Charging output w/3 phase alt

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I referred to this a bit in a different thread but thought I'd post this FWIW re my 3 phase 180W alternator charging on my 73 Commando with a normal headlight: (WRONG! - NOTE posted later - I checked and found I do not have a standard bulb which, per what I've read, is a 45/40W; mine is an 80/100W. I forgot I had changed to this last year.)

Charging (voltage at battery), headlight off:
Idle (900RPM) 12.6v
1500RPM 14.6
2000 RPM 15.0
3000 RPM 15.17 (doesn't get higher regardless of increased RPM)

Headlight on, low beam:
Idle 11.6
1500 11.9
2000 12.71
3000 14.12

Headlight on, high beam
Idle 11.38
1500 11.7
2000 12.2
3000 13.35

Interestingly, with the headlight on, the battery is discharging until around 2k RPM and even then the alt is just barely keeping it charged. With hi beam you have to be around 2500 before the battery is no longer discharging. The 180W alternator was installed by a previous owner and I have no idea how old it actually is or how those figures would compare to a new alternator. Obviously, you can cruise along comfortably in 4th with the high beam on at around 60MPH with no worries re charging.
 
FWIW back at you. Those seems like regular 180w single phase numbers on a pre Markiii Commando.
 
Mike,
What was your battery voltage with the engine off? Are you using the Lucas rectifier and matched zener diodes or an electronic regulator/rectifier (Podtronics, etc.)? Keep in mind that any resistance in connections and switches from the rectifier to the battery will reduce the voltage seen at the battery.

Interesting chart. I'll have to take some measurements on my Interstate for comparison. It is running a 3-phase Lucas stator, but a Podtronics regulator/rectifier and a home-built wiring harness.
 
Batt voltage with engine off overnight - 12.66 (fully charged). System is standard Lucas rectifier and standard (pair) zener diodes. All connections are new (harness), additional heavy grounds to everywhere(!), and all connections are well cleaned/treated with deoxit/dielectric grease. I don't recall that the (original) alternator on my '71 could keep the battery charged at anything below around 2k RPM regardless of load but I may be mis-remembering.

I'll take another look at the headlight - I don't really know what I've got; I bought it from OB last year.
 
Thanks for posting those numbers, Mike. I'll check mine when I get a chance (next week, I'm out of town this weekend) and post the results. That sounds similar to what I'm seeing though. My LED voltage monitor goes green at about 2500 rpm with lights on, or about 2000 rpm with lights off.

edit: actually your lights-off readings look a lot better than what I'm getting. I have the Sparx R/R. I wonder if it's going bad?

Debby
 
The bulb on my headlamp is an OSRAM 64194 12v 100/80W. I think that's quite a bit higher load than oem. I bought the lens from OB last year when I dropped the original on the garage floor but the bulb from somebody else - can't recall who. I updated my first post to include this information.

After checking ratings, I found that the oem bulb would draw around 4 amps on high beam, the OSRAM draws 8.3 (and makes me wonder if the standard size wiring is sufficient. Some checking is in order...
 
MexicoMike said:
The bulb on my headlamp is an OSRAM 64194 12v 100/80W. I think that's quite a bit higher load than oem. I bought the lens from OB last year when I dropped the original on the garage floor but the bulb from somebody else - can't recall who. I updated my first post to include this information.

After checking ratings, I found that the oem bulb would draw around 4 amps on high beam, the OSRAM draws 8.3 (and makes me wonder if the standard size wiring is sufficient. Some checking is in order...

I thought 60w was more appropriate.
 
pvisseriii said:
FWIW back at you. Those seems like regular 180w single phase numbers on a pre Markiii Commando.

All "pre MkIII" Commando alternators were the 120w RM21. "MkIII" alternators were 180w single-phase RM23.
 
I thought 60w was more appropriate.

I believe that 60/55 watts is maximum for DOT. A 100/80 watt bulb is for "off-road only". But since Mike is in Mexico it doesn't apply. The stock Lucas wax candle was 50/45 and most halogens are 60/55. I have a 100/55 (Hella) in my bevel Ducati and I get lights flashed at me from 1/2 mile away on the high beam.
 
"But since Mike is in Mexico it doesn't apply."

LOL...yeah anything seems OK on the road here, from a couple of lanterns for "headlights" (yes, on a CAR!) to 6 Super Oscars - seen both examples. Gotta say, the guy with the Oscars could see a LONG WAY at night!

Oddly enough, Mexico has fairly strict car inspection laws on paper but out on rural roads you can't see any evidence of it at all. But at least there's still no ethanol here so my FG fastback tank should be OK for the forseeable future.
 
