Poor man's Pro Vari

[Dampmaskin]

The mini has a long cord, about 6 ft, so the power is well away from my face and hands.

Well that's good for safety I suppose. I hope the cord is also thick, because at these low voltages and high currents, the resistance of the cord will be significant, even over just a few feet. Depending on the thickness of the cord, you may even lose a whole volt or more (just a guesstimation). I have considered upgrading the cord of my own USB passthrough for this very reason.

 

[carlko]

I was thinking about getting a bench quality power supply - 30 v 10 A, variable to a very fine degree - when I decided to try the series batts first. I was aware of the problem of putting them in series but the mini has a good pcb and the li mn are supposed to be safe. The main reason for using the batts is the unit is portable - I can walk around with the batt box in my pocket and the cord and mini will reach to my mouth easily.

 

[carlko]

Right now I'm constantly monitoring the batts and cord - everything so far is fine, no temp increase. The batt box is cheap, $1.50, and the wires are silver colored, not copper, and very thin. I was going to replace them with better copper wire but I stink at soldering, so I just hot glued the switch with the neg lead and the positive batt contact with lead - already had one wire break loose from the contact. I'm sure I lose some current through the wires and the absurd on/off switch, but I'm getting good volts and amps. And for now I test the voltage of the batts while using - my current use shows each batt at 3.85, so they're working well together.

 

[carlko]

I should have said what the colors mean - they are the colors of the led button which you press 4 times to change. Unloaded voltage is:
blue - 2.75 purple 3.5 red 4.0 green 4.8. I can't test the loaded voltage but based on the ohms and amps, it certainly drops significantly, especially when connected to the power supply. I think it stays very steady when used with the batt box.

 

[Dampmaskin]

I'm sure I lose some current through the wires and the absurd on/off switch, but I'm getting good volts and amps.

Did you measure the voltage under load? Measuring without a load will not reveal the voltage drop of the cord.

 

[p.opus]

Nevermind...I misread.....

 

[drmarble]

My only concern is the mini variable voltage module. When you feed it more than the 5.2 volts it was designed for it has to dissipate much more heat to drop the power. Maybe it is a simple resistor voltage divider, maybe it is an IC. Still, it has to dissipate more power. Fortunately, your finger is right on it and can feel it getting hot. If nothing shorts out, your batteries should be safe, but put in better wires to try to avoid a short. If a wire snaps and touches the other, you have a dead short and the batteries could react negatively (explode). You could put a one ohm 10 watt resistor in one wire. That would drop 2 volts at 2 amps and would decrease the power that the mini has to dissipate.

 

[carlko]

Did you measure the voltage under load? Measuring without a load will not reveal the voltage drop of the cord.

I can't measure the loaded volts on the mini because the current passes through the pcb and I don't have the device to put on the 510. I can read the amps and the numbers in my OP show calculated voltage using amps and ohms. I can read the loaded volts using a box mod and get about 4.5 - 4.9 from the power supply and about .5 volt loss from the batt box - that all calculates correctly given the ohms I know I have and amp reading. An interesting thing - when using the power supply the amps through the mini fluctuate a lot - as much as .4, but when using the batt box, there's no fluctuation.

 

[carlko]

My only concern is the mini variable voltage module. When you feed it more than the 5.2 volts it was designed for it has to dissipate much more heat to drop the power. Maybe it is a simple resistor voltage divider, maybe it is an IC. Still, it has to dissipate more power. Fortunately, your finger is right on it and can feel it getting hot. If nothing shorts out, your batteries should be safe, but put in better wires to try to avoid a short. If a wire snaps and touches the other, you have a dead short and the batteries could react negatively (explode). You could put a one ohm 10 watt resistor in one wire. That would drop 2 volts at 2 amps and would decrease the power that the mini has to dissipate.

I've been using these minis for about 1.5 years and there's never been any extra heat from the power supply - so nothing detectable on the cord, mini or batts. The mini has a very good pcb which regulates volts and amps. I would replace the wires in the batt box but I'm very poor at soldering. I hot glued the switch and the batt contact that has the positive wire - pretty impossible to get a short in the box now.

Edit: As I said earlier, I have put a shorted Vivi on the mini and it just flashes then turns off.

 

[carlko]

Brief update:

I tracked 2 efest li mn through a complete usage and the voltage decreased on each exactly the same until about 3.5 V - then one began decreasing faster. When the loaded voltage dropped to 2.9 I stopped. I then tried 2 ultra fire protected li ions - they don't work above the purple (3.5V) setting - my guess is the amps cause the batt protection to shut the batt off. Since I only have 2 efests and charging is 4 hours, it will take a couple weeks before I know if I'll continue with this.

 

[carlko]

All is going well with this set up. Some of you asked for pics but unfortunately I've lost my blue tooth connector - hardly ever use it. Here are some pics from ebay:
This is like the mini I'm using. The one I have was bought about 1 year ago from a web site that doesn't carry them any longer. I just ordered one of these:
Mini Ego V V USB Variable Voltage Pass Through Battery for Ego 510 | eBay

The battery box I'm using. Very cheap but works. If this goes well another couple of months I will look for a better box:
2 x New 2 AA 2A Battery 3V Holder Box Case with Switch Black | eBay

Bullet connectors - suggest using male on one pole and female on the other which will make reversing the polarity impossible:
http://www.ebay.com/itm/50-Male-Fem...ideo_Connectors_Terminals&hash=item2ecee50d0a

 

[carlko]

I decided to do another followup because I've discovered a couple things and have some new ideas. First, I was convinced by reading so many good reviews that the Itaste MVP2 was a great PV, so I bought one. That was about a month ago and to date I've recharged it a total of 3 times. It just doesn't get much use as the vape is inferior to my batteyrbox/mini setup - noticeably so. It does have a nice ohm meter and I did get to try the Iclear 30, which I will never buy one because I rebuild my own heads and this one is the head from the abyss - no doubt the grommet intentionally recessed to make sure we couldn't build our own with the result they made sure I will never even look at another Innokin product - good job.

Anyway, venting aside, the bb/mini is working like a charm. There are simply no safety issues(assuming you don't do something stupid like hooking the bb into the ps - oops) and it finally occurred to me what I've done is no different that a Madvapes style VV box mod, only the regulator and potentiometer are already attached to the PCB, along with a great switch - no soldering required - and all for $9 - yeah, that's what they are now on ebay.

So I've ordered a mini voltmeter to attach to my battery box, and now I'm thinking I can pull the PCB out of the mini and attach a voltmeter between the PCB and the connector to get loaded voltage. The reason I'm following up here is I hope there are some modders out there that will try this as well. Though I'm sure I can do it, those who have more experience will no doubt find better ways than me. I'm going to wait till my mini VM comes in to see how it works and its accuracy, but if all goes well I'm going to build a box with the mini PCB and two VM's - 1 for the battery box and 1 for loaded voltage. Then, down the road, I would like to up the bb to 18650's.

Final word - this really does give a better vape than the MVP2. It isn't quite as good on a power supply, but perhaps there are some with better power supplies who would like to try it. But on 2 efest 14500s in series, it's fantastic. Anyone want a slightly used MVP2 for 1/2 price and shipping, a headless Iclear30 included?