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#146323 - 11/22/06 09:10 AM Battery Voltage - what should a good battery read?
Armando Offline
Member

Registered: 04/24/05
Posts: 543
Loc: Simsbury, CT
I am thinking that the battery on my 02 bike is about to fail. I started to get concerned when I hooked up the timer delay on my Kisan flasher which is supposed to stop the turn signal timer if the brakes are applied. I noticed that this sometimes works and sometimes it does not. I read the manual an it says that the input from the hot lead needs to be 12V. So I tested my battery with a multimeter and it the volts range from 11.3 to 11.5. Never quite upto 12V. So, I am thinking it is time to change the battery before it leaves me stranded somewhere. Given that the bike is 5 years old, I have to assume the battery life is nearing the end. My question is, what is the voltage of a new/healthy battery?
_________________________
Armando Vargas
'02 R1150RT
'98 Concourse - Gone
'86 Concourse, The Original - Gone
'88 Yamaha Virago 750 - Gone
'82 Yamaha Heritage Special 650 - Gone
'80 Yamaha dual sport 250 - Gone

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#146324 - 11/22/06 09:53 AM Re: Battery Voltage - what should a good battery read? [Re: Armando]
smiller Offline
Member

Registered: 03/27/04
Posts: 12279
Loc: Asheville, NC
The terminal voltage of a typical lead-acid automotive battery should be around 12.6 - 12.8 volts at room temperature. To test you must fully charge the battery and then disconnect the charger and let the battery stabilize for a few hours before taking the reading. A good reading is a good start but it is possible that a battery will show a proper open-circuit terminal voltage but still have diminished capacity so some sort of load test should also be performed. If the battery passes all tests then it might be time to look at the bike's charging system, but in my experience these problems lie with the battery the vast majority of the time.

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#146325 - 11/22/06 09:58 AM Re: Battery Voltage - what should a good battery read? [Re: smiller]
Mr. Frank Offline
Member

Registered: 08/28/04
Posts: 507
With a five year old battery and low readings it's time for a new battery. Be glad you got a painless heads up.
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Mr. Frank Hattiesburg, Mississippi 2004 R1150RT

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#146326 - 11/22/06 10:06 AM Re: Battery Voltage - what should a good battery read? [Re: Mr. Frank]
smiller Offline
Member

Registered: 03/27/04
Posts: 12279
Loc: Asheville, NC
Quote:

With a five year old battery and low readings it's time for a new battery.


Yes, I should have also added that if you have a 5 year-old motorcycle battery that seems in questionable condition then toss it and use the test procedure on your new one...

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#146327 - 11/22/06 10:12 AM Re: Battery Voltage - what should a good battery read? [Re: smiller]
Global_Rider Offline
Member

Registered: 02/03/04
Posts: 956
Loc: Canada & the Alps
Quote:

A good reading is a good start but it is possible that a battery will show a proper open-circuit terminal voltage but still have diminished capacity so some sort of load test should also be performed.




Since your average person doesn't understand the term "capacity" it can be easily understood by comparing two vessels of water; a kitchen sink and a swimming pool, both filled with 12 inches of water (we'll assume 1" of water equates to 1 volt and we'll assume a fully charged battery is 12V).

Both have the same pressure at the openning of a 1" drain at the bottom...same as electrical pressure (voltage), yet when you open both drains for 15 seconds, you'll find that the level in the kitchen sink has changed a lot whereas the level in the swimming pool hasn't at all. Openning the drain is like pressing the starter button except in this case the draining water is turning a paddle wheel instead of a starter.

And that is why a battery with capacity can continue to crank the engine over for minutes (letting it cool after every 30 seconds of cranking) whereas the battery with far less capacity (due to sulfation caused by a lack of periodic charging) has the starter "clicking" 5 seconds later after you hit the starter button.
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All the best, Alex Alex's BMW Motorcycle & Global Touring Page No fancy ego boosting certifications; just a lot of great rides and memorable experiences.

