Battery Voltages -- Surprise!

[br5495]

BR... good to hear from ya!

Yes, I did run the eGo900mAH and the USB eGo on that rig with just the DMM on the DC scale (giving the DC mean voltage). On a freshly charged 900mAH and USB units (which have the "newer" waveform) I did see a slight increase in the mean DC voltage.. but not enough to write home about. Your "taste test" doesn't surprise me at all.

Thanks Scott. I'm not much of a meter reader, so all I've been going by other than taste tests is a DC voltmeter. According to it, my USB eGo has been regulating a tad above 3.2 volts, which is a wee bit higher than some of my earlier batteries. There is no sag to speak of. The battery shuts down before the voltage drops to 3.1. These measurements were monitored while vaping from a 2.5Ω cartomizer.

 

[Scottbee]

OK, as promised I have done some more runs. This time I used a "new" 900mAH eGo so that we could observe the PW action as the internal battery voltage (cell) "sagged".

Now please, please, please... before you try and decipher into the minutia... realize that this scope (a B&K 2530) has only marginal resolution and granularity. Trying to resolve better than 40mV on raw voltage or calculated RMS is a waste of time and energy. So view the numbers with an understanding that a few percentage points either way is more or less meaningless.

I think the data is pretty self explanatory. But if somebody wants to dialogue this I can give some additional observations and assumptions.

 

[progg]

removed link.

 

[Scottbee]

removed link.

Why?? I think I liked it.....

 

[progg]

Why?? I think I liked it.....

I didn't hear back. Didn't want to accidentally give bad info.

http://www.eznec.com/Amateur/RMS_Power.pdf

 

[Scottbee]

I didn't hear back. Didn't want to accidentally give bad info.

http://www.eznec.com/Amateur/RMS_Power.pdf

I only perused it..... but it looked like decent information.

The bottom line is: if you have a fixed and constant DC voltage and you want to calculate the power.... the math is simple (EI or E**2/R, etc..). But, if you have a time-varying voltage and you want to use the same math, then you need to find the RMS voltage for the waveform and use that value in your power calculations.

 

[Katya]

I think the data is pretty self explanatory.

It is?

 

[Rocketman]

Scottbee,
Do you think the duty cycle increase as voltage decays is designed in, or inherent as the circuit has less operating overhead?
I understand that it levels out the RMS voltage, a little, as the battery discharges, helps the vapor, but is it more of a deficiency in the stability of the timing circuit? Serendipitous benefit?

 

[Scottbee]

Scottbee,
Do you think the duty cycle increase as voltage decays is designed in, or inherent as the circuit has less operating overhead?
I understand that it levels out the RMS voltage, a little, as the battery discharges, helps the vapor, but is it more of a deficiency in the stability of the timing circuit? Serendipitous benefit?

This is only supposition on my part... since I can't crawl into the Chinese engineers noggin and summon the design intent.... but I think this is completely intentional. I think it is a "best effort" approach at regulating the delivered voltage as the cell voltage sags.

My guess and $.02.

 

[jimho]

This is only supposition on my part... since I can't crawl into the Chinese engineers noggin and summon the design intent.... but I think this is completely intentional. I think it is a "best effort" approach at regulating the delivered voltage as the cell voltage sags.

My guess and $02.

I would call it a hypothesis - clearly they are increasing the duty cycle as the peak voltage drops and maintaining constant RMS voltage - burden of proof is on someone that wants to argue otherwise.

 

[MacDiver]

I had always wondered why I get more than twice the battery life, much more actually, with my 3xAA box mod with two 14500 batts in parallel that I do with a single 14500 box mod. I've been vaping on these batts for a couple of hours or so now. I get most of if not all day from two batts in this box mod. That never happened with a single bat box mod.

Anyways when I tested the batteries with no load they read 3.8v. Hit the button and the voltage drops to 3.6v, not bad. Now when I pop a battery out the voltage drops down to 3.3v under load which explains the drop off in vapor that I always had so quickly with just a single batt. I also see a difference of about 0.2v under load between having just one batt and having two. This is with a standard 2.2 ohm joye atty. An LR atty makes an even bigger difference.

The single 14500 can't supply the amps (power) the LR atty is calling for. For LR510 and LR306 applications at 3.7 volts an IMR battery is needed.

http://www.e-cigarette-forum.com/fo.../105037-high-drain-batteries.html#post1580259
http://www.e-cigarette-forum.com/forum/madvapes/127262-about-low-resistance-specific-batteries.html

 

[DC2]

Ummmm, yeah, what they said.

 

[Kelemvor]

just had revisited my old post #161 ...... nananananaaaaaa

 

[Scottbee]

just had revisited my old post #161 ...... nananananaaaaaa

I'll give you all appropriate credit for that post.

I did not see the change in pulse widths with the old firmware..... but it may just be that I missed it. With the irregular widths of the old system it was just hard to follow.

With the new firmware it's a lot easier to "analyze"..... and the variations are obvious.

 

[Kelemvor]

i could just say i felt it with my tongue, but didn't really tried that

 

[Scottbee]

There's some interesting stuff in here. Unlike the previous eGo and Riva batteries that I had tested, this unit runs at a fixed (84Hz) frequency. Completely uniform and repeatable pulse widths. I DO NOT know if this means they worked on the protection algorithm or not... I haven't tested it.

OK... I have now tested it. They apparently have not improved the protection algorithm. I now need to put a new MOSFET in my USB eGo..... <sigh>

 

[Kelemvor]

any chance that you can do this testrun with a joye510 mega battery? there are still controverse discussions about he little ones and i would like to be able to link them to a visible fact.

much later this year i may be able to make my own tests, but for now it would be really appreciated if you could effort the time once more.

 

[mdocod]

13mm x 45mm proprietary LiCo cell with a true 650mAH?

Most 14mm x 50mm cells barely make it there under moderate drain rates.

The eGo cell is likely over-rated, and if it it really a LiCo cell, it certainly should never be used for low resistance atty/cartos.

Eric

 

[Kelemvor]

just from experience the ego battery is less overated than any 14500.

 

[AlexTM]

There are a lot of people who use LRs on eGo batteries, so why exactly shouldn't they do that?