The cache: Container is a gray KenLoc Box hidden in plain sight. Hold the battery in place on the bottom of the box then lift the front cover from the bottom. Make sure you close the box before leaving. Muggles probably won't know how to open the box, but now you do. And remember, if you borrowed the battery from your bedroom smoke detector, replace it before smoking in bed tonight!
If you forgot to bring a battery, there's a loaner you can get nearby at GC1W91P just down the street a bit thanks to Rhes and Bean Scene!
The location: Back when I was a kid there were no hybrid or electric buses or cars since batteries just couldn't do the job needed. If you wanted to run a bus on electricity you needed to bring a long extension cord. That's just what was done with the electric trolley buses in Chicago and other cities. The "extension cord" was strung along the streets above the road and the buses used a pair of booms to connect to the power. I remember a lot of wires over a lot of streets when I was a little kid. Of course you needed special places for these trolley buses to turn around. This location was the trolleybus turn-around for the #80 Irving Park route. Here's a picture of one of those trolleybuses at this corner (looking northeast) from 1972.
several more pictures from this corner. They are from an era where Chicago's street signs were yellow and buses were green. We used to call the CTA buses our Big Green Limousines. This turn around was used for electric trolleybuses until 1973. This little "park" still has the original steel poles that supported the electric wires. The cache is on one of these poles. The pole on the southeast corner even still sports an old battered CTA sign.
The history: In 1896 an electric streetcar route was opened to serve this area which was a nearly undeveloped part of Chicago at the time. A map from 1897 shows the area with the recently finished streetcar line as a dashed red line on the map.
There are some other items of interest on the map as well. The Indian Boundary Line which is now Forest Preserve Drive, can be seen cutting across the area. The County Poor Farm is right here, of which you can get a great history by visiting some of Cachew Nut's nearby caches for his Crazy Train series including the now archived Crazy Train 3 cache which used to be right across the street from here, and the still active Crazy Train 4 cache just north of here which is a must-see for history buffs.
By 1928 the area had developed so much that the Chicago Motor Coach company started sending it's Narragansett-Austin buses west from Neenah Ave (where this cache is) to Harlem Ave. When that service was discontinued in 1930, the CTA created an extension bus route (#80A) from here to Harlem Ave. In 1948 the electric streetcar route was converted to trolleybuses, with the turn around right here. The #80A extension route remained since the trolleybuses turned around here.
In January of 1973 the electric trolleybuses on this route were replaced with motor buses and this turn around was used as a terminus for the regular #80 buses and the #80A extension. In 1983 the #80A route was renumbered to #80W and extended to the Rosemont/River Road station of the Blue Line, and, in 1988, was merged into the main #80 route.