Is it possible to use an eGo battery board as just an electronic button?

[slimest]

Colleagues, today I got two spare eGo boards sold as DIY. Some kind of gift Seems that they are fake, not from Joye: slightly different plastic button, blue leds. Well known that these boards don't stabilize 3.3V output correctly and burn frequently (weak output mosfet?).
My idea is to make just electronic buttons from them. And this button should support all protection, as in eGo: overcurrent, discharge, too long button push etc. This is the main point.
Of course I can solder another, more reliable mosfet, IRLML6402 fits perfectly.
But, as far as I understand, I have to remove any pulse generation. And I am not shure, how protection will work if everywhere on the board will be DC, no pulses.
Has somebody any knoledge and experience about this? Or my idea is just utopia?

 

[WillyB]

My advice, use it as is or start from scratch. As far as Joye, I believe the eGo Scottbee pulled apart a long time ago had a Hello-16 (I think that's the number) PCB assembly. He also said at the time that there was no true protection circuit (like with the Li-Ions we use), just a 'melt down' feature.

 

[slimest]

Thanks for your answer.
Seems to me, that current protection really exists. I tried shorted accumulators - they blink several times, but did not switch power on. And nothing melted Maybe I'm talking about later hypostasis of the batteries - 2010-1011. For me the most valuable feature of eGo boards - undercharge protection not 2.5V but 3.3V

 

[Rocketman]

One of the 900mah eGos I have tested with a 1.6 ohm carto went from PWM to pure DCV at about 3.35 volts, and cut out at 3.3 volts.
Just a few puffs before going to DC the duty cycle went close to 100%. The voltage indicated on a cheap DC meter approached the scope calculated RMS voltage.

I don't recommend 1.6 ohms but this time, this eGo handled it. Charge life was lower.

For resistances 1.7 ohms or above the eGo circuit board should work fine.

 

[slimest]

Rocket, thanks, as far as I understand, this board worked as it should be. Regulator tried to keep 3.2 voltage on heater. Pulses became as wide as possible. Quality board My idea is to force the board work without anu pulsations, just as if it's mosfet. With an AMR battery I could get stable 3.6-3.7V... Just dreaming...

 

[Rocketman]

I believe the regular ego board senses cell voltage and will only increase duty cycle as cell voltage falls. A higher voltage causes the chip to reduce duty cycle.

The VV eGo board has a High setting that I believe would be straight through (I don't have one to test).

With a nearly charged cell my test showed the 900 mah eGo with a 1.6 ohm carto cut duty cycle to about 87% with an RMS voltage of about 3.49 volts (3.20 volts indicated on cheap DVM) It's hard to see in low res photo but cell loaded voltage at the connector was 3.68 volts.

 

[slimest]

Yes, peak voltage is about 3.68... But (mmmm, don't know English for this term) effective (?) voltage still the same - 3.2V... For heater peak voltage does not matter.. It needs power
Well, seems that I am asking about something impossible...

 

[Rocketman]

I think for heater purpose the RMS voltage gives the heat.
Average seems close but RMS heats things up.

The eGo with a bigger battery (seems they have done that already) would give the higher output for longer.

But then, a straight 3.7 volt mod gives a harder hit until it falls to eGo level. A Big 3.7 cell falls really slow

 

[slimest]

Rocket, you are right. In any way I will test these boards. Just imagine: only IMR accumulator (say, 18500 from AW, shorter) this board and connector! Should be very compact and lite... Maybe also a small charger.

 

[jhonutz]

here you have ego board schematic

 

[slimest]

jhonutz, thanks a lot. This is the first real eGo diagram I met. Hope it will be useful for many users.
Hahaha, 2 LEDs in parallel

 

[jhonutz]

it`s a joyetech PCB, change C1 with 470nF and will have on out 4.2V (in original have only 3.3V)

 

[slimest]

jhonutz, hahaha! I just thought about this! Thanks again. Great advice!

 

[Rocketman]

jho,
The R6 was added?

Thanks for posting the schematic.
Some of us are too lazy to trace it out

 

[slimest]

Interesting if R6 is optional (what option) or makes something special

I just imagine: with R6 a board is genuine Joye, without it it's fake

 

[Rocketman]

So far, I'm having a little problem seeing the path for charge current. Maybe something in the order of 300 to 400ma.
The gate to source turn on must be really low for Q1, to turn it on for charging.
The 5.1 resistor that supplies U1 VDD can't be it (2watts?)

If the substrate diode in Q1 is being used could that be the cause of some of the eGo failures? If the charger fails?
Guess it's nap time. I'll look again when rested


Just ohm'd out one and the Batt positive goes to Q1 and the 2 resistors as shown. So it's back to school to look at that Mosfet circuit to see what actually stops the charging.
Anyone got an answer?


Never mind. The Gate to source will be about 3 volts with a discharged cell.
That's enough to control it and turn charge current on.
Reverse drop measured about 0.5 volts at 1ma.
So Q1 gate controls both vape current and charge current.
If it fails (atty sizzles without pressing button) it might not stop charging.
Good thing the charger stops.



Just ignore me, I'm thinking while I type

 

[slimest]

jhonutz, is it possible to put the schematic in a higher resolution? Or just a link please...

 

[jhonutz]

URL=http://imageshack.us/photo/my-images/39/ego12.jpg/]

[/URL]

 

[slimest]

Thanks again

 

[delchrys]

I accidentaly shorted my ego-t battery, i think my MOSFET is fried now. It only blinks a couple of times and is not firing the atty. Is it possible to bypass the MOSFET or remove it from the board??? What the reaseon of the MOSFET BTW???