kick only using a capacitor (and no battery)
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·^That pretty much sums it up. Since a magneto makes its own power, there is no need to get external power to the coil to spark the plugs. If you ride pretty much all of the time and can guarantee that your capacitor will always have a charge, then in theory it would work, but I wouldn't rely on it. With that being said though, with a minimal system (headlight, brake/tail light, kick only) you can get away with a very small battery, even a nice little battery pack, but that topic has been covered ad nauseam on this board.
British bikes with an alternator system will work with no battery and a capacitor wired in to help energize the alternator and fire the ignition. It was a common chopper conversion in the '60s and '70s and that continues to this day.
A Sportster uses a generator and coil with points ignition will not start without a battery no matter how many capacitors you bolt on it! Totally different animal. So it is a Magneto, or a battery, no in between!
Robbie
A Sportster uses a generator and coil with points ignition will not start without a battery no matter how many capacitors you bolt on it! Totally different animal. So it is a Magneto, or a battery, no in between!
Robbie
G
Guest
·So do I......
Get one that is retard-able...
Don't get a fixed mag nailed down at full advance...
A bear to start..!!
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G
Guest
·Yeah......
Can't see it...But, you dang sure will feel it....
.........
.....................SMOKEN..............................===================================================================
............This little Guy is going to wake up really fast............
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ok, i have a decent understanding of the charging and ignition systems. i guess where i got misled is if you look at a post a few away from this one, titled "battery inside the primary" or something like that, there is a gentleman speaking about his 55 pan, and hiding his battery. there is a tangent about capacitors, and HATCH specifically mentions using a capacitor instead of a battery or a mag. sooo...i guess i need Hatch to chime in here, and explain what he meant, or if was bringing triumph technology to a BT topic. i didnt think the capacitor deal was possible, but if it is, i'd like to know about it.
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933 Posts
Noticed that. I'd like to hear more (if he cares to expound)............
I'll give you my .02, which you can take for what it's worth, but I went down this road a few years ago and this was my experience (excuse the lay electrical explanations, and this only applies to HD since I know nothing of other makes):
- generator vs alternator: I can't imagine this working unless you had an alternator motor
- Voltage regulator/rectifier: (assuming we agree it must be an alternator motor) you need a shunt drop regulator/rectifier. as I understand it, that's old technology. Newer, and high output stuff is probably not using that. I know of no way to tell from looking at one. the difference is basically in the way it releases or sheds off electricity. Shunt drop passes any on, and only dumps excess back to ground. The later method (not sure what it's called) only passes on electricity when it sees a need. The point here is that a shunt drop version will allow some electricity to pass when kicking, but the other won't. If you hook one up and kick the bike w/ a light on, you'll know right away which one you got b/c you'll see your light flicker, or not.
- Points vs. Elec ignition: my experience and most will probably agree, that electronic ignitions are pretty sensitive to voltage. So that means you will be limited to points (hell, i like points)
- lastly, do not expect it to start like a bike with a battery or a good magneto. it will work reasonably well, but there is a trade-off.
I think Scott is spot-on about the regulator. I know Triumphs, and had a few running with no battery AND no capacitor. Starting was almost the same as with a battery. Running no different, save the horn never worked (too much draw).
Triumph all used a zener diode as a regulator, and it operates exactly as Scott stated for a shunt drop reg.
Cosmo
Triumph all used a zener diode as a regulator, and it operates exactly as Scott stated for a shunt drop reg.
Cosmo
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OK....I spoke too soon. Thinking back I could have sworn I did it on a generator motor, but I can't remember which bike for sure. Yes, it is triumph technology. I thought the capacitor worked as a miniature,quick charge/discharge battery replacement, and that it actually fired the points as opposed to exciting the alternator. I agree with the magneto thoughts....they work great, and look soooo cool. Sorry if I confused the issue. Old age and beer are my only flimsy excuses....hatch
Just joined here, and I found one of my favorite topics to geek out on -- motorcycle electrics. Electrical engineering was my major in college before I dropped out (long story). And when I worked as a motorcycle mechanic in a former life Limey electrics were kind of my specialty.
Lots of people run capacitor/battery eliminators. Most people don't know why they work. This is pretty much it:
if you look at the charging system of a bike under an oscilliscope while you kick it through, you see that the voltage doesn't stay constant...it isn't a straight DC voltage, but more of a pulse DC. This is especially true of alternators because assuming your alternator is putting out an AC sine wave, it goes through the rectifier which essentially inverts the netgative half of the wave form.
So instead of the wave looking like a positive hump, and then a negative hump (google sine wave to see what I mean), it looks like a series of positive humps....going from zero volts to 12 to zero to 12.
NOw when the bike is running at normal RPM these occur so fast as to not matter, but at low RPM when kicking it's a big deal to your coils.
Coils fire because the volte drops, collapsing the magnetic field inside of them creating the spark. That's why they fire when the points open -- when electricity stops flowing.
Well, at low RPM voltage is dropping both when the points open and when the voltage out of the alternator drops to zero. No steady spark.
