I know the Nitecore i4 also comes with a car cigarette lighter as well as a mains lead.
Edit. on the i4 2 of the bays are linked. Bay 1 & bay 3 are linked to each other. Bay 2 & bay 4 are linked to each other. So if you want to charge 2 batteries (the same) using bay 1 & bay 3 will take twice as long to charge than it would if you used bay 1 & bay 2.
Lifted from a torch website
The primary difference between the Protected and Unprotected batteries is that the protected batteries have a small circuit board, typically on the bottom of the battery, that stops the charging or discharge of the battery in certain circumstances. Some of the circumstances in which the circuit include: Over-Charge, Over-Discharge, Short-Circuit, and in some cases, overheating. Over-charge protection cuts off the charging process at 4.2V, while over-discharge protection cuts off the battery at 2.8V. UNPROTECTED lithium batteries produce 4.2 volts of power when fully charged, then quickly fall to 3.6 volts output. They output 3.6 volts until they are mostly discharged, at which point the voltage falls rapidly. If they are discharged below 3 volts, they will be ruined and no longer usable. The user must be very careful not to let this occur.
Now for us what this means is, that if you are using an electronic device (typically VV or VW) that has protection circuitry built into the device (such as a Vamo) then you want to be using unprotected batteries.
If you are using a mechanical mod that has none of this fancy electronic trickery then you want to be using a protected battery.
Or to put it another way, I use unprotected batteries in my Vamo because the Vamo is protected. & I use protected batteries in my bike lights, because they are cheapo chinese crap (best & cheapest lights I've ever had) without any protection circuitry in them
