From:Dave Hennessey
Subject:RE: Batteries Date:Thu Aug 16 10:41:23 2012
Response to:17696
How many amp-hours?

The original H-3 batteries were probably 12 amp-hour. But like Backyard Bob (and John Fairgrieve in a different thread) says, the battery is only used to give you enough juice to get the bike started***, and to run the lights when the bike is not running.

6-volt batteries are pretty rare now. Years ago, you could find a suitably-sized 6v lead-acid battery for your bike at the "battery warehouse", but since almost everything converted from 6v to 12v back in the 1950's and 1960's, today nobody makes any lead-acid batteries of the proper size.

Fortunately, many of the "Exit" signs in commercial buildings have a 6v gel-cell battery to keep the sign lit when the power goes off. Why 6v? No idea, but thankfully they are. So that's what we're using in our antique bikes - "Exit" sign batteries - because that's about all that is available today in 6 volts.

The gel-cells don't last very long, but they're cheap to replace and readily available. And they fit. Another alternative is the 6v "lantern" batteries, but they're getting harder to find (and more expensive).

I use a gel-cell in my Henderson - magneto ignition and battery-generator lighting. I think it's a 4 amp-hour. We're all pretty much in the same boat.

*** Even with a totally dead battery, a generator will make enough juice when spinning to start the bike IF there's enough residual magnetism left in the generator's field coils/pole shoes. Kick-starting may not get the generator spinning fast enough, but often push-starting will work.

Alternators don't have "residual magnetism". You can push-start an alternator-equipped bike only if there's some juice left in the battery.


Batteries used to be a simple thing.