Battery may be bad. If you're seeing between 13 to 14 volts when it's running from the charger, assuming you've revved it up to 2000rpm+, that's nominal although nearer 14vdc is desirable.
Do a load test as follows to see if the battery is any good:
- charge the battery up so that, 1 hour after you remove the battery charger, the battery reads between 12.55vdc and 12.65vdc. REASON: each of the 6 cells puts out 2.1vdc, and 6 x 2.1 = 12.6vdc, so if the battery is any good at all - you must be able to see it at very near 12.6vdc. And NOT immediately after removing the battery from your trickle charger. Let it set for 1 hour then check it. If after 1 hour you can never achieve 12.55vdc to 12.65vdc, battery is no go.
- p.s. a battery that is in poor shape loses any charge you put on it *fast.* Yesterday I read a Yuasa battery (from a decrepit cb750 '71 I just bought) -- I read the battery 1 hour after pulling the charger off, it read 12.4vdc -- bad sign there because that was the closest by charging it I could get it to 12.6vdc. Well it dropped down to 4.7vdc in just a few hours.
- if you can get the battery to read 12.55vdc -> 12.65vdc one hour after removing the trickle charger, put the battery in the bike and hook it up. Get your voltmeter handy. Now turn the key on but DON'T START THE BIKE. Just make sure the light and dashboard lamps have come on.
- now with the ignition on, but engine not running, read the battery. The battery is 'under load' right now -- it's providing power to the lights etc.
- If the battery drops well below your 12.6vdc, your battery is no good.
Battery plates lose material over time and become unable to hold a charge.
So even though your charging circuit's putting out 13-14vdc, if the battery is no good, it doesn't matter.
Now luckily your charging circuit seems like it's in good shape. When you get the battery issue sorted out, rev the bike to 2000rpm+ and verify you're seeing close to 14vdc across the battery -- meaning your charging circuit is fine.
