Battery issues????

[Chris750]

I seem to be having problems with starting my bike.
My bike won't start unless I charge the battery. Then when I put the battery back on it will start first time.
After I run it for a few mins then turn it off, it won't start again, the engine turns over but not fast enough to catch.
I'm thinking either the battery has had it or the bike is not charging the battery.
How do I test this. I don't have a voltmeter but can buy one if it will help.
I don't want to buy a new battery and find out its something else, any advice would be great
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Current Rides: GSXR-750 WS, GSXR-1000 K5, KTM EXC 300

[BigGeeking]

best off getting a multi meter and putting it on the battery terminals when on tick over and when you increase the revs you should see the volts rising then you will know if it is charging. and when you are increasing the revs you should see your head lights getting brighter.
the light thing works on mine but my bike is 10 years old

[FretGrinder]

^ this

If the voltage doesn't go up when you turn the ignition on and check it with a multimeter, this will probably means that your regulator/rectifier has died and you need to get a new one.

Also, when checking the voltage with a multimeter, check that the voltage doesn't go above 14.7 ish volts. if it starts to go higher than that it could be overcharging your battery, which means getting a new one.

If you find that it is the regulator/rectifier that has gone and you have trouble sourcing one for your bike see this thread explaining how to modify one from a different one to fit yours -

https://www.bikechatforums.com/viewtopic.php?t=217955&highlight=regulator+rectifier

Hope this helps...
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Yamaha MT-09

ಠ_ಠ

[Chris750]

I will get a meter and test it. The reg and rec seem to come as seperate parts on my bike.
Am I right in assuming if there is no increase in voltage the rec could be brocken. If the voltage increases above 14.7 the reg could be the problem?
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Current Rides: GSXR-750 WS, GSXR-1000 K5, KTM EXC 300

[MickC]

The rectifier converts the ac voltage to dc , so if that was shot you probably wouldn't get anything, the regulator is what controls the dc voltage
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[Chris750]

Right I have a meter now.

My batery is reading 12.9 volts after charging when its off the bike.
As soon as I put it on the bike and turn on the ignition it drops to 9.8 volts.
Is this normal?
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Current Rides: GSXR-750 WS, GSXR-1000 K5, KTM EXC 300

[P.]

[Chris750]

Battery is two years old but it has had a bit of abuse.
I may just buy a new one and see if it sort out my issues
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Current Rides: GSXR-750 WS, GSXR-1000 K5, KTM EXC 300

[MickC]

on mine i get 12.1 (lights on-always, US model so no off switch), the test you want to do is rev the engine to 3000rpm you should get 14.4v at the battery, if not you'll probably have an issue with the charging system, tests for which can be found in the manual.
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Previous: CG125,XS250 (converted to 400),Z250A, GPZ550, Norton Commando, XS500, 78 Laverda Jota, GPZ1100,Harris bonneville, XV750 (mono shock),TR1