# CAR AUDIO : Determine Your Ampere's Pull **URL:** \ **Category:** Canada Nissan Automotive\ **Created:** [January 11, 2010, 11:38pm UTC](https://forums.speedlife.net/t/car-audio-determine-your-amperes-pull/137333 "2010-01-11T23:38:56Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![gerrydevis](https://avatars.discourse-cdn.com/v4/letter/g/e19b73/32.png) [@gerrydevis](https://forums.speedlife.net/u/gerrydevis)\ **Post date:** [January 11, 2010, 11:38pm UTC](https://forums.speedlife.net/t/car-audio-determine-your-amperes-pull/137333/1 "2010-01-11T23:38:56Z")
Hi to all, This is all Information I myself have gathered from the MECP Installers Guide book. **Alright Here’s the Question!** I am trying to figure out how much pull on my alternator I am getting from the amp. Here is the formula We use to figure this out **I = (Po - n\*Po + Po) / V** Now **I = amperes Po=RMS n=efficiency V=voltage** So for me its: **I = (3000 - .8\*3000 + 3000) / 13.8** So I do this 3000\*.8 and i get 2400 3000-2400=600 600+3000 3600/13.8 260.87 This is my amperage draw correct? and if I’m correct for everyone else heres an easier equation for this: **I = (2-n)Po/V** So for me this would go 1. 2-.8 =1.2 2. 1.2\*3000=3600 3. 3600/13.8 And there we go. 260.87!!! Now, We must remember that Most Class D Amplifiers have a 80% Efficiency Rating and Most Class A/B Amplifiers have a 60-70% efficiency Rating! ---
**Author:** ![kazzxtrismus](https://avatars.discourse-cdn.com/v4/letter/k/3bc359/32.png) [@kazzxtrismus](https://forums.speedlife.net/u/kazzxtrismus)\ **Post date:** [January 31, 2010, 8:28am UTC](https://forums.speedlife.net/t/car-audio-determine-your-amperes-pull/137333/2 "2010-01-31T08:28:55Z")
IF YOUR RUNNING 3000 WATTS RMS… YOU MUST BE DEAF! PLEASE REMEMBER MOST AMPS ARE ADVERTISED AT PEAK. AND THEIR ADVERTISED POWER IS BASED ON 14.4V 261 AMPS MEANS YOU SHOULD BE RUNNING 2 ALTERNATORS AS IT IS NOT SUGGESTED TO RUN MORE THAN 1 BOOSTED ALTERNATOR… MOST ARE OUTPUTTING 85 AMPS AND CAN BE ALMOST DOUBLED WITH A MODICUM OF RELIABILITY (caps on purpose, i know you know about the difference between RMS and peak) ---
**Author:** ![stelalouis](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/stelalouis/32/3393_2.png) [@stelalouis](https://forums.speedlife.net/u/stelalouis)\ **Post date:** [May 12, 2011, 11:16pm UTC](https://forums.speedlife.net/t/car-audio-determine-your-amperes-pull/137333/3 "2011-05-12T23:16:27Z")
nice application is this and I liked it . ---
**Author:** ![katlinfrench](https://avatars.discourse-cdn.com/v4/letter/k/bb73d2/32.png) [@katlinfrench](https://forums.speedlife.net/u/katlinfrench)\ **Post date:** [June 29, 2011, 11:18pm UTC](https://forums.speedlife.net/t/car-audio-determine-your-amperes-pull/137333/4 "2011-06-29T23:18:25Z")
Yes , I am also agree here that its a good and nice application here that you posted for us and we got familiar with it.