i just bought a rustler off ebay and it came with a promax 885600 charger. it has the gauge on the front. does any one know how i know when the battery is chrged? it goes from 0 to 5 charged and 0 to 5 discharge. thanks for your help.

You really should get a charger that shows you the mah charged , along with voltage and amp rating .

You can figure it out closely by knowing the amperage and actual capacity delivered by charger. And/Or the battery is full when it is quite warm.

I would just charge my battery at like 3, till it got warm, then it is done! LOL pretty simple. I like simple......hehehe..