Well, if they're 1800mAh (1.8Ah) packs, then 1C is 1.8A. You can charge them more slowly if you like, and that's reputed to make them last longer, but I've honestly never tried it. All I meant by saying you wouldn't have them charging at 1.8A for an hour was that they will reach 4.2V / cell before an hour's up, and the charger will reduce the current. It winds up taking some bit more than an hour as a result, that's all.