Battery charger gets hot during charging....

[radex5owner]

So my battery charges up very nicely, which I do after 35-40 miles on the charge on my Rad Expand 5. There are 2-3 bars left so it about 50% used.  However, I notice the charger gets really hot. I take the battery pack  off to charge it, since the bike lives in a shed when not ridden.  Thoughts?

[rjp]

that's normal. make sure the charger has air space on all surfaces so it can cool as much as possible.

[Muskie1]

 I am overly cautious, mine gets warm. I charge mine in my living room in a steel crate with a  cable attached to it. Cable  runs out the front door.

I do not do this for personal safety but for the dumbest dog that I adopted. 
He would try to attack it.
If it catches  I can drag it out.

[DickB]

So my battery charges up very nicely, which I do after 35-40 miles on the charge on my Rad Expand 5. There are 2-3 bars left so it about 50% used.  However, I notice the charger gets really hot. I take the battery pack  off to charge it, since the bike lives in a shed when not ridden.  Thoughts?

2 bars is anywhere from 12% to 25%.