Hi everyone!

I would like to calculate, how long a battery will last for a given discharge rate?

In theory the calculations seem to be very straightforward. The battery specs provide a given Kilowatt/Amp per hour. Then, for a given rate of discharge, one can find how long the battery would last? That is; Amp per hour/Amp rate of discharge = flight time in hours.

In one of his tutorials Oscar covers the battery basics. He uses Amp per hour to calculate the battery autonomy. I am not sure, but I understand, that the voltage and the Intensity of the battery drops, as it is being used? Therefore, how accurate can be to assume a constant amperage, and voltage (nominal tension), for the battery discharge calculation?

In theory the battery can not be discharged beyond 80%. By using the nominal tension and the Amps per hour, provided by the manufacturer, are we considering the rate of discharge to be above 80% of battery capacity?

T-motors provides tables, with the battery consumption for a given thrust. Using those, one can figure out the battery discharge rate on a multicopter.

Thanks so much for your inputs!

Oriol

Assuming you don't want to go below 80% capacity of battery, and all other electronics on the quad is ignore. And the amp draw is constant.

((Battery capacity in AH) x.0.8) / (Amp draw in A) = (Flight time in hour)

Please correct me if I am wrong

(15-Mar-2023, 01:45 AM)voodoo614 Wrote: Assuming you don't want to go below 80% capacity of battery, and all other electronics on the quad is ignore. And the amp draw is constant.

((Battery capacity in AH) x.0.8) / (Amp draw in A) = (Flight time in hour)

Please correct me if I am wrong

Hi voodoo614!

I would say that, if you can not discharge the battery below 80%. Then the battery capacity you can use, is battery capacity times 0,2.
I will try to find out more info, and post what I find out.

Cheers,

Oriol

Hi!

According to Micah Toll on his book DIY batteries. Most manufacturers rate their cells at the extreme end of the battery capacity, beyond 80%. Also, the batteries are discharged at a very low discharge rate; 0,2 C of their maximum discharge rate.

At the end, one has to test on its own, to find out what the real capacity of a battery is?

So, it is wise to, at least, avoid doing the calculations for long range, using the maximum discharge rate.

Cheers,

Oriol