If you want the packs to last, charge at 1C (1x the capacity of the pack), so in your case, 3.0 amps.

I've had packs that are 5 years old, have had over 500 cycles and only now are struggling to push out 80 amps.

they've always been charged at 1C, and ALWAYS have been put on a storage charge if left for more than a day.

Hi Paul:

To charge at 1C you would charge a 3000 mAh LiPo battery at 3 amps. To charge at 2C (Which is what I normally do...), you would charge at 6 amps; for 3C you would charge at 9 amps and so forth. If you are charging two of these batteries at once, and want to charge at 1C, set the charge rate at 6 amps; for two batteries at 2C set it at 12 amps, and so forth.

I normally charge five 4,000 mAh batteries at one time at 2C on my Power Lab 8 charger. I set the charger to charge at 40 amps (5 times 8 amps). I know of many who have very good results charging as high as 4 to 6C! I'm just not in that big a hurry... I charge my five batteries for the morning session in less than 25 minutes. Takes me that long to choose which plane to fly and to load it and my fight box into the van!

I also have a CellPro 10S charger and use that to charge additional batteries at the field off my car battery if I need them. I set that charger to 1C.
 
Later - Bob Hunt  

In  your case it probably wont matter but exactly which 4s 3000mah batteries do you have? Different brands can be charged at different rates. Maybe you can post a link to the exact battery? Most batteries these days can be charges at a minimum of 2c or 3c. I try to buy batteries that can be charged at 5c for myself then I charge them at 3-4c to take it easy on them. When I charge from storage mode I pretty much follow the same procedure as Bob does.

From the specs it looks like this one. http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=20442 . If so that battery is rated at a 5c charge. Even if you max your charger out you wouldn't even be hitting 50% of that batteries charging capability. So feel free to charge up to full speed with the charger that you have. That battery can be charged at 15 amps max.

In my experience with nano-techs, while you can charge them at 5C, they lose their punch fast.

AS a matter of fact, it seems like anything you do to those packs, they loose their punch. Even leaving them sitting charged seems to have an effect.

I've been running a 3000 4s in one of my 3D planes, and while it only got charged at a max of 2C, it's weaker than a 2200 4s now.

In my experience with nano-techs, while you can charge them at 5C, they lose their punch fast.

AS a matter of fact, it seems like anything you do to those packs, they loose their punch. Even leaving them sitting charged seems to have an effect.

I've been running a 3000 4s in one of my 3D planes, and while it only got charged at a max of 2C, it's weaker than a 2200 4s now.

The Hyperion batteries seem to be of much higher quality. I've had most of mine for three or four years and use them a lot. They have seemingly lost nothing. The best always costs a bit more... and it's always worth it!

Bob Hunt