Variable voltage booster?

[jmanning]

So I have built an Evercool mod. It was relatively simple and I and am very pleased with the results, except that I have to use 2 batteries and for any battery life the mod has to be fairly large. I am running 2 18650s. What I would like to know is if there is a similar simple variable voltage booster circuit, so that I can use say a single IMR18650 and vary the output between 3.7 and 5v?

 

[mwa102464]

there must be, the provari is using it

 

[Rockproof]

I'll be waiting for some of the more versed modders to chime in on this one as I would like to build the same thing.

 

[Java_Az]

A booster alone wont work if you want to get into the 3 volts area. With a booster chip the input voltage has to be lower then the output. A fully charged li ion battery is 4.2 volts. There is a TI booster chip folks have modded to trick it down to around 4.4 volt range. To get into the 3 volt range you would need a buck/ boost chip. Which just means it will regulate the voltage down if the battery voltage is higher or boost the voltage up in the battery voltage is lower then the set output voltage

 

[Gummy Bear]

TI makes a sweet little booster chip. PTN04050C.
It is the one I used. search the threads and you will find more stuff about it than you need to know. This forum has all the info for you to get it up and running.
Edit:
as Java just said the output can only go down to about 4.4v. but that is a great vape voltage

 

[WillyB]

So I have built an Evercool mod. It was relatively simple and I and am very pleased with the results, except that I have to use 2 batteries and for any battery life the mod has to be fairly large. I am running 2 18650s. What I would like to know is if there is a similar simple variable voltage booster circuit, so that I can use say a single IMR18650 and vary the output between 3.7 and 5v?

Of course it's doable (more or less), but you are a very heavy vaper.

Nuck's guide should provide you with all the details, if you don't like the presets you should be able to go with a trimmer.

https://docs.google.com/Doc?docid=0AXdaMZo4FKMVZGhqdnE4YnNfNDNjN2Q0cHBoZg&hl=en

Here's another take on it.

Another Fistpack

Done note though that when you go to one 18650 you'll be cutting your Evercoool vapes in less than half.

None of these regs/boosters are 100% efficient and with the boosters you'll be putting extra current demand on the cell as it 'boosts' over the cells voltage.

 

[asdaq]

And there's MisterD's varbox, also Nuck based with a pot:

http://www.e-cigarette-forum.com/forum/modders-forum/114510-boxmod-variable-voltage-w-digital-reader-bottom-feeding.html

 

[Gummy Bear]

For what it's worth:
I get about 5 hours from a 18650 (ultrafire) boosted to 4.5 v with a 3 oHm C2.

 

[SurvivorMcGyver]

So I have built an Evercool mod. It was relatively simple and I and am very pleased with the results, except that I have to use 2 batteries and for any battery life the mod has to be fairly large. I am running 2 18650s. What I would like to know is if there is a similar simple variable voltage booster circuit, so that I can use say a single IMR18650 and vary the output between 3.7 and 5v?

A booster alone wont work if you want to get into the 3 volts area. With a booster chip the input voltage has to be lower then the output. A fully charged li ion battery is 4.2 volts. There is a TI booster chip folks have modded to trick it down to around 4.4 volt range. To get into the 3 volt range you would need a buck/ boost chip. Which just means it will regulate the voltage down if the battery voltage is higher or boost the voltage up in the battery voltage is lower then the set output voltage

One word - Sepic.... It's the best of all worlds (for function anyway -- It does lag in effeciency a bit though). If the buck/boost will go sepic -- take that road - you'll be happy you did.

 

[SurvivorMcGyver]

Just a passing thought to clarify and support Sepic design is that Buck/boost is an "either/or" kinda logic - it doesn't like the "egual to" volt in - at least that's my experience and confirmed by a third party. Sepic on the other hand, literally, doesn't care.....

 

[Minus1724]

So I have built an Evercool mod. It was relatively simple and I and am very pleased with the results, except that I have to use 2 batteries and for any battery life the mod has to be fairly large. I am running 2 18650s. What I would like to know is if there is a similar simple variable voltage booster circuit, so that I can use say a single IMR18650 and vary the output between 3.7 and 5v?

I´m working on just that just need a box .

I went with a 100k pot with a 20 in series , and a diode in series with the atty connector. And a 100k resistor between the Volt-out and adj pin.. that gives me the range from 4,0v. to 5,0v ..
and a mini USB in (for charging the bad boy) , from my Titan PCC , then i get the indicator for low power.

( cheep fistpack )

 

[rannox]

I´m working on just that just need a box .

I went with a 100k pot with a 20 in series , and a diode in series with the atty connector. And a 100k resistor between the Volt-out and adj pin.. that gives me the range from 4,0v. to 5,0v ..
and a mini USB in (for charging the bad boy) , from my Titan PCC , then i get the indicator for low power.

( cheep fistpack )

Im pretty much building the exact thing for a buddy, tried using the stock flat pack, and it just couldn't handle the output the board needed.

What diode are you using, what battery, and what box?

 

[Minus1724]

I´m using

a, 1N4001 Diode to get a 0.6V. voltage drop to the atty

Battery: AW 18650 Protected 2600 mAh Rechargeable Lithium Battery
Box : ELECTRONICS PROJECT BOX BLK ABS 83 x 54 x 30mm____en001 on eBay (end time 22-Mar-11 18:09:06 GMT)

The lowest the chip can go is normaly 5v.... using the diode gets it down to 4.4v... and the resistor between adj and Vout gets it down to 4v. under load

remember the 100uf caps

 

[rannox]

Cool, thanks. Ya I've built one before, but without the charging circuit. Just seeing if it would handle a bigger batt like an 18650.

Ive got the board built and ready, just need to put a 18650 in it, I have pretty much the same box too, haha.

Just gotta pick up a decent battery and Ill be good to go.

 

[WillyB]

I´m using

a, 1N4001 Diode to get a 0.6V. voltage drop to the atty

Kinda pushing that little 1A diode a bit aren't you?

 

[Minus1724]

yes.. but it is still running.. Think in the future, I have to change it

 

[breaktru]

MisterD inspired me to build one. Still on the breadboard and deciding to either put in in a box with a digital display or in a copper tube. With no load I have 4.25v to 5.9v. With a 2 ohm wire wound load resister I'm getting 3.95v to 5.6v. I picked up a couple of tenths of a volt by going with (2) 180uf electrolytic caps instead (2) tant 100uf caps. Also using a 3 amp diode.

 

[Minus1724]

here is my take on the VV booster mod

 

[CritterBuddy]

here is my take on the VV booster mod


View attachment 30918View attachment 30919View attachment 30920View attachment 30921View attachment 30922

Cool... details??

 

[breaktru]

Real nice Minus, very neatly done. My suggestion is to beef up the wiring on the higher amperage portion to 18 gauge. From the Vout to the 3a horn button and to the atty. oh... and of course to the 3a diode.