scooter electrical

Let'sgoflying!

Let'sgoflying!

Touchdown! Greaser!
Joined
Feb 23, 2005
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west Texas
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Dave Taylor
Dad has a Honda Elite 50S, 1997 2stroke.

(12V) battery shows up dead, he replaces, it was >1yr old.
New battery dies quickly, boiled off.
System voltage checks at 15-18v
On advice repair shop they change VR. Two of these burn up.

Alternator? Rectifier?
 
Let'sgoflying! said:
Dad has a Honda Elite 50S, 1997 2stroke.

(12V) battery shows up dead, he replaces, it was >1yr old.
New battery dies quickly, boiled off.
System voltage checks at 15-18v
On advice repair shop they change VR. Two of these burn up.

Alternator? Rectifier?
Click to expand...

Hard to tell from your information. My first guess would be some sort of wiring problem that's caused all the rest of the symptoms. I don't think it's likely that the alternator could cause excess charging voltage but it is plausible if the winding is supposed to be isolated from ground and now there's a short between the coil and the engine. Same thing with the rectifier. Typically on these small engines the alternator is either a single coil feeding a 4 diode bridge rectifier with the bridge driving the regulator. You might disconnect everything (coil, bridge, and regulator) then check each for any shorts to ground (one of the four terminals on the bridge would normally be grounded.

I have seen some setups where there is no regulator and the only thing that limits the alternator output is it's impedance (kinda the scooter equivalent of a trickle charger), are you certain your's has a regulator?

Also for higher output some engines use a three phase winding and a 6 diode bridge. In that case there would be three wires from the coil instead of two.

In applications where the output current needs to be fairly high (like more than 10A or so) the regulation is done by controlling the excitation as it is with the alternator on a car or airplane. In that case a short in the excitation winding or the wires to it could cause excessive output even if the regulator was good. This kind of setup will have one or two smaller wires coming from the alternator to the regulator in addition to the wires attached to the rectifier.
 
Let'sgoflying! said:
Dad has a Honda Elite 50S, 1997 2stroke.

(12V) battery shows up dead, he replaces, it was >1yr old.
New battery dies quickly, boiled off.
System voltage checks at 15-18v
On advice repair shop they change VR. Two of these burn up.

Alternator? Rectifier?
Click to expand...

Is this the same bike you posted a picture of the diode bridge you were trying to find a replacement for?
 
Let'sgoflying! said:
like father like son,...my bike (27 yrs older than his) had an electrical problem too!
Click to expand...
At one point my dad had something like 14 Honda 750s. I don't think I've ever seen one with an electrical problem though. Did someone hack at the electrical system at some point?
 
Dave, I used to work with a guy who killed anything electronic he was around--he couldn't even wear a wristwatch--it'd die within a few days, not from anything he did mechanically--it would just stop working.

Are you like that?! Some aura of anti-electrons? ;-)
 
jesse said:
At one point my dad had something like 14 Honda 750s. I don't think I've ever seen one with an electrical problem though. Did someone hack at the electrical system at some point?
Click to expand...

it turned out to be a bad rectifier.
found a used one, battery no longer 'leaks'

Troy
I have a device break every week if not every day.
Yesterday was an electronic safe.
Who knows what today will bring.
I find the more stuff I get, the more fixing I do.
I'm thinking of replacing all my gadgets with Amish versions.
 
Let'sgoflying! said:
it turned out to be a bad rectifier.
Click to expand...

Sounds like a shorted diode in the bridge. That will kill a battery in short order. Had that happen in a 1974 Subaru years ago. Twice.

Oh, nevermind. I see you were cooking them, not draining them.
 
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