Get the maximal value from counted values

I use Grafana to visualize data. In order to show data availability I want to determine the number of packages/data received within a certain time, select the max and compare to the current numbers.

In Q1 I count the numbers of value in the database.
SELECT count("temperature") AS "count" FROM /^$sensor_list$/ WHERE $timeFilter GROUP BY time($__interval) fill(0)
Result looks good:

Metric Packages Received
11527.count 288
11525.count 288
11524.count 288
11556.count 287
11350.count 286
11526.count 279
11348.count 276

Now I would like to determine the maximum value from Q1 by using Q1 as Subquery in Q2.

SELECT max("count") FROM (SELECT count("temperature") AS "count" FROM /^$sensor_list$/ WHERE $timeFilter GROUP BY time($__interval) fill(0)) 

The result is not what I expected:

Metric Packages Received
11556.max 1
11528.max 1
11527.max 1
11526.max 1
11525.max 1
11524.max 1
11350.max 1
11348.max 1

How can I get the maximum Value from the Q1 result set.