Calculating how long the leisure battery would last running 3x 5v USB fans...

[scimmiamagia!]

If we had 3 x 5V USB fans on all the time, how long would a fully charged leisure battery last?

 

[TripleBee]

If we had 3 x 5V USB fans on all the time, how long would a fully charged leisure battery last?

A few days?
If you have 2x80Ah batteries = 160Ah. 160x12V = 1920Wh.
What amps do your fans draw?
1920Wh / 5V = 384Ah.

Basic electrics and maths.

 

[Wannabecamperman]

A few days?
If you have 2x80Ah batteries = 160Ah. 160x12V = 1920Wh.
What amps do your fans draw?
1920Wh / 5V = 384Ah.

Basic electrics and maths.

...Except that assumes lithium batteries that can discharge fully. The standard AGM batteries would be half that amount.

 

[TripleBee]

...Except that assumes lithium batteries that can discharge fully. The standard AGM batteries would be half that amount.

The value 80Ah means that you can draw 80A for one hour, and then the battery will be flat.
This only when the battery is new, and after that hour you charge it back up.
Of course, this is not the ideal way of using that AGM battery.
It was just for instructional purposes.
As long as we don't know the full specs of the fans, we can't answer that question.

 

[RockinNRollin]

Negligible impact; far less than the 'fridge. I think I tested ours on low power as being 2W or something. They should say on them what the draw is.

 

[yossarian]

OP's profile says they have a Beech. I suggest you work in native energy units rather than Ah because Ah becomes complicated by system voltage.

Long story short: OP has about 500 Wh useable energy if the leisure battery is in good condition. The usb smps is around 90% efficient at best.

USB fan power requirement is around 2.5W if it is within USB 2.0 spec.

(500 *0.9)/ (2.5 * 3) = 60 hours.

 

[Wannabecamperman]

I can confirm that I have a small 6 inch USB fan which uses less than 5w.

 

[secret lemonade drinker]

Do not forget the power consumption of the DC to DC converter that is changing your 12v supply to 5v to run your fans, and how many of them are you using, a real world example: we stayed on the Spanish side of Gibraltar in a marina for three days, two nights, the beach did not move and had no ehu, the waeco tcx21 cool box took 48 hours to flatten the leisure battery whilst maintaining 5 degrees inside when it was 33 degrees ambient, I run 2 usb fans and have never noticed an effect on the leisure battery but we moved on most days

 

[Azteccamper]

Do not forget the power consumption of the DC to DC converter that is changing your 12v supply to 5v to run your fans, and how many of them are you using, a real world example: we stayed on the Spanish side of Gibraltar in a marina for three days, two nights, the beach did not move and had no ehu, the waeco tcx21 cool box took 48 hours to flatten the leisure battery whilst maintaining 5 degrees inside when it was 33 degrees ambient, I run 2 usb fans and have never noticed an effect on the leisure battery but we moved on most days

Just stayed in that marina €12 p/n. Great spot.