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For the discussion of Arduino related topics.
By embedded_hobbist
#200141
I want to use Arduino Pro Mini 3.3V, here:

https://learn.sparkfun.com/tutorials/us ... o-mini-33v

it says:

"If you have a supply that’s greater than 3.3V (but less than 12V), you’ll want to connect that to the RAW pin on the Mini. This pin is akin to the VIN pin, or even the barrel jack, on the Arduino Uno. The voltage applied here is regulated to 3.3V before it gets to the processor."

So in order to achieve longer time duration on the circuit, it is better to use a 6V Sealed Lead Acid battery or a 3.7V Lipo?
By Valen
#200142
That entirely depends on the capacity of the battery, quoted in units of mAh(ours). A huge 3.7v lipo might last longer than a small 6 volt SLA battery.

The internal voltage regulator burns away the excess voltage above 3.3 volt. Current use is the same. If you really want to improve the voltage regulation efficiency then you might consider supplying it with a stepdown DC-DC regulator on the 3.3 volt pin instead. But that will have consequences, like voltage ripple which your application might not like.
By Valen
#200146
Both!

Each has it's pro's and con's! A lipo weighs less for the same capaciy. But requires more accurate circuitry to prevent crossing undervoltage (discharge) and over-charge (voltage) limits. Lipo's can catastrophically fail if abused (fire!). SLA is more robust. SLA is heavier, but more lenient when it comes to charging.
#200147
Thank you...

My concern is this:

Since a 6V Sealed Lead acid is more far (it has more "space" 6Volts-3.3Volts = 2.7Volts) than 3.3 Volt that Arduino operates, doesn's mean I have more...time availiable for my circuit to work more in duration, until it discharges (under 3.3Volt) and stop working?

Than a LiPo which is 3.7Volt so more close to 3.3 Volt?

I hope I didn't confuse you,

Thanks....
By jremington
#200150
Estimate battery lifetime from the battery capacity, measured in Ah (Ampere hours) or mAh (milliAmpere hours), divided by the average current draw in A or mA, respectively.

If you use a switching step down converter on the lead acid battery, it will draw less current from the battery than the circuit draws from the step down converter.

Either type of battery can be destroyed by over-discharging. The lead acid battery should never be discharged below about 5.4V and the LiPo should never be discharged below about 3.0 V.