Need to figure out power consumption...

Thread Starter

jsmith24

Joined Jul 10, 2013
23
Hi all,

I'm trying to figure out my power consumption so that I can estimate run time for a given battery. Normally this would be pretty straight forward - I'd get a crude estimate by dividing AH by current. However, the current is only a few times per day, as follows:

Current draw:
220 mA for 30 seconds per day.
35 mA for 2 minutes per day.
3.5 mA for 12 hours per day.
20 mA for 12 hours per day.

Battery: 12V, 9AH SLA.

Can someone help untangle my brain to see the obvious thing that I'm missing?

Thanks,

Jack
 

Alec_t

Joined Sep 17, 2013
14,280
As an approximation, ignore the first two quantities. That leaves ~23.5mA x 12 hours, = 0.282AH per day. If you discharge the battery, say, half way (it's bad for the battery to flatten it) you have 4.5Ah capacity; so the life-time would be 4.5/0.282 = ~16 days.
 

dl324

Joined Mar 30, 2015
16,846
I wouldn't run the battery lower than 10.5V. Using SLA 0.05C discharge data and extrapolating; 16-20 days ballpark...
 
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