Welcome to the forum!
I'm a regular in the evic vt
thread here.
It is the charging cable or wall adapter.
The evic needs over a 1/2 amp to charge, you've got basically 2 high powered cell phone
batteries.
We have seen many reports of this and its always been the cable. The cable shorts or breaks inside at the end where it bends. This causes low to no charging.
Use a 1 amp charger with a good cable. If you have a micro USB phone with Android there's an app to check the output of your cables its called Ampre its free, then you know.
One major issue that confusing is that many times the cable will charge a phone cause its laying flat. When plugged into the evic its up high and strained. This causes bad cable to lose connection through the wire. When plugged into phone hold the plug in the phone and wiggle the cable to see it cut out charging.