ProVari Variable Voltage Mod

[sharpster]

Hi everybody, well after wanting one for the last 4 months I finally bought a black one--yeaaa. So hello to everyone and I hope I don't make anyone crazy withh some stupid questions.
I have a SSLiquinator and have been looking everywhere for Boge steel regular resistance CUT ones. Finally found some and ordered 15 at 2.35 wach. Ok that wasn't bad but when paypal was checking me out and we got around to shipping it was $125 WOW the company selling them was in Australia [ needless to say I didn't confirm daaaa. Would anyone here know where I could get some or I guess I'll have to buy a cutter at Lowes??

 

[Vaporologist]

Why not just by them from vaporescence? Theirs are cut specifically around the thickness of the LQ caps... And if you are up to the task, I would suggest learning how to cut or punch your own. It's way more cost effective imo.

 

[Dark Jester]

Would anyone here know where I could get some or I guess I'll have to buy a cutter at Lowes??

You don't even need an official 'Dremel' for this. Just search around the net for a cheap 'rotary tool'. You don't even really need variable speeds or the high powered ability to cut through steel pipes in order to cut a quick notch in cartos.

Here's a cheap kit from Harbor Freight for only $15 on sale right now: Professional 4 Speed Rotary Tool Kit

I will add a few words of caution, these things can be dangerous to handle. When cutting through stuff they sometimes have a tendancy to 'grab' the item you're cutting and jump in the direction the wheel is spinning. This can potentially cause some damage if that rapidly spinning blade contacts flesh. Make sure you have a firm grip on both the tool and the item you are cutting, and don't put yourself in the cut-off wheel's path.. I've nicked myself a few times using them over the years. Nothing serious, but it definitely perks you up and makes you respect the tool you're holding.

 

[MiXoLoGiSt]

Only problem is Harbor Freight has horrible tools that never last long. I would just buy a REAL dremel that way you know its going to last.

 

[Dark Jester]

I'd agree if I was using it to do anything a normal dremel does. For just cutting notches in carts though, I doubt that's gonna burn a motor out any time soon.

 

[ricks]

I would get the one from Harbor Freight. I think I saw one for under 10 bucks.

I'd agree if I was using it to do anything a normal dremel does. For just cutting notches in carts though, I doubt that's gonna burn a motor out any time soon.

 

[debb]

I got my dremel from Walmart...works great for what I do....slotting carts, drilling fill ports, even cut a carto metal case to make a slotting shield....

 

[blacklung]

Does anybody know if the ProVari is more efficient(battery life) at bucking or boosting the voltage?

 

[mendnwngs]

I don't know any specifics of what circuit the Provari uses, but its been my experience that the efficiency doesnt change too much from lower than input to higher than input. The DC-DC circuit takes the input voltage, "Processes" it then sends out the desired voltage.. This happens regardless of the output setpoint being higher, or lower than the source voltage.

Higher voltage out, puts heavier current demands on the battery, and Lithium batteries get unhappy with higher loads. The battery will loose "efficiency" as the current demand on it is increased. So, at higher wattage / voltage you will see a decrease of actual battery capacity, but thats due simply to the nature of the battery, and theres not too much we can do about it currently. Lower internal resistance cells tend to handle higher current loads better tho.. The batteries that Provape sells (IMR AW) are (IMO) quite literally the best in this regard.

 

[Dalton63841]

Does anybody know if the ProVari is more efficient(battery life) at bucking or boosting the voltage?

The Provari is actually not your run of the mill buck/boost. It uses pulse width modulation. In a nutshell, output voltage is determined by duty cycle. It's efficiency is determined by amperage. 3.7v with a 1.5ohm atty(9.13watts @ 2.47amps) will need recharged sooner than 5v with a 3ohm atty(8.33watts @ 1.67amps)

 

[blacklung]

thanks guys...



More questions to come when I have a moment to word them properly in my head.

is there a calcuator or formula for figuring that out Dalton? (" 3.7v with a 1.5ohm atty(9.13watts @ 2.47amps")
well, I know there is.... but do you have a link or sub forum I can find it in.


and


before I re stock on 306s....
should I go with the LR (1.5 ish up to 2.0ohm) and run at 4.2V or less or go with 2.x-3.0 ohm and run at a higher voltage? is battery life the only benefit of running a higher ohm at a higher voltage?(or longer atty life? etc.)
I think I've read that most people are using higher ohm at higher voltage when it comes to the Provari, just wondering why?

 

[Dalton63841]

HV atties DO last longer than LR atties. The coil is made stronger to withstand the higher voltages. As for the 306, the general consensus is that they only taste good at low resistance. I'm not sure why.

