Can Some One Explain? - RC Groups
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Aug 15, 2004, 08:29 PM
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Can Some One Explain?

Can anyone explain what C/10, C/20, C/30 or C1, C10 means in regards to charging?
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Aug 15, 2004, 08:51 PM
Registered User
It's a way to describe battery charge and discharge rates. The 'C' is the nominal battery size - eg. a 650 mah bat has a 'C' value of 650 mah. DOH.

The number 10, 5, 1, 2, ... is a scaler. If the scaler is written as a divisor "/10", then C/10 means current flows at 1 tenth of C. Example: C= 650mah then C/10 is 65mah. Or C10 is 650mah times 10 or 6500mah (6.5 amps).

Hope this helps.

Aug 15, 2004, 09:24 PM
Space Coast USA
hoppy's Avatar
MIke is right on-
To avoid confusion, the multipliers may be written as 2C, 10C, etc and the fractions could be written as 1/2C, 1/10C....etc.
Aug 16, 2004, 08:32 AM
Proud member of LISF and ESL
They are used to rate the ability of a battery to serve up its energy and also to rate how fast you can charge it.

A 900 mah battery rated at 10C discharge can put out 9 amps or 10 X .9 amps
(900 mah is .9 amps)

That same battery may have a 1C, 1.5C or 2C charge rating so you would charge it at .9 amps, 1.45 amps or 1.8 amps depending on the rating. Charge it at 10 C and you can kiss it goodby and or start a fire, or worse.

Be aware that the batteries used for receivers and transmitters are typically rated at 1/5 to 1/10 C for charging. Motor batteries will be rated higher for charge. So don't charge your transmitter or receiver batteries like motor batteries. The cells are different.

For motor batteries:

Typicaly NICD batteries can be charged at 2-4 C. Some higher.
Typically NIMH batteries can be charged at 1-2 C. Some higher
Typically Lithium batteries are charged at .5-1 C. Some higher.

Best to know what you have and what it can take. Charge or discharge at too high a rate and you can weaken the cell, seriously damage it, start a fire or, in the case of the lithiums, cause an explosion.

be careful!

Outstanting information thread on Batteries - buy, build, use, maintain
Aug 19, 2004, 01:50 AM
Registered User
Thanks all. The list comes through again. It all makes sense now.

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