Wouldn't you only need 8?

he would need 20 so he can have fresh batteries for his 4 wii remotes when they run out of power 8+8. but since you can charge ten at a time, then you would have 20.

im pretty happy with my setup of a 4 battery charger that works in 15 minutes :)

I buy 36 packs of batteries for about $6.

Environmentalists probably hate me right about now =P

I use a rayovac rechargable battery for my wiimote, Its about $10 at walmart plus the extra rechargable batteries.

Cebrain answered for me. The one problem with the charger is it is a slow charger, so it takes 12-20 hours depending on the mAh. Although, the independent charging is a benefit, because if you place a discharged battery and a full battery in a quick charger, it will charge it as a pair. This will cause the full battery to overcharge which is bad for the battery and will cause it to die. I personally had ~30 rechargeables, but 3 of them have died and no longer hold a charge, but they died before I got this charger.

The rechargeables should last ~2 years before dieing completely, so at Rath's price your looking at them being the equivalent of ~$38 of regular alkaline batteries (+ any gas if you make a special trip) if you replace them every week for one controller, so this charger will pay for itself eventually, and it will do it quicker if you use all of the batteries all the time.

 (note, I don't work for any battery companies or resallers whatsoever, I just happen to be a proponent of saving money and having all my batteries fully charged when I need them )