I have a 110v 2hp motor that has 3450 Rpm. Can it spin a car alternator (180amp) ? The alternator will be doing it's intended job. Charging a pair of AGM batteries and supplying power for a 12v system (lights and car audio). Basically I just want the electric motor to be the car motor. Thanks in advance.

 

Yes. This is a pretty common thing to do for a high power battery charger.
Just ensure the regulator in used as normal, either the alternator has an internal one or the external one.
You may need to connect a small 12V lamp as in the car to start the alternator. Have a look at the info for your particular alternator.
But if your batteries are small, just a mains driven intelligent battery charger may be a better way to go.

 

I have a 110v 2hp motor that has 3450 Rpm. Can it spin a car alternator (180amp) ?

Yes, but not for the full 180A.
One horsepower equals 746W so the maximum output for the motor power would be about 1500W, thus the maximum output current for an alternator with 80% efficiency would be no more than about 0.8*1500/13 = 92A.
But likely that's significantly more than what you need.

 

The batteries are XS POWER AGM D6500 . I'm needing approximately 150 amps to power a class D amplifier.

Yes. This is a pretty common thing to do for a high power battery charger.
Just ensure the regulator in used as normal, either the alternator has an internal one or the external one.
You may need to connect a small 12V lamp as in the car to start the alternator. Have a look at the info for your particular alternator.
But if your batteries are small, just a mains driven intelligent battery charger may be a better way to go.

Yes, but not for the full 180A.
One horsepower equals 746W so the maximum output for the motor power would be about 1500W, thus the maximum output current for an alternator with 80% efficiency would be no more than about 0.8*1500/13 = 92A.
But likely that's significantly more than what you need.

The alternator and batteries powered the system already. I just removed it from the vehicle and it's hopefully going to be my shop's system. To better explain, my Grand Cherokee's motor is trashed. So I'm taking the sound system out and putting it in my shop. I priced a few power supplies and just can't bring myself to paying two grand . Lol

 

It's all about power. The alternator in the car is driven by an engine that can supply 100x the power needed for the 180A. The 2hp electric motor is way smaller so doesn't have the power to drive the alternator as hard as the car engine, hence will deliver less amps.

 

It's all about power. The alternator in the car is driven by an engine that can supply 100x the power needed for the 180A. The 2hp electric motor is way smaller so doesn't have the power to drive the alternator as hard as the car engine, hence will deliver less amps.

That was what I needed to know. Thanks. I'll have to find another power source.

 

I'm needing approximately 150 amps to power a class D amplifier.

You may want to budget some funds for the hearing aids you're going to need with that amp cranked up.

 

You can get a mains-powered 2000W Class-D amplifier for £319
https://www.thomann.co.uk/behringer_ep2000_europower.htm?glp=1
which is cheaper than one of those batteries.
https://www.ebay.co.uk/sch/i.html?_....m570.l1313&_nkw=XS+POWER+AGM+D6500+&_sacat=0

 

You will not need the full power all the time as the average power in the audio signal is quite a bit lower that the peak unless you are driving a steady tone.
And most modern amps have advertisement department ratings that bear little reality to their actual power output. I would doubt your 2KW amplifier actually has a continuous power anywhere near that, and if you would be driving your speakers at that level I hope you have good medical and third party insurance against self and others getting damaged hearing.

 

I'm taking the sound system out and putting it in my shop.

A much better option to listen to music in your shop:

Ear protection with bluetooth audio

 

Add a standard car battery to handle the high peak currents, which is usually to the subwoofer.
At even the highest listening level, the average current will be much less than the peak and should be readily supplied by the 2HP motor driving the alternator.

 

A friend of mine actually did that about 50 years ago, from a surplus alternator from a '68 Plymouth Valiant, if I recall correctly.
Please note that automotive alternators (claw pole) are very, very inefficient.

https://www.intechopen.com/chapters/38166

 

Please note that automotive alternators (claw pole) are very, very inefficient.

Yes, they apparently go as low as 55% efficiency.

 

You will not need the full power all the time as the average power in the audio signal is quite a bit lower that the peak unless you are driving a steady tone.
And most modern amps have advertisement department ratings that bear little reality to their actual power output. I would doubt your 2KW amplifier actually has a continuous power anywhere near that, and if you would be driving your speakers at that level I hope you have good medical and third party insurance against self and others getting damaged hearing.

That is the low end. I'm peaking 3200 watts for subs and 65 watts for 4 full range . Lol but you're correct I want be playing at my max . I just see what I can get away with and that'll be that. Thanks for the help

 

Yes, they apparently go as low as 55% efficiency.

It beggars belief that it is possible to make a rotating machine that bad!

 

It beggars belief that it is possible to make a rotating machine that bad!

Not when you are trying to build millions of units as cheap as possible.
The economics for a vehicle alternator is when the part cost savings by the low efficiency design (minimum magnetics and small wire size) is offset by the need for a more expensive cooling configuration (bigger fan and case).

 

Back when automotive alternators were first developed, the auto’s demand was relatively low: the electrical load would consist of the headlights , the windshield wipers, some accessory lights, an AM radio, a seldom used cigarette lighter, the spark plug coil and not much more. The inefficient Lundell alternator was adequate.

Nowadays, you have dual and triple zone A/C, power windows and mirrors, power seats, heated seats and mirrors, window defrosting, power locks, power tailgates, multiple radiator fans, full fledged infotainment systems, cameras galore, Lidars, electric assist power steering, ABS, internet and phone connectivity, several power outlets, sensors literally everywhere, multiple engine and transmission actuators, active suspension and dozens of microcontrollers with ancillary circuitry. Oh! Almost forgot, the stupid auto-stop system.

Over a decade ago all this increased load levels were foreseen and 48 volt system was proposed. Standards were drafted. But the cheapskate auto manufacturers considered it too costly.

 

110v 2hp motor that has 3450 RPM
Most car alternators attain maximum power at 2400 RPM.
The ratio is 1.44 : 1

Quote "Basically I just want the electric motor to be the car motor."
If the 2 AGM batteries will not take you back to the free charging station, you could turn down the volume on steep hills.

 

Most car alternators attain maximum power at 2400 RPM.

I think that's closer to 6000 RPM or above, which can be readily achieved from the motor with proper relative pulley sizes.

 

Back when automotive alternators were first developed, the auto’s demand was relatively low: the electrical load would consist of the headlights , the windshield wipers, some accessory lights, an AM radio, a seldom used cigarette lighter, the spark plug coil and not much more. The inefficient Lundell alternator was adequate.

Nowadays, you have dual and triple zone A/C, power windows and mirrors, power seats, heated seats and mirrors, window defrosting, power locks, power tailgates, multiple radiator fans, full fledged infotainment systems, cameras galore, Lidars, electric assist power steering, ABS, internet and phone connectivity, several power outlets, sensors literally everywhere, multiple engine and transmission actuators, active suspension and dozens of microcontrollers with ancillary circuitry. Oh! Almost forgot, the stupid auto-stop system.

Over a decade ago all this increased load levels were foreseen and 48 volt system was proposed. Standards were drafted. But the cheapskate auto manufacturers considered it too costly.

The 48 volt auto electrical system is pushed primarily by the sellers of the required pieces. It has not caught on because it is a dumb idea!
As for the motor spinning the 180 amp alternator, it will be noisy and it will produce heat as well. And it will be much bigger than an actual power supply. And incredibly less efficient. You will need a speed increase to get the rated power and so with 4000RPM on the alternator you will hear it.
Of course with that loud a sound system you will not notice the motor/alternator sound very much.