Automobile Alternator Current

GA PWSlack.

In theory one could upgrade the diode bridge, reduce the magnetic flux density with more laminations of iron in the two cores, extend the squirrel cage windings and rewire the stator. One must do at least all four of these steps or fire becomes a real risk. (Notice: I'm not saying by doing all four, one cannot start a fire.) But by doing this, one will have built a new bigger alternator that happens to use a few of the original parts. Get a new alternator or reduce the load.

if you look at the parts manual for your car you may see that there are different types of alternators available for your car without affecting your insurance.

ie for my car there is the standard 75 amp and an uprated 140 amp ie if i was to tow a caravan and charge extra battery on caravan

High output

This product is an ideal solution if you have recently installed a large in car entertainment system and your existing alternator is not coping with the demand of you new install. Alternatively this product range can be used for many other type of use, here are some of the projects we have undertaken; marine longboat upgrade to supply large battery bank in 24 volt for internal lighting, very large ICE installation for competition use, farmer using our high output alternator to charge a very large battery bank, wind powered electricity supply project, ice cream van high output alternator to supply slush puppy machines, off road high output alternator to supply 24 volt winch motors. We will work alongside you with your project, custom building a High Output alternator to suit your exact requirements.

Our High Output alternators are available in 12 volt or 24 volt, from 70 amps going right through to 200 amps. We have an extensive range of these products available in stock ready for immediate dispatch.

We can also up-rate your existing alternator to a higher output if required. This is done within our own workshops and will normally take about 7 days to rebuild.

When i switch on the Air conditoner and the power amp with all the light ON , the engine`s rpm drop and the amps ,almost 70.

This means that your engine is too weak, if you further increase the alternator the engine will go even more down. What you do not mention is if this happens when you car stays or when you drive. If this happens when your car stays and engine runs idle then you should have a look at its idle rpm. It can be possible that by only rising it your problem is solved.

Agreed - sounds like the symptoms described happen at idle speed. What does kumarr expect? An alternator gives some output at idle, but won't produce maximum current at that speed. It's not limited by engine power - a bit more accelerator will increase output. It is probably fine at normal driving speed.

Higher-output alternator only helps if the demand is greater than something like max output. But it would be easier to switch off some of the load.

Cheers........Codey

A good reply due to audio problem.

Bass note are more in time than treble notes & peak-power problem can be resolved to a limit by an additional hi-capacity cap but it needs a professional sense where to put & what special specs needed.

Should be of very low Equivalent series resistance (ESR): and nearest to the Out-put stage with shortest connecting leads.

Have a nice day!

go to a shop that rebuilds alternators (look in the yellow pages). there are optional rotors and stators for most alternator frame sizes, that should allow them to tailor an alternator to your needs. Police cars and ambulances have heavy loads at idle, as well as ham radio people. not to mention the "loud stereo crowd".

a lot more info at: http://electricalrebuilders.org/

including member look-up

Some very good suggestions have been made so far. The idle speed is important, most newer vehicles will adjust idle speed automatically to account for load. The capacitor, designed for high power amplifiers, installed nearest the amplifier, will help with higher volume bass loads. Another thought is to replace the battery with an "Optima, Yellow-Top". This battery is a deep cycle battery, and designed for extreme loads, especially car audio amplifiers. Don't forget that the size, guage, of the power wire to the amplifier is critical also.

You did not tell us the specs of the vehicle, or the power amplifier. You didn't mention if the problem only occurs during idle, and if you have automatic transmission. (Does putting the car in neutral during idle help?)

The final answer may be simple, if you need more amperes, you'll have to replace the alternator. That may still not resolve the idle problem though.

Some cars already have alternators that produce 120 amps, some diesel VWs for example, especially often the 2.0 TDI motor....

Using an even larger alternator will tend to load the motor up some more, but provided your motor management computer (assuming you have one!) is working correctly, it should speed the motor back up to the correct tickover speed almost immediately.....

If its not doing that I am most surprised.....

If its an old car, increase the tickover speed to 1000RPM at the carb....

What you have described is common among cars with high powered sound systems and / or auxiliary lighting systems.

What you need is more current. As suggested, a capacitor or two, or whatever number of amps you have, will help. More battery power will also help. Pack the most powerful battery you can. The deep cycle battery design should also help. If you have a custom installation with multiple amps in the back of the car, consider putting a second battery back there also. Just be sure to use a sealed battery that will not vent sulfuric acid fumes into the interior of the car. Find a battery that was designed for a trunk mount from the factory. They will have vent hoses that will allow you to vent the fumes to the bottom of the trunk floor.

The high output alternators may not be needed. What you need is a faster alternator speed at idle. Smaller alternator pulleys will help, as will larger crankshaft pulleys. An alternator re-builder should be able to help with the small alternator pulley. Crank pulleys will be harder to find. A group that is familiar with your brand of engine would be a good starting place.

If you do go to a larger output alternator, do not forget to upgrade the alternator output wiring. The problem you are seeing, is from voltage drop to the lights. Using heavier gauge wire from the alternator to the battery, and accessories will help that.

