Electronic – 1C charge/discharge rate in battery instruction manual

chargedischarge

Instruction manuals and discussions mention battery charge and discharge rates in terms of "1C", "2C" and so on, without giving an indication of what "C" is. I presume it is not a Coulomb. What is readily available for most batteries or battery packs is the capacity in Ah and the nominal voltage, eg 12V 22Ah golf cart battery pack. The "22Ah" implies a discharge rate of 1.1A over 20 hours. Using Peukert's law we can estimate the discharge at different rates, eg the above battery would last 13 hours at 1.5A discharge rate (assuming a Peukert's constant of 1.3). All that is great – what exactly is the "C" and what do people mean when they say "I would not charge it above 3C" ?

Best Answer

First,

'The "22Ah" implies a discharge rate of 1.1A over 20 hours.'

Only if the manufacturer says so. It might as well mean 22A over 1 hour, or any other combination that multiplies to 22Ah.

C is generally the capacity divided by 1 hour, so for your battery it would be 22A. Hence eg. 'charge at 1C' can be stated, independent from the capacity of a battery.