Re: 1982 Honda CB 650 -- Electrical / Charging problems (as usual)
- From: "FB" <flying_booger@xxxxxxxxx>
- Date: 27 Apr 2006 10:53:09 -0700
ben@xxxxxxxxxx wrote:
I checked the voltage yesterday while the bike is running, and
reving... 8 volts or so, I took off the stator cover and sprayed
electrical parts cleaner and used some high grit sanding paper to clean
off the stator/coils...
I really doubt that you sanded the enamel insulation off the stator
coils. That would be a very expensive less in what not to do.
Alternator stators have only enamel for insulation, if you pierce the
enamel, the coils short out to each other.
I think you may be talking about slip rings on the alternator rotor?
Does that alternator have carbon brushes? When brushes wear out and get
short, there isn't enough spring pressure to push the brushes against
the slip rings hard enough to make good contact. So there is high
resistance and the excitation current to the rotating electromagnatic
field is reduced.
How many wires go to the alternator, three or five? A three wire
alternator has an external permanent magnet rotor and the voltage
regulator simply rectifies AC current and shunts excess current to
ground to be burned up as hear.
But the five wire alternator will either have brushes or it is a
brushless type that Kawasaki and Honda used. That type is what is
called an "excited field" alternator.
The regulator will have a large power transistor that passes full
battery voltage to the
alternator rotor until the voltage reaches a certain level. Then the
transistor stops passing voltage. The transistor is ON or OFF, nothing
in between.
Charging voltage tests are done with a fully charged battery that is in
good condition
When you increase RPM, the voltage should rise to something like 14.5to
15.5 volts at 5000 to 6000 RPM, then you should see a sharp decrease in
voltage. It's best to use an analog voltmeter with a needle instead of
using a digital meter that takes its own sweet time counting
millivolts.
When you decrease the RPM, the transistor should turn ON again and the
voltage should rise and fall noticeably as you cross and recross the
RPM at which rising voltage triggers the transistor.
now when i'm running the engine its at about
12. I know I need about 13-14v to successfully be charging the battery.
That tends to indicate the battery plates are sulfated. Sulfation is a
normal process that takes place when a battery is discharged. Lead
sulfate forms on the spongy lead plates and charging current from the
alternator or a battery charger cannot penetrate the lead sulfate
layer. All that the battery can accept is a "surface charge" on the
plates.
Motorcycle alternators are not very powerful, compared to a car
alternator. A motorcycle alternator cannot raise the voltage of a badly
discharged or sulfated battery, all it can do is boil the water in the
battery.
Motorcyclists think that they are doing their battery a favor if they
keep adding water as the level lowers. Water has a lower specific
gravity than electrolyte, which is a 50/50 mix of water and sulfuric
acid.
The normal chemistry of a battery takes the sulfur out of the
electrolyte and attaches it to the spongy lead plates. The remaining
electrolyte is mostly water, which doesn't conduct electricity that
well. All the alternator can do is boil the water out of the battery.
So, if your battery seems to always need water, chances are the plates
are sulfated, and it will only get worse, because the alternator simply
cannot charge the battery and neither can a battery charger.
Any ideas? I mean... something changed. Possibly a loose connection
somewhere or high resistance somewhere? I am thinking of sodering
anything that looks suspect. What wires should I soder, which wires
shouldnt I?
Look for connections coming out of the alternator that have insulation
that is turning brown or black. Also, look for the two DC outputs from
the regulator for burned or blackened connections. Coonections that
have burned and blackened are poor conductors of electricity, they burn
it up as heat instead.
Also, some Hondas with shunt-type have a remote DC sensing wirethat
goes up to the instrument panel, instead of sensing voltage directly
off the battery. I don't think you have that type of permanent
magnet/shunt regulator though.
Also, check your engine-to-chassis ground cable and look for bad ground
connections from the voltage regulator to the chassis if your machine
has to use a chassis ground instead of a ground wire.
And if it comes down to it, where would I buy stator/coils/etc for it,
aftermarket or OEM?
Check with Electrosport USA.
.
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