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ok there is a lot of misinformation floating around out there and i was hoping to get a clear concise answer from a knowledgeable sort whose gift with the vernacular would far exceed my own which lacks polish as much as my posts lack punctuation.


stock alt. multiple batteries.

the theory goes that if you have up to 4 batteries on your stock alt. the alternator will actually work less and you will have found the magic beans that make you forget you ever had a cow.

it was explained to me like this.....if you have 4 buckets all filled with an equal amount of water and all connected via tubing at the same level. 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.


ok i know that if this was batteries instead of buckets that the hole would vary from a tiny pinhole to a huge gaping hole. and that there is a point of diminishing return where you are simply going to let the smoke out of your alt.

does this really need to be in question format?

well it's more like this..
the batteries will act to keep the voltage stable at 12VDC if the alternator is overworked, and the more batteries you have in parallel, the more amp-hours you'll get out of the package.
the thing is, the batteries shouldn't be drawn from when the car is running. The alternator should be supplying all of the current at a higher voltage than the batteries supply in order to recharge the batteries, and still give ample current to the system and vehicle.
when the alternator is drawn beyond it's limits, you're going to burn up the alternator regardless of how many batteries you have.. although the batteries will prevent the voltage rails from dropping below 12VDC for a longer period of time if the over-demand of current persists for a long period of time.

basically all you'll do is help in masking the death of your alternator by having more batteries..

the battery bank is more useful for SPL events when you have to run the system with the engine off several times between opportunities to recharge the cells.

this is all explained in those charging system links I provided though.
whoever tried to tell you that line of bull about the batteries making up for a stock alternator doesn't have a very good understanding of electricity.

the batteries will provide current when the alternator is drawn beyond it's limits.
at that point the batteries are no longer being recharged, AND the alternator is dying a slow death burning up the diodes and brushes.
Once the batteries are tapped out, the voltage rails will sag below 12 volts, and you'll have an alternator trying to recharge 4 batteries instead of just one, and still power the car and the audio system if you're too stupid to turn it off while the batteries recoup.

that's my angle on it anyway.
everybody seems to have a different idea of how things work.
I'll note I've never fried an alternator though :)

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

"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

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

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.

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.

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...

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. :)

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?