Battery Consumption

[moonloopsun]

Hi guys,


I am new here and still not an engineer and have not much knowledge in Battery / electricity but have a major project I am working on and would be very happy to get some answers..



I am trying to build a machine that is using a spin motor that work periodically in set times (650 spins a day: 10 turn per minute than a few minutes rest) by a simple electric circuit and position it in a place without electricity connection.


The manufacture of the motor sent me these consumption values: Voltage: 3 - 12VDC, Current @ maximum efficiency: 0.17A. On the machines provided power supply I have the follow values: 3v / 1.2A




They also claim that when it is operated by strong 2 x AA batteries it will be able to work for around 8-9 weeks (defined amount of movements periodically in a day - around 650 turns total).


I try to find a way to operate the machine longer without any need to change the batteries every second month.


I try to look at a solution of connecting a 40000mAh portable usb power bank to it through a 'step down voltage device' that will provide it the right amount of Voltage and Ampere.


Like this one:



https://www.amazon.de/gp/product/B07WJ82KPF/ref=ppx_yo_dt_b_asin_image_o00_s00?ie=UTF8&psc=1





My questions are:


Is it true that in these settings with a 40000mAh power bank, the machine will be able to run 20 times longer than when it will when running on 2x AA 2000mAh batteries ?


Is it safe to have the machine connected to such a power bank constantly and have it stored in a close place ?



Thanks a lot for your time !

 

[ratstar]

a) I guess so, but you meant 10 times longer, because there is 2 batteries. if you had 20 AA 2000mAh batteries in parallel then it would be the same.

b) I heard (its maybe not true.) if you make sure you recharge the batteries consistently and never let them get more than half empty the batteries last longer.

Whats the grand scheme here, im interested.

 

[moonloopsun]

Thanks a lot for your answer.
It's basically a few watch winder machines that i bought and i try to rebuilt them inside a cabin without access to an electricity plug, so i want to make sure that i will not have to change the batteries every few weeks, rather every few months..
Not sure if my best power supply option will be to use a usb power bank with a usb step down device, or to built my own power source from different lithium batteries....
In the assumption that the machine takes 3Volt and 1.2A, (the engine inside spins 650 times a day, 10 times for each period of 1 minute straight, than a few minutes pause. And every 12 hours it will rest for 12 hours). will the power bank be really able to run the machine for 6 months ? Won't it turn off when the machine puts to sleep in between the turning cycles ?
Could you please recommend me what would be the ideal situation for this subject ?

Thanks you so much for your time

 

[ratstar]

Give yourself more than you need, or do an experiment to see how long the batteries actually last.

 

[moonloopsun]

Is there a risk with running a power bank for long inside a closed cabin ?

 

[ratstar]

Batteries are inherently dangerous, but ppl have 2000 watts going into their house every day and it seems to be safe as long as u treat it the right way. Id say in general the more amp hours in the batteries, the more dangerous they are - the same as compressed air.

But I think you would be ok. =)

 

[kpatz]

The trouble with lithium ion batteries like those used in power packs is overdischarge will damage them. If the power bank drains too much while you're gone, the cells can go bad, and they can fail catastrophically when recharged again.

There's usually a protection circuit in a power bank to prevent this, but if the batteries get low and the pack shuts down, not only will your watch winder stop working, but self discharge will eventually destroy the cells in the power bank, unless you get it back on a charger soon.

Since the motor can operate on 3-12V, you don't need a step down converter. You could power the motor directly off the 5V output of the power bank. It may draw more current and spin faster though... but then spinning faster means it finishes faster, so it could be a wash in terms of overall power consumption over time.

Maybe add a solar panel to recharge the power pack during daylight, then it could stay charged longer, it could even work (almost) indefinitely then. You could even use NiMH AA cells with a solar charger.

Or just use battery powered watches instead of the wind up kind.