Review on Enegitech 4 Pack 9V 1200MAh Non-Rechargeable Li-Ion Batteries For Smoke Detector, Fire Alarm & Multimeter by Robert Jackson

I bought these Lithium batteries for smoke detectors around the house. Since I have a battery tester ( a real one not one that puts a small load on the battery and measures how much the voltage drops), I decided to measure the capacity compared to a top-of-the-line Alkaline battery. This test measures how long a battery will last while it is supplying power to a resistive load. The attached chart shows the result. The capacity of the batteries, measured in milliampere-hours is on the horizontal, x-axis scale, and voltage is on the y-axis. A 9V alkaline is supposed to have a capacity around 500 mA-hrs and that is what I found in my measurement. In contrast, this Li battery has a capacity of 1000 mA-hr (less than the 1200 mA-hr claimed but still quite decent). The price for these batteries is about twice the cost of first-rate, name brand alkaline units, but about four times that of the generic brands. So if it's a critical application, like a smoke detector on a 14 foot high ceiling(in my case), these might be worth the cost.