the radio i am getting comes with 600mAh NiCd batterys. between NiCd and NiMh which is better? Should i get some batterys with more mAh's?

Nicads are fine. The milliamps available determine how long you can fly, but also how much weight you fly with. 600mAh is enough for an hour or so of flying time... with a regular 4or5 servo setup on a plane. Do you need more between charges?

gus

no i was just wondering how long they last and if i needed to get better ones

Ditto. For a typicaly 40-60 sized plane, a 600mah pack is fine, be it NiCd or NiMH. There are several reasons for using NiMH, such as lighter weight and the fact that NiCds will be phased out in the next several years due to the toxicity of Cd. NiMH do not offer better capacity, but they can offer more capacity at the same weight of a NiCd. This is because if all else is equal, NiMH cells don't weigh as much as NiCd cells. I think this is where the confusion starts as vendors will make claims like "Our NiMH have more capacity than NiCd." You gotta read between the lines... all they are really saying is if you have two packs at the same weight, the NiMH will have more capacity becasue a large NiMH cell (say 800mah) weights the same as a smaller NiCd cell (say 600mah.) Of course a 800mah pack has more capacity compared to a 600mah pack. As for the weight savings, the diff between NiCd and NiMh on a 600mah pack is probably a ounce or less... not enough to worry about on 99% of planes. Cheers.

How long will they last? Depends on your plane setup and flying style. On a trainer, probably 6 ten minute flights would be safe. But, I'd suggest you get a bettery checker and check your batts before every flight, even if you just charged the battery.

I too had the same question a while back. I did a good bit of research and though it seems NiMH's are making a good showing, it still seems as though the experienced pilots are sticking with the NiCd's. Many of the touring pilots use a variety of battery packs, but then they also use regulators and redundancy packs as well. There can be more to this subject than what appears just on the surface of the topic. When I was asking about this I asked several guys at the field. Many have years of experience in building and are considered top notch builders. These guys have 25 -30 years experience and up. Hands down the majority are still using NiCd's. Maybe it's a reluctance to change. Maybe it's just the old school vs the new school. There have been several post on this subject and much info can be gained by doing a search on the subject. In the end you will have to make your own decision because you will get gobs of info supporting the old vs the new.

As to capacity. I used a 600 mah in my trainer and a 40 sized stick. Now mostly use 1100 mah NiCd's in most of my other larger airplanes. I have a 1700 mah in a Pitts with a gas engine. Keeping your battery charged with a charger at roughly 10% of the capacity is a good rule of thumb. Stock kit chargers charge at 50 mah will never get a higher capacity battery up to a full charge. Also want to cycle about every 3 months and it's a good idea to change batteries at a 3 year interval. When cycling you can see if the battery is loosing charging ability if you have a charger that tells you how many mah's was received when cycling, so the three year interval can be less, but many pilots won't use a battery for more than three years. This is a wide open subject with much information to be learned. I am still learning.................. Good luck and have fun.

If you plan on flying more than six-ten minute flights in a session, buy a field charger, because your transmitter will be low also. More capacity in the plane really won't increase your flying time if your tx is dead. There is nothing wrong with Ncads, they are another thing to upgrade after you get enough stick time to know what you need, not just what you want. Have fun along the way...JIM

Roger brought up a good point; if you go to larger capacity packs, you'll need to buy a charger because the one that came with your radio equipment won't be enough. And if you're going to buy a charger, you should absolutely get a "peak detection" charger.

If you're going to buy a new Peak charger, you might as well invest in one that also "cycles" your packs to keep them performing properly. Finally, if you're going to invest in a Peak Detection Charger/Cycler today, you might as well get one that can also maintain Lithium packs, because they'll be replacing NiMH's within a few years. MUCH lower weight for the same capacity.

Wait awhile before you get the stuff you don't need right now. Your "Wall Wart" charger will keep your existing packs charged, and is all you'll need for a while. (Year or so.) DO spend the $15 for an Expanded Scale Voltmeter. You want one that places a load on the pack while testing it. Tower has them, most hobby shops should.
Dennis-

would the hobbico voltwatch reciver battery monitor from towwer work ok?

It works for NiCad but is not recommended for NiMH.
Short story is that the unit is designed for the discharge curve of NiCads and not NiMH packs.