Power consumption calculation

[Yog67]

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.

 

[cjdelphi]

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

 

[Audioguru]

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.

 

[cjdelphi]

Nobody makes a 5v battery... yet lol

 

[cjdelphi]

Mixing two battery chemistries to produce 5v surely can be done, this battery is close at 4.5v

 

[Yog67]

Nobody makes a 5v battery... yet lol

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.

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