I personally would only use a charger that had the same amp output that the vape device is rated at. If my vape device had a max amp charging of 2 amp I'd only use a charger that itself was maximum 2 amp output or below, say 1 amp.
This below is an excerpt from charging advice I once read.
"Most phone chargers are fine, but we would recommend avoiding the latest generation fast chargers (3.2A) as if there is a fault in your vape this could damage your battery. For the best overall battery life, use a USB wall charger capable of delivering no more than 2A."
As a safe rule of thumb go the same or below, never above.