We have a small home fire extinguisher in the utility room.
We first put one in here back in September 1986.
One of the properties of small children is they get into everything, and you have to watch them all the time. In this case the grandchild was attracted to the fire extinguisher, and in the process of telling him to "leave it!", I noticed that it was undercharged.
I believe this happened once before, with my own kids -- they noticed it was undercharged and needed to be replaced.
I found a replacement at Lowes for $19.98. First Alert HOME1 Rechargeable 1-a:10-b:C Residential Fire Extinguisher. Model FE1A10GR195.
The first step is to remove the old fire extinguisher.
The new one is smaller than the old one, and has then a smaller bracket. So we remove the old bracket.
Thankfully, the mounting holes are still in the same place, so we can just reuse them to mount the new bracket.
Then we put the new extinguisher on the new bracket
and we are ready for another 15 or 20 years. Just to be sure, we check and see that it is properly charged.