M401 battery and USB Passthrough correct voltage

[mvc]

Hello,
I have a automatic M401 USB PT which I got from absolutelyecigs and was wondering what voltage it runs. After checking it with my multimeter and I activated it (pull some air) I got reading of 3.28v. I checked my manual M401 battery I got from the same place and saw it runs on 3.7v (it was used for some time). Also checked my M401 charger and saw it gets like 4.2v. I have a few KR808 batteries and checked them - they were something like 3.7v, 3.8v and 4.2v (that one was just charged fully).
1. So the question is why this difference and is the USB PT voltage right? After reading a lot I think it should be at least 3.7v and maybe closer to 4v to get good vapor.
2. The second question is for my second M401 battery - after fully charging it it reads 2.83v - is the battery gone?

 

[Kurt]

Hello,
I have a automatic M401 USB PT which I got from absolutelyecigs and was wondering what voltage it runs. After checking it with my multimeter and I activated it (pull some air) I got reading of 3.28v. I checked my manual M401 battery I got from the same place and saw it runs on 3.7v (it was used for some time). Also checked my M401 charger and saw it gets like 4.2v. I have a few KR808 batteries and checked them - they were something like 3.7v, 3.8v and 4.2v (that one was just charged fully).
1. So the question is why this difference and is the USB PT voltage right? After reading a lot I think it should be at least 3.7v and maybe closer to 4v to get good vapor.
2. The second question is for my second M401 battery - after fully charging it it reads 2.83v - is the battery gone?

I'll take a crack at this, although I don't own a 401. 2.83V if fully charged probably means it is not viable anymore. If the charger charges the batts fast, that is convenient, but it reduces the number of cycles the batt will have in its life. Most batts are good for 200 cycles or so, but that can be shortened. Slow charging is best for batt longevity.

As for the PT, 3.28V sounds right for a PT. Most stock PVs and PTs that are not specifically batt mods run at significantly less than 3.7V. A 510 regular batt only puts 3.1V on the coil, not 3.7V. You need considerably more batt capacity to get up to 3.7V actually on the coil. Just checking the batt voltage doesn't tell you what the voltage on the coil is.

You might see what others have measured on 401 hardware:

M-401/402 "Mini" & M403 Super Mini - E-Cigarette Forum

Hope this helps some. Like I said, I don't have a 401, but it looked like you were waiting a bit for some sort of reply.