2 'AA' alkaline batteries, I believe.
Take the old dead battery out and look closely at it. The Type is written on the battery.
1.5 volts upwards, depending on the number of cells required by the remote. Each type of remote is different. Usually, either on the battery cover or inside the battery compartment, there is a small diagram showing the size and number of batteries required.
It is the same if you have can recharge your battery or you buy disposable, the Bluetooth remote may require a AA battery or a Lithium 3.0V coin battery. It will depend on what type of remote you have.
Open it up and look see. You now know what replacement battery to buy.
You don't! I tried using a screwdriver to pry open the remote. The remote must be taken to a dealer and they change it. I was shocked when I found out, but it was fairly painless to have them do it.
The CR1620 battery is a lithium battery. This battery is small and is meant for watches and other devices that take small coin size batteries. It can be found online.
According to the 1997 Mercury Cougar Owner Guide : Each remote takes ( 2 ) coin type , 3 volt lithium batteries ( # 2016 )
open your remote handset up.take the battery out..look at the battery identifying marks..go to your supermaket and buy one,replace it, simple
Anyplace that sells batteries can tell you the correct size to buy.
pansonic 2012
The best way to remove the cover to your remote depends on the type of remote you have. Alot of remote controls have AA battery at the back of the remote. You simply unhook latch and slip down the cover to insert the battery.
SwatchBattery has a lot of coin type batteries. http://swatchbattery.com/ . My 2002 300M remote uses a CR2016 (3volt) battery which they carry.