Hello I have a question the device I'm powering up needs 12v 2amps to run it. Well it said that but i measure it at 1.6amps close to 1.7amps. and i have also a arduino on it going from the 12v down to 5v with no problem. Right now currently it's on a Power adapter but i need to make it portable.
So i have a bunch of 18650 batteries and battery holders with connectors on the ends. I was thinking of just putting together 4 of them and make it close to 14v to 16v sense the batteries can go that high and my device will take up to 20v and the arduino buck converter can go from 20v down to 5v it is made for it.
But if i did that in 2 hours the batteries would be dead or low enough not to power anything up. So my question would be what would be the best way of using the 18650 batteries and getting my device a longer power time? I was thinking of using some kind of buck boost converter and keeping it at 3.7v input and output would be 12v 2amps. But i think it would cut the current time the mah down to half or worse 1/4 current. Not sure so i was thinking of paralleling a bunch of the 18650 batteries to higher current and get more run time. Not sure if this whole idea would be good. So I really need help can someone please help me out? Thank you.
Power is Volts times amps. There is nothing you can do to change that. If you drop to 3.7 V, you will increase the amps relative to that. The battery won't last any (appreciable) amount longer or less.
To increase the time the device will run, you need to increase power. Since volts are limited, your only option is to increase amps. You can run any combination of volts/amps you want, but you will require more batteries. Of course, the other option is to reduce power consumption. Arduinos have several options to do that using sleep methods and sometimes combined with hardware modifications and other voltage regulators. You don't go into what 12V hardware you are using but it may also have some method to save power.