Topic: 75 CB550 Stator Question

[The Machine]

Bike is not charging, I replaced the reg/rect (Rick's Motorsport). Checked all connections. Did the stator test from Rick's video

Continuity test was good, 1.2 all around and stator is not grounding out. But when I checked the AC volts with bike running, at idle it showed consistently .2 and when I rev it up it'll go up to 1.0. I believe I have the setting correct on my multimeter (see pic).

Am I doing something wrong or I have a bad stator? Mine doesn't look burnt out, these rarely go bad but with my luck it's probably bad lol. I've checked all the wiring coming from the stator to make sure it's not kinked anywhere and all connections are clean. 

[The Machine]

Hi Cal, my battery (Shorai lithium) is full charge it's at 14.35. Shouldn't the output from the stator be a lot higher? The wiring is correct, it's the same set up as my last rec/reg and it worked fine. Just all of the sudden it stopped charging. I've tested both reg/rec and seems fine, ohm reading was good. I've checked the ground wires and those are all good.

I've read almost all the post about this and I'm at a lost.

[The Machine]

Started to do your checklist and all the sudden it's charging now. BUT... when I slowly increased the throttle I noticed some smoke coming from the green wire from the regulator (batch with the blk and wht wires). The wire melted the electrical tape I had on it and is very brittle now. This green wire is a ground, does this mean I have a bad ground? 

[TwoTired]

Hi Cal, my battery (Shorai lithium) is full charge it's at 14.35. Shouldn't the output from the stator be a lot higher?

No.  If the Vreg sees 14.35V, its should turn down the alternator field voltage so the stator can't make much power at all and protect the battery from overcharge.

The stator should only make full power when there is enough load to weaken the battery (lowering the voltage) or the battery is depleted (also low voltage).

If you want to see full power from the stator the field coil voltage must be high.  But, beware of overcharging the battery, when that occurs.

There are other charging systems that make the stator produce full power all the time, and then shunt what the system doesn't need into ground.  The SOHC4 isn't one of those.

Cheers,

[jaytee-nz]

Thread hijack here with a theoretical question (primarily for TT).
With a fully charged new battery and assuming all is well in the alternator, v reg, wiring departments, how long would it take to discharge the battery while the engine is at idle speed only and with a couple of engine re-starts thrown in as well ?
I get about 10 minutes of idling time before things go south. Trying to establish if I have a charging problem or not.

[The Machine]

Hi twotired, thank you for the explanation. Can you explain why or what would cause the green wire from the regulator to heat up like it did when I revved the motor?

[TwoTired]

Thread hijack here with a theoretical question (primarily for TT).
With a fully charged new battery and assuming all is well in the alternator, v reg, wiring departments, how long would it take to discharge the battery while the engine is at idle speed only and with a couple of engine re-starts thrown in as well ?
I get about 10 minutes of idling time before things go south. Trying to establish if I have a charging problem or not.

Need a "balance sheet" comparing outgo (Discharge) with Input (charging).

Do you know the total load you bike places on the electrical system?  Stock bike drains at a rate of about 10 Amps.  This is about the same for a 750 or a 550.

The alternator is capable of about 150 Watts for a 550 or 210 watts for a 750.  Assume the desire is to keep the system at about 12.6V and you get charging systems that peak at 12A for a 550 and 14A for 750.   Leaving charge for the battery available at 2 Amps and 4 Amps for each example in a cruise situation.

Both charging systems make about 1/3 of peak power at standard idle speed.   That would be 4 amps for the 550 and 4.6 Amps for the 750.
 For both bike the battery will deplete at about a 6 amp rate during idle.

The battery is the buffer for the electrical system.  The 550's stock battery is 12AH rated vs. the 750 14AH rated.  The rating system isn't exactly straightforward, though.  But an approximation is that you can 12 amps or 14 amps out of each battery for one hour each before declaring it depleted.  (its  actually less than that as the spec is for a load adjusted for a 10 hour depletion rate that takes it to 10V.  Then they do math to equate an amp hour rate.)

Anyway, at idle, a 6 amp draw means something akin to 2 hours for the 550 and a bit longer for the 750 only idling.


These are all approximations, though.  As the book numbers are stated for diagnostic and replacement purposes.  Due to manufacturing tolerances, some charging systems can actually make a bit more than the failure threshold numbers printed in manuals.  None should make less.

If you have modified the bike's load parameters, the regulator parameters, or the battery parameters.  You have to know what the magnitude of change to each in order to make a corrected "balance sheet" or electrical budget for the changes you've made.

Further, few actually idle to battery depletion.  Normal operation mixes idling with cruise.  Now you need to know the percentage of time spent in each mode to know depletion rate.  Cruise puts 2 to 4 amps into the battery .  Idle takes 6A out of the battery.  So, you need to be in cruise about 3 times longer than idle in a periodic rate for the smaller bikes.

Any of this help?


Cheers,

[TwoTired]

Hi twotired, thank you for the explanation. Can you explain why or what would cause the green wire from the regulator to heat up like it did when I revved the motor?

Did you monitor the voltage during such an event?  Do all your system loads use this same green wire?

The insulation melts when the current through the wire is too high.  Check your battery to frame connections, and all your electrical loads return paths to Battery NEG connections.

Mostly, the green wire melts when the battery is connected backwards.  This forward biases the rectifier diodes making them behave like a short (through the alternator stator windings) between the plus and minus terminals.  This allows the battery to dump its energy into the circuit (hundreds of amps) generally melting both green and red wires (Honda convention colors), as those are smaller diameter than the wires in the stator.  A failed, shorted rectifier can do the same thing, btw.

Cheers,