Battery Voltages -- Surprise!

[WillyB]

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.

I think you have missed my point and I don't think it is a useless number in this example. What I was inferring that Joye (and others) may have chosen to not charge their batts to the usual 4.2V cut-off for reasons of battery longevity. I used KR's universal 4.2V charger for both batts and obtained the differing numbers.

Charging batteries to this voltage level (3.92V/cell ) has been shown to double cycle life.

And although you call these numbers 'useless' it seems that the batteries that come off the chargers at about 4.2V (by your own examples) also have a higher loaded voltage.

The flash light fanatics will often mod their cheap UltraFire/TrustFire chargers (with diagrams and tutorials) to make sure their Li-Ions come off the chargers at slightly less than 4.2V (for longevity reasons). As far as I can tell they are going by 'useless' surface voltage to determine this.

I guess I'm wrong, but that a Joye batt comes off the charger at what is described as the ideal voltage for longevity caught my eye.

 

[Scottbee]

OK....

So I take a brand new eGo/Tornado battery and pull it off of my TW mains charger right after the charging cycle is complete. I put it on the Fluke, unloaded, and it reads 4.17V.

What does that tell us?

I guess the next thing for me to do is put the Fluke on one of the batteries that I have that is open.. and monitor the voltage right at the battery during the charging cycle to see what the exact cutoff threshold voltage is.

I could also charge one of my Kangers on the Joye charger using the adapter (which is actually what I do all of the time).

But once again.. I don't expect any big changes in my overall findings. I have absolutely located the source of the voltage drop in the Joye batteries. It is not the the actual battery itself. It is absolutely in the FET switch. And as soon as my Digikey order gets here.. I plan on making it "go away".

 

[KingVapor]

eGo/Tornado that performs at 3.7v under load... that would be great. Where do I send my extra battery to?

 

[Scottbee]

Ask me again in a couple of days!

I thought my components would be in today.... hopefully tomorrow. Then I have some micro SMD soldering to do. No coffee for me...

 

[Scottbee]

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!

Well.. after a little more probing it would appear that I made a rookie mistake!

I assumed we were just dealing with good old fashioned analog circuitry here, and nothing but plain DC. I believe I am mistaken!

It would appear that the gate voltage isn't really just .8V, and the output isn't just 3.1V (solid). Those are pseudo-RMS values! Yep, there appears to be a frequency component to both the drive and the output! My guess would be a poor-mans form of pulse width modulation (those sneaky lil' bahstahds!).

Time to put down the meter and pull out the oscilloscope! I'm traveling over the next few days though... it'll have to wait!

 

[Kelemvor]

i suspected something like that, otherwise a 510 would make decent vapour wit h a 3.3V batterie, which it does not.

some vendors, did mention pulsed voltage in the past. some of those superminis, did not remember which it was.

those ozzi test should be interesting

 

[h8isgr8]

... Yep, there appears to be a frequency component to both the drive and the output ...

And this is plainly obvious by waving a KR808 battery back and forth while observing the LED. You can easily see the PWM flicker effect.

 

[Scottbee]

And this is plainly obvious by waving a KR808 battery back and forth while observing the LED. You can easily see the PWM flicker effect.

I wasn't talking about the KR8 battery. As was mentioned numerous times in this thread, the KR8 has a completely different setup and appears to give almost the full battery output. I doubt it is modulated, but I'll check.

Also, on both the KR8 and the Joye models, the LED output is a different channel than the FET drive.

 

[zoomie61]

Now I'm curious though...is the Tornado/ego not all that it's cracked up to be? Last night I would have skipped my mortgage payment to order one but now I wonder... I really want to go to the HV or longer lasting units but I just can't decide what to get dang-it.

 

[BanjoMan]

My e-cig journey is far from over, but after almost 6 months of buying and trying a LOT of stuff I've come to really appreciate the experience I get out of the battery mods like the Bartleby and Little Chuck (to name just a few). Hell, even the 10440 units I have put my stock auto batteries to shame. I have attys that WON'T EVEN VAPE with a stock battery, but throw them on a mod and they come back to life.

I just got my first parts order from MadVapes so for now I'll be spending my time working with the 14500 box mods. I might try 5V one day, but for now I have everything I need.

 

[Knapweed]

And this is plainly obvious by waving a KR808 battery back and forth while observing the LED. You can easily see the PWM flicker effect.

It feels like batteries aren't the only thing being waved back and forth in this thread.

J/K there's some awesome info in this thread and I never appreciated just how complex these devices were. It might also explain why my silver batteries perform significantly better than the white ones on my 601. The silver ones activate with less of a draw than the white ones and I just put it down to that but maybe they are delivering more current to the atty.

