What does “6,000 cycles at 80% DOD” mean, and how should you compare cycle-life claims?

Direct answer: “6,000 cycles at 80% DOD” means the maker’s test used 80% of the battery’s capacity each cycle and counted roughly 6,000 cycles before an end-of-life point. The numbers can only be compared when depth of discharge, charge rate, temperature and the end-of-life criterion match.

Depth of discharge (DOD) is how much of the rated capacity is used each cycle. At 80% DOD a 100Ah battery delivers about 80Ah per cycle. Cycle life is the number of such cycles completed before the battery falls to a defined end-of-life point, usually a percentage of its original capacity. That percentage differs between makers. None of the Redway pages linked here states it, so ask.

Redway’s own pages show different figures because they describe different test conditions. The 12V 100Ah page says more than 6,000 cycles at 80% DOD and 0.5C, and more than 4,000 at 100% DOD and 0.5C. The 48V 100Ah golf cart page says more than 6,000 cycles at 80% DOD and more than 15,000 at 60% DOD, with no rate stated. The PM-LV51200-5U rack page says more than 8,000 at 80% DOD and 0.5C, and more than 10,000 at 60%. The forklift pages say “5 years or 3500 cycles (DOD 70% 0.25C)”. These are different definitions, so do not rank products by the headline number.

Rate matters. 0.5C means charging and discharging at half the rated capacity per hour (50A on a 100Ah battery), and 0.25C is half of that. A result at a gentler rate does not transfer to a harder duty. Temperature matters as well, and the pages we read do not state the test temperature.

A cycle count also says nothing about calendar life. Redway lists design life separately (10 years on the golf cart and 12V pages, 20 years on the rack pages) and warranty separately (5 years on the golf cart pages, 3 years on most of the 12V pages, 10 years on the rack pages). Cycles and years are different promises. A warranty should say which limit applies first and what usage is excluded.

To compare suppliers, ask each for the same five items: DOD, C-rate, temperature, end-of-life criterion and the test lab or report. IEC 62619 sets safety requirements for industrial lithium batteries, not a cycle-life promise, so a certificate list does not answer this question. Confirm any figure in writing from Redway engineering before it goes into a business case.