How do i gifure out how much power can i run?

[THEKINGsBACK]

i dont really know the formula to find out how much power i can run but i got called Matt at mechman today and they actually make a 270 amp alt for my escape so im going to order that around Christmas time and order a new kinetik 1400 for the front and two 1800 in the back also upgraded big 3 wont be charging a super high voltage prob say around the 14.4 mark thanks in advance

[Robert8252]

I'd run 4k daily on that setup. Should do fine.

[Mosin]

nvrmnd

Edited November 10, 2010 by solo_x18

[hdorre]

I'd run 4k daily on that setup. Should do fine.

Yes, 4.5k tops

[THEKINGsBACK]

ok good so 3.5k is prefect for that application...

[Robert8252]

If you want to figure a ballpark of what electrical you need just add the amps together. Usually 1amp of power from a alt is ok to consider 10 watts. So 270amp alt would be about 2,700 watts not including your cars electrical. Any thing else you will be pulling must come from batteries and the batteries need to hold a decent charge to be able to play for a extended amount of time in order for the alternator to be able to keep up with them.

[THEKINGsBACK]

If you want to figure a ballpark of what electrical you need just add the amps together. Usually 1amp of power from a alt is ok to consider 10 watts. So 270amp alt would be about 2,700 watts not including your cars electrical. Any thing else you will be pulling must come from batteries and the batteries need to hold a decent charge to be able to play for a extended amount of time in order for the alternator to be able to keep up with them.

thanks man.. that helps alot.. now i must start planning... hope to start building again around january

[snafu]

Hmmm . . . I like the idea of this thread, but let's get the facts straight. You could get a rough guesstimate with nothing more than a current clamp and a DMM. For the sake of this argument, let's assume the vehicle in question is equipped with a 140 amp alternator from the factory.

1. Bring the vehicle to operating temp so that the engine temperature causes the electric cooling fan(s) to be ON - a short drive is typically in order here

2. Turn the engine OFF and install a current clamp around the alternator charge lead within 12 inches of the alternator - the closer the better.

3. Start the engine, close the doors, and turn every conceivable accessory ON that you may use when driving - AC, Fan on HI, Bright lights, etc.

4. Rev the engine to 2,000 RPM and note the reading from the current clamp - let's say that was 90 amps.

140 Amps - 90 Amps = 50 Amps, therefore, 50 amps of surplus is available from the alternator (ideally - in the real world, this will be 10% less or so).

Now, let's figure how much amplifier power those 50 amps can sustain on MUSIC:

50 amps x 14.4 VDC = 720 watts

This gives us 720 watts of INPUT available for amplifier(s). Consider that Class D amplifiers are 75% or so efficient or so on average and Class AB amps are 60% or so efficient on average.

720 watts x 75% eff = 540 watts of Class D Power

720 watts x 60% eff = 432 watts of Class AB Power

But, Music is dynamic in nature . . . so, let's assume for the sake of this argument that it has a duty cycle of 50%.

540 watts / 50% = 1,080 watts of Class D Power when playing music

432 watts / 50% = 864 watts of Class AB Power when playing music

These are best case scenario numbers as a 150 amp rated alternator from one of the OEMs will likely make less than that at operating temp. AND, this does not take into account playing music at a stop light with the engine at idle, where the alternator would not be able to keep up. Finally, without having a carbon pile load bank (or a bunch of current hungry halogen headlights) to properly load down the alternator, you really have to go off of its rating. This is a guess-ti-mate but it will get you in the ballpark.

So, let's look at the "1 amp per 10 watts" suggestion and work it backwards:

Class D

10 watts / 75% eff = 13.33 Watts IN

13.33 Watts / 14.4 VDC = .93 Amps

.93 Amps x 50% duty cycle = .47 Amps

Class AB

10 watts / 60% eff = 16.67 Watts IN

16.67 Watts / 14.4 VDC = 1.16 Amps

1.16 Amps x 50% duty cycle = .58 Amps

So, we're talking an average of just over half an amp between to supply 10 watts of amplifier power when reproducing music. That may be useful when discussing alternator output in correlation to test tones (100% duty cycle) but not to music. So, it's festivus for the restofus . . .

[Robert8252]

Lol. Nice detail. I stated "not including yours cars electrical". But very nice detail with realistic numbers. Thumbs up

[THEKINGsBACK]

Lol. Nice detail. I stated "not including yours cars electrical". But very nice detail with realistic numbers. Thumbs up

lmao.... very detail....i feel like he wrote me a small thesis paper.. and i appreciate it..