The Capacitor acts as a very fast charging/discharging battery. When the voltage goes up, it charges, when the voltage drops to zero, it dumps its charge essentially evening out the waveform and letting the coils build up a good spark.
So will it work with a particular bike? Triumphs and BSA, sure. ran one for years. I've even run them on electronic ignition and while you would think it wouldn't work it did.
I've verified they work on alternator shovels too, and generator pans. The only danger with a genny harley is that it could theorhetically lose polarization if it set to long -- But since you dont have a battery, the worst that would probably happen is screwing up your regulator. And you shouldn't let your bike sit.
Hope that helps, YMMV,
Lots of people run capacitor/battery eliminators. Most people don't know why they work. This is pretty much it:
if you look at the charging system of a bike under an oscilliscope while you kick it through, you see that the voltage doesn't stay constant...it isn't a straight DC voltage, but more of a pulse DC. This is especially true of alternators because assuming your alternator is putting out an AC sine wave, it goes through the rectifier which essentially inverts the netgative half of the wave form.
So instead of the wave looking like a positive hump, and then a negative hump (google sine wave to see what I mean), it looks like a series of positive humps....going from zero volts to 12 to zero to 12.
NOw when the bike is running at normal RPM these occur so fast as to not matter, but at low RPM when kicking it's a big deal to your coils.
Coils fire because the volte drops, collapsing the magnetic field inside of them creating the spark. That's why they fire when the points open -- when electricity stops flowing.
Well, at low RPM voltage is dropping both when the points open and when the voltage out of the alternator drops to zero. No steady spark.
The Capacitor acts as a very fast charging/discharging battery. When the voltage goes up, it charges, when the voltage drops to zero, it dumps its charge essentially evening out the waveform and letting the coils build up a good spark.
So will it work with a particular bike? Triumphs and BSA, sure. ran one for years. I've even run them on electronic ignition and while you would think it wouldn't work it did.
I've verified they work on alternator shovels too, and generator pans. The only danger with a genny harley is that it could theorhetically lose polarization if it set to long -- But since you dont have a battery, the worst that would probably happen is screwing up your regulator. And you shouldn't let your bike sit.
Hope that helps, YMMV,
Thanks, I totally spaced on the intro board. I've now intro'd.
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Welcome bdgr....It sometimes is nice to know the complete story....and you told it. thanks...hatch
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I am a Mag man but like to run in combo with a small battery, and a franks with my generator bikes. I have even gone as far as running a small lil battery from an "EXIT" sighn. Please Don't steal the ones from your place of employment! We need to focus on ocupational safety here!!!!
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209 Posts
For the past couple of months I've been running this small "car alarm" battery in the oil tank I made for my bike because it was actually small enough to fit and it was only $12. Until yesterday, it provided plenty of power to start my kick only, non-magneto 74 ironhead. I think the vibrations have finally gotten to it though, as it had no charge at all yesterday when I tried to leave work.
http://www.amazon.com/dp/B0010Z4MDK/ref=pe_175190_21431760_C1_cs_sce_3p_dp_1
I've heard good things about the shock-proofness of these ballistic batteries, so I went ahead and ordered one last night. At 2.5x2.5x4.25 inches, it's smaller than the car alarm battery I had and still produces 8ah instead of 5 from the other battery. It's not much bigger than a capacitor, but it's supposed to start a 600cc sport bike so maybe it will be just the ticket for me.
http://www.ballisticparts.com/products/batteries/4cell.php
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http://www.amazon.com/dp/B0010Z4MDK/ref=pe_175190_21431760_C1_cs_sce_3p_dp_1
I've heard good things about the shock-proofness of these ballistic batteries, so I went ahead and ordered one last night. At 2.5x2.5x4.25 inches, it's smaller than the car alarm battery I had and still produces 8ah instead of 5 from the other battery. It's not much bigger than a capacitor, but it's supposed to start a 600cc sport bike so maybe it will be just the ticket for me.
http://www.ballisticparts.com/products/batteries/4cell.php
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457 Posts
all i can speak from is personal experience. on my 40 knuck with a Hunt mag, no battery, and a Cycle Electric 12V generator (the kind with the regulator on the end), it runs just fine with or without the *battery eliminator*. the reason i keep it on mine is that i heard it's supposed to act like a small battery and help even out the fluctuation in voltage, as well as reducing the flickering of the headlight at idle.
in application, i can't really tell it's doing a darned thing different with it installed or not, but i keep it wired in to be on the safe side.
btw, i wouldn't pay the outrageous price for a *battery eliminator*. it's just a capacitor. i forget where i got this info but just get a big electrolytic capacitor rated for at least 4700 microFarads and 25 volts. 35 volts is even better and more microFarads doesn't hurt either. you can grab them off eBay for like $6 a pop.
-dan
in application, i can't really tell it's doing a darned thing different with it installed or not, but i keep it wired in to be on the safe side.
btw, i wouldn't pay the outrageous price for a *battery eliminator*. it's just a capacitor. i forget where i got this info but just get a big electrolytic capacitor rated for at least 4700 microFarads and 25 volts. 35 volts is even better and more microFarads doesn't hurt either. you can grab them off eBay for like $6 a pop.
-dan
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