I'm in the process of building my first nitro (RC8B3.1) and I have a question regarding receiver batteries.
I'm planning on running LiFe batteries, and I have a few brand new ones that I misbought a few months ago, but they are only 1450 mah.

How much runtime am I looking at with a 1450mah receiver pack? I don't mind changing out packs throughout the day, but I need them to last at least 45 minutes + warm up, so pretty much an hour straight. Would this be doable?

Absolutely, you'll be fine. Especially since they're new. I've got a Turnigy 1700 mAh LiFe in its 3rd year, still capable of more than an hour of running. However, if running 45 minutes or more, make sure the battery is fully charged.

1450mah will be plenty for and hour main...I used to run a 1500 nimh back in the day with a pair of digital savox in truggy with zero issues....as long as you are running good quality servos that are digital coreless or brushless as they will run with less draw...old analog ones will struggle.....

Your 1450 mAh LIFEPO4 battery pack should indeed be more than enough for an hour straight run. But do not try to go 90 minutes or more on it, on one charge.

A healthy 2S LIFEPO4 battery pack is fully charged at 6.6 volts (3.3 per cell). It will also keep the voltage above 6 volts for 90-95% of its capacity. Then it will go empty pretty quickly.

Just make sure that it is fully charged before each use, always balance-charge it at 1C charge (1.4 Amps in this case) and do not ever let the cells go below 2.2 volts each (Minimum 4.4v for your pack).

LIFE (or LIFEPO4) batteries are pretty good. I run a 2000 mAh 2 cell pack on one of my 1/8 nitro buggy's receivers, powering Savox 1256 and 1258 servos ( Savox servos are known to be Amps hungry servos).
I can go up to 1 and a half hours on one charge without problems. And this for over 3 years.

Hope this helps.

regards,
DLD. _