As for the math, it is basic Ohm's Law. There is a formula that everyone should know, but to keep math to a minimum I just use this: Ohm's Law / Watt's Law Calculator

 

[jimho]

The Provari is actually not your run of the mill buck/boost. It uses pulse width modulation. In a nutshell, output voltage is determined by duty cycle. It's efficiency is determined by amperage. 3.7v with a 1.5ohm atty(9.13watts @ 2.47amps) will need recharged sooner than 5v with a 3ohm atty(8.33watts @ 1.67amps)

Have you put it on a scope?
I don't believe they are doing PWM to regulate the RMS voltage. Buck/Boost regulators do in fact generate pulses and most can be tuned or programmed a bit, but I do not believe they are using full blown PWM and adjusting the duty cycle to give you the full range RMS voltage from 3V to 6V. This was discussed way back when, before the beta. It's possible that they are tweaking the duty cycle to keep the voltage locked though...


Also, through my testing with earlier builds, with the IMRs, I found the efficiency to drop by a good percentage at higher voltages. I did most of my testing across different attys keeping the wattage about the same... Remember as the battery's loaded voltage drops, it needs to crank more and more current to boost... I found it to be most efficient around 4.2V - rarely went below that because of issues with LR attys that started to kick in around 2 ohms...


Don't get me wrong- I love this device but I don't think they used PWM wholesale the way you're suggesting here....

 

[jimho]

HV atties DO last longer than LR atties. The coil is made stronger to withstand the higher voltages. As for the 306, the general consensus is that they only taste good at low resistance. I'm not sure why.

As for the math, it is basic Ohm's Law. There is a formula that everyone should know, but to keep math to a minimum I just use this: Ohm's Law / Watt's Law Calculator

In general I agree with you- the premise would be that the HR atty was made by using more wire as opposed to a thinner gauge.

Also, temperature of the wire is a function of current and wire gage- on paper, the longer resistance wire would run cooler because it would be passing less current but would still be giving off as much energy in heat.....

However, if someone were to use say 36Ga wire in the coil where they previously had the same lenght of 32Ga or 34Ga, the atty would be stressed even more by running hotter across a thinner wire....

 

[Dalton63841]

Have you put it on a scope?
I don't believe they are doing PWM to regulate the RMS voltage. Buck/Boost regulators do in fact generate pulses and most can be tuned or programmed a bit, but I do not believe they are using full blown PWM and adjusting the duty cycle to give you the full range RMS voltage from 3V to 6V. This was discussed way back when, before the beta. It's possible that they are tweaking the duty cycle to keep the voltage locked though...


Also, through my testing with earlier builds, with the IMRs, I found the efficiency to drop by a good percentage at higher voltages. I did most of my testing across different attys keeping the wattage about the same... Remember as the battery's loaded voltage drops, it needs to crank more and more current to boost... I found it to be most efficient around 4.2V - rarely went below that because of issues with LR attys that started to kick in around 2 ohms...


Don't get me wrong- I love this device but I don't think they used PWM wholesale the way you're suggesting here....

Hmmm see that is interesting... Good to know honestly, but now I am curious. I get quite a bit more battery life when I use my 2.5-3ohms, than when I used 1.5-2ohms.

 

[jimho]

Hmmm see that is interesting... Good to know honestly, but now I am curious. I get quite a bit more battery life when I use my 2.5-3ohms, than when I used 1.5-2ohms.

I use 3.5's and 4.2's ;-) with the IMRs I couldn't run below 1.9/1.8 without errors. Even at 3.3V.
I definitely get better mileage with standard attys.
I can't remember the exact number but I think it was around 20% worse at 6V at the same power level than 5V....

 

[Marst]

Today the new black batteries arrived. Let's see what they bring. The red managed app. 1 ml per load.
Interesting: multimeter says 4.2V, Provari thinks 3.9 when fully loaded with Pila loader.
Also carto: multimeter says 2.5, provari 1.6 Ohm.
Only With output Voltage they say the same from3.3 to 6.0.
I'll check with another Multi when it arrives from DX.


Sent from my iPhone using Tapatalk

 

[jimho]

Today the new black batteries arrived. Let's see what they bring. The red managed app. 1 ml per load.
Interesting: multimeter says 4.2V, Provari thinks 3.9 when fully loaded with Pila loader.
Also carto: multimeter says 2.5, provari 1.6 Ohm.
Only With output Voltage they say the same from3.3 to 6.0.
I'll check with another Multi when it arrives from DX.


Sent from my iPhone using Tapatalk

When you swap your springs for the new one that comes with the provari batteries, do yourself a favor and clean it out real well.....

 

[Killjoy1]

Also carto: multimeter says 2.5, provari 1.6 Ohm.

That's a pretty big difference, but at least some of it could be accounted for by the internal resistance of your multimeter. Put your probes together and it will read this resistance, then just subtract that from the reading you get on the atty. Mine, for example, is a cheapo multimeter from an auto parts store and reads 0.4 ohms extra due to this ;-)

 

[emonty]

The Provari is very accurate!