What do charge rates mean, and is there a noticeable performance difference between high and low rated packs?
Charge rates are just what they sound like. It is the amp rate at which you are capable of charging a specific battery pack. Most commonly you will see this at 1C, 2C, and all the way up to 5C. Well what is “C” in this scenario? It is the amp hour of the battery packs. While most are familiar with the milliamps, the amp hour is that number divided by 1000. So for a 5000mAh battery, 1C would be 1(5) or a 5 amp rate, 2C would be 2(5) or a 10 amp rate, and 5C would be a 25 amp rate. A 1C charge or discharge should be an hour long process. 2C cuts that time to about 30 minutes. Balancing can extend the overall time but this gives you a ballpark in terms of the time it will take at any of these rates.
Your charge rate used to make a big difference in overall performance in the days of NiMH and NiCad cells. The faster you charged the more punch you would get. This also tended to lead to less cycle life. With LiPos the difference really isn’t that obvious. It’s not a night and day performance difference charging at a faster rate. Opposed to charging packs at faster rate you would see more benefit from charging your packs just before use because you would maximize capacity. The main reason to charge at a rate that’s higher than 1C at this point is to reduce charge time: 1C = 1 hour, 2C = 30 minutes, and 5C =12 minutes. Balancing tends to be an equalizer here, though. At a 5C charge rate, it is more likely for cells to get out of balance. The farther they are out of balance the longer it takes to balance at the end of a charge cycle. This can, in turn, increase overall charge times.
Higher grade batteries can handle these rates at little to no degradation but lower grade cells have a much higher probability of failure at higher charge rates. Make sure to charge your battery according to manufacturer recommendations to ensure long life and great performance.
Joshua Barker, MaxAmps