A "Must Read" about batteries and lighting

[Marshal_Mercer]

Go here to read an article from Yuasa about bike batteries. Very informative reading, especially about using high wattage lights that draw-down charging power below 13 volts.

I have been keeping an eye on my voltmeter, as I use 85/80 watt head lights. With the bike at idle, and the air temp high enough to turn on the fans, my voltage drops to 12.6. That is the resting potential of the battery without being charged by the alternator, so says the article. Oops!

Marshal

 

[John Pearson]

Good read. Now it's got me wondering....think I'll go ride.

 

[dduelin]

I have been keeping an eye on my voltmeter, as I use 85/80 watt head lights. With the bike at idle, and the air temp high enough to turn on the fans, my voltage drops to 12.6. That is the resting potential of the battery without being charged by the alternator, so says the article. Oops!

Marshal

This is not something to worry about. An alternator normally is belted or geared so it isn't really putting out much current at idle rpm and as long as you are not idling the bike for hours (days really, sulphation takes days, weeks, months to fully harden) at a time 12.6 system voltage while idling won't contribute to sulphation. Blip the throttle from idle and the voltage jumps up - as it should. The Goldwing example has a system voltage at highway speed of 13.5. That is an oops!

Many old BMW airheads are in this situation as the original 280 watt Bosch alternator was barely sufficient to keep up with the loads of a stock bike when every terminal and wire was clean and corrosion free as the alternator is driven at engine speed and needs to run above 3000 rpm to begin generating enough current to stay even with system loads. Extra lights and heated gear had to be turned off when riding in an urban setting where rpms were low or times of idle are high compared to riding speeds. The first year I owned my airhead I would have to charge the battery weekly as it would fall into the low 12's or high 11's during a ride. Removing and cleaning all the charge system wires helped but I did not fix it until replacing the diode board restored full output.

 

[RaYzerman]

The Goldwing example has a system voltage at highway speed of 12.6. That is an oops!

Are you perhaps referring to an older Goldwing model? I haven't noticed this on my GL1800. It has a 1000W alternator, and only when I have heated grips and jacket liner on does the voltage at highway speed drop below 14..... lower at idle by perhaps 1/2 volt or so as expected, but more juice than you could ever want.

 

[dduelin]

Are you perhaps referring to an older Goldwing model? I haven't noticed this on my GL1800. It has a 1000W alternator, and only when I have heated grips and jacket liner on does the voltage at highway speed drop below 14..... lower at idle by perhaps 1/2 volt or so as expected, but more juice than you could ever want.

I don't know what Goldwing model was used in the article, it doesn't really matter. What matters is the theory and application behind the reference article.

 

[ChipSTer]

Go here to read an article from Yuasa about bike batteries. Very informative reading, especially about using high wattage lights that draw-down charging power below 13 volts.

I have been keeping an eye on my voltmeter, as I use 85/80 watt head lights. With the bike at idle, and the air temp high enough to turn on the fans, my voltage drops to 12.6. That is the resting potential of the battery without being charged by the alternator, so says the article. Oops!

Marshal

At 12.6 @ idle you should be ok... Provided it goes up with RPM increase... You are at 'status-quo'... not putting any 'juice' in nor taking any 'juice' out... break-even if you will... I really, really, really need to get a voltmeter for mine.... Last summer, after about 15 minutes @ idle before shutting down, it wouldn't crank... Either my battery is dying or I'm drawing too much 'juice' @ idle...

 

[Marshal_Mercer]

At 12.6 @ idle you should be ok... Provided it goes up with RPM increase... You are at 'status-quo'... not putting any 'juice' in nor taking any 'juice' out... break-even if you will... I really, really, really need to get a voltmeter for mine.... Last summer, after about 15 minutes @ idle before shutting down, it wouldn't crank... Either my battery is dying or I'm drawing too much 'juice' @ idle...

I changed my headlight bulbs over the weekend. Took the 85/80 watters out and put 60/55 watters in. I saw 0.4 volts of extra juice at idle. Even my Honda heated grips at setting #4 use only 0.2 volts at idle. I see 13.9-14.0 volts at 4,000 rpm now, where I saw 13.6-13.7 volts before.

What prompted me to do this was that I was at 7,000+ feet of altitude in our local mountains, at idle, and the rpm started to drop from 1,000 rpm; 1,100 is what I set at home. The voltmeter ran below 12.6 as the rpm dropped, as one would expect. A little tug on the throttle cleared its head, but started my wondering about my reserve. So, out came the bright bulbs.

Marshal

 

[TomD]

Don't worry to much about lower voltage at idle. If you are maintaining 12.6 at idle the battery will be fine. If you are at 12.6 when running at speed you are in trouble. The alternator needs RPM to become fully excited. As you put more load on the system the voltage regulator will call for more output and voltage will climb to 14 - 14.4 volts, this is normal. After the load is off and/or battery voltage rises the voltage will drop, usually to 13.3 to 13.5 volts. If the bike starts, the lights are bright and all gauges and warning lights are happy, enjoy the ride. The voltmeter is a good diagnostic tool. If you are running down the highway and are not between, lets say, 13 to 14.8, something is getting tired. The battery has an amp hour rating and bike batteries usually fall into the 14 to 18 ampere hour category. So even the smaller battery can put out 2 amps for 14 hours. Slight discharge at a red light or even stop and go traffic for an hour really shouldn't hurt anything.The alternator is big enough to pick up the load and re-charge the battery once speed resumes.

Tom

 

[Marshal_Mercer]

Don't worry to much about lower voltage at idle. If you are maintaining 12.6 at idle the battery will be fine. If you are at 12.6 when running at speed you are in trouble. The alternator needs RPM to become fully excited. As you put more load on the system the voltage regulator will call for more output and voltage will climb to 14 - 14.4 volts, this is normal. After the load is off and/or battery voltage rises the voltage will drop, usually to 13.3 to 13.5 volts. If the bike starts, the lights are bright and all gauges and warning lights are happy, enjoy the ride. The voltmeter is a good diagnostic tool. If you are running down the highway and are not between, lets say, 13 to 14.8, something is getting tired. The battery has an amp hour rating and bike batteries usually fall into the 14 to 18 ampere hour category. So even the smaller battery can put out 2 amps for 14 hours. Slight discharge at a red light or even stop and go traffic for an hour really shouldn't hurt anything.The alternator is big enough to pick up the load and re-charge the battery once speed resumes.

Tom

I agree -- normally. As the temps drop, I use Gerbing's heated pants liner, jacket liner, and gloves. I also use a pair of PIAA 910s or Hella FF50s at night. Those plus the relays, GPS, GMRS radio, and voltage leaks perk my attention to small stuff.

Marshal