Pilot_Guy

I'd like to start a thread on understanding Li-Po batteries and the safety one should consider and practice when using them in your hobby.


I don't know a lot about them only the basics like the MAH rating like 900 means how much capacity the battery has(the higher this number the more fuel or "capacity" it has. The other number(the "C" rating) is the batteries discharge rate meaning how fast it will discharge. The faster the discharge rate the more power your motor will receive, but it will be a shorter flight time.

I like a battery for my Dauphin that is 900-1200 MAH and 10C discharge rate...Makes for a nice, long, comfortable flight.

Of course Li-Po should never be over charged beyond 4.2 volts in each cell or discharged no lower that 3.2 volts in each cell. A Low voltage cutoff is recommended or when you feel the helicopter start to lose power, immediately land and kill the throttle. On my Dauphin's 800MAH 10c battery pack, I set a time limit to 7 minutes regardless if the battery still has lots of power or not.(I have a beep that goes off on my watch after 7 minutes. These batteries are to expensive to ruin, so 7 minutes is the cutoff no matter what. This ensures the battery is not over discharged.

As a safety precaution, charge on a flame proof surface like bricks or sand...keep a fire extinguisher in the area and don't fly over dry brush or dead grass..it will catch the forest on fire if you have a battery incident

This information is the best to my knowledge and if ANYTHING is not accurate PLEASE say so and I will edit it. I'm not a pro, just a guy that wants to know and learn about all aspects of this great hobby. Also many new guys don't know anything about these special batteries..so I hope this thread will help them out.

Please feel free to add things or correct me..... much appreciated.

aircrash

Hi Pilot_Guy,

Well said. A few additions.

It will be a shorter flying time but it will be a good one, as you`ll have power to the throttle when you need it.
Also in a higher discharge rate battery the battery itself will not have a hard time, and will not get hot and so be damaged. If you fit a low discharge rate battery to a high current demand heli then the battery will be degraded or even damaged only by a few flights.
The discharge rate is not so important on a 180 motor helicopter though, as the current demand is not so big, that almost any battery can handle/output.
So the discharge rate shows how many amps a battery can deliver and if you know how many amps the motor(s) draw then you can calculate what is your needs.

You can also take a voltage indicator and check the battery voltage. As long as the voltage indicator is a good one, with good accuracy, then you can monitor the battery voltage (which shows the charge state) and be able to use semi-discharged batteries for a short flight.
I mean you use a battery only for 3 minutes and then you let it sit. You haven`t marked it and you have put it among other batteries you have.
You don`t have to guess which battery is not fully charged and at which level, you measure the voltage and if it`s close or above 3.9V then you can use it for a short flight.
Even if you have no voltage indicator you can use a semi-discharged battery, and you have no problem even if it is a fully discharged one, as the 3in1 or 4in1 will not let you to run the heli at all if the battery voltage is too low. So the battery is protected.

Also the 3in1 or 4in1 has a low voltage protection. That will reduce power (and make the heli lower the altitude by itself) so to protect the battery from a low voltage discharge. This makes you feel it`s loosing power as you said.
So you can fly until the heli reduces power, except if you fly in a resident area above a house or something so you don`t want to have reduced power for a good returning at base with no danger to hit somewhere.
In this case a timer as you use is the best.

You can find cheap batteries in ebay.

Spiros