Reserve Capacity (RC) is a battery rating signifying the time, in minutes, a fully charged battery can continuously deliver 25 amps at 80F (27C) before its voltage drops below 10.5 volts. This measurement indicates how long the battery can power essential vehicle accessories if the charging system fails. For example, a battery with an RC of 120 can supply 25 amps for 120 minutes before reaching the specified voltage threshold.
This metric is crucial for evaluating a battery’s ability to provide power in emergency situations and serves as a useful indicator of its overall health and longevity. Historically, it was a primary specification, reflecting the understanding that battery performance beyond starting power was vital. A higher value generally denotes superior ability to sustain electrical loads, potentially preventing a vehicle from becoming stranded due to electrical system issues.