The battery symbol comes on the dash with a set of dings. Usually seem to notice it when going up a hill, when engine drops down a gear and ends in about 10 seconds. This is a newer alternator and battery. Did this the first ride with new alternator. Any thought on what to check?

 

The charging system and the battery. This can be done at most big box auto parts palaces. It can also be the serpentine belt and tensioner is aging and the spring is weak

 

Everything having to do with the serpentine belt.

 

New serpentine belt also, leaning towards the tensioner.

 

It is recommended to replace the belt and tensioner as a pair at the same time.

 

But before that, just check your battery terminals.
The battery should be firmly secured (screwed) to the floor. The terminals should be clean without any white coating and tightly screwed to the battery so that it cannot be turned with bare hands.

 

The problem most likely is a bad connection at one of several possible points, starting with the battery terminals.

In detail, what led to the alternator and battery replacement?