Battery dies when riding ...

....then is alive again.
Was riding with my son tonight, he on the '85 Maxim 700. After about an hour of suburban stop and go with some longer parkway stretches thrown in the engine balks and stalls going away from stop and when he tries to restart there is no juice. As traffic was still a bit heavy we decide to leave and double up back home. Coming back to retrieve it a half hour later it starts up. Wasn't an instant power start but turned over strongly enough.
I rode it home and felt it was running slightly rough but it still ran pretty strong. It's always hard to tell with a helmet on.
One thing I did notice is that when I put on the brakes the headlight would dim. It would also dim in synch to the turn signals blinking
Don't know how old the battery is exactly, a few years at least.
When it comes to electrical I don't know much so any thoughts from the more "tuned in" among us would be appreciated.

 

Your battery holds the key.
Either its too old to hold a deep charge and provide the AMPS the Bike needs to draw for the headlight, instruments, signals and brake light ... or,

It's not getting charged by the "System"

Charge the Battery with an Automotive Charger.
Let the Battery Charge until the Charger tops-off the Battery.

Then ...
Put the Battery to a test.
Start the Bike and measure the Voltage.

You need to see a Climb in Voltage as RPM's increase.
At or about 18-Hundred RPM's the Voltage should be 14.2 ~ 14.5
Holding steady at 14.2 or slightly above at all rev's above 2,000 RPM's

Yes? Charging System is Good!
No? Charging System needs troubleshooting ...

Check alternator brushes.
11mm is the Low limit. Replace the brushes if they are shorter than that!

 

Be careful using the charger! You can damage/destroy your battery.

Inportant: Unplug the battery from the wiring loom.

There are motorcycle chargers, maybe a charger that puts out low Amps (1A), or a Battery Tender, but for sure one that turns OFF when charged. a hydrometer is useful to check battery condition.

A hour on my car charger was enough to fully charge my battery (the one time I had to use it). Batterys can boil dry, plates inside the battery can warp.

Also check the battery terminals for tightness and corrosion (at both ends) and that connector plugs are clean and tight, check the 3 large white wires that come from the alternator (under the seat is a connector for them, the can melt) and that the battery is topped off with distilled water.

 

Battery tenders should come standard with any MC purchase. Park it, plug it in, and a good portion of potential current and future electrical problems are prevented.

$30 at Battery Plus stores for the Jr. Think of the headaches it prevents.

 

In daylight this morning I checked battery fluid levels. All low. Refilled and am putting it on the charger. Will report after today.
Thanks for all responses so far.

 

Battery Tenders are good for keeping a Charged Battery from losing it's charge ... but, a Dead Battery needs more of a Charge than the Tender can provide.

I need to have a Battery Charger on hand for all kinds of Battery Charging.
The Automatic one I have from Sears is a 2-10-50. Charges at 2 Amps, 10 Amps and Supplies 50 Amps for Jump Starting the Car.