Most of this isnt new, and alot of it has been said elsewhere in this post, but I thought I would collect what I believe are the best features and list them here in a single post. So --
The VV add-on unit should be a self contained unit that doesnt alter the existing GGTS. It should simply screw on for the VV functionality, and when removed the GGTS returns to its full current manual functionality. VV units have to connect with the positive pole of a battery, so the most logical place for the unit would be between the CT and the Battery, with the existing GGTS manual button operating the VV functionality. The following is the functionality I would like to see in a VV add-on to the GGTS:
1. Single battery with a voltage booster.
2. Ability to adjust voltage up and down.
3. Digital display to visually show your atty/carto ohms.
4. A low battery alert.
5. Reverse battery protection.
6. Battery monitoring.
7. Short circuit protection.
8. Auto amperage limiting system that can be toggled on or off.
9. Thermal monitoring.
Comments to the above:
1. Single battery with a voltage booster where voltage can be adjusted from 3.2 ‐ 7.4 volts underload in 0.1 volt increments. An IMR high drain 18650 3.7v is the ideal batt for a VV with a Booster because of the 10C discharge capability. For those wanting a shorter PV, they can use an IMR 18350 3.7v batt. With a single batt, high drain capabilities and safe chemistry like IMR batts, all the dangers of stacking are eliminated.
2. Different attys and cartos with different resistances have different voltage sweet spots. By varying the voltage you now have a tool to find the perfect sweet spot independent of what batts you use.
3. With different attys and cartos it is a MUST to know the resistance before adjusting the voltage. Advertised ohm ratings arent always reliable, plus resistance will increase with use as the heating element starts to carbon over. Without knowing the actual resistance of your atty or carto, adjusting the voltage is just a crap shoot. Knowing the resistance you can adjust your voltage accordingly and squeeze every bit of life out of an atty/carto. In this case, some sort of digital display is necessary. It doesnt need to be large, just visible. For those wanting an all metal look, a small window with a metal shutter that slides over the window to conceal it would work.
4. Some sort of battery alert is necessary before the batt goes totally dead and you freak thinking that your VV unit has died. By changing the batt when alerted, this helps you keep your PV working at max vaping pleasure all the time plus it helps to avoid unjust expletives directed at Imeo.
5. Reverse battery protection that keeps the circuitry safe if the battery is installed backwards.
6. Battery monitoring which shuts the PV off once a battery has reached a designated end of charge will prolong battery life and prevent batts from venting due to being over discharged.
7. Short circuit protection that shuts the PV off to protect the PV against shorted cartos and attys.
8. An amperage limiting system saves attys. Any VV owner can attest to that. However, for some situations (i.e. dual coil cartos) there needs to be a way to turn off the auto protect so a user can select what voltage they wish to use.
9. Thermal Monitoring to provide an alert and/or shut the device off when it detects a high temperature condition. A must have safety feature.