4.2V would be the highest that a battery would come off the charger, but thats pushing the limits. Closer to 4.1V would be better, but anywhere in between 4.1-4.2V is fine.
It all depends on the charger your using too. Some chargers cut off slightly sooner then others. I use an E-Power, which also uses non-proprietary batteries and my charger stops charging at 4.10V, which is exactly where I want it.
It depends on what device the batteries are in, but most PVs that use non-proprietary batteries will cut off at around 3.3V and will no longer fire the PV bc they need a recharge.
I recommend not letting your batteries drain all the way down though. For one, the quality of the vape will be greatly reduced at the very end of a battery cycle, so by not letting them drain all the way down, and switching to a fresh battery, you can skip that weak vape that you get with a battery thats almost fully drained.
Another reason that your batteries will last longer by throwing them back on the charger before they drain all the way. Non-proprietary batteries get about 300-500 charge cycles in the batteries lifetime. When you dont let the battery drain all the way, you dont use a full cycle. So by always doing that, the battery will last longer for ya. For example, if you recharge your battery when theres 50% left, that means you only used 1/2 a charge cycle. So if you do that 2 times in a row, the battery takes that as one full charge cycle, instead of 2.
Your best bet is to get a digital multimeter if you dont have one already. That will allow you to check the voltage off your batteries, so youll know when to throw them back on the charger. Personally, I always put my batteries back on the charger when they get to around 3.5-3.6V. By doing that, there isnt a big drop off in the quality of the vape that you get from an almost dead battery.
Also with a multimeter you would be able to check the actual resistance of your attys and cartos that your using. And by checking them before you use a new carto for the first time, youll be able to catch one that is DOA, and then you wont waste the juice that you would have put into that carto, bc youll be able to tell if its a DOA before you even use it.
You can get a multimeter for fairly cheap at a hardware store or something. Many ecig vendors also sell them as well.
If you really dont want to spend a ton of money, you can get one of ebay for really cheap.
Check here:
DT830B digital multimeter | eBay
This is a search for the DT-830B Digital Multimeter. This is the multimeter that Madvapes and a few other vendors sell. Madvapes sells it for $10 and others sell it for between $10-15.
You can get the same multimeter on ebay for under $5 with free shipping. Just scroll through the pages on ebay and find the cheapest one. The only downside is that it does ship from China, so it does take about 2 weeks, but for the price its not bad at all. Thats what I did, and it works well. I got one for $3.43 shipped, which is a damn good deal. Its obviously not the best multimeter ever, but it serves its purpose well and accurately checks your batteries voltages and the resistance of your attys and cartos. Mine shipped from China and I got it in 12 days, which really isnt that bad.
So if you want to get one, and dont necessarily need to have it right away, getting it on ebay might not be a bad idea.
I just checked quickly, and on the first page theres one for $4.19 shipped. That would be a good deal, and if you scroll through a few pages, you might be able to find one for even cheaper.
. i also do have a DMM already. i found myself constantly checking the voltage throughout usage and recharge
