Topic: run time for a MME and D7 on a 6volt sla

[Tommy E.]

I was just wondering how long a bp-50 would run these two units.
thanks in advance

[peeeper]

I'm not familiar with the BP-50 but I do know that 6V is the lowest operating voltage of the MME.  This means that the MME will drawl more current from the battery, which will decrease the amount of life of the battery.  Also note that when the 48V phantom power is engaged the MME needs to take the input of +6V and change it to -48/+48V.  This will dramatically decrease the life of the battery.  The best solution is to use a 12V 7Ah battery and run it all day long

I hope this helps.

[greenone]

Which is great, except a 12V would release the magic smoke on his D7. A D7 draws about 200mA; a MMe I'm not sure of. But a BP-50 is 7ah so even if it draws 1000mA, you're looking at 4-5 hours.

That said, my 1000mA rig (V2/ADC-20/D8) failed to last 3 hours tonight on a BP-50, so your mileage WILL vary...

[peeeper]

Right I forgot to add that  

[peeeper]

FYI:  running a MME at 6V will use roughly 917mA where as running it off 12V will drawl roughly 458mA.

This is P/E = I (watts / voltage = amps)

The MME produces up 5.5 watts.

[Tommy E.]

Thanks to everyone for your replies.  I ran them last night for about four and a half hours with out any problem.  From the calculations i made after searching the archives, I think it should run them for like five and a hlaf hours.

[Brian Skalinder]

Thanks to everyone for your replies.  I ran them last night for about four and a half hours with out any problem.  From the calculations i made after searching the archives, I think it should run them for like five and a hlaf hours.

The calculations in the archive are strictly ballpark estimates.  I strongly suggest testing in a controlled environment (i.e. simulated field testing at home) if you may often run into a situation in which you want to run the system close to its max run-time.  (But maybe last night was controlled testing?)

One thing to keep in mind:  the higher the current draw and lower the battery capacity, the less efficient the setup.  Reduced efficiency may change (i.e. lower) the .80 fudge factor in the run-time estimate calculations.

For example, let's take a 1000 mA draw on both a 10AH and 5AH SLA.  The run-times may be calculated as 8 hrs for the 10AH, and 4 hrs for the 5AH.  BUT, you're using the 5AH battery's capacity less efficiently, so you may only get 3-1/2 hrs out of the 5AH SLA (even though you calculated 4 hrs run-time).

I don't know if you'll encounter a noticable loss in efficiency relative to the calculations, but...it's worth testing out at home, IMO.

[Tim]

I used to run a d8 and minime off of one 6v bp50 for a regular 2 set jam show, 4 hours without a problem.