How do I check for total current draw of my electrical system?
 

I'm getting ready to upgrade my alternator, and I was first looking at the FD alternator as my 3 month old rebuilt s4 alt has just died....so it apparently can't keep up. I'm running an E-fan and I'm getting ready to install a single amplifier(~600w RMS @14.4V) and single subwoofer into my car. So my question is, I need to know how to test what the total current draw of my system is now before I add the sound system. I'd hate to get an FD alt just to find out that it isn't adequate either.

I know you can test for a current leak by putting the meter inline with the car off, but can you use this method for a told current draw? I'm not sure, but I don't think my meter will read that kind of current, so how do I test this? I want to see what the draw is if I turn on the lights, efan, radio, etc. so that I can ensure I get a large enough alternator.

To find amperage (current) draw, divide watts by voltage (120) . example 30 watts divided by 120 volts = . 25 amps

when your lookn at your current draw you want a alternator with at least 20% headroom

also you amp when it peaks uses about 40 amps but the rms rating is what u really should be lookn at and the rms current draw is 20 amps

The above posts elude me, but if your a simple person as I am, then by hook or crook aquire a current clamp and read it as you turn different items on in the car.

https://www.rx7club.com/attachment.p...&stc=1&thumb=1

https://www.rx7club.com/attachment.p...hmentid=225703

well...let's try this another way...what's the current draw of a stock s4 TII with pretty much everything running? I think I"ll take that and just test the current draw of my efan and I found the amp draw specs of the amplifier I'm using...so I can just add it all up and see what I need.l

While starting there's a 37 amp draw if the engine is warm/hot. Goes away after letting the key go back to ON.

Key to ON, engine off: 4.8 amps

THen turn the heater FAN on with the above: 14.4 amps

Then turn the keadlights on with the above: 27.6 amps

Then headlights to high beam with the above: 30.7 amps

Then radio to ON and the antenna going up with the above: 31.8 amps

Then radio On and the antenna all the way up: 31.1 amps

Then step on the brakes with the above: 39.9 amps

All the above was with the engine off and key to ON.

It's too much trouble to do it with the engine running. I've no vested interest doing so. Too time consuming.

The above done with a Fluke 410i. You can make a clamp from a kit from..........JAYCAR IF I remember right. Much cheaper that way.