# Why is my bike only creating 8.5 volts

My battery has been running flat during rides, but when i put it on the charger over night it comes up fine.

I did a voltage check on the battery when running and it sits at 8.5 to 9 volts at idle. I bearly increases when i rev the bike up.

I though it could be he regulator/rectifier, but i just swapped that out and nothing changed?

Anyone have any ideas?

Looks

Bad stator. Go though the tests in the manual. Chances are, it has continuity to ground. I assume you made sure all ground wire connections are good.

This may or may not be the problem. But is your battery ok. It may take a charge but may be discharging it self too. I see this alot at work.

Ever get this fixed? I'm having similar problems. My stator does have continuity to ground (on the white & yellow wires), but isn't that normal for stock bikes that do not have a floating ground?

No, still working on it.

My battery has been running flat during rides, but when i put it on the charger over night it comes up fine.

I did a voltage check on the battery when running and it sits at 8.5 to 9 volts at idle. I bearly increases when i rev the bike up.

I though it could be he regulator/rectifier, but i just swapped that out and nothing changed?

Anyone have any ideas?

Looks

V=I*R

if your battery is discarged to about 6 to 7 volts, then I'd expect that the charging system wouldn't put out more then your 8 to 9 volts. you have to think about the voltage difference betwen your battery and the charging voltage. if your battery is discharged to 6 volts and your charging voltage is 14V, then the difference is 14-6 = 8 volts. lets say that your battery has an internal resistance of 1ohm( wild guess). so then you wip out v=IR and you calculate the charge current. V=IR, V= 8 , I is in amps, and R = 1 ohm. the answer is 8 amps. 8 amps is a pretty big charge.

If you are the guy designing the regulator, you probably only want to charge the battery at a max of 3 amps ( it says right on the battery that the max charge current is 3 amps), so how do you limit the current? so back to the example, if you want 3 amps and your internal resitance is 1 ohm. then you use V=IR again to find you max allowable voltage difference. V=3*1 . the answer is three volts. so in the imaginary example with the 1 ohm battery, the max voltage you can apply to your 6 volt battery is 9V [6+3=9].

so this getting kinda long. but my point is that with a limited current charging system... your charge voltage is not going to be very far from the battery voltage.

Below based on my bike, a WR450 -03:

It should be charging at 14 V/120 W at 5,000 r/min.

If the regulator is broken it would charge over 40 volts. So, I dont think its the regulator that is the problem, probably the stator. Just do a voltage check before the regulator and you will see. (should be around 40 volts when revving).

Not sure if i'm right here but, if the stator wasn't working would he not have spark and then the bike wouldn't run?

WR CDI is DC, if the battery has voltage, the bike will run with a bad stator.

You need to do the stator tests.

Below based on my bike, a WR450 -03:

It should be charging at 14 V/120 W at 5,000 r/min.

If the regulator is broken it would charge over 40 volts. So, I dont think its the regulator that is the problem, probably the stator. Just do a voltage check before the regulator and you will see. (should be around 40 volts when revving).

if the battery is dead then it will not charge at 14V. at most it will only be a few volts higher then the battery voltage. what he needs to do is charge the battery, make sure that it can be charged above 13 volts. then kick start the bike and make the measurment.

My battery has been running flat during rides, but when i put it on the charger over night it comes up fine.

I did a voltage check on the battery when running and it sits at 8.5 to 9 volts at idle. I bearly increases when i rev the bike up.

I though it could be he regulator/rectifier, but i just swapped that out and nothing changed?

Anyone have any ideas?

Looks

Seeing what appears to be normal voltage does not mean the battery is OK. I think you have a dead cell on that battery and it is a load on your regulator. Do you have a Aussie battery or an American battery? An American battery will leak acid into your cables since you're from down under mate. Aussie batteries are designed to be upside down. cheers:thumbsup:

So i have tested my stator.

And it has continuity to ground, is that normal

It is running at about 15.5volts before the regulator, and drops to around 8 and 9 when reved up.

The battery charging voltage is down to 5-6 volts.

To verify the testing i disconnected the battery and did all the testing again, and that yeilded the same results.

I have looked at most of the ground connections and they seem to be clean and making good contact.

I am at a loss here.

Is it a bad connection at the stator causing the continuioty to ground, is the stator stuffed, or is it some thing else.

Looks

WR CDI is DC, if the battery has voltage, the bike will run with a bad stator.

You need to do the stator tests.

I did the stator resistance test, and i came in within spec. But it is that close to a dead short anyway. What could be wrong with the stator to cause it to pass the resistance test, but not create enough voltage.

Looks

Short to ground, caused by failing insulation/enamel.

How old is your battery? The 1st thing is to make sure the battery is good.

Just becaues it comes up over night doesn't mean it good. You can test &

How old is your battery? The 1st thing is to make sure the battery is good.

Just becaues it comes up over night doesn't mean it good. You can test &

NO SHIRT!!! see post 11

How old is your battery? The 1st thing is to make sure the battery is good.

Just becaues it comes up over night doesn't mean it good. You can test &

I am doing most of this testing with the battery disconnected. The battery is fine as it will last three days of starting before it needs recharging.

Thanks for everyones help so far.

Looks

Does the bike run well without the battery??? Do you have any electrical extra's (road kit, light kits etc.)

My 06 battery was running down after each ride. My bike, however, when cold and tested showed good charging voltage. My problem didn't kick in until the stator got hot. Replaced the stator, happy battery and no more problems.