At first I read the subject line and thought someone wanted to BBQ the packs.

Yes 1C means 1 times the current/capacity. So to charge a 5,000mah battery at 1C you set your charger to 5,000mah (1,000mah = 1 amp). 2C you would charge at 10,000mah (10 amp) and so forth. However, most recreational and some pro chargers can only charge up to 5 amp.

Knowing the brand of your charger is meaningless, what model is it and how many watt output is it capable of.