Largo Flying Club - Electric Flight Batteries

The batteries we use in our electric aircraft have numbers and letters that tell us something about the battery, as you can see below the batteries come in all kind of shapes and sizes. .

What does "C" Mean for Lipo Batteries?

The letters and numbers can tell us allot about the battery. First the letter "C". . . ."When talking about a LiPo battery the letter "C" is the capacity of the battery. Most LiPo batteries now days are rated 10C to 30C. The higher the C rating the better the battery.

How is the Capacity measured in a Lipo Battery?

The Capacity of a battery is measured in Milli amp hour (MaH) 1000 Mah = 1 amp. If a battery is rated at 2200mah it should power a motor that uses 2200mah for 1 hour, a motor that uses 4400mah or twice the power for 30 minutes. . . .and so on.

What do you mean rated?

Manufactures rate there batteries with a "C" Discharge rating. For example a 1000mah (1 amp hour) battery with a 15C rating is safe to discharge at 15,000mah or 15 amps. Do not exceed the discharge rating of the battery, it will shorten the life span of the battery and may even catch fire!

1000mah x15C=15,000mah

To convert mah to amps just divide the mah by 1000

Example: 1000mah / 1000 = 1amp

Do not buy a battery that has a "C" rating less than 15C no mater how cheap it is. You will be disappointed and waste your money.

How fast can I charge the battery?

Most manufactures recommend the battery be charged at 1C or less.

For Example if you have a 2200mah battery the charge should be at 1C 2200mah. (2200mahx1C=2200mah). I Have found by charging at .5C I get a better charge and a better balanced pack.

What is the balance plug for?

Now days lipo batteries have a balance plug that is used to monitor and/or charge the battery.

Many chargers use this plug to monitor the voltage of each cell as charging the battery to make sure all the cells have the same amount of charge. (this will be talked about later)

There are also many ad on balancers that plug into the balance plug that will do the same thing if a non balance charger is used

How long will it take to charge the battery?

Well it depends on how much it was used. If the battery was totally drained it will take 1 hour to charge if charged at a 1C charge rate. It is not a good to drain the lipo all the way.

Could I use Nickel Cadmium (NiCad) or Nickel Metal Hydride (NiMH) Batteries instead of Lipo?

Yes, but again you would be disappointed. The NiCad & NiMH batteries are 2 to 3 times the weight of lipo batteries for the same capacity.

How much do Lipo batteries cost.

The price range is around $8 for a 2 cell 800mah pack used in the small co-axel helicopters and small foamy park flyers to over $500 for the high performance 6cell Helicopters.

Cost Per Flight

I keep track of how many flights I get on some of my packs before the pack is no longer useful.

Here is what it cost me per flight for fuel (the battery)

Plane: Small Foamy

Battery: 3 cell lipo 800mah

C rating: 20-30C (16/24A)

Battery Cost: $12

First use date: 5/23/08

Flights: 70 as of 12/31/08 one cell in pack is starting to puff up, battery still in use.

Cost per flight: $0.17

Plane: Small Foamy

Battery: 3 cell lipo 800mah

C rating: 20-30C (16/24A)

Battery Cost: $12

First use date: 5/23/08

Flights: 56 as of 12/31/08 and still going strong.

Cost per flight: $0.21

Plane: E-Flight Ultra Stick

Battery: 3 cell lipo 4100mah

C rating: 15C (61A)

Battery Cost: $64

First use date: 1/13/08

Flights: 81 as of 12/31/08 and still going strong.

Cost per flight: $0.78

Lipo general information

Rated voltage per cell: 3.7v

Full charge per cell when on charge: 4.2v per cell MAX

Typical voltage after charge is complete: 4.1v - 4.2v per cell

Drained cell: 3.0v (Do not drain a cell more that 3 volts)

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