Battery Voltages -- Surprise!

[Tanner S Hyde]

An update.

As has been suspected, the ~.6V drop in the Joye products is built right into the FET switch circuit. It is not due to internal resistance in the battery itself.

I have pulled apart one of my Mega batteries and am doing a circuit analysis. Although the analysis isn't anywhere near complete, what I can tell you is this:

With a 2.5Ω load applied and the switch energized, the measured voltage right at the battery is approximately 4V (freshly charged). This is also the FET source voltage.

The drain voltage is in the 3.1V range (as previously noted) and this is the output voltage of the complete package.

The gate voltage is approximately .8V.

I haven't gotten far enough to figure out where the gate voltage is sourced from...... but I will!

NOW were talkin! I'm excited to see if we can get the intended voltage out of genuine Joye batteries...

 

[Fenix-T]

Strange. I get 3.94v from my Joye510 battery that I got from Vaporkings.

I get 3.6v from my Gemini.

 

[Kelemvor]

fully charged and under load ?

PS: just got my resistors out of the garage and may test some batteries myself

 

[Scottbee]

OK.... I figured out part of the circuit,and I know where the "source" of the V-drop is. Now to see if I can get the drop out of there without violating any of the other functions (charging, cutoff, etc..).

It may be quite simple..... maybe not.

 

[Fenix-T]

Ohhhh, wait. So this is about 3.7v batteries losing voltage under a load??

Normally, things do lose voltage under load, right?

 

[Fenix-T]

Okay, okay. I see what you are saying by reading more deeply. The circuit isn't complete without a load (your 2.5 ohm wire) and you put your meter in with the circuit. But, I think the voltage drop you are seeing is from the meter itself.

 

[Scottbee]

Okay, okay. I see what you are saying by reading more deeply. The circuit isn't complete without a load (your 2.5 ohm wire) and you put your meter in with the circuit. But, I think the voltage drop you are seeing is from the meter itself.

No, I'm sorry.. that is not correct. I have clearly explained exactly where the voltage drop is. It's not in the meter.

 

[Scottbee]

Well... somebody had to be the first to let the smoke outa one of these bad boys.

If anybody was wondering what the inside of a Tornado/eGo (TorneGo) battery looks like, here it is:

If you believe the printing.. it's genuine Joye.. and it's 650mAh!

 

[beast775]

this is a very exciting data info post.it is answering the whys?? of my batt questions.ive been checking my batts now also,i have noticed a decrease in longetivity in volts in 1 mnth steady usage in stock joye batts.i will put forth my findings when they die.great info scottbee.

 

[asidrave]

Well... somebody had to be the first to let the smoke outa one of these bad boys.

If anybody was wondering what the inside of a Tornado/eGo (TorneGo) battery looks like, here it is:

If you believe the printing.. it's genuine Joye.. and it's 650mAh!

I am following this thread closely..you are doing a great job Scottbee

My next purchase is a ego/tornado...havent decided which yet. looks like its very possible to replace the battery if and when they do die

 

[Scottbee]

I actually found a source for the 130450R's..... They go for a couple of bucks if you get them in volume. But I doubt I'd ever really do that.

 

[AlexTM]

Well... somebody had to be the first to let the smoke outa one of these bad boys.

And who else should have that honour?

Would the actual battery be fairly easy to replace? Stingy minds want to know!

 

[Scottbee]

The hard part is getting the switch housing off of the tube (without damage). Once that is done, it's just a quick solder job.

 

[Lightgeoduck]

Thanks scottbee people like you save me the trouble of having to do it myself... or least finding the best way of doing it..... I almost was going to disassemble my one spare battery assy just to see....

if you find a way to turn that button assy into a screw in type so it's just a drop a new battery in let me know

otherwise like you said in another post it might just be easier to pay the 20so bucks for a new assy..... I mean its a HELLAMEGA ecig anyway

 

[Scottbee]

if you find a way to turn that button assy into a screw in type so it's just a drop a new battery in let me know

Well ya know...... that actually would be that hard. But I have yet to find the 130450R's without solder tabs.

 

[Lightgeoduck]

well take some measurements of that battery and when I go to electonics town here in japan I will try to find a compatible one... unless you already know

also if I knew of a battery of any kind that is close to the size I can bring a sample with me

 

[Scottbee]

As one would expect.. a 130450 is 13mm x 45mm.

Lookie here:

Li-lon Cylindrical Battery(130450 650mAh 3.7V) 130450 lithium ion battery CN;GUA

 

[Lightgeoduck]

cool thanks I will PM you my findings in about a week

 

[WillyB]

Strange. I get 3.94v from my Joye510 battery that I got from Vaporkings.

I get 3.6v from my Gemini.

Those numbers caught my eye. My 14500's and KR808 batt come off the charger at almost 4.2V. Just checked my Joye 510 batt and got 3.95V. Maybe these unloaded voltage numbers do tell us something.

From Battery U and Wikipedia I found 2 interesting statements.

Lithium-ion cells are charged with 4.2 ± 0.05 V/cell,except for military long-life cells where 3.92 V is used to extend battery life.

3.92V/cell is the best upper voltage threshold for cobalt-based lithium-ion. Charging batteries to this voltage level has been shown to double cycle life. Lithium-ion systems for defense applications make use of the lower voltage threshold.

 

[Scottbee]

As I've mentioned a number of times.. the "unloaded" peak surface charge voltages of these cells is almost a useless number. I can tweak that number all over the map just by changing the charge algorithm.

Put them on a load and then read the voltage. That is telling you something.