Re: Payload Power Sources

David Akerman

The discharge capacity in Ah changes a little, due to internal I2R losses, so you get a bit more Ah from lower currents vs higher currents.  That's also why the voltage is a bit lower.  It's not showing you the run time directly - you need to divide Ah by A to get h, so your 0.25A load will run for more than 8 times the 2A load will.

On Fri, 27 Mar 2020 at 13:02, Joe WB9SBD <nss@...> wrote:
I am very confused on a battery pack.

Say you have a pack that can run 1 amp of current draw for 10 hours.
One would think that if you only drew 0.5 amps that it should run for 20 hours or close to it true?

Now many of you old timers here will remember these awesome surplus packs that looked like this.

These things were OLD like 20 years old when we used them yet the power they could provide was incredible!
They were rated at 7500mah, incredible! Sadly this supply of "NOS" dried up and new packs were very prohibitive in prices. Easily ending up being like $100 bucks a flight!

But I found a source for Brand new ones, that would make it like $15 to $30 bucks a flight! YES!

But it's performance curve makes absolutely no sense to me!

This makes zero sense at all. I can draw 2 amps  or 0.25 amps and it changes the lasting run time by only like 15 minutes?

That doesn't make any sense!


The Original Rolling Ball Clock
Idle Tyme

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