Got my son an HPISpring 2 Sport RTRDrift 350z. Seems like a lotta fun so far. Spending the money on the car, I had to go cheap on the batteries and charger. Hey, I'm a noob, whadya want.

So yeah, we purchased whatever Radio Shack had pre-Xmas:
7.2V2000mAh Ni-Cd batt & chrgr combo.
http://www.radioshack.com/product/in...ductId=2062121

Then went back to RS to get this:
7.2V3200mAh Ni-MH batt
http://www.radioshack.com/product/in...ductId=2147160

Key questions are, how long should these batteries be charged for and how long should they be good for, given maximum usage. We're getting about 45 mins from the Ni-MH after charging for some time. Is it okay to charge overnight? The charger has no indicator to say when it's charged, so how do we know, aside from trial and error.

Looks like this is the place for answers. Hope to hear back.

Get yourself a peak-detection charger. It will generally save you the problems of:
long charge times
unable to detect when battery is done/in progress of charging.
overcharge
undercharge.

Get one and charge your battery at 3-4 amps (3.3 is the sweet spot). This will let it charge faster, and they usually tell you if there was an error, if its in progress of charging, and when its done. (by screen or a single LED). Some more advanced chargers can charge LiPo, tell you how much voltage and mAh is in the battery, and so on.

Heres a good, cheap, efficent charger that gets the job done.:
www3.towerhobbies.com/cgi-bin/wti0001p
or
www3.towerhobbies.com/cgi-bin/wti0001p

If you're looking for more peformance, get one of these:
www3.towerhobbies.com/cgi-bin/wti0001p
hobbyking.com/hobbycity/store/uh_viewItem.asp

Thanks for the details Theo. Without the peak detection charger, is there any way to know, given the makeup of the battery and specs, how long it should charge with the charger I'm describing? Is it hours? Overnight? Believe it or not, neither the 2 batteries or the charger came with any literature suggesting anything except generic labels: "Make sure the battery is fully charged." Duh.

Does it say what the charge rate is in amps?

The front of it says, "5 Hour Charger" and on the back, embossed it says "Output 9v 560mA." It does have a switch for NiCd and NiMH. Thanks!