Thanks guys, really interesting stuff.

 

[cptr13]

Ya, this is frustrating, I just ordered a tornado yesterday. Ahh well...

 

[Scottbee]

I wasn't talking about the KR8 battery. As was mentioned numerous times in this thread, the KR8 has a completely different setup and appears to give almost the full battery output. I doubt it is modulated, but I'll check.

Also, on both the KR8 and the Joye models, the LED output is a different channel than the FET drive.

Just got back from being out of town for a few days. Had the chance to put the KR808D-1 battery back on the tester and look for modulation in the loaded output.

As I suspected, there doesn't appear to be any PWM (modulation) in the output of the KR8 battery. Just good old fashioned DC... straight from the battery through the FET.

 

[Scottbee]

Now I'm curious though...is the Tornado/ego not all that it's cracked up to be? Last night I would have skipped my mortgage payment to order one but now I wonder... I really want to go to the HV or longer lasting units but I just can't decide what to get dang-it.

I dunno.. I think the Tornado/eGo (TorneGo) is a great device. Long battery life and an excellent vapor producer. It's just not a true 3.7VDC device.

It gets its performance from tried-and true 510-class batteries with high mAh ratings (for longer life), classic 510 atties, and an innovative cone that changes the draw and vapor temperature. It just plain works.

 

[Mooler]

"Dr. House" Scottbee Amazing research, thanks. All the PV listed in this thread are great, for various reasons, flavor, battery life, vape, size, it all comes down to perference. I fixed my 510s short battery life by getting the spaghetti wire USB passthru (auto!) and I love them - the long wire surely loses watts - but still has better vape than batteries. They were 9 or 12 each, well worth it. But because I want to vape on the go, I need the longer battery - so I've just ordered the Tornado. Another option is the extended 510 battery, its 280mAh Joye 510 Extended Life Battery - Manual Blue (cignot also has PTB carts Anyways, thanks!

 

[Scottbee]

I haven't given up on this and I'm certainly not ignoring it! Over the last couple of nights I've only been able to throw an hour or two at it. I can bypass the Joye PWM voltage drop easily enough.. and that gives me full voltage (3.7VDC+) to the atty. But that bypass angers the charging circuit on the ASIC (Application Specific Integrated Circuit). It will take some more time and work to come up with a simple solution that satisfies all of the requirements.

And my wife hands out "time" in small and infrequent increments...

 

[Scottbee]

Well.. I finally found the time to dig out the old Tek scope and hook it up to the battery load tester.

As suspected, there is a form of PWM (Pulse Width Modulation) going on here... but the pulse widths aren't consistent over a nominal period.

I'm not the best at taking pictures of scope screens... but here ya go:

It's set at 2V per division vertical. The probe is a 10X, so you can take the RMS meter output and multiply it by 10 to get the real number. As you can (hopefully) see, the output is pulsed between 0v and "rail", which is the actual battery voltage (approximately 4V). The net effect is output "power" that is consistent with a 3.0-3.1VDC source voltage.

Enjoy!

 

[Scottbee]

Oh... and I tested the KR808D-1 battery too. As suspected... straight DC... no modulation.

Pictures available if you're going to be that way about it.....

 

[ohioguy]

I’m following the thread, but I’m in a bit over my head. A couple questions do come to mind.

Is the “Pulse Width Modulation” part of an overall deliberate design, or could it be due to adapting whatever parts are easily (cheaply) available?
Can someone speculate on advantages / disadvantages if this battery setup? Why would Joye want the slightly lower voltage?

Question on the chargers, several have quoted cut off voltages and such. Are they really that accurate anyway? I would guess the tolerance would be wide, and would be slightly different from one production run to another.

The big question. The 510 is not a high quality precision instrument. It’s a tube made of tin, with a brass alloy end, pressed on. The batteries are the cheapest available. It’s reasonable (for me) to believe they are built as cheaply as possible. So are things like cut off voltage, or peak vs. rms voltage really engineered to plus or minus a tenth of a volt? Or was the design basically thrown together and the exact voltages were just a matter of chance?

 

[Scottbee]

I could speculate abut why Joye used the PWM power delivery method.... but as with any speculation, I could be dead wrong.

I think they came up with a ASIC (Application Specific Integrated Circuit) that properly handled switching the battery and negotiating the handoff to charging mode. The PWM was probably parasitic.... so they dropped the resistance of the atty to handle the reduced effective voltage. Workable solution. And then us wackjobs started running that same atty at true 3.7V.. and realized we liked full voltage even more.