Advantages and Limitations of NiMH Batteries(3) Advantages and Limitations of NiMH Batteries(3) Advantages30 – 40 percent higher capacity over a standard NiCd. The NiMH has potential for yet higher energy densities. Less prone to memory than the NiCd. Periodic exercise cycles are required less often. Simple storage and transportation — transportation conditions are not subject to
regulatory control. Environmentally friendly — contains only mild toxins; profitable for
recycling.LimitationsLimited service life — if repeatedly deep
cycled, especially at high load currents, the performance starts to deteriorate after
200 to 300 cycles. Shallow rather than deep discharge cycles are preferred. Limited discharge current — although a NiMH battery is capable of delivering high discharge currents, repeated
discharges with high load currents reduces the battery’s cycle life. Best results are achieved with load currents of
0.2C to 0.5C (one-fifth to one-half of the rated capacity). More complex charge algorithm needed — the NiMH generates more heat during charge and
requires a longer charge time than the NiCd. The trickle charge is critical and must be
controlled carefully. High self-discharge — the NiMH has about 50 percent higher self-discharge compared to
the NiCd. New chemical additives improve the self-discharge but at the expense of lower
energy density. Performance degrades if stored at elevated temperatures — the NiMH should be stored in
a cool place and at a state-of-charge of about 40 percent. High maintenance — battery requires regular
full discharge to prevent crystalline formation. About 20 percent more expensive than NiCd — NiMH batteries designed for high current
draw are more expensive than the regular version.more info:www.good-battery.com
