# Power consumption calculation

Discussion in 'General Electronics Discussion' started by Yog67, Dec 24, 2016.

1. ### Yog67

2
0
Dec 24, 2016
Hi guys. I'm completely new to electronics. I need a little help actually. I will keep it short.

Let's assume I'm having a battery of 9000mAh and a device rated as 5V, 55mA. My question is if I'm powering the device with that battery. How long will the battery last in hours assuming it had full charge? I would like to know the calculation steps for this. Thanks.

2. ### cjdelphi

1,096
104
Oct 26, 2011
Is the battery 5v or not? Supposing it was 5v then it's a case of (but i'm not claiming 5v bstteries exist)

9000mah (capacity)
/
55ma
=163 hours

Last edited: Dec 24, 2016
3. ### Audioguru

3,116
696
Sep 24, 2016
Nobody makes a 5V battery. It might be 7.4V then a low dropout regulator will have a 5V output until the battery voltage drops too low.

4. ### cjdelphi

1,096
104
Oct 26, 2011
Nobody makes a 5v battery... yet lol

5. ### cjdelphi

1,096
104
Oct 26, 2011
Mixing two battery chemistries to produce 5v surely can be done, this battery is close at 4.5v

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6. ### Yog67

2
0
Dec 24, 2016
Thanks for the reply guys. BTW if it matters take battery as 11.42 V, 74.9 Whr for the 6000mah for instance.

Last edited: Dec 24, 2016