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Does the battery charge while idling?

20K views 10 replies 10 participants last post by  "Captain D"  
#1 ·
I guess the title asks it all.

I prefer to ride when I can during the winter, but sometimes a big snow or persistent icy conditions has kept me off the roads for up to a month or so at a time.

Both my rides live outside all year 'round. If I had to use a tender, I'd end up with a power line stretching down the yard and across the sidewalk, just waiting for some sue-happy passerby to trip over. :roll: Taking the battery and bringing it indoors wouldn't my first choice either.

On my Vespa scooter, the battery will charge while idling. When it's snowbound and I can't get it on the road for several weeks, I"ll start it up and let run it for a while (usually about 20 minutes) just to keep the juices flowing, so to speak. I've been doing this since 2004, it's never needed a tender nor has it ever failed to start right up.

So, does anyone know if my '05 VLX will charge on idle so I can do the same thing? Good idea, bad idea?
If so, is there a minimum or maximum amount of time I should let it idle?

Just curious. Thanks.
 
#2 ·
Not really.. iThe charge you get from about 15-30 minutes at cruise speed will take about 4 hours at idle. Same as for your car.
 
#3 ·
I believe that most bikes will actually drain the charge if left idling for too long with the lights on. 700-900 rpms is just not enough for the charging system to charge. I could be wrong, but I'm sure others will chime in with their .02 worth.
 
#4 ·
It's not that it won't charge on Idle, a simple test is to measure the battery voltage when the bike is switched off with a voltmeter and then start it and measure the voltage at idle, an increase at idle speed is what you are charging at..

The problem is that as soon as you switch on the light and starter use a chunk of power and the battery needs a good run to get that back..so starting it every day for a few minutes can use more than you put into it and discharge the battery rather than charging it..

On a small scooter the engine is so small that it takes a lot less from the battery to start it and therefore can make it up quicker..

John.
 
#6 ·
..so starting it every day for a few minutes can use more than you put into it and discharge the battery rather than charging it..
Just to be clear, I don't start the scooter everyday for a few minutes. You're right, I'd discharge the battery in no time if I kept that up.

My regimen for my scooter is to start it up and gradually run it up a high idle (a heavy rubber band or my grip lock on the throttle does the trick) for about 20 minutes about once per month assuming I don't get out to ride at all during the previous month.

For all I know, even that may be unnecessary.

Let me phrase my question a little differently perhaps...

If I didn't run my Shadow for a winter month without using a tender, all other things assumed to be in good condition (I use stabilizer and the battery is new)...Am I likely to have starting problems or will I probably be good to go after that amount of time?
 
#8 ·
An old style battery loses charge faster than a AGM battery (about 3x faster).
So 1 month without charging would yield a mostly discharged standard batter.
An AGM battery could probably handle a month of sitting.

I heard that there is a solar-powered battery tender now. My old solar-battery charger can't be left on the battery because it doesn't "tend" the battery, but it works well if you remember to disconnect it.

Happy New Year
 
#9 ·
I know my bike will charge the battery at idle, but I don't know if yours will. To know for sure check your battery voltage with a volt meter, then start your bike, let it idle and check it again. If the voltage is higher after starting then your battery is being charged. If I don't start my bike every month during the winter months, I will charge the battery with my 1 amp charger about 4-6 hours. I'm still using my original battery.
 
#10 · (Edited)
I guess the title asks it all.

So, does anyone know if my '05 VLX will charge on idle
Tough to say from here whether yours will charge at idle or not... send it to me for about 6 months and I'll let you know! :-D

Or you could just put a voltmeter to the battery when the bike is idling and if you measure 14.0V or more, you are charging.

By using an in-line wattmeter, I found I need to drive my Shadow 6-10 minutes to fully recharge after starting it, idling would take much much longer. As for the comment about using another type of voltage regulator(MOSFET), well, sure, some are more efficient than others but the stator will have limited output at idle, that will be the limiting factor. Sure some voltage regulators may be tweaked for higher voltage at low engine RPMs but what really matters is amps. Unless of course you're riding a Gold Wing, which is equipped with an electromagnetic alternator which is capable of putting out higher current at idle than a permanent magnet alternator. I believe our stators are rated at about 400W @ 4000 RPM ... any less RPM and it puts out less power.

Some stators are wound to have a relatively flat output curve, but those tend to have overall less power compared to those that considerably vary output power with RPM.

The big problem with starting a bike every month and letting it idle for 20 minutes is you are going to circulate the condensation all over the engine and then when you shut it off, you'll get even more condensation that will sit for 30 days. Either ride your vehicle to normal operating temperatures every 2 weeks or so or store it properly with clean oil, take the battery out and top it off every 30 days. When you take the whole engine and crankcase to normal operating temperature, the condensation will vaporize and vent out of the crankcase through the breather tubes. This is why most manufacturers recommend putting in fresh oil for storage.
 
#11 · (Edited)
No cost test

Crank it up, point the headlight at something that you can see it shining on, rev it and see IF the headlight gets brighter with increased engine speed...
Mine does ~
PLUS ~ MOM says NOT to idle fer a long period on accountta it`s not charging the battery...
SO~ Check out these two suggestions,
Dennis