This is currently a known issue with our older version of charts - to calculate the width of columns, we find the smallest distance between two consecutive columns and use half that distance for the column’s drawing space. So when there is a single column we run into a special case, and in the older version of charts we would give this column a fixed width, which doesn't work well on charts with large ranges (as you found). The new release, due out in a few weeks, resolves this by using half of the range as the column width, however this is really a best guess, since we don’t have anything to go off for a single column.
There are a few solutions, one of which will work with any version of charts, so I’ll suggest that - this workaround is just for the case where you have a single column, and involves creating an extra “hidden” datapoint, which has a y-value of zero (or whatever the baseline of your column series is). This way the column won’t be displayed, but the column width for your lone column will be calculated from the distance between the two datapoints you provide, allowing you to customise this exactly as you need.
I hope the above helps. Being able to easily set the width of the columns is an issue high up our priority list so this should hopefully be resolved fairly soon.