Diodes not lowering voltage as expected

[mars_mcc]

Hi, I'm hoping someone might be able to help me with a question I have...

I'm using two 14500 3.6v 900mAh protected batteries in series in a simple box mod. I would like to get the voltage down to around 4.5 or so for use with 901 atomizers.

I've read in a few other threads that I could use diodes to lower the voltage without creating a lot of heat, and that depending on which ones I tried I would get varying amounts of voltage drop... so, I picked up some assorted rectifier diodes at Radio Shack (#276-1653) to try. (they are labeled "1N4001" through "1N4007")

I must be doing something wrong or missing something though, because no matter which ones I've tried, each diode only drops the voltage at the atomizer connection about .2v-.25v. (I've tried every single one in the package of 25). I can link them in series, which works, but that means it would take about 4-5 diodes to drop the voltage by 1v (not practical to fit them all in the box)

Can anyone think of what I might be missing?

(for background, I've made 2 Nicosticks with LED/resistors so far without any issues, and they both work great. I'm now looking for a little higher voltage, to see what kind of difference it makes, plus this is just really fun, of course.)

Thanks in advance for any help or advice!

 

[CaSHMeRe]

hey mars ... you are having the same issues we were having when we were testing diodes and resistors ... we ended up having to solder 3-4 inline to get anywhere near where we wanted to finally be.

get a 2w .75 ohm resistor ... should drop you in the 5 - 5.5v neighborhood ... you may also want to try a 1ohm 2w resistor ...

Because resistors are cheap ... you may want to explore and get several between .5ohm and 2ohms to find what may work best for you and your application.

Just for reference:
1 Ohm 2 Watt Resistor - VETCO.NET

hope that helps

 

[mars_mcc]

Thanks Cash, I'll try those instead (and thanks for the quick reply!)

 

[kinabaloo]

Wanting to go from 7.4/8.2 down to 4.5 is really a big waste.

Perhaps just use the extra battery as a spare (perhaps switched). A fully charged 14500 will be about 4.2V.

I can sort of understand wanting to use 2 small 3v batteries in series and then lowering the V but you may be taking it too far!

Your best bet if you wish to continue is a voltage regulator; because it would give you a longer consistent output V. Will get warm/hot so keep away from the batteries (same applies for diodes & resistors).

ps: if you decide to use a resistor, a 2W should be ok but the value 2.2 ohm would be more suitable. ... If you really want to go that route

 

[CaSHMeRe]

Thanks Cash, I'll try those instead (and thanks for the quick reply!)

no problemo mars ...

Wanting to go from 7.4/8.2 down to 4.5 is really a big waste.

Perhaps just use the extra battery as a spare (perhaps switched). A fully charged 14500 will be about 4.2V.

not when loaded ... HUGE difference ... 4.5v is roughly just like a fully powered PT at 5v unloaded ... That single volt increase can make a world of difference

 

[kinabaloo]

If you want to be the next big thing in vaping, use that extra power usefully.

Three ideas: better coil; bigger diameter, can take more power, still a little over 1A but at greater voltage the power would be greter, up from say 3.5W to 6W.

Pass the current through a nichrome juice heater, or vapor heater, rather than waste in in a resistor just warming the case.

Third I've forgotten ... too much wine

 

[kinabaloo]

no problemo mars ...



not when loaded ... HUGE difference ... 4.5v is roughly just like a fully powered PT at 5v unloaded ... That single volt increase can make a world of difference

The load drop with a decent battery is maybe 1 volt max (proly less than 0.5 V).

What we really need to match higher power coils is faster juice supply. Hence my investigation of direct juice supply.

 

[kinabaloo]

Put a blunt message that may or may not be significant ...

I suspect that some people like a burnt taste because it is like an analog - and that may not be a healthy move ...

I do myself though crave a bigger vape, but not a burnt one. So need better juice flow and beefier coil; both together. Just upping the V is not the real answer, imo

 

[kinabaloo]

no problemo mars ...



not when loaded ... HUGE difference ... 4.5v is roughly just like a fully powered PT at 5v unloaded ... That single volt increase can make a world of difference

I guess the OP measured the 4.5v off-load, so it's a fair comparison.

I think that when using existing attys, a good 3.7v battery is sufficient (more than, if anything); but that's my take; you're welcome to your own take

Post Protection will be kickin in soon Good night, all ...

 

[kinabaloo]

Ok, one last post,,,

What is the easiest and best imo thing to do is use the two batteries to power two atomizers and join the two into one mouthpice. I've played with this arrangement - and it's luxurious

The straightforward (kindof) way to get the vape you dreamed of ...

This from a guy who gets through the day on Merlot and Scotch Bonnet (that's a Hot chilli btw)

Available from PureSmoker and Janty by 2010 I predict ...

Or maybe only from me

But I think it would be foolish of any serious player to miss the boat on the 2 atomizer design,

 

[Cisco]

Your work is well appreciated kinabaloo...

I ran a test on my pv for some real world under load calculations

I have a 510 with an atty that has a ohm reading of 2.6ohms, With a freshly charger battery at 4.1v the under load amp draw is 1.38 (Volt meter must be part of the circuit to get this reading). With the ohm reading and the under load amp draw and using ohms law I can calculate the voltage drop.

2.6ohms(atty) x 1.38amps(under load draw) = 3.588v

So from a freshly charged battery that has a reading of 4.1v the Atty is getting 3.588v under load, that is a voltage drop of .512v. Thats a 1/2 of a volt drop under load on a fresh battery.

there is more to calculating the actual voltage at the atty then just battery voltage minus diode's and resisters.


Cisco...

 

[kinabaloo]

Your work is well appreciated kinabaloo...

I ran a test on my pv for some real world under load calculations

I have a 510 with an atty that has a ohm reading of 2.6ohms, With a freshly charger battery at 4.1v the under load amp draw is 1.38 (Volt meter must be part of the circuit to get this reading). With the ohm reading and the under load amp draw and using ohms law I can calculate the voltage drop.

2.6ohms(atty) x 1.38amps(under load draw) = 3.588v

So from a freshly charged battery that has a reading of 4.1v the Atty is getting 3.588v under load, that is a voltage drop of .512v. Thats a 1/2 of a volt drop under load on a fresh battery.

there is more to calculating the actual voltage at the atty then just battery voltage minus diode's and resisters.


Cisco...

I'd say spot on.

I;m used to 3.5 ohm coils. Let's say at best 0.5v but as battery fades this will increase.

A good battery like a 14500 will be like this. A smaller (in capacity and physical size) battery will be worse.

That's why mods not only last longer but perform better.

Technically, the voltage drop is due to 'internal resistance' of the battery; how well it can put out the current. For this, generally bigger is better; though it depends on the design; a backup 'speciality' battery may be designed to last years but with only low current required and it will be made to do that. Hence some lithium batteries, even ones marked 14500, don't work for vaping.