they will work fine to get you light on the skids. this would carry you through several packs in RADDs, but it won't get much lift with 7.4V and the stock gearing/blades (flat bottoms and a 10T or even 11T pinion are best for 2S lipo). it won't hurt anything if you want to try the pack out. just be careful not to overdischarge it, since you're flight times will be short.

btw, i calculated it a while ago and i recall it required a total of 4 stock chargers and 5 packs to fly all day non-stop (minus 10min motor cool down periods).