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#146328 - 11/22/06 10:34 AM Re: Battery Voltage - what should a good battery read? [Re: Armando]
Global_Rider Offline
Member

Registered: 02/03/04
Posts: 956
Loc: Canada & the Alps
Quote:

Given that the bike is 5 years old, I have to assume the battery life is nearing the end.




Sounds like it in your case, BUT 5 years shouldn't be considered a normal life for a battery. The flooded lead acid batteries in my BMWs last 8 full years, failing in the middle of the 9th year (the others with little supervision lasted 7 years) and the one in the car I just sold is going on its 17th year.

I'm not at all impressed with the "gel" cells in my 2003 and 2004 GS Adventures, despite some of their advantages. They start the bike fine during normal temps, but they act as if they have minimal capacity, even when new. And when it nears freezing...no comment.

Do you use a battery maintainer of some type?

I have two; a 3 stage, 12V, 900mA YUASA Hot Shot Battery Charger-Maintainer and a 5 stage Optimate III Battery Optimizer.

To be honest, after years of maintaining batteries, my 12V 1 Amp MANUAL battery charger does a far better job in making my batteries last...in conjunction with monitoring via a digital voltmeter...but that means supervision...not recommended in most cases and certainly not with sealed gel cell batteries.
_________________________
All the best, Alex Alex's BMW Motorcycle & Global Touring Page No fancy ego boosting certifications; just a lot of great rides and memorable experiences.

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#146329 - 11/22/06 11:42 AM Re: Battery Voltage - what should a good battery read? [Re: Armando]
AndyS Offline
Member

Registered: 11/03/02
Posts: 3857
Loc: Somerset, Great Britain.
You need to know more than the terminal voltage of your battery.
Typically the terminal voltage will be in the region of 12 volts, but when cranking the engine or other high loads, strange things happen so you need to know load voltage.
Take your battery to a battery dealer or even your bike workshop. They should have the relevant test gear to measure the battery on load.
An 1150 RT battery capacity is 19Amp/hour
The low temperature test current is 170 amps.
Donít just ditch your battery. Think of the environment .
Get it tested and put off spending unnecessarily until after Christmas.

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#146330 - 11/22/06 05:32 PM Re: Battery Voltage - what should a good battery read? [Re: Armando]
Good_Fixs Offline
Member

Registered: 07/27/04
Posts: 132
Loc: San Mateo CA
My three years old BMW battery voltage read 12.5 but it will not do more than two cranks on the engine. So some old battery (but not dead yet)will still show good voltage reading but you know what people say? No juice no use. Thanks

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#146331 - 11/22/06 07:46 PM Re: Battery Voltage - what should a good battery read? [Re: Good_Fixs]
glwestcott Offline
Member

Registered: 03/08/05
Posts: 127
Take a voltmeter and measure the voltage when you hit the starter. It shouldn't drop to more than 11.8 or 11.9 volts. If it goes below that and your battery started out at full charge - i.e. over 12, you have a bad battery that doesn't have the capacity to handle the draw when you start the bike. By the way, you don't have to take the reading off of a hard to get to place, if you have an accessory plug, just hold your meter probes in it and hit the starter. Last time I had a bad battery, I measured fully charged at rest, yet cranking the starter dropped the voltage to 11.6. Put a new battery in and everything was hunky dory.

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#146332 - 11/22/06 10:12 PM Re: Battery Voltage - what should a good battery read? [Re: glwestcott]
Armando Offline
Member

Registered: 04/24/05
Posts: 543
Loc: Simsbury, CT
I will try this tomorrow.

Thanks all.


Quote:

Take a voltmeter and measure the voltage when you hit the starter. It shouldn't drop to more than 11.8 or 11.9 volts. If it goes below that and your battery started out at full charge - i.e. over 12, you have a bad battery that doesn't have the capacity to handle the draw when you start the bike. By the way, you don't have to take the reading off of a hard to get to place, if you have an accessory plug, just hold your meter probes in it and hit the starter. Last time I had a bad battery, I measured fully charged at rest, yet cranking the starter dropped the voltage to 11.6. Put a new battery in and everything was hunky dory.




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