Dual Batterys or High Amp Alternator?

[GaryTJ]

And PLEASE! don't go cheap on the cables. But good copper wire with the more strands the better.

We had a ford truck at work that fused the starter relay together every time the truck was started and it was because of the increased amperage draw on the initial surge of current flow. Everything else was good, it was just a cheap cable.

 

[chickenwing]

WOW!! Thanks for the explanation LMAR and Crash really helps. So I am going to go look around and see if I can find the load tester somewhere local. So from how i understood it when I turn on headlights or any of the other accessories there should be no drop. Correct me if I'm wrong but I did look at the power wire to the alternator today and its like 8 gauage so I am going to upgrade that for sure it cant hurt.

 

[crash2]

WOW!! Thanks for the explanation LMAR and Crash really helps. So I am going to go look around and see if I can find the load tester somewhere local. So from how i understood it when I turn on headlights or any of the other accessories there should be no drop. Correct me if I'm wrong but I did look at the power wire to the alternator today and its like 8 gauage so I am going to upgrade that for sure it cant hurt.

We don't use load testers anymore at work. Instead we use an electronic type that uses frequency and is more precises but can only do a standared plated type of battery. We also got a new fancy one that can do any type of battery but that one is not a quick test (takes up to 20 minutes).

Your going to get a voltage drop with any power consuming device you turn on. Its a matter of how good of a battery/alt you have to quickly compensate for it. One thing thats common with the older vehicles is a noticable voltage drop with a blower in high.

 

[Totalled]

Put a Ford 3G alternator on it. Now no matter what I turn on all at once, the voltage drops and then goes right back up to 14.3 at the battery.

 

[Binder]

, YET we CAN install TWO 6V batteries in parallel with each other and thus we now have in all reality a BIG 12V battery that is capable of drawing 1000 amperes!

Should read "series"......A typo I'm sure.:;

 

[Lone Watie]

Very informative thread. I will add that an alternators rated output is at a certain RPM not at idle. many of the low buck high output alternators put out no more at idle than a stocker.

this is a great place for info and parts. they can also build you a mad scientist alternator with more amps than even frankenstien can handle.
http://www.alternatorparts.com/

 

[greenie]

*hearsay warning..

RedTops are JUNK these days.

back to my hole..
:beer:

 

[Lamar]

Very informative thread. I will add that an alternators rated output is at a certain RPM not at idle. many of the low buck high output alternators put out no more at idle than a stocker.

this is a great place for info and parts. they can also build you a mad scientist alternator with more amps than even frankenstien can handle.
http://www.alternatorparts.com/

Dear Lone Watie;
To the best of my knowledge, all vehicle manufacturers rate the output of the alternator according to it's MAXIMUM power output. Please note that this output can be at any given RPM range, which is usually the vehicle's normal operating RPM range.

Most modern alternators can achieve their max rated output at a relatively low RPM, which is usually around 1,500 RPMs at the alternator shaft, and NOT the crankshaft. At what RPM an alternator achieves it's max output is wholly dependent upon the size of the alternator's pulley. This is in comparison to the generators of yesterday, which seldom reached their peak output as the RPMs required for such a feat were simply too great. This is an advantage of an using an alternator over a generator.

Also, please note that a high output alternator does nothing more than restore a vehicle's battery/batteries at a faster rate. While this might sound like a good thing, in all reality what it does is shortens the life of the vehicle's battery/batteries.

Also, a high output alternator is a power robber. It takes power to make power and in the case of vehicle alternators, that power must come from the engine. A 200 amp alternator works all of the time and it takes twice as much power to spin a a 200 amp alternator as it does to spin a 100 amp alternator.

This is not so bad for a V-8 motor as they are well equipped to handle an entire array of power robbing accessories, but when a person installs a 200 amp alternator on a 4 banger, the difference can be noticed in reduced performance and increased fuel consumption.
Your friend;
LAMAR

 

[Travis1]

Unless that red top is 8-10 years old. Start by replacing it with a non-crap battery.

