Is this enough battery.
 

I have a 1600mAh NIMH Rx battery.

In your opinion will it last 40 minutes?

How best (rate wise) would I charge it to get the most run time out of it?

40 min. in what 1/8 off-road? I'm not the guy to answer that part but for longest life I would charge it at 100 mah or .1 amps and yes it will take forever, like 16 hours. You could cheat a little and charge at like .15-.16 amps and I would still think you would be safe. I've charged my reciever packs at up to 1C which would be 1.6 amps but that might cut down your run time. I'm sure others will chime in on this for you.

It all depends on what vehicle the battery in For 1/10 scale touring. I've had the 1600 last a 1 hr main with plenty to spare. I normally charge mine at .5c or .8 amps; for best results. Most receiver battteries can't handle a high charge current.

I have a 1650 rx pack in a Tmaxx and it'll easily last 40min, it goes several hours between charges. This Tmaxx runs an upgraded strg servo and still lasts a long time even with teh added drain from a 175inoz servo.

For rx batts, I try to charge them at 0.5amps as a slow charge, when I've absolutely got to get it charged as fast as possible, I'll use 1amp.

Thanks guys.

It is for a 1:8th buggy. Hopefully I will get enough time between races to do a (slowish) charge before the main...

Of course I will be TQing so will have plenty of time :)