Battery being drained, won't hold charge - 1985 Magna V45 (US)

[twistekeys]

Just got my 1985 Honda V45 Magna the other day. It was running alright and besides other small mechanical kinks the battery went dead on it. No big deal, it's an old bike. So I went and got a new battery and decided to go for a ride today. It went well, the bike ran spectacular, but there was one thing...

After about 50 miles we stopped to take pictures, when I tried starting again it just clicked... I bump started the bike and got going again no problems. At 70 miles in we stopped at a burger joint and as I went to start the bike the lights went dim and there was no sound. So I bump started the bike. it ran fine for about 2 miles. This is when it started to seriously backfire (literally) and I was at 100% throttle going 55mph. As soon as I letoff the bike completely cut out. With absolutely no electrical response.

(As a note, after installing the new battery the bike would buzz for 3-4 seconds after switching the key to on, but would start normally.)


OBVIOUSLY it's in the charging system, but what exact part is it? Ever heard of this?

 

[AlphaDogChoppers]

Your first mistake was not bothering to check the integrity of your charging system when you replaced the battery. There is a good chance your old battery was just fine. You've also considerably shortened the service life of your new battery. Did you give it a conditioning charge at 1 A or less before putting it in the bike? Did you promptly recharge it after running it dead? If it has been sitting in a discharged state for a few days, you might be buying yet another battery.

I see this all the time. Battery is dead, so it must be the battery, right? Bad assumption.

I wrote an article about diagnosing the charging system. It was written with the Harley charging system in mind, which is a single phase stator. Your bike will be a 3-phase stator, so you will be measuring voltage from three stator wires, not two.

http://alphadogchoppers.com/wrenching/2005/chargingsystem/