock Yuasa on my 2006 KTM 950 Supermoto lasted just short of 8 years (~40,000 miles). The exact same battery lasted 6 years (~ 25,000 miles) in my 2007 950 SuperEnduro. In both cases, the batteries were kept on Battery Tender brand tenders when not used, stayed strong until they failed; and in both cases failed regulators (a known potential weakness) were responsible for the batteries’ demise. I suspect the lower life in the SE was because it was used much more often in slow technical (more heat generated) stuff than the SM: so both may have actually lasted longer if not for the regulator failures.

    As as aside, I replaced the battery in the SE with a Shorai Lithium battery (very very light), never put it on a tender, and got 5 years (~20,000 miles) out of it before it failed (heard a “pop” form within it) while trying to start it on a 35 degree day (cold temp starting is something of an issue- or at least it was with early lithium batteries).

    I have pretty much the same results with most of my bikes, but I listed these because they are very similar bikes with the same battery maintained in similar ways.

    So I’d say the Yuasa claims are pretty accurate.


    The longest I ever got was 8 years on an original OEM gel type. Always on a battery tender. Four years was the shortest on the same type same conditions. Battery gremlins are real so you never know. Went with a Yuasa last time out. Two years and counting.

  • DickRuble

    “When will my motorcycle battery die?” — Easy: when the temperature is around 70F, the sun is up, your wife and kids are visiting the in-laws, and it’s your first day off work in the past three months. Failure guaranteed no matter if your battery is Li+, gel, or any other technology.

  • Old MOron

    Hey JB, a little help, please:
    Why am I seeing this MOronic pop-up lately?
    What is Dennis up to?

    • DickRuble

      Don’t be nervous.. it’s just a bad, really bad, moment to go through.. Once it’s over.. you won’t feel a thing…

  • Michael

    I know the answer to the question…
    Answer = yesterday! At the gas station while on my commute home

    Bike is only a couple of years old.