Does your hobby charger have a discharge capacity test? Charge on a dumb charger that shuts off at a full-capacity voltage range, then complete a discharge test cycle to verify the actual cell capacity? Discard those old/cheap cells and get some fresh pulls from a laptop pack?
I don't have a Hobby Charger so I can't help you much with that. I think some chargers let you select a discharge rate so if you could select a lower rate, it might help. Or maybe your cells really are 12mAh...
do you know the discharge current you are applying? It seems like you are using a very high one, and those very old cells may have a very high sag under a big load.
try to find out the amperage you are using to discharge, and use some realistic value (1 amp, i.e.)
EDIT: if the batteries are that old, they may be damaged too
First of all, you have a very good hobby charger. I just found a manual for it online. Before I continue, do you have a DMM? If you do, measure the voltage of the Samsung cells. If one is below 3V, be careful. If one is over 4.3V, be careful, too.
Set it to LiPo setting and 3000mAh capacity for the Samsung cells (multiply the value if you charge in parallel). Its a safety function. If the battery is not full after the charger has tried to fill in a certain mAh value, it will stop. You have Samsung 30B, those are rated at 3000mAh, but you can only charge to 4.2V, so you lose about 200mAh. Normally, you should enter a mAh value of 105% the rated capacity because charging is not 100% efficient. But since you cant charge them completely (unless you can set the charger to 4.3V), the math is 2800mAh * 105% = 2940.
After you have charged all the cells, let them rest for about an hour and measure voltage. If the voltage has fallen too much (about 4.1V) those cells are probably not safe to use. Then run a discharge at 3A. If they dont return at least 2000mAh, they are not really good anymore.
As for your Ultrafire cells and those chargers: all crap, dispose them the proper way and stick with the Samsung cells. You could open the chargers and remove all the crap inside and use them as charging cradles.
IF you really (and I strongly advise you not to do so) want to charge and test the Ultrafire batteries, charge them outside in your cheap chargers and then run a discharge test at 1A.
100% would be 3000mAh. From what I understood, only one of those settings should be available.
Set charging to LiPo at a 1A rate? Let it finish? It should have to finish settings, one after the current has dropped to 100mA (you can remove the cells at this point) and complete stop when the current has dropped to 30mA.
If it took 3 seconds to reach 3V, something definitely was wrong. Maybe you have insanely high resistance in your leads? Some pictures would be nice, also check the voltage while charge and discharge with a DMM. The fact that the charger showed 4.2V and the cell rests at 4.06V implies that either the resistance in the leads is extremely high or that the cells are beyond dead.
As harsh as it may sound, I agree. If they will not hold there voltage under a 1 amp discharge for any length of time, toss them, you are far better off and safer for doing so.
Will the ultrafire’s hold there voltage under a 1 amp discharge?
The cables might be part of the problem. You should have a DMM, a cheap one for ~10$ is fine. How can someone spend that much money on a hobby charger and not have a DMM.
Your wires might also be a problem.. try to run a discharge at 300mA or so, that should work. A DMM would be useful because you could measure the voltage during charge/discharge and see if there is any discrepancy between the voltage displayed by the DMM and the one displayed by the hobby charger.