I finally dug out my Hobbico trainer, and Super Sportster.

Both have OLD NICD rx batteries, and I know both need to be replaced before I start flying.

I have been looking at lipo rx batteries on the market. Do a lot of people run these, or should I just keep it simple a buy a new NIMH battery?

If I do run lipo, can you wrap the battery in foam to protect it from vibration. Like I did with my NICD. I know lipo's will get hot when used on electric planes. But with the low draw of power as a rx battery, will it still run hot?

Also I finally made the switch to spektrum. What RX should I use for .40 size planes?

Thank you.

Well, some use them. I do not. The new A123 technology, is more suited to use. They are lighter in weight, and are available in several capacities

But, you can also go to NiMh. I have several now, most 6 volt packs to avoid any issues with low voltage re-boot situations with the digital receivers. With the exception of the two planes with A123 technology, all the others have 6 volt NiMh 1200mah packs. Two planes are equipped with a pair of these in parallel.

So, it's up to you. If you do go with LiPo packs, you will probably need a regulator which adds both cost and complexity. In my opinion, for beginners, and that's what this forum is about, it's best to keep it simple and avoid the regulator route for now.

CGr.

Yup, if you run a Lipo with all but an exepensive reciever and high end HV servos then you're going to need a regulator.

For what you're doing the KISS method is probably best, a 5 cell NiMH pack. A123's are good, charge quickly, and can be run without a regulator, but require a specific charger.

Depending on the current drain, in most cases going with a 5 cell 2000 mah Sanyo Eneloop cells will give you all the advantages you get with LiPo with none of the problems. You can charge them with your old Nixx charger as well and charge them in place. With LiPo's it is advised to always remove them from the model for charging.

Let me expand on what's been already said......Yes you can run Lipos......but by no means required......a new 700 mAh Nicad will be ok
There are different kinds of Li-XX batteries....Li-ion and Li Fe are a couple....they have the advantage of not needing to charge as often, and hold the voltage better......the down side is with LI-ions you will need a voltage regulator, plus everything for a Li Fe battery such as a good battery charger and longer charge times....a Lipo's max charge current should not exceed 1 amp....
While Li-ions and Li fe batteries seem to be safer during the charge process than Li-pos they still need to be watched
A Lipo if it gets punctured can burn very hot.....they can also burn from over charging.....
In my opinion there is no need to run a lipo get your self a couple of 6V 1100 mAh batteries...that will last you a day of flying plus a tad
Now I do run some Li-Ions in my bigger aircraft...with a voltage regulator....I am getting ready to build a glow trainer I'll run a Nicad 700 mAh in that....

I would get NiMH at a minimum. Don't mess with NiCds. If you have a high quality charger, capable of multiple chemistry, I'd go with the A123/LiFe packs. I've gotten a few and am really digging them. I have some 1800mAh ones, and I can fly a few days in a row w/o recharging them and they hold their voltage really well.

I run lipo in all my planes. Is it because they are better, not really. Like every battery system out there, they have their disadvantages but provided you feed them correctly and know what you're doing with them, they should be fine. That's been my experience anyway.

A123 batteries? Man I have been out of the loop for a while. Are these similar to the 123A flashlight batteries?

I think I'm just going to keep it simple, and run NIMH.

How many volts should I run, 6?

A123 is a trade name for Lithium Iron Phosphate batteries.

Yes, a 6v NiCad or NiMH is fine.

Same here.
I use them in all my glow planes, from a high wing trainer to a 26 year old pattern plane.

All get a Castle BEC/Regulator and the batteries vary with the application from a 2s 750 mah to a 3s 2200 mah.