What do C-rate and continuous vs peak discharge mean on a lithium battery spec sheet?

Direct answer: C-rate is current relative to capacity: 1C on a 100Ah battery is 100A, 0.5C is 50A. Maximum continuous discharge is the current the battery (usually its BMS) allows without a time limit under stated conditions. Peak discharge is a higher current allowed only for the time shown in brackets, such as 5s or 10s. Compare continuous with continuous, and peaks only when the durations match.

Worked examples from Redway pages (our arithmetic for the C-rates). The 48V 100Ah high-current golf cart battery lists 230A maximum continuous discharge, about 2.3C, and 250A peak for 10s. The 48V 420Ah forklift battery lists 300A continuous, about 0.7C, and 1000A peak for 5s. The 12V 100Ah lists continuous discharge of “50A (0.5C) or 100A (1C)”, meaning two versions, and no peak figure.

Why duration matters. Other pages show peaks of 720A for 3s (36V 250Ah forklift), 200A for 10s (48V 100Ah standard golf cart), 315A for 30s (72V golf cart models) and 700A for 30s (80V 690Ah forklift). A 30-second peak and a 3-second peak describe very different capabilities, even at the same current, so do not rank batteries by peak current alone.

What drives each number. Continuous limits come from the cells, the busbars and, often decisively, the BMS and its switching components, plus heat. Peak limits allow for short events such as starting, accelerating, climbing or lifting. If a load needs high current for longer than the peak duration, the BMS may cut out.

How to match a load. Find the load’s continuous current (motor controller limit, inverter input current) and its short-term demand and duration. The continuous need should sit below the battery’s continuous rating with margin; the short-term need should sit below the peak rating for no longer than the stated time. Ask the supplier how the BMS reacts just above each limit: delay, warning or immediate cut-off.

Charge rates use the same idea. The 48V 420Ah page lists 200A maximum continuous charge at 10–45 °C, roughly 0.5C. Charge limits often depend on temperature, so read the brackets. For a golf-cart case, see standard vs high-current 48V golf cart batteries.