If your lights are dimming because of higher wattage lights, try using a relay harness to power them. There are aftermarket harnesses that are sold specifically for higher powered headlights. If you can not find them, they are easy to fabricate. I would be glad to help you with the design if you want. Good luck.

You state the the amp meter shows 70 amps. What does the voltage meter show? It should still produce 13.5 volts. If it does not, then I have to ask the question, do modern alternators use voltage regulators? If so, check the voltage regulator. One of the ways that the voltage regulator helps to keep the voltage up, is to send a signal to the engine to increase the power! In "the old days" it was one of the least expensive fixes.

you cant.

you can get a new higher output alternator of same dimensions.

as for the ac the engine should compensate by reving up.

try increasing tickover to about 900 rpm.

by the way alternater wont give full output under 3000 rpm at tick over they typicly give out about 15% of max out put which will drop of course when engine slows for a/c

Regards.

One of my friends was saying that Alternators are made to run at their max speed to caterfor slow or idle-running of vehicle & it uses regulator to regulate on higher speeds.

And after a point of end of regulator control SLIP_CLUTCH on the Alternator pully works to keep the alternator speed limited.

I hope you will have some information on it. !

Have a fine day !!!!!

.

ive never heard of that system.

its not used on cars, in the uk, i will look it up and see where it could be fitted.

it doesent matter if the unit goes over 3000 rpm. the alternater/unit gives max output at 3000 rpm going past this is not a problem for alt it just doesnt give any more output.

the a/c pump on some commercial motors uses a slip clutch which is activated by electromagnet so presure in a/c is maintained at a constant.

perhaps this is what your friend means

Never seen it in either the UK, USA or Germany either....

Ok time for a quick lesson in automotive alternators and automotive voltage regulators. The magnetic field produced by the rotor is generated by the current level permitted by the voltage regulator. This is because the Biot-Savart law states the magnetic field generated by electromagnetics is:

Now without going through the three dimensional calculus to generate a case specific equation, one can see that the magnetic flux density (B) is proportional and can get modulated by current. So the spinning magnetic field of the rotor then produces in the stator windings voltage with Faraday's Law of Maxwell's Equations.

Again three dimensional calculus must be applied to this to show that the voltage produced is proportional to the change in the magnetic flux density. In the alternator case this change in B gets determined by the magnitude of the magnetic field from the rotor and the rotational velocity of the rotor. So as the rotor velocity increases from normal engine throttling, the voltage regulator decreases the current into the rotor windings to obtain the same output voltage.

There is no slip clutch!

bit complicated, but yes.

the only refrence i can find to slip clutch is on motor bikes.

as the last person states alternator regulate them selves, why would they fit a clutch?

by the way the refrence to slip clutch on a/c was wrong it should have read.

there is an electromechanical disenagement of the drive, basicly its an electromagnetic clutch to drop the drive when max presure is obtained though i would of thought a presure dump valve inside the compressor would have been a better soloution, as there are les things to go wrong.

if i was engineering anything i would always make it with as few breakable bits as possible

refrence the alternator, just found this intresting link.

read and learn

http://oljeep.com/gw/alt/edge_Alternator_Theory.html

Regards.

I have been working on XRay Film processors by Kodak [and some other makes]

All the chemical pumps use Magnetic-Clutch to aviod leakage [Blades impeller remains in Chemical while drive is attained from an Electromagnet revolving outside.

You may be well knowing the Old Speedometers working.

All the Magnetic clutches are basically Slip-Clutch as it has no mechanical coupling like a belt-pully or gears coupling.

nice

but whats that got to do with cars ?

Slip-Clutch was under discussion!

As far as I am aware, in the western world, it would appear that none of us seem to have ever seen an alternator on a car with any form of clutch on the Alternator.....slipping or not..... or at least nobody else has upto now proclaimed that they have seen such a system....

So it really has little to no bearing on the subject matter of Automobile Alternator Current, unless you live in India it would appear........which is why someone questioned the validity of your comments with respect to this blog..... Simple.

It might be interesting to hear which vehicles have such a system in India (as an Off Topic Post of course!), photos would also be of some academic interest I feel....

You're right, of course. There are no slip clutches in alternators because there is no need for them. If either the amperage or voltage goes above design limits, the regulator can turn the field curent down to essentially nothing if need be. Clutches are used on air conditioner compressors, not alternators.

Just as the voltage is low enough to need the alternator to work, the clutch would be turned on, dropping the voltage even further.

An electric clutch on an alternator just makes no sense.

As far as remember the early voltage regulators would just protect against overvoltage by opening the charging circuit.

Regards.

All the Electronic or other types always have some limits; no one has an infinite capabillities .

This is the reason in more sophisticated systems more than one way is used to get the required results.

HP the top in Test Equipment & Power Supply design used Electronic as well as Electro-Mechanical+Eletromagnetic devices like; Electronic Voltage-Regulator Variac [Variable-Volage-transformer] simultaneously.

Variac portion was named by HP as pre-regulator & the other as Regulator.

Why not in such alternators which cannot be driven on a constant speed?

I fear you friend has a too-active imagination. Slip cluthes are not used on alternator drives because they would add needless complexity for no useful reason. The regulator does not reach a point at which it cannot regulate -- there is no "end" of regulator control.

I have to agree with you completely.....

Thanks