Bike charging system

 

At the end of last year, my Honda Shadow VT1100C stranded me on the return
trip from NY to FL, requiring me to truck it home & place it in storage for
the winter.

I dragged it out and am trying to troubleshoot teh electrical problem, and
remember all the details of the failure.

Original problem - would spin over, but not start until battery died (in teh
rain of course). I found a loose wire on the neg post of the battery, but
buy then the battery was dead. Bike would start with a jump, but only ran a
few miles before it quit (headlight dimmed and no more ignition), and I had
to coast into a driveway (did I mention the rain - it was the end of the
hurricane season).

So I bought a new battery and had it charged at a local (where I was) bike
shop who did some troubleshooting. I was told the bikes charging system was
not charging the battery. They did some measurements, tried a used voltage
regulator (no change), and told me I needed a new stator ($350+), plus a
weekend wait in the middle of nowhere. We opted to rent a truck & drive home
as the $$ were daunting.

So I am here with the bike apart - I trickled the new battery all winter &
it appears good. I got the bike started & it runs fine. I have the
maintenance manual for the bike & performed the resistance checks on the
stator per its recommendations - all 3 leads measure within the 0.3-0.5 ohms
with no shorts to ground.

So I am stumped. What voltage should I be measuring at the battery when the
bike is running?
When off and at rest the battery is now reading about 12.5VDC.
When running (idle) it reads about 12.25V.

Maybe I should drive it & measure the batt voltage a few times?

Any suggestions?

Thanks for the help!

SpiderG

 



That's about right...  depends a bit on temperature and whether the meter is
accurate


kicked in so COULD be alright, but I would immediately be suspicious of the
alternator - by 2000 rpm it should be well above 12.5 volts and say 3000 rpm
should be up at around 13.5 to 14.25 volts.....

Nick

 

Thanks for the reply Nick,

I've revved it up quite a bit, and although the voltage increases, it never
goes above 12.something. I think this is where it was decided that the
stator was bad, but as I said, its resistance measurements check OK...

Any idea if I could disconnect the alternator & measure its output running?
What should I be looking for, AC volts?

Thanks again
SpiderG



voltage

 



Not sure what the volts would be at the AC side of the rectifier pack - I guess
around 15 to 20 but this will depend on the alternator design and even whether
you can get to that side of things when its running - the fact that it never
get above 12v means ....

1) either you meter is duff (check it on another vehicle / car - should be
around 14 volts +/- 0.2 volts at 2000 rpm upwards)

2) something on the bike is duff in the alternator circuit - this includes
fuses (if any) wiring, rectifier pack, regulator, and the alternator itself
maybe just brushes if these are replaceable.

Really, if you are not familiar with such things, 10 mins with an auto electric
expert or down at the dealer will (should) identify the problem....

Nick

 



Well, the meter is a 3 month old Fluke 189 - seems to be OK on other
measurements, so I'll rule that out.


Well, I can trace the circuit in the manual, pulled the connectors &
performed the troubleshooting measurements as described there on the voltage
regulator and stator & they are OK.
There is no fuse between the alternator - voltage rectifier - battery that I
can see on the schematic, or from tracing the wiring.

I also swapped the voltage regulator for a used (but tested OK) one last
year with no change, so I am thinking I can rule out that part...

This is the root of my confusion.

I've had the bike to the dealer for other maintenance (well, it could be
this or this, lets replace this first & see if that fixes it), so I must get
more desperate before I go that route.

SpiderG