It's not just theory, it is the laws of physics.
Current flows according to ohms' law formula; I = E/R, Where I equals current, E equals voltage, and R equals circuit resistance. This is NOT theory. It is the physical nature of electricity.
A bike draws the same amperage whether it be from a motorcycle battery, a car battery, or a truck battery. If the battery is 12 V rated, it is compatible, and the device connected to it determines the current that flows through the circuit.
A motorcycle battery has capacity to deliver many hundreds of amps, a car battery 1000s. Neither delivers any until connected to a load. And, it can't push any more current than the load circuit demands. A starter motor draws hundreds, an instrument bulb draw fractions of an amp. Each device draws current based on its offered resistance to current flow. A starter motor has low resistance. Check the formula. Plug in low values of R, where E =12 V and you get high values of I. It's the law.
Charging systems provide a small fraction of the power available from a battery. Another law, Watt's Law dictates P(Watts) = E * I . The 750's 210 watt peak alternator, provides 17.5 A peak. The 550's 150 watt alternator provides 12.5 A.
Auto alternators are usually stronger to charge the larger batteries they employ. Even those are only a fraction the capability of their batteries. They can provide 60, 100, even 120 amps in the right circumstances. But, only when the demand is placed on them. Car batteries can provide thousands of amps, again only when there is a demand.
Car batteries are charged using the same voltage potentials as motorcycle batteries. 14.5V is still the peak limit in both vehicle systems. The routine maintenance charge level is 13.8 v which is usually an average measurement.
No you cant use a car Bat if the Volt is the same as the bike. The Amps are the issue not the Volts.
This makes no sense at all. You can't have current without resistance. Other wise batteries would discharge without ever being connected. Fortunately it's against the law, Ohm's law.
If you were to disconnect the battery after starting your car, the voltage would skyrocket and fry all the electronics in the vehicle.
The battery is also a very large capacitor. The capacitance is used to stabilize the voltage regulation. Without the capacitor, the regulator loses some stability, and high voltage spikes can damage computer electronics whose sensitive inputs are unable to withstand these excursions. However, when jumping a bike from a car, there is no reason to disconnect the vehicle battery from the charging system. And, there are no computers in the average SOHC4.
Today's car alternator produces well over 100 amps. And when measuring volts when the car is running, some go over 14 volts. A bit more than these old bikes can handle. The books say 13.8, but I've measured almost 15 volts on some cars.
Just what do you think is at risk in the SOHC4? Certainly noting is at risk at 14.5 V which is routinely found in the SOHC4. Even 15 V is not unheard of. And, the battery can take such over voltage for short periods of time without too much outgassing. Lighting will, of course be brighter. But, it will usually survive up to about 17V, beyond which the filaments begin to burn out due to excess wattage consumption. A rated 50 W bulb @ 12.8V becomes a 98 W bulb at 18V.
The battery does absorb the charge, but if it is already fully charged, the electricity has nowhere to go but up the jumpers to your bike.
This is patently false. If you continue to provide power to a fully charged battery, it continues to absorb the excess power, converting the power to heat, and separating the Oxygen and Hydrogen from the Sulphuric acid compound via electrolysis.
You can not push electricity where it doesn't want to go. The must be demand for it, or it simply doesn't go anywhere.
The real eye opener for me was working a M/C parts counter for a few years and seeing what can be damaged by doing this stuff.
I don't doubt you encountered lot's of damaged stuff at the parts counter. But, your evidence is heresay regarding part returns. And, it's coming from people that seldom have a clue about things electrical and are often ham handed, if not outright liars who refuse to admit they reversed lead polarity even momentarily.
Besides, it's been my experience that theory and reality don't always agree.
True, theory and reality can disagree. But, the laws of physics are utterly reliable, when understood.
