How to calculate the necessary power of an alternator?

[dedeleco]

Attention, I persist, an alternator gives a sinusoidal voltage, even three-phase and therefore we can not connect anyhow !!
Read site it's written

* Dual Iraggi Alternator Package includes the following ...


*2-300 amp Iraggi Alternators
* bracket kit
* Hardware (nuts, bolts, washers, etc.)
*Replacement belt
* Regulator plug for each alt.
* Detailed pictures of install process.

There is a connector for each alternator in the special regulator !! "Regulator plug for each alt"
It is not connecting the alternators like ordinary small batteries or rechargeable batteries !!!!!
Snon they will die !!
http://cgi.ebay.com/ebaymotors/SPECIAL- ... ccessories
The three-phase gives three sinusoidal voltages and currents offset by 120 ° and therefore if they are not in phase, they will flow into each other with currents fixed by the internal resistors and this basic property is true whatever the alternator power !!!!!
Do not import anything or take scrap good alternators !!!!

[Alain G]

dedeleco


Recent alternators are equipped with their own rectifier and regulators and it is DC that goes to the battery, not AC!

I don't see why you keep saying you have to synchronize them!

I have in the past, when I worked as a heavy machinery electrician, installed on several equipment a second alternator to supply 12 or 24 volt DC hydraulic pumps, we took the one available without looking at the mark or amperage.

[dedeleco]

A single alternator is strictly without rectifier and regulator which is sometimes outside the alternator.
In this case it is a continuous electrical source with internal protection and regulator using an alternator.
Check where the rectifier regulator is.

[Alain G]

A single alternator is strictly without rectifier and regulator which is sometimes outside the alternator.
In this case it is a continuous electrical source with internal protection and regulator using an alternator.
Check where the rectifier regulator is.

Stop arguing! All new alternators are fitted with a rectifier / regulator!

30 years ago we installed GM Delco with everything integrated to connect directly to the battery!

[Forhorse]

+1
I am not a big specialist in auto mechanics, but until now all the alternators for automobile that I have seen have the diode bridge and the integrated regulator, direct output direct to the battery without any other device.

[dauphin95]

Hello,

How to calculate the necessary power of a 12V car alternator, to operate at 100%, 9 headlights of 130W.

Knowing that it will be a second alternator in addition to the one that is mounted.

I have two different calculations !!

The first 9x130 = 1170W output of 0.75 (1170x0.75 = 1560w: 12 = 130A

Le second 9x130=1170:12=97.5A

What is the correct calculation ???
I don't want to go wrong to order this second alternator!

Thank you to enlighten me!!!

Your calculations are far too optimistic.



An alternator has an efficiency close to 50% and its belt transmission has one of the order of 90%.



Electric power to be supplied: 130W x 9 = 1 W.



Power absorbed by the alternator: 1 / 170 / 0.5 = 0.9 W.



Alternator rating to be provided: 2 / 600 = 14 A.



Pay attention to the power taken from the engine:

1 CV = 736 W -> 2600/736 = 3.5 CV.

By taking a security of 15% which takes account of any misalignments and mechanical friction, the real practical power will be close to 4 CV.



The most powerful model we can offer you is a 12V 160A - see attached data sheet. It should suit you because its priming speed is quite low (1 rpm).



Public price incl.VAT = 522.65 EUR. 1 piece available to date. Delivered without pulley.



Rotation speeds of the engine and the alternator:

Minimum alternator speed> ignition point (1 rpm) = engine at idle speed.

Maximum alternator speed (approximately 15 rpm) <manufacturer data = maximum engine.



Diesel engine: 2000 rpm <cruising speed <4000 rpm.

800 rpm <Idle speed <1200 rpm.



Taking these considerations into account, the pulley ratio allowing to load correctly when the engine is idling and to obtain a maximum load at cruising speed brings us to a ratio between 2 and 3.

Advice: do not exceed a pulley ratio of 3.5 (premature wear of the belts).

Reminder: pulley ratio = diam. engine pulley / alternator pulley diam



Sincerely,



Frederic DESMONS

Electricity Product Manager for PROSHIP

[Forhorse]

Whatever

[Alain G]

Dolphin

I support Forhorse!

It's complete rubbish!

There is no yield calculation to do because the real power is calculated at the output of the alternator!

Keep a margin of 25 to 30% in wattage, this is the only calculation to do!

The loss is beyond the alternator and must not be calculated on the wattage available!

A total of 1800 watts for the 2 alternators is more than enough, even at idle!

Tell us what the use is, is it for a rally?

[chatelot16]

the technique is complicated ...

dynamo = direct current

alternator = alternative

except that in real life the bike dynamos are alternators and the car alternators have built-in rectifiers which make them equivalent to dynamos: and even better than dynamos because the built-in rectifiers prevent the return of current from the battery when it don't spin fast enough

so no problem we can put car alternator in parallel to add power without asking metaphysical questions

[riversideblues]

Hello, I have a Peugeot 306 1.9L TD 90CV car from 1994 with a 12 V 70 A alternator. I would like to add two long range headlights of 130 W each and put 100/90 W lamps (headlight / code) for the lights. original. So 460 W of lighting at the front.
So my question is Is this possible without risk to the alternator and the battery or the wires?