Ni-Mh batteries Advantages and disadvantages!

Modern batteries based on Ni-MH batteries, as a rule, are considered capable of working at temperatures of the order of -20 °C, when under light load they are able to provide up to 90% of their nominal capacity, but under heavy load at such a low temperature you should expect only 40 % of full capacity. At temperatures around 0 °C and low discharge currents, these batteries can provide about 95% of their capacity at room temperature and about 90% of full capacity at high currents. Despite a significant decrease in capacity under heavy loads at low temperatures, in the case of low power consumption, these batteries are considered fully operational in the cold. Ni-MH batteries are gaining more and more popularity (especially in the most common AA and AAA "finger" battery formats), and their capacity is increasing every year. If the capacity of the first batteries of AA format did not exceed 700-800 mAh, now small AAA batteries have similar parameters, and for the most popular AA format it does not make sense to buy cells with a capacity of less than 1600-1800 mAh. It is important that new Ni-MH batteries after purchase must go through 3-5 full charge-discharge cycles before they will gain a full charge (that is, reach peak performance). This does not mean that you should avoid short cycles, as with Ni-Cd batteries, but if you do the training at the beginning, the batteries will go into working mode faster and hold a charge better. Note that the functions of bringing NiMH batteries into working mode (as well as "training" NiCd batteries) are implemented in some modern charging devices (battery conditioners). But the main disadvantage of these batteries continues to be a rather strong self-discharge, and if you hope that once a charged NiMH battery can be put in stock, then you will be disappointed - they tend to be completely discharged in 30-60 days (depending on the conditions storage). Advantages of nickel-hydride batteries: provide a 40-50 percent advantage in specific energy capacity compared to the former leader - NiCd; have significant potential for increasing energy density; less prone to the memory effect - charging cycles can be as short as you like, and full discharge is not required often; environmentally friendly - contain only moderate toxins available for recycling; inexpensive; available in a wide range of sizes, parameters and performance indicators. Disadvantages of nickel metal hydride batteries: withstand fewer charge/discharge cycles compared to other technologies (in general, a little more than 500 cycles for modern batteries). Moreover, it is mainly a surface rather than a deep discharge, and the service life is directly related to the depth of the discharge; poorly withstand peak loads: the optimal mode of operation under load is from one fifth to half of the nominal; limited service life - if high peak loads are repeated repeatedly during the work cycles, then the performance indicators begin to deteriorate after 200-300 cycles and the work time until full discharge gradually decreases; performance is severely degraded if these batteries are stored at high temperatures. At temperatures close to 0 °C, more than half of the charge can be saved; a more complex charging algorithm - these batteries heat up a lot during charging with large currents, so careful voltage regulation and a longer charging time than NiCd batteries are required; NiMH batteries cannot be charged as fast as NiCd. Charging time is usually 2-3 times longer than that of NiCd. The recommended discharge current is from one-fifth to one-half of the value of the nominal capacity; have a very high self-discharge (up to 30% per month) - need to be frequently recharged after storage; about 20-30% more expensive than NiCd batteries of comparable capacity.