Good morning all,
The end goal of my questions is to determine the best battery to use for my robot.
I have totaled up all the current draw for all the electrical components and it comes out at 8.3 amps.
The battery voltage needs to be 24 volts in order to have enough power to drive the Nema 34 stepper motors effectively.
The 24 Volts are stepped down to 12 volts using a DC-DC converter which I believe is for automotive or marine use. That is further stepped down to either 5 volts or 3.3 volts for the various sensors, arduinos, and Raspberry Pis.
At 24 volts, the two stepper motors, while powered, should draw about 1.2 Amps each (they are 3.5 amp steppers). At 12 volts there will be less than 1 amp of draw.
All the rest of the current consumption is in the 3.3 to 5 volt range.
2.4 Amps consumed at 24 volts
1.0 Amps consumed at 12 volts
4.9 Amps consumed at 5 volts or less
Obviously, not everything is running all the time, however, it is possible. Now comes all the questions....
As far as discharge rate is concerned on the battery, ultimately all current draw is at the 24V level. I am guessing that my 4.9 amps of draw at 5 volts is probably a different amount at 24 volts - guessing it would be less than one amp? What is the conversion or how is this calculated?
Regarding Amp Hour rating, it is my understanding that this rating is the amount of Amp that the battery will provide in one hour of time after which it is drained. So, a 10 Amp hour battery can only provide 10 Amps at the batteries voltage for 1 hour at which point it should be charge again. Is this correct?
Finally, what battery chemistry would be best for this type of application. I have SLA on a similar robot and it works, but I would like something that weighs less and has a better discharge rate.
Thanks in advance!
Chris D