9V battery of NiMH composition
For some 9V batteries, you can find the manufacturers, mentioning it as the low-discharge products. The label, low-discharge, on the battery design indicates that the product is capable of holding the charge for longer period. You can find this feature in NiMH 9V battery. However, the older models of NiMH batteries do not have this low-discharge capacity. Thus, look for the reliable 9V batteries of the reputed brands. You may use this type of 9V battery for your fire alarm system, in which you need to place the battery for more than a year.
Know the capacity of your 9V battery
The capacity of 9 Volt Rechargeable batteries is 250 mAh. The price of these batteries may be slightly higher. However, as the battery capacity is very high, you will find a superb quality in these products.
In addition to NiMH, Lithium Polymer is another chemical composition, found in 9V batteries. There is a gel-type electrolyte in this battery. The energy density of this battery is much higher than that of the lithium-ion cells. However, lithium-ion cells are also reliable for your everyday usage.
Choose 9 Volt Rechargeable batteries, checking their chemical compositions.