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Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: MBHOTAPER on March 29, 2011, 06:34:30 PM

Title: apogee current draw question
Post by: MBHOTAPER on March 29, 2011, 06:34:30 PM

Does anyone know what the current draw is for the mmp? I have seen threads for the mini me estimated at 800ma using ad only.

I am trying to calculate the dvd bat time (5400mah) I should get for my mbho 603a (4.5ma) w/the apogee mmp using phantom power.

Normally this is not an issue but I am going to a 4 day fest (wanee) and accurate batt time is needed.

thanks!

Title: Re: apogee current draw question
Post by: drewloo on March 30, 2011, 10:06:53 AM

I'm not an electronics whiz so I may be totally off here but the power requirements are listed as:

MMP  6-14v 3W
MME  6-16v 5.5W

if current = power / voltage, then at 9v:

MMP = 333 mA
MME = 611 mA 

However I'm not sure if/how mic current draw enters the equation.  Hopefully someone can confirm or dispel my calculations.

Title: Re: apogee current draw question
Post by: kirk97132 on March 30, 2011, 04:28:14 PM

One thing to remember when doing your math is to take the final answer and multiply it by .80 (80%) since you are not able to use 100% of a batteries capacity. 


Your basic formula for power is V(volts) = W(watts) X A(amps)
In case you need it here is Formula for Wh and mAh:
To convert to mah  it is :
WH/volts= answer x1000

Say a battery is rated 53 WHr and the nominal voltage is 12.5 volts.
53 WHr/12.5 Volts = 4.24 Amp-Hr
4.24 amp-Hr x 1000 milli-amp/amp= 4,240 mah

Title: Re: apogee current draw question
Post by: SmokinJoe on April 06, 2011, 05:13:15 PM

The math is a good estimate, but the best test is just running it.  Just set everything up in the house...  mics, minime, recorder running normally.  Run the minime on battery, the recorder on AC.  Record the random house sounds, set the gain to whatever it is at a typical show..  Let it run until the battery goes dead, overnight if necessary.  The next day look how long it recorded.  Depending on the recorder, the clock will stop at that point, or it will start recording dead air.  Either way, you can figure out out.  Different mics use different amounts of phantom power, so do the test using the mics you will run at the festival.  On the other hand running 16/44 vs 24/96 shouldn't matter much, and recording loud music versus a quiet house shouldn't matter as far as battery life is concerned.

Then subtract 1 hour for safety.

Title: Re: apogee current draw question
Post by: 12milluz on April 06, 2011, 09:03:36 PM

Quote from: SmokinJoe on April 06, 2011, 05:13:15 PM

The math is a good estimate, but the best test is just running it.  Just set everything up in the house...  mics, minime, recorder running normally.  Run the minime on battery, the recorder on AC.  Record the random house sounds, set the gain to whatever it is at a typical show..  Let it run until the battery goes dead, overnight if necessary.  The next day look how long it recorded.  Depending on the recorder, the clock will stop at that point, or it will start recording dead air.  Either way, you can figure out out.  Different mics use different amounts of phantom power, so do the test using the mics you will run at the festival.  On the other hand running 16/44 vs 24/96 shouldn't matter much, and recording loud music versus a quiet house shouldn't matter as far as battery life is concerned.

Then subtract 1 hour for safety.