How to calculate voltage drops

[mazzasec 5,000+ posts]

Ok my new setup is going to consist of a Sundown Saz3000d running at .5 1 deka under the hood and 3 dekas in the rear. 250 amp alt and big 3. Think my voltage will drop any lower then 13.5 at full tilt?

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[stophatin 10+ year member]

take a volt meter at the battery and measure the voltage drop yourself, with system at full tilt.

Forum members can do fancy equations and make educated guesses all day but thats the real way to check

 

[ultimate157 5,000+ posts]

Yes.

No.

Maybe.

No?

Yes.

That is a summary of the answers you will receive.

Just measure it yourself. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Ali1 10+ year member]

to discover voltage drops, place voltage meter on your dash

 

[mazzasec 5,000+ posts]

I mean whats everyones prediciton onm what it might drop to!

 

[blackbonnie 5,000+ posts]

what deka's are you running?

 

[DidUHearThat? 10+ year member]

Ok my new setup is going to consist of a Sundown Saz3000d running at .5 1 deka under the hood and 3 dekas in the rear. 250 amp alt and big 3. Think my voltage will drop any lower then 13.5 at full tilt?

Oh, yeah your voltage will drop. How far depends on a lot of things. Usually alternators only put out about half their rated voltage at idle, so your really only getting about 125-150 amps at idle, but drawing upto 250 amps.

Add up how many reserve amp hours combined from each battery and divide it by 125 amps (loss). That should give you an estimate of how long till full discharge, but in reallity your system will stop working when you hit about 10 volts, so divide that number by 4 (1/4 discharge from full voltage).

Then it depends on the music. Slow beats could stretch your power by double or more. 60 Hz sine wave, test tone, at full tilt could drain your system in 5 minutes or less.