VV mod help

[CraigHB]

Does this look right? I can get only 5.2v now from stacked 3v batts freshly charged then its pretty much impossible to use any atty/carto

Not sure what linear regulator you are using, but standard ones like the LM350 have something called dropout which means they need some amount of input voltage above output voltage to work properly. Since people usually use 3.7V batts in series, it's generally not an issue since dropout for a standard regulator is around 1.5V. In that case, input is typically 7.4V and max output is typically 6V. You can alternatively use a low dropout regulator which allows you to run input voltage closer to output voltage. The On Semi NCP630a is good low dropout linear regulator to use in a mod. You can get them from madvapes or from electronics vendors like Mouser and Digikey.

Also, if you mean 3V batteries as in the LiFePO4 ones, they don't have the highest drain capability. They can sag more than 3.7V Li-Ions under load. That further exacerbates any dropout issues.

 

[cyris69]

I see, didn't know about stacking two 3.7v batts I used the lifepo and normal lithium 3v batts.

I went ahead and bought smartvapes dual 18650 altoids vv so i might try this circuit one more time with duals.

 

[jhonutz]

for step down you can use only 2 battery, 3 or 3.7V each, for step-up use one battery is simple . you want to use a linear regulator for this you need 2 baterry li-ion,connected in series or an 7.3V pack li-polimer.

 

[cyris69]

Can I use a MC34063P? I found it on a usb charger for a car cigarette lighter outlet.

 

[TomCatt]

No that regulator only outputs 0.2 amp; this is not enough for vaping.

 

[cyris69]

@jhonutz

You are so right, it works now!! I can go from 3.7-6.7v and my inline display works perfectly! Video/images to come!

 

[cyris69]

Guess I lied, maybe my pot is f'ed up is hot glue conductive? Now I can only do min and max so unloaded it is 3.70 or 6.70, loaded its 3.7 min and 5.5 max no in-between...