C/10 means charge at 1/10th the capacity, (3000mAh at 300mAh, 2400 mAh at 240mAhs).
Forget all you've read.
I'd do a 10 amp charge for 14 hours on a battery pack(multiple batteries) and a 10 amp 6-8 hour charge on a single battery.
From the web:
Do a C/10 (c = capacity i.e. 2400mAh pack is charge 1c at 1.2A) charge for 14-16 hours, the magic of "slow charge" is that it equalizes the cells. As the cells fill up some will get full before others, but at the C/10 rate there is no danger of over charging because the cells that are full can safely dissipate the "over charge" as heat, without damage, giving the other cells time to fill up. This is also why it's a good idea to occasionally C/10 charge all your packs, in normal use over a number of cycles they will start to become unbalanced and the C/10 charge will rebalance them.
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