My motorcycle battery wont hold charge.?

I have a 03 ninja 500 with 5600 miles on it, the battery and the rectifier is about a year old. I notice it didn't have enough volts to start the engine since it's been seating for 2 weeks but thought nothing of it. So I jumped started it and it works. I let idle for about 5 to 10 minutes. To make sure nothing is wrong with the charging, I turned the engine off but again the battery is dead. So I repeat the jumping process, idled it, turned the engine off still the same problem. Please help and thank you I bought the bike last year, ran great other than the battery if anyone is wondering


You aren't charging a battery by idling, you have to ride it. That being said, it's possible the battery is done especially if you don't ride it on a regular basis.


Buy a new battery...problem solved. You can confirm this by getting the battery tested, but I can tell you now, that's your problem. If you live in the UK, Halfords will test it for free and sell you a replacement. I'm sure you have a motorcycle dealership in the USA.

Tim D

Get a multimeter and get the voltage both with the engine running and not running. But I suspect you will be shelling out for a new battery soon.


get a small 'battery tender' and leave it hooked-up .........................


First check the battery voltage and distilled water level before starting. Then start and while the RPM's are above idle, check the battery voltage again. It should be higher than before starting. If it is the same, the alternator is not charging. If it is higher, turn the engine off and check the battery voltage again. Disconnect one of the battery terminals. Check the voltage in the morning and if lower, the battery isn't holding a charge and needs replacing. Previous answers correctly pointed out higher RPM's and longer interval for sufficient re-charging are necessary after using an electric start. Troubleshooting is easiest when possible causes are eliminated.

Robert S

Your battery could be low on electrolyte/water.It should have small screw caps.You should use distilled water but tap water will work in a pinch.Also motorcycle batteries do not last as long as car batteries and it could be shot even if it's only a year old,also check the terminals,they can loosen from vibration.


A battery is what you need. Or, you need to drive it for an hour on the road. Also run them for 1/2 hour, so go out for a drive. When you are low you GOT TO RIDE IT SOMEWHERE, highway speeds or 50MPH for that length of time. I found that to be the pits when it was raining so I bought a 10A12V battery charger. It also has an adjustment switch for 6V. Good for car or bike. As you got a bike, you make sure all the battery cells are full of water(as water evaporates and the acid does not evaporate) Make sure the level is right and then put on the charger. You disconnect the negative bike wire and move it out of the way so there is no shorting and put on the battery charger cables and leave it for several hours (4) as the battery has some power in it. And then it will be full. Then disconnect the battery charger and reconnect the negative wire. You can pick these chargers up cheap at GARAGE SALES OR PAWN SHOPS. I bought mine new in 71 for my car and it is still running perfectly. Best buy I ever made. Beat jumper cables hands down. Maybe you can even rent one from a rental shop. But it needs to be 10amps. The 6 amp ones are not strong enough. .I had a kick starter. When you are low so the electric starter does not work, turn the key on so the lights light up on the speedo, then push the bike down the road down hill if you can and jump on the bike and clutch it in and shift into second and bounce down on the seat as you release the clutch. The tire turns over the motor and the bike starts. As soon as it starts pull in the clutch lever and rev the motor. Now shift to first. It push starts easier in 2nd than first. But second is a dog to take off with so you do not start there. . It is good if there is no cars on the road and it does not do it on gravel or sand. It has to be on pavement. , if you are light as a feather, then you will not be able to force the wheel to turn in second so click it to 3rd. just to jump start it.

duck you sucker!

If you got a cheapie battery like from Batteries Plus; 1 year is about their useful life. Bit less with vibes or hard bumps, like I Used to do with the Honda on Sandario Road. Tempting! A stock Yuasa or glass mat replacement, maybe a few years. Even less if you leave it discharged, long, and DON'T check the water! Many neglect this as hard to get to and see. Low water causes sulfation, a hard "crust ' of insoluble, oxidized lead sulfates that replace a %age of the plates' area and reduce A/Hrs even if it charges up. Also, as said, 20 minutes idle wont charge nuthin'. Takes 2500 RPM or so for 45 minutes, like, ride her with headlamps out on expressway. If not too far gone, charge overnight, then, use a battery tender.


To recharge the battery a typical motorcycle (even my liter-bike) has to run at cruise rpm's (over 2,000) for at least 20 minutes. Your assumption that a motorcycle will recharge its battery at idle is false. Didja know you can look at the volts across the battery while the engine is running? Why yes, you can. Ain't life amazing?

don r

There is an alternator to charge the battery. Jump starting only gets the starter going, not charge the battery. Have the alternator checked. Have the battery checked since they can die and sulfate if not kept charged.


sounds like something is draining your battery. Next time if you are not going to usr it for 2 weeks , disconnect the battery


Batteries can fail.


Occasional riding 12 months is the usual lifespan of a bike battery. Replace it. As others have suggested for about the price of the battery you can buy a small smart charger. This will keep the battery topped up & roughly double its life.


Get the battery charged and load tested at a bike shop. Replace if it fails the load test. Check the voltage across the battery when the engine is running. Check at idle and check at 2000 rpm. Voltage should be at least 13.5V at idle and 14V or over at 2000 rpm. Voltage is low, the rectifier or stator could be shot.


Let's see... 5,600 miles in 16 years is 350 miles a year, 7 miles a week, 1 mile a day.... If you don't ride the bike very often you should charge the battery every now and then or hook it up to a battery tender. Batteries hate being flat/near flat for long periods, and sulphate forms when the voltage drops, making any subsequent charging ineffective. But that's one for another question. A battery that's flat or near flat needs more than a few minutes idling to fully recharge. Modern CDI ignitions needs a lot of draw to make a spark. The C stands for capacitor, and they need a lot of power to build up the charge that makes the spark. Not like the old points ignition systems. But I digress. Put a charger on your battery for a few hours. If you <have> to use a car charger, run it on the lowest possible setting and let it cool for half hour, every half hour. Don't overcharge it if there's a chance it's still good or you will kill the battery, but if it's headed for the recycle plant anyways, it won't matter. To test if the bike is charging itself, measure the voltage across the battery terminals. A cheap volt meter is about $10. Get one. A good battery will show 12.5V when the engine is not running. With the engine running, it'll be 14.5V. It's effectively flat at 12V. Less than 11V, it's had it. Recharge the battery for a few hours. If it loses it's voltage over night, it's shorted out internally (sulphated) and you need to replace it. One final thing, you mentioned a recent new regulator - one year old but you don't do many miles so let's call it brand new - so I'm thinking there is a possibility your stator may be faulty (cooking the alternator and/or regulator). In which case, check the battery actually contains acid. If you have an undiagnosed fault that is killing you regulator and alternator, then we are overcharging and boiling the battery, hence no power. A symptom of a faulty reg will be over 14.5V at the battery when running the motor. You nay see 18.5V or more. And you may be blowing a lot of bulbs.