NFPA 505 talks about protection of chargers in #3 below, but this could be done in a number of ways, not just putting it on a stand.

8.3.2.1 Facilities shall be provided for the following:
(1) Flushing spilled electrolyte
(2) Fire protection
(3) Protection of charging apparatus against damage by
trucks
(4) Adequate ventilation for dispersal of fumes from gassing
batteries

Thanks for the replies. This came up because someone put one of the pallet jack chargers on a pallet and is using it while it is on the pallet. No-one really knows who or why. All other chargers in the facility are on racking about 18 or so inches up off from the floor. It looks like I should dig into the manufacturer's specifications to see what they would like to see for mounting. Thanks again.

I might note that the as I read the "eye wash" rules, it is not so much a distance from the -charger-, as it is distance (or must be able to be reached within time frame) from the "battery service area", which most but not all the time is the same physical area as where the charger is located.
I might also add that, in the USA, the distance/time frame to reach the eyewash station vary state to state. it is one area the states that have their own OSHA seem to feel safe with making a distance change to a shorter distance/time frame, but this gets a long way from the original question, so please forgive an old man's mind wondering.

Some are on the floors, and others are mounted on walls. Doesn't appear that there are standards regarding the placement of chargers. There are rules as to where the ey wash stations must be located in regards to the chargers

most chargers have an airgap to allow airflow, and free flow of air around any transformer (which at it's heart, what a charger really is) can be very important, for cooling, but I would expect the mounting standards to be manufacturer's design specific, and not really something ANSI would pay a lot of attention towards.
What brings up the question? I have seen plenty of chargers bolted to the floor, in plants that I knew were often inspected for all sorts of safety concerns.