I HAVE A SKYRC B6 CHARGER. I WANT TO KNOW IF YOU INFORMATION ON DISCHARGING A LIPA 2.700 MAH 7.4V AND H901A LIPO 1400MAH 7.4V BATTERY

Based on experience I can tell you that it is is generally the temperature/cutoff/individual cell monitoring sensor in charger that dont allow the batteries to take a charge. Once the same condition is detected 3 times by the same charger it considers the batteries to be bad and refuses to accept it. I have 2 batteries that wont charge on one charger but works perfectly fine when i charge it on my other Makita charger so basically there is no problem with my batteries.
I would suggest first you check the voltage of your drained battery by a test multimeter. For 18volt battery if it is close to 18volts 1-2 volts less is just fine! Then there is no issue with your battery. Makita chargers are very expensive hitech which is useless in my opinion the lipo chargers (used in rc hobby) example skyrc are better quality cheaper and does a better job and you can easily charge your makita battery with it as well but this is only recommended if you decide not to go with Makita charger any more. Some basic information about multi chargers for Li-ion battery to follow the safety is make sure you use the right connectors with correct polarity. For 18v volts max voltage should not exceed more than 20.50 and the allowable charge current is 2.7amps also ensuring that batteries dont heatup.

That's what's happening to me I bought another battery it still didn't work so I thought it was the charger I bought a new charger and the same thing happened now I don't know what to do

Tip #1: Wait at least 15-20 minutes after you drain a battery to charge it.
This allows the battery to cool down before each charge cycle. I would make sure the battery is cool to the touch before charging it again, but 15 minutes should be alright.

Pointer #1: If the battery is hot after use, then it is a good sign that your battery is getting old.
Anything warmer than about 140 degrees is dangerous; if your battery is this warm after flying, it's time to replace it. I wouldn't use it anymore so it doesn't explode. This is a good indication that in the near future you should look to getting a new one. I would recommend a higher quality / mAh battery (keep the same voltage, though) if the battery running out is a stock battery.

Tip # 2: Wait at least 15 minutes after charging a battery to use it.
Once again, this is to let the battery's chemical processes have a break.

Pointer #2: Battery terms to understand when buying a RC battery.
mAh: Milli Ampere Hour. This is basically the electric charge transferred by a current of one milliampere for one hour. I'm no electrical genius, but the higher the mAh, the longer a battery will last per charge. This is the one part of a battery that you can change without damaging the heli.
Volt: The electrical pressure. Basically this determines how much power can flow to the motor. For lipo batteries the voltage comes in multiples of 3.7 volts, or 3.7 volts per cell.
Cell: An independent 3.7 volt battery.
If you would like a little more in-depth explanation, I found this howstuffworks article helpful.
Litium-Ion (Li-Ion): a type of battery that has a rigid cell structure and shape. It is safer than a lipo battery, but not as efficient.
Lithium-Polymer (Lipo): a type of battery with a flexible cell structure and shape. Lipos can catch fire and explode if mistreated or dropped on a hard surface. BE CAREFUL! Although more dangerous, they are more efficient than li-ion batteries and can come in practically any shape with the same cell count.
Look below to see how the li-ion (on the right) has two defined cylindrical shapes in the package, whereas the lipo to the left is just a rectangle with no visible curvature or cells.

the packs may need to be balanced..most good chargers have an option to balance your packs out..one cell may be stronger so it is running off that cell then acting dead

For lipo you need a specific charger and you can use lipo two cells dont go on three cells you push it to hard.

The difference in capacity between 1320mAh and 1300mAh is minor (we are talking about a 1,6% difference, this is below production variance anyway). If the voltage and battery type is the same and the new battery fits inside your device, there will be no problem.

Note, the 1300mAh is the capacity of the battery (how much energy it can store). The main information this value gives is how long a device can work without the battery needing a recharge. You need to be concerned only about the output voltage of the battery (measured in Volts, abbreviated V, and the chemistry type of battery like NiMH, LiIon, LiPo, NiCd). The voltage should match the original so that your GPS device works properly without getting fried or underpowered; the chemistry type must match so the battery and the charging electronics do not get damaged when the external charger is connected.

You are not doing anything wrong, chances are that you just did not fully discharge this battery before charging. You will notice that all batteries will vary from charge to charge, but this is normal. Have fun with the cars. Hope this helps.

Did the charger come with the helicopters? It sounds like the packs are being overcharged or charged at too high of a current. Lipo packs are more sensitive to charging and discharging than NiCD and NiMH packs. I got my first helicopter last year so I don't have as much experience with them as cars and trucks, but I will help if I can. I have a Venom Beacon that came RTF with a Lipo pack and charger and I have not had any problems. I would also suggest a Lipo sack to put the packs in while charging. It would keep them from catching fire if they would happen to explode. Good luck.

I just had this happen to mine too. I think this is a design problem with the camera/battery combination. My camera has a lithium polymer battery (most do now). Lithium polymer (lipo for short) batteries should never be allowed to discharge below about 2.75 volts. Letting the battery discharge below that level will actually permanently damage the cell.

In order to keep that from happening, the device that uses the lipo should have protection circuitry that prevents the battery from falling below that level. I think this is where the Casio camera may have an issue. I found that if I left the battery in the camera for about a month, I was not able to charge it! Lipo battery chargers are more sophisticated than typical charges because lipos need to be charged in a specific way. The first thing a lipo charger does is to check the voltage of the battery you insert into it. If it is below a critical minimum voltage, it will not even charge the battery (Casio charger blinks red continuously).

There are a couple tricks you can do to get the battery to charge, but that's not the important thing here. I think Casio needs to address this issue with our cameras. It would be nice if we could just update the firmware in the camera, but I'm not sure we can do that. I intend to contact Casio to see if they know anything. Based on how many posts like this I have read, I bet they do.

Good luck to use all.