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ridr4lif wrote:Most cars charge between 13.6 and 14.4 at about 2000 rpm's. At idle, the alternator isnt turning fast enough to really produce much voltage.

So to answer your question, YES, the car can be at 12.8 volts when the car is running, but the car is most likely at idle.

tedd

thanks tedd, thats what i thought. So thats directly linked to the concept that my alt. puts out around 100amps at idle and 180amps at 2000rpm.

Most cars charge between 13.6 and 14.4 at about 2000 rpm's. At idle, the alternator isnt turning fast enough to really produce much voltage.

So to answer your question, YES, the car can be at 12.8 volts when the car is running, but the car is most likely at idle.

tedd

can i get a question cleared up here rq? Should the voltage stay at 13.8-14.4 constantly when the car is on? I.e. if the alternator is charging the battery is the voltage higher? Can a car ever be at say 12.8volts when the car is on?

I guess what im wondering is is the voltage always strictly say 12.5v from battery and 13.8-14.4v alternator?

well, maybe smart, but not educated when it comes to electricity or automotive charging systems. There is a difference between being naive and being ignorant. :)

To put it simply and undeniable fact:

If your alternator is not sufficent enough to run the car, system and recharge a single battery it is dying.

Thats the bottom line, anyone who says different is not to smart.

The alternator charges at 13-14.4 Volts... If you sucking the alternator dry it is already over its rated capacity and its true final limits (Where it starts to burn up). It doesnt matter what batteries you have or not... To late...

yea the whole bucket thing had me too. my opionion was that if the leak never exceeded the fill rate that may work but when the hole was open more and water gushed out then you are trying to play catch up and the second bucket and the third and the fourth are all suffering too until you can close the hole and fill them all up.

that's fine.. we were both writing at the same time.. and your approach was sufficiently different to give another angle to understanding the issue.

the problem as you noted, is that the hose filling the buckets doesn't have the flow rate to do the job described by the multiple battery proponent.

before anyone brings up 16 volt batteries though, those are for one purpose, which is supplying higher voltage to the ignition system (coil and ignition box) in things like drag cars, where you want a very high voltage to ensure clean firing of the spark plugs in high compression settings like blown drag motors.

Nevermind, didn't see Kikis post beforehand. :)

"you could drill a hole in the first bucket and as the water leaked out you could have a hose at the end of the line of buckets filling them at the same rate as the leak that the hose doesnt work any harder than it would to keep the same level in just one bucket and you have the advantage of the other three maintaining a full load of water."

Bad reasoning. Anyone who is having trouble with a stock alternator is suffering because the alternator cannot provide necessary current to charge the system. Batteries aren't supposed to supply ANYTHING when the car is running, a bias is applied to them and they are in a charge state. Ideally, all would be overflowing from the supply given to them. Instead, if your alt is the problem, the draw will be too great for the supply to maintain, and while multiple batteries will be able to supply their reserves for longer, that is a worst case scenario and all will eventually drain out regardless. Batteries won't supply other batteries anyway, they will drop their current simultaneously.

"you could have a hose at the end of the line of buckets filling them at the same rate as the leak"
This particular line is what kills all reasoning above.

Most people that want to rely on batteries just don't understand that the only purpose of a battery is to start your car in the morning. The alternator/regulator should do everything after that point

ok we are in agreement then..... i just figured if i was wrong this would be the place to find out....