Eletrical Power Requirements GPZ1100--should have done the math

So, something I didn't think of and should have on the installation of my Dyna2000 with 2.2ohm coils. 

Whats happening, since installation it runs great, more power smoother etc...   However on the first long ride ~50 miles I blew the 20amp main fuse.  No big deal pop a new in on my way thinking it was just an old fuse.   Then on the way home from work..already road 60 miles in, pop another one leaving work.  Hummmm...whats going on here.  Put another one in, and bit more concerned something ain't right here, but it runs and I need to get home.  Make it about 10 miles in and test the volts on the volt meter/tach...crap...10.5 volts, should be 14.   Bikes running, shitty part of the highway need to keep going as far as possible.  Over the next 20 miles volts dropping and I'm going faster.   Need to make it to the last toll gate so I can pull off for pickup...just as I cross the gate blllaaaaaahhhh no power.  

Ahh....boys come get Dad, bikes down again.   Battery still has volts, but no amps left, so its not the battery, has to be rectifier or stator.  So at work start talking to the EE buddies..and it dawns on me as I calculate the power draw..the Dyna2000 uses 2.2ohm coils, I had been using 3.0ohm coils, with the Dyna2000 computer and the 2,2ohm I'm pulling more than 20amps across that fuse.   Lower ohm coils require MORE amps than higher ohm coils DOH!  And as the volts dropped it needed even more amps to keep up..until it either fried or over heated and shutoff.  

Solution, go back to 3.0ohm coils or shed amps somewhere else.  2.2ohm provide better stronger spark, so I want to keep those if possible.  I'm thinking LED headlights, taillights blinker etc...  Also I'm going to replace the rectifier and stator...they are ancient.   The headlight alone is 7amps less with a LED. 

Hopefully this lesson learned for me will prevent somebody else F'ing up like this.  What a dummy should have done the math.

577nitro-

Hi 577, the below calculation formula should help you get your numbers (between 10 & 13 amps dependent on voltage for the coils) If you are exceeding the circuit capacity why not add a stand alone 20amp supply to the coils and dyna through a by-pass relay ? Just out of interest what is the output of the stock charging system ( if you are running in excess of. 20 amps you must be getting close to it's output max 
PS: you might want to look at what gauge cable you are using (there is a calculator in my fault find guide, FAQ section - I can't seem to post links on an iPad !!)

 

Wookie58: Thanks for the info.   I don't think a separate circuit would work, unless I had another power supply.  It's the main bus fuse, the draw would still be more than the charging system can put out.   The fuse's blowing was a warning I didn't listen too.   If the voltmeter is wired to the charging system then the out put should be 14.2-ish volts and at least 20amps, or 284 watts max...I think if the math is right.  There is a lot lost to heat I think, this wires get pretty dang hot.  It's entirely possible that the battery is going bad, maybe lost a couple cells.  I need to do more testing tonight, once we unload it from the truck....all 540lbs of it.

Thanks
577Nitro

Yup...did the math with 2.2ohm coils at 13.5volts is 12.26amps for just the coils, with the lights and computer....yup...too much.

PS: Just found out you can have your stator rewound for higher output.  Need to find some place I guess.  

PSS:  RickyStator,com  

577nitro

The 2,2 ohm coils are for drag race and short distance only. There is no advantage or more hp power on a daily driver bike, you only generate extra heat and trouble. Use the 4 ohm coils and you are safe.

The 2,2 ohm coils are for drag race and short distance only. There is no advantage or more hp power on a daily driver bike, you only generate extra heat and trouble. Use the 4 ohm coils and you are safe.

I Believe you…only used them because that’s what came with the kit, and they said to use them.  It said nothing about race use or short distance.    I have some new 3.0 ohm coils I’m switching back to them, and getting a new stator and rectifier.   

There is a cheaper easier alternative, the factory ballasted systems use 2 ohm coils so you could simply fit a ballast resistor in the supply line to the coils (you could still fit a relay to by-pass the resistor during cranking for better cold starting - don't know what the weather is like in your part of the world) the Kawasaki resistors are expensive but the below is an option (check the current rating of whatever you buy)

 

You're probably fine but check the insulation along the main fuse wire(white wire) to make sure it didn't melt.
And I'm not sure of your exact model of bike, as it's not in your signature, but some of those 1100's came with 30amp main fuses instead of 20 amp. Double check your owner's manual.

