Charging system questions?

I understand there is definately more starting power on tap by switching a 6 volt system over to 12 volt. My question is , what is the advantage , if any , for useing an alternator instead of a generator? I am talking strictly antique farm tractors here. 12 V alt VS 12 V gen??

Actually the starting POWER of a 12V system vis a vis a 6V system remains constant if the AH rating of the 12V battery is the same as that of the 6V battery.

The advantage of the alternator is improved reliability and higher output, especially at lower RPM.

Dean

If you switch to 12 volts and keep the 6 volt starter they really crank fasttttttt which can improve starting, although it can sometimes be a bit tougher on starter drives and gears.

On smaller tractors with good heavy batteries and 0 or 00 gauge cables and a well tuned good engine and the right oil, they can start okay at the stock 6 volts. IM NOT SAYING 12 DONT MAKE THEM CRANK FASTER duhhhhhhhhhhhhhhhhh Im ONLY saying the original design served them well (smaller tractors) for many years ifffffffffffff well maintained but notttttttttttt if they are not. My 6 volt tractors started at 6 volts in cold temps and that was kind of neat....

The genny is fine if originality is an issue but an alternator is cheap and reliable and pumps more amps even at lowwwwwwwww RPM. I prefer the 3 wire GM 10SI family they are cheap and readily available.

If you swap polarity due to an alternator dont forget the ammeter leads and ignition coil leads need swapped.

John T

Generally speaking, a generator wastes half the power it could potentially make due to it's lack of recfifiers. It's like having a four cylinder engine that only fires on two cylinders. It also relies on the charge output to be carried by brushes which presents a wear and design problem. Alternator makes full use of its potential and does NOT use brushes to carry charge output. That is a HUGE advantage.

As as far as 6 volt versus 12 volt, they are not equal. They could of been, yes, but for the most part, things never evolved that way. Most 6 volt starters with the proper sized batteries do NOT have equal cranking torque and RPM when compared to their 12 volt counterparts. But, some of that is due to better design over time, and not just the voltage differences. With 6 volt starters, there were size limitations to get more cranking power. As the voltage climbs, more cranking speed can be made in the same physical size starter.

One example is these two Delclo starters used on the Continental Z134 gas engine. 6 and 12 volt versions:

Delco 1109457 6 volt - no load - 5.7 volts, 60 amps, 6000 RPM.

Delco 1107654 12 volt - no load 10.3, 75 amps, 6900 RPM

Both have equal 11 ft. lbs. of torque when completely locked and not turing, but other wise the 12 volt starter always turns the engine faster.

I respectfully disagree.
The 12v will spin the 6v starter (or a 12v starter) with greater force, cranking the engine faster. This results in more rapid starting )and in some cold areas) starting at all. I do agree that if both had the same AH capacity they would both have the same Physical power till they are dead. Jim