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How do you read the voltmeter?


Riderdrumr

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Riderdrumr

Had an issue starting the bike this AM to go to work. Seemed like the battery was low. However, I did get it started and rode the 37 miles here. I kept an eye on the voltmeter the whole ride. With all heated gear on, it read 13.8 for the first part of the ride. Mid way it was 13.9. The whole ride I was lowering my heated gear as well as the seat and grips. By the time I arrived at work, it read 14.0. 

 

When I try to start the bike this afternoon, will I be able to? Should I order a new battery right now? Can someone give me a brief education about how to read the numbers on the dash voltmeter?

 

Thanks!

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The dash volt meter is more of a reference, not really trusted to be accurate, but to show a difference from normal running when there is an issue.

How old is your battery? How often and how far is the bike ridden normally? Is it on a maintainer (battery tender) when not in use?

The only sure say to know the condition of the battery is to have it tested, voltage and load test. If you have a proper volt meter, or access to one, the first step would be to measure voltage. I've often seen it posted that a reading of 12.5 volts is about a 50% discharge.

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old_farmer

I think you would need to see what the volts are when you turn on the ignition before starting. It would be better if that was something you watched over time to check for trends. I just started looking at that after I hooked up my recently acquired GS-911 and noticed the voltage readout. The 14v suggests to me that you have a functioning charging system.

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dirtrider
2 hours ago, Riderdrumr said:

Had an issue starting the bike this AM to go to work. Seemed like the battery was low. However, I did get it started and rode the 37 miles here. I kept an eye on the voltmeter the whole ride. With all heated gear on, it read 13.8 for the first part of the ride. Mid way it was 13.9. The whole ride I was lowering my heated gear as well as the seat and grips. By the time I arrived at work, it read 14.0. 

 

When I try to start the bike this afternoon, will I be able to? Should I order a new battery right now? Can someone give me a brief education about how to read the numbers on the dash voltmeter?

 

Thanks!

Morning Riderdrumr

 

As mentioned the on-board voltmeter is not a very good instrument to tell battery condition.

 

It's main usage is to tell you that your charging system is working OK & that your entire system load is not grossly exceeding your alternator's output at the RPM you are running at.

 

You need the key to be on for it to work so the on-board voltmeter isn't even very good for telling you static base battery voltage after sitting overnight as with the key-on your battery is then seeing system load.

 

You need an accurate remote voltmeter hooked directly to the battery posts to tell you much about battery voltage (like static voltage after overnight sitting, then during engine cranking) but even then it is not nearly as good an an actual battery load test. But even an actual battery load test doesn't always tell the  correct story on a battery's cold starting ability. 

 

If your battery is over 3 years old, or older, then  you might think about replacing it before it leaves you stranded. If under 3 years old then it might still be OK but that is no guarantee.

 

You need to check the battery static voltage after motorcycle sits overnight, if low then you need to find out why. 

 

If battery shows low in the above test then you need to check for excessive parasitic battery drain.

 

If OK per above then you next need to check battery voltage during cold engine cranking.

 

 

 

 

 

 

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old_farmer
33 minutes ago, dirtrider said:

Morning Riderdrumr

 

As mentioned the on-board voltmeter is not a very good instrument to tell battery condition.

 

It's main usage is to tell you that your charging system is working OK & that your entire system load is not grossly exceeding your alternator's output at the RPM you are running at.

 

You need the key to be on for it to work so the on-board voltmeter isn't even very good for telling you static base battery voltage after sitting overnight as with the key-on your battery is then seeing system load.

 

You need an accurate remote voltmeter hooked directly to the battery posts to tell you much about battery voltage (like static voltage after overnight sitting, then during engine cranking) but even then it is not nearly as good an an actual battery load test. But even an actual battery load test doesn't always tell the  correct story on a battery's cold starting ability. 

 

If your battery is over 3 years old, or older, then  you might think about replacing it before it leaves you stranded. If under 3 years old then it might still be OK but that is no guarantee.

 

You need to check the battery static voltage after motorcycle sits overnight, if low then you need to find out why. 

 

If battery low in above test then  you need to check for excessive parasitic battery drain.

 

If OK per above then you next need to check battery voltage during cold engine cranking.

 

 

 

 

 

 

This is timely advice for me as my 2017 is running original battery and I now have all the necessary bodywork off to install Darlas. Thanks!

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Riderdrumr
1 hour ago, Hosstage said:

The dash volt meter is more of a reference, not really trusted to be accurate, but to show a difference from normal running when there is an issue.

How old is your battery? How often and how far is the bike ridden normally? Is it on a maintainer (battery tender) when not in use?

The only sure say to know the condition of the battery is to have it tested, voltage and load test. If you have a proper volt meter, or access to one, the first step would be to measure voltage. I've often seen it posted that a reading of 12.5 volts is about a 50% discharge.