I looked back in your posts and found that you have an 81 GPz. Partzilla list the main fuse as a 30amp for a 81 GPz1100 B1.

photo:partzilla


photo:filebase-Mcdroid/KZJOE900

If you choose to go the "bigger fuse" route in line with the build spec I would still advise using a by-pass relay. The original wiring and switchgear etc wasn't designed to handle a constant 13amp load when new so, 40 years on I think you would be asking for trouble expecting it to cope now (IMHO)

wrote:

Ahh....boys come get Dad, bikes down again.   Battery still has volts, but no amps left, so its not the battery, has to be rectifier or stator. 
.....
 I calculate the power draw..the Dyna2000 uses 2.2ohm coils, I had been using 3.0ohm coils,
.....

Ok.  Hold on here.  What GPz1100 do you have?  It is the 81, 82, or 83-85?

In any case, all of the 81-85 GPz1100 wiring diagrams do show a 30A main fuse.  But the manuals also show that the OE coils have a primary resistance of 1.8 to 2.8 ohms, which is pretty much what I'd expect the Dyna 2.2 ohm coils to measure.  These coils do not use any ballast resistors.  Also, the 1981 model has a secondary fuse that feeds these two ~2.2 ohm coils using a 10A fuse.  This 10A fuse is shared with both the coils and tail light circuit.

The Dyna 2000 manual says "An innovative dwell control scheme maximizes spark energy all the way to 16k RPM.  They Dyna 2000 can be used with 2.2 ohm or 3 ohm stock coils.  For maximum high RPM energy, use the Dyna DC4-1 gray coils."

The mention of the "dwell control scheme" here is key.  Once the ignition is computer controlled, you can do some fancy thing with the coil dwell time (the amount of time the coil in energize, or charging).  The computer can leave the coil completely off until the motor starts to turn, so the coils draw zero power when the bike is first keyed on.  But more importantly, the computer can chose to do a similar thing while the bike is running, and wait to energize each coil at just the right time to allow it to fully charge before the spark plug fires. This would draw much less average current that the simple voltage and resistance calculation, since the coil spends a good part of the time unpowered.  Given that the stock ignition used roughly 2.2 ohm coils, I'm guessing that the stock electronic ignition was also smart about how it controlled the dwell time.

I'm guessing the Dyna 2000 is optimized for the 2.2 ohm coils.  Those are the coils that shipping with the full Dyna 2000 kit.  I would not add ballast resistors to the system, as it was not designed to be used with one.

If you have the 3 ohm coils, the Dyna manual says those will also work.  Even if the Dyna 2000 is optimize for the 2.2 ohm, it's likely that you'll still have full spark at the modest 8500 RPM redline of the 1100.

Here is a second thing. 

Battery still has volts, but no amps left, so its not the battery, has to be rectifier or stator. 

That doesn't seem right to me.  The charging system (rectifier and stator) can put out a maximum amount of current.  If the total current used by the bike electronics is more than the output of the charging system, that extra current is drawn out of the battery.  If you run like this for long enough, the battery will discharge, the voltage will drop, and eventually the bike will stop running.  At that point, the battery should read low voltage.  It shouldn't want to start or run without a jump start or plenty of time on the charger.  The charging system may get pretty hot along the way, but the end result is same (dead battery).  If the charging system is not performing well, that would just cause the battery to discharge faster.  If your battery has volts, I don't think your problem is in the charging system.

I would say that the battery/charging/rectifier/stator system is unlikely to have anything to do with the fact that you are blowing the main fuse.

I would also guess that the 2.2 ohm coils with the Dyna 2000, if properly connected, should not  be causing the fuse to blow.  

If you can confirm that your bike was original equipped with a 30A main fuse, I would put the 30A in.  But I would also look very hard for any wiring faults or faulty devices that could be drawing excessive current. 

For example, the turn signal canceling unit on my '78 Z1R had failed, and it blew the main 20A fuse several times.  But mostly the bike ran fine.  I happened to remove the box from the mounting bracket and found the back of the box melted.  I couldn't see any damage unti l removed it.  Once I replaced the box I never blew another fuse.





 

DOHC I don't disagree with you, however during periods where both coils are energised Ohmes law is still relevant. With that in mind and the fact that the wiring is getting warm (probably due to lot's of little age related resistances) as I suggested, fitting a by-pass with it's own power supply to take a significant load off of the original wiring would be a smart move for reliability. 

wrote:

however during periods where both coils are energised Ohmes law is still relevant.

 

Absolutely. Ohms law gives the peak current. My point was that being smart about dwell reduces the average current. And the average is what determines things like wire heating, and is more directly related to causing fuses to open.

wrote:

fitting a by-pass with it's own power supply to take a significant load off of the original wiring would be a smart move for reliability. 

I completely agree. I was going to endorse that as well but forgot. If nothing else this mod takes the load off the aging switches, like the ignition and run/stop switch.

I still am concerned that this fuse blowing is caused by some underlying fault, one that just happened to coincide with the 2.2 coil change.