what the heck keeps a motorcycle battery charged

[mydlyfkryzis]

Only real difference is that on modern bikes the zener diode is built into the rectifier. When the battery is charged it'll dump excess power to ground.

Unless the bike uses electromagnets. In which case the ecu with regulate how much power is sent to the electromagnets, and it will regulate itself to produce power equal to consumption.

there are 3 types of charging systems in use:

1. Permanent Magnet Rotor: This type generates current and voltage in proportion to RPM. The alternator is itself is unregulated. the output is put through a rectifier and then a zener diode to ground the excess voltage. The rectifier and diode can be either separate or combined. My CB360 is this type.

2. Brush type alternator: This unit has no permanent magnets. The field (on the rotor) is varied by the voltage regulator to maintain output. The rotor is connected the the regulator/rectifier through 2 brushes riding on a commutator. The older CB750's were like this. The brushes and commutator rings wear out and need to be replaced periodically.

3. Brushless alternator: Similar to the brush type.. The field coil does not rotate (so no slip rings and brushes needed). The rotor passes through the center of the coil and is magnetized by the field coil. Because of no rotating electrical parts, it is maintenance free. The field coil is also regulated to maintain output.

The regulators on #2 and #3 can be run by an ECU or a stand alone regulator. My NH750 has a stand alone regulator.

You can't kick start a bike with type 2 and 3 charging systems as they put out no voltage without the field coil being energized.

Fuel injected bikes need the battery to start the fuel pump. Dead Battery, no fuel and the injectors don't work.

Older bikes with the type 1 alternator can sometimes be kick started. My CB360 can barely be, lot's of kicking. It is easier to push it and bump start it. Bump starting turns the generator a little faster, so there is enough voltage for a spark.

I won't even touch the older Harleys and such with generators....

[Johnj]

So, if you have a kick start, you could have a fully funtional bike without needing a battery?

You are correct. I had several 650 Triumphs and a 650 BSA without batteries. They had capacitors instead.

[mydlyfkryzis]

So, if you have a kick start, you could have a fully funtional bike without needing a battery?

You are correct. I had several 650 Triumphs and a 650 BSA without batteries. They had capacitors instead.

Capacitors are in some respects, a form of battery.

Essentially, you need a device (battery/capacitor) on the generating circuit to store at least a small amount of voltage for a reference and to even out the uotput from an alternator/generator/dynamo. without a reference voltage, the output can vary quite a bit.

[ledzep12184]

wow, you guys know your stuff. I'm not sure whats wrong right now, I made the mistake of buying an old bike for my first - and its a bit of challenge keeping the thing together. The sad thing is that the physical engine runs great, but all the peripheral systems seem to be failing. I don't want to get taken at the shop but I love riding the thing too much just to let it sit.

I discovered today that the bike will turn over whenever I put it in neutral. I had been just starting it in gear. I think maybe the extra strain was detrimental to the starter.

[earwig]

The alternator will not produce enough power at idle to keep a bike and all of its electronics/components running. On my bike the ecm, clock and fuel pump would laugh at me if I disconnected my battery. As far as just needing a battery to turn the bike over isn't true either unless your bike is old as hell and very primitive.

[Sev]

Only real difference is that on modern bikes the zener diode is built into the rectifier. When the battery is charged it'll dump excess power to ground.

Unless the bike uses electromagnets. In which case the ecu with regulate how much power is sent to the electromagnets, and it will regulate itself to produce power equal to consumption.

there are 3 types of charging systems in use:

1. Permanent Magnet Rotor: This type generates current and voltage in proportion to RPM. The alternator is itself is unregulated. the output is put through a rectifier and then a zener diode to ground the excess voltage. The rectifier and diode can be either separate or combined. My CB360 is this type.

2. Brush type alternator: This unit has no permanent magnets. The field (on the rotor) is varied by the voltage regulator to maintain output. The rotor is connected the the regulator/rectifier through 2 brushes riding on a commutator. The older CB750's were like this. The brushes and commutator rings wear out and need to be replaced periodically.

3. Brushless alternator: Similar to the brush type.. The field coil does not rotate (so no slip rings and brushes needed). The rotor passes through the center of the coil and is magnetized by the field coil. Because of no rotating electrical parts, it is maintenance free. The field coil is also regulated to maintain output.

The regulators on #2 and #3 can be run by an ECU or a stand alone regulator. My NH750 has a stand alone regulator.

You can't kick start a bike with type 2 and 3 charging systems as they put out no voltage without the field coil being energized.

Fuel injected bikes need the battery to start the fuel pump. Dead Battery, no fuel and the injectors don't work.

Older bikes with the type 1 alternator can sometimes be kick started. My CB360 can barely be, lot's of kicking. It is easier to push it and bump start it. Bump starting turns the generator a little faster, so there is enough voltage for a spark.

I won't even touch the older Harleys and such with generators....

With the exception of large displacement touring bikes the majority of rides now-a-days are three phase permanent magnet alternators.

The alternator will not produce enough power at idle to keep a bike and all of its electronics/components running. On my bike the ecm, clock and fuel pump would laugh at me if I disconnected my battery. As far as just needing a battery to turn the bike over isn't true either unless your bike is old as hell and very primitive.

It should be making just enough power to keep the minimum stuff going. Which is to say - fuel pump, ignition and your headlight. Possibly even the brights.

If you start throwing in the horn, turn signals, and brake lights then you're in a state of discharge.

As for laughing at you when the battery is disconnected, all the electrics on your bike are run across the battery. Disconnecting the battery breaks the alternator circuit and everything dies.

One of the neat (illegal) tricks that some racers used to do was pull the magnets out of their alternator. Save themselves a couple 4-5lbs, and make their bikes THAT much faster. Of course they were running on nothing but battery power. So they had to hope that they would finish the race before the battery dies.

That and I can start any of my bikes with the alternator disconnected. Just can't keep it running indefinately, tends to stop after the battery fully discharges.

[slimcolo]

there are 3 types of charging systems in use:

Magnito?

[mydlyfkryzis]

Magneto is an ignition system, not a charging system. Magneto systems can be kick started without battery. On the bikes with magnetos, you could start them with no battery, but if you didn't have a battery, you generally overvolted the lights and other electrics. The systems back them were primitive.

[mydlyfkryzis]

With the exception of large displacement touring bikes the majority of rides now-a-days are three phase permanent magnet alternators.
[/quote]

I don't disagree with this, but I believe the reason is more mechanical. The permanent magnet (PM) generators are more durable at high RPM. If you engine is redlined above about 9000 RPM, you probably have a PM type alternator. The reg/rect is lighter too. If you are building a sport bike, the advantages of a PM alternator (High RPM/Light Weight) outweigh the more consistent output from a field powered alternator.


Edit: Add cheaper to the PM alternator too...

[Johnj]

there are 3 types of charging systems in use:

Magnito?

Magnitos are an ignition part and have nothing to do with a charging system. They do work like a generator or alternator, ie magnetic induction.