Battery Voltage

[Vision]

I've had headlight bulbs burning out and a high idle so I replaced the resistor; and bought a multimeter. After replacing the resistor the idle dropped in half which is good; am waiting on the bulbs. If I'm measuring the (DC) voltage right the battery at idle is around 16.5v. Is this a problem?

[scooterfan]

Yes, this is a problem. The voltage reading is not suppose to be much higher than 14 Volts.
I assume you mean you have replaced the voltage Regulator. If not, the Voltage Regulator, or the battery itself might be faulty. Some battery cells might be damaged. You also need to make sure that the correct size battery has been mounted on the scooter. The current battery might be too small for the scooter.

[Vision]

"I assume you mean you have replaced the voltage Regulator."

Yes.

I've been running this battery for 2.5 years. Is it the right size?

Mighty Max Battery YTX7A-BS Battery Replacement for GTX7A 32X7A 44023 CTX7A Battery Brand Product
Voltage: 12 Volt
Amperage: 6 AH
Chemistry: SLA, AGM
Terminal: Nut & Bolt

https://www.amazon.com/gp/product/B00K53DSZ6/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1&pldnSite=1

[scooterfan]

The battery size is fine but if the battery voltage got too low at some stage the battery might be faulty.

[Vision]

Just took the multimeter to the battery again and to my car's battery.

Agility:
13.5v when off
16.5v at idle

Car:
10v when off
14v at idle

Can't tell if there's a problem. If this is a problem would it be a stator problem? Too much charging? 

[Iahawk]

I wasn't aware a battery could generate that kind of voltage (13.5 when off).  That is much higher than the the usual 12.5 - 12.7.  ...and 16.5 at idle? did you check at higher than idle speed,  when it's really charging? I don't know exactly what's wrong but you obviously have a charging issue.

[Vision]

No, haven't checked it at higher rpm's.

[Vision]

17.75v at full throttle.

Agility:
13.5v when off
16.5v at idle
17.75v full throttle.

Car:
10v when off
14v at idle

[jeeves]

17.75v at full throttle.

Agility:
13.5v when off
16.5v at idle
17.75v full throttle.

Car:
10v when off
14v at idle

Way too much voltage on the scooter.  You said that you changed the regulator/rectifier .
When and why did you change it?

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[Vision]

I changed the regulator/rectifier (sorry all, not a resistor) last night because headlight bulbs are burning out. Also the throttle was high.

The numbers I'm posting are with the new rectifier, producing a more relaxed idle.

[jeeves]

Voltage at idle should be around 13.7V, and 14.3-14.7V at higher rpm.

Is the new rectifier original Kymco or an aftermarket one?

I had to change 2 rectifiers on my scoot, and only the OEM were good.

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[Vision]

It's aftermarket but do think it decreased the voltage.

I'm starting to think the stator is putting out too much voltage, and that burned out the original rectifier and increased the idle.

Probably need to check the voltage of the stator output; and find some videos online to do it.

Would the CCI have any effect on these readings?

[jeeves]

It's aftermarket but do think it decreased the voltage.

I'm starting to think the stator is putting out too much voltage, and that burned out the original rectifier and increased the idle.

Probably need to check the voltage of the stator output; and find some videos online to do it.

Would the CCI have any effect on these readings?

Decreasing voltage is not good enough, it has to be in the specified limits.

Didn't have a good experience with aftermarket rectifier. It just didn't work.

Checking the stator should be done.

CDI, as far as I know, doesn't have any effect on voltage.


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[scooterfan]

It's aftermarket but do think it decreased the voltage.

I'm starting to think the stator is putting out too much voltage, and that burned out the original rectifier and increased the idle.

Probably need to check the voltage of the stator output; and find some videos online to do it.

Would the CCI have any effect on these readings?

As far as I know a stator simply can not put out higher than normal voltage.

Maybe you should also check if the voltage keep on kreeping up quite fast just after the engine has been started. If so, that can be an indication of a faulty or incorrect voltage regulator.
Like somebody mentioned here — maybe only an OEM regulator should be used.

The 13+ voltage reading you got when the engine was not running could be normal - but only if you got the reading just after the engine was running, or just after the battery has been charged with a charger. The Voltage should drop to less than 13 volts after the battery was just standing for a while.

[scooterfan]

It's aftermarket but do think it decreased the voltage.

Would the CCI have any effect on these readings?

Good question. The way a DC CDI on our scooters works - the CDIs have capasitors which generates high voltage for the spark plug. The CDIs draws volts from the battery, and feed the capasitors to generate high volts. The stator only triggers the capasitors to release the high voltage to the coil and spark plug.
To my mind this means the CDIs should have diodes to prevent a back flow of higher voltage to the battery. Faulty diodes can indeed cause a higher voltage reading at the battery.

This is only speculation, but yes - I think there is a possibility that faulty diodes in a CDI can cause higher voltage readings at the battery.