MexicoMike said:
"But since Mike is in Mexico it doesn't apply."

Oddly enough, Mexico has fairly strict car inspection laws on paper but out on rural roads you can't see any evidence of it at all.

Since when in Mexico does the laws in the books have to do anything with the laws on the street?

You need to abide my the Lucas Laws™ which clearly state that if you try to exceed the energy output of an amphetamine-induced inchworm you're asking for trouble.
 
Sounds more like a RM23 180w. single phase from the Mark III.
You sure it's a 3 phase?
3 phase will have 3 hot wires form stater instead of 2.


Added. My Dreer had a RM23 with electronic gauges, Boyer ign, Halogen 65/55, 8AH battery. Headlight would flicker at idle, apply brake, motor would die.
Installed Sparks 220w. 3 phase, end of issue.
 
Well, one thing seems clear - the original rectifier/diodes - despite being escapees from the "ancient electrical equipment" museum, are certainly capable of doing the job.

"Sounds more like a RM23 180w. single phase from the Mark III.
You sure it's a 3 phase?"

If I understand it correctly, the 3 phase has three wires from the alt while the single phase has 2, mine has three wires so I am ASSUMING it is 3 phase but I may be understanding it incorrectly

For more FWIW, I measured the actual amperage draw (fuse removed/ammeter in its place) of items with the ignition on (engine not running).

Ignition on .1 A
Headlight low beam 6.6A (which includes tailight)
Headlight High Beam 7.8A (ditto above)
Brake light 1.8A
Horn 1.2A

Then I measured with engine running at 4000RPM with no lights - 4A (trispark)

So it seems to me that the absolute maximum amperage draw one could expect to see with everything on at the same time - maybe sitting at a stoplight with the hi beam on (with my 100/80W bulb), blowing your horn at the guy in front of you with the bike revved to 4k to do a dragstrip start or wheelie would be about 15A. With the oem headlight bulb, that would be around 11A. Why the heck is there a 35A fuse? Also, the wiring for that 35A fuse is TINY compared to the wiring for a 30A 12v circuit in a car or boat. Seems a 20 fuse would be safer and even at that the wiring still looks too small to me. OTOH, I've not had a problem with it...
 
MexicoMike said:
So it seems to me that the absolute maximum amperage draw one could expect to see with everything on at the same time - maybe sitting at a stoplight with the hi beam on (with my 100/80W bulb), blowing your horn at the guy in front of you with the bike revved to 4k to do a dragstrip start or wheelie would be about 15A. With the oem headlight bulb, that would be around 11A. Why the heck is there a 35A fuse? Also, the wiring for that 35A fuse is TINY compared to the wiring for a 30A 12v circuit in a car or boat. Seems a 20 fuse would be safer and even at that the wiring still looks too small to me. OTOH, I've not had a problem with it...

Because 35A isn't always 35A... one of those British things...
 
MexicoMike said:
If I understand it correctly, the 3 phase has three wires from the alt while the single phase has 2, mine has three wires so I am ASSUMING it is 3 phase but I may be understanding it incorrectly

Just because the stator has "three-wires" doesn't automatically make it "three-phase".


MexicoMike said:
Why the heck is there a 35A fuse?

"35A" as written in the manuals and handbooks refers to it's BLOW rating! Which is 17A continuous rating.

If you replace an original 1-1/4" British glass fuse with another type, make sure that you don't fit a 35A continuous rated fuse instead, as it won't blow until 70A. :shock:
 
Hmm, maybe I'd better take that regular Buss 35A fuse out of there. :shock:

I thought a fuse's rating was its rating - I have never seen a fuse (other than specifically designed slo-blo fuses) where a 35A fuse wasn't supposed to blow until 70A. But I guess it's time-related...
 
MexicoMike said:
Hmm, maybe I'd better take that regular Buss 35A fuse out of there. :shock:

I thought a fuse's rating was its rating - I have never seen a fuse (other than specifically designed slo-blo fuses) where a 35A fuse wasn't supposed to blow until 70A...


Charging output w/3 phase alt
 
Interesting - never seen anything like that in the USA. Not to say we don't have them but I've never seen one. The regular glass Buss fuses that are used in older cars/bikes just have a rating stamped on one of the end caps them - like AGC 15 or AGC 20, etc. This seems to me to be very confusing - at least in the USA. If the manual says you need a 35A fuse, you go to the auto parts store and buy a 35A fuse, not a 17A fuse.

However, I totally agree that the 17A makes more sense in light of the wire size. OTOH - I seem to recall that I blew some 20A fuses back when I was first trying to get the bike to run 5 years ago but my memory could be faulty...
 
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