I commute on this bike. The bike hadn't been ridden in about 3 weeks. So I started it this past Sunday and it fired right up. I let it run for a minute and shut it down. I would've let it run longer but I knew I was going to take it today. I bought the bike used in Nov. '19. It had 8400 miles when I bought it and it now has 20300. I am not aware if the battery had been changed before I bought it. I don't keep it on a tender because I ride all 12 months and about 10-13k miles per year. 

 

I guess I better test the battery or just get a new one.

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Riderdrumr

I'll pick up a voltmeter this weekend. The bike started right up as normal both yesterday for the ride home and this morning. :dontknow:

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22 hours ago, Riderdrumr said:

I commute on this bike. The bike hadn't been ridden in about 3 weeks. So I started it this past Sunday and it fired right up. I let it run for a minute and shut it down. I would've let it run longer but I knew I was going to take it today. I bought the bike used in Nov. '19. It had 8400 miles when I bought it and it now has 20300. I am not aware if the battery had been changed before I bought it. I don't keep it on a tender because I ride all 12 months and about 10-13k miles per year. 

 

I guess I better test the battery or just get a new one.

I wouldn't start a bike and let it run for a minute to check if it will start the next time.  Each start takes time/miles to recharge the battery. I've been on club rides on a cold morning watching riders start their bikes to check, twenty minutes latter when the group was ready to head out they needed help.  

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dirtrider
On 2/24/2021 at 10:09 AM, Riderdrumr said:

I commute on this bike. The bike hadn't been ridden in about 3 weeks. So I started it this past Sunday and it fired right up. I let it run for a minute and shut it down. I would've let it run longer but I knew I was going to take it today. I bought the bike used in Nov. '19. It had 8400 miles when I bought it and it now has 20300. I am not aware if the battery had been changed before I bought it. I don't keep it on a tender because I ride all 12 months and about 10-13k miles per year. 

 

I guess I better test the battery or just get a new one.

Morning Riderdrumr

 

With your motorcycle sitting for 3 weeks that lowers the battery SOC (state of charge)  as the modern BMW motorcycles have a basic & continuous battery drain (even when just parked). Not a lot of parasitic drain but enough to continually lower battery SOC.

 

That 3 week drain coupled with an engine start but not enough engine run time to re-charge the battery is probably what gave you the slow start the next day. 

 

Even so, after sitting 3 weeks & just one start it shouldn't have acted like that UNLESS you either have some extra parasitic  drain (some added accessories that use a little power even when turned off), or your battery is getting near end-of-life so doesn't have it's full storage ability. 

 

Probably wouldn't hurt to have your battery load tested just to see what you are working with. Also might not hurt to put a battery tender on that battery if allowing the motorcycle to sit that long.

 

If you start it again after sitting for a while at least allow it to run long enough to replenish what was used to start it.

 

Also, remember it takes quite a while while longer to re-charge that starting battery if you are riding with heated grips, heated seat, & heated clothing all on at the same time, especially on the BMW wethead as the   wethead doesn't have as much alternator output as the older external alternator BMW's had. 

 

Added: BMW wethead riders manual states:  (( Connect a float charger to the battery if the motorcycle is to remain out of use for more than four weeks))

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Riderdrumr
On 2/25/2021 at 9:14 AM, strataj said:

I wouldn't start a bike and let it run for a minute to check if it will start the next time.  Each start takes time/miles to recharge the battery. I've been on club rides on a cold morning watching riders start their bikes to check, twenty minutes latter when the group was ready to head out they needed help.  

You know, I wondered about that. Thanks for the anecdote.

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Riderdrumr
On 2/25/2021 at 9:25 AM, dirtrider said:

Morning Riderdrumr

 

With your motorcycle sitting for 3 weeks that lowers the battery SOC (state of charge)  as the modern BMW motorcycles have a basic & continuous battery drain (even when just parked). Not a lot of parasitic drain but enough to continually lower battery SOC.

 

That 3 week drain coupled with an engine start but not enough engine run time to re-charge the battery is probably what gave you the slow start the next day. 

 

Even so, after sitting 3 weeks & just one start it shouldn't have acted like that UNLESS you either have some extra parasitic  drain (some added accessories that use a little power even when turned off), or your battery is getting near end-of-life so doesn't have it's full storage ability. 

 

Probably wouldn't hurt to have your battery load tested just to see what you are working with. Also might not hurt to put a battery tender on that battery if allowing the motorcycle to sit that long.

 

If you start it again after sitting for a while at least allow it to run long enough to replenish what was used to start it.

 

Also, remember it takes quite a while while longer to re-charge that starting battery if you are riding with heated grips, heated seat, & heated clothing all on at the same time, especially on the BMW wethead as the   wethead doesn't have as much alternator output as the older external alternator BMW's had. 

 

Added: BMW wethead riders manual states:  (( Connect a float charger to the battery if the motorcycle is to remain out of use for more than four weeks))

Thank you! All good advice. I appreciate it!

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