I've had the same problems you described on my wife's Jeep. Wasn't the altenator or the wiring on the vehicle to blame, it was the lousy red top battery. Had a friend with a cherokee, similar deal.

When I replaced the red top with a walmart everstart maxx, the electrical problems regarding low output went away. When I thought back, I realized they showed up shortly after replacing the 8 or so year old OEM battery.

I am far from alone with those red top problems.

EDIT: The symptoms were, battery voltage was good, and it would pass a load test. But it had nearly no reserve capacity. Alternator was doing it's job, as far as it was concerned.

 

[Lone Watie]

Dear Lone Watie;
To the best of my knowledge, all vehicle manufacturers rate the output of the alternator according to it's MAXIMUM power output. Please note that this output can be at any given RPM range, which is usually the vehicle's normal operating RPM range.

Most modern alternators can achieve their max rated output at a relatively low RPM, which is usually around 1,500 RPMs at the alternator shaft, and NOT the crankshaft. At what RPM an alternator achieves it's max output is wholly dependent upon the size of the alternator's pulley. This is in comparison to the generators of yesterday, which seldom reached their peak output as the RPMs required for such a feat were simply too great. This is an advantage of an using an alternator over a generator.

Also, please note that a high output alternator does nothing more than restore a vehicle's battery/batteries at a faster rate. While this might sound like a good thing, in all reality what it does is shortens the life of the vehicle's battery/batteries.

Also, a high output alternator is a power robber. It takes power to make power and in the case of vehicle alternators, that power must come from the engine. A 200 amp alternator works all of the time and it takes twice as much power to spin a a 200 amp alternator as it does to spin a 100 amp alternator.

This is not so bad for a V-8 motor as they are well equipped to handle an entire array of power robbing accessories, but when a person installs a 200 amp alternator on a 4 banger, the difference can be noticed in reduced performance and increased fuel consumption.
Your friend;
LAMAR

Thanks for your opinion lamar.

 

[Travis1]

Also, please note that a high output alternator does nothing more than restore a vehicle's battery/batteries at a faster rate. While this might sound like a good thing, in all reality what it does is shortens the life of the vehicle's battery/batteries.

Your friend;
LAMAR

A higher output alternator also allows you to run more accessories before pulling the battery down.

An engine doesn't need the battery there if the alternator is putting out enough power to keep the engine running. BTDT, had a totally dead pair of batteries on my rig, managed to get a bump start and it would stay running as long as I kept my RPMs over 2000.

As long as the alternator is regulated properly, I don't see how a larger alternator would shorten a batteries life, other than by charging at a rate faster than the battery can accept.

 

[crash2]

In a properly designed system a battery is only there to start a vehicle and help with the shock loads(lamens terms) on the system.

With that said at idle an alternator, even a high output may not be capable of keeping up with load requirements. Example a 130 amp alternator and your wanting 100amps out of the system the alternator may not produce that 100amp requirement at idle.

 

[Travis1]

Is it hard on an alternator to be spinning too fast? Not sure how to phrase it.

But lets say you want more amps at idle, so you swap pullies to achieve that. But, now, lets say the alternator is spinning twice as fast as what the original pully would have allowed it to do.

 

[crash2]

Is it hard on an alternator to be spinning too fast? Not sure how to phrase it.

But lets say you want more amps at idle, so you swap pullies to achieve that. But, now, lets say the alternator is spinning twice as fast as what the original pully would have allowed it to do.

It will wear out twice as fast. Remember there is still a consumable in the alt (brush's). I would go for maybe 1/3 more speed.

 

[GaryTJ]

And brushes will skip at to high an rpm. computer's do not like erratic voltage. The battery helps a lot to modulate things.

 

[chickenwing]

Well I went to schucks and had them use there tester and at 800 rpm with no loads it was 14.2 volts and with all loads on 13.7. So im guessing its all good . Just my gauage insode reads wronmg it reads around 10 with loads on.