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Offline Airbourne1

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Alternator Charging Check
« on: 20 August, 2014, 06:37:07 PM »
 As I have just past the magic seven year extended waranty period I thought I'd check the state of my charging circuit. I'm assuming that it is the original battery as I got the bike with 7K miles. Now has 14.5k miles on it.

 12.55V battery charge engine off. (Manual states "13.00-13.20, Less than 12.3 = Under charged").
 @ 5000 RPM 14.00V. (Manual states "<15.5V". Not sure if this means 'up to' or 'more than').

 These readings after a seven mile ride home.

 All seem a little low. Would it be better to take readings after a longer ride or do I need to start questioning the condition of my alternator?

Offline richardcbf

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Re: Alternator Charging Check
« Reply #1 on: 20 August, 2014, 07:28:21 PM »
My guess is that the battery is just a little 'tired' and if it's not going flat (not being given or not accepting enough of a charge such that the engine can't be cranked over) the charging system (alternator & regulator/recifier) is probably OK.
This is what Yuasa (the manufacturer of the Honda oem battery) say about battery condition.....

Prior to conducting this test, make sure the battery has not been recently charged.
You must wait at least one hour after charging your battery to conduct this test.
- Adjust voltmeter to DC volts (20 volt range).
- Place voltmeter leads to the battery terminals. (positive to positive and negative to negative)
- Read voltage and refer to the chart below.

100% Charged: 12.60v
75% Charged: 12.40v
50% Charged: 12.10v
25% Charged: 11.90v
0% Charged:  less than 11.80v
See also:

Apart from that, you have the workshop manual, but for others....

Page 18-7
Be sure the battery is in good condition before performing this test.
Warm up the engine to normal operating temperature.
Stop the engine, and connect the multimeter between the positive and negative terminals of the battery.
To prevent a short, make absolutely certain which are the positive and negative terminals or cable.
Restart the engine.
With the headlight on Hi beam, measure the voltage on the multimeter when the engine runs at 5,000 min-1 (rpm).
STANDARD: Measured BV < Measured CV < 15.5 V
(measured Charging Voltage should be Greater than the measured Battery Voltage and Less than 15.5V)

BV = Battery Voltage (page 18-6: Fully charged: 13.0 – 13.2V, Under charged: Below 12.3V)
CV = Charging Voltage
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Offline Airbourne1

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Re: Alternator Charging Check
« Reply #2 on: 20 August, 2014, 07:49:12 PM »
 Many thanks indeed.Very helpful.

Offline Nuff

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Re: Alternator Charging Check
« Reply #3 on: 21 August, 2014, 12:16:09 AM »
Sounds to me like it's about perfect.
Take my advice or not, I really don't care. I'm just telling you what I think and would do on my bike.