2s 18650 discussion

[RickAdair]

John said:

Oh no, I didn't do it board side. I did it on the tap connector on the pack side. Mine switches between 2s and 3s just fine and shows .02V on cell 3, but that could just be mine for all I know. I'll try a couple more boards today and see if I can get the same one cell high behavior. 

The reason it looks at cell 3 at all is we don't want to get people into a bad situation if they should just happen to plug a 3s battery with a damaged third cell into the board with it set for 2s. But where the cutoff should be is going to be a function of where all the boards read the phantom cell. 

We'll get you working one way or another.

Gotcha. I did just try shorting it with a small solid wire in the jst and on the solder pads. Reads anywhere between .6 and .9 on cell3. Thanks for the info. Good stiff to know!

[John]

Hi Rick,

We checked some more boards, and it turns out that some of them just... do... that. The analog front end is speced for 3 to 6 cells (but also down to 4 volts total), so spurious readings on cell 3 while running it with two aren't shocking.

Anyway, we increased what it calls acceptable for the third cell up to 1.5 volts, and posted it in the 8-7 firmware in the Early Firmware thread. That should make yours work without further problems. 

[valld]

Great, I like that quick problem solving! Guess we are now ready for 2 cell configuration!

[RickAdair]

Thanks John! You guys over there keep amazing me. Glad it was a quick fix. I'll get it loaded and verify operation today.

[adski]

I must be lucky, my board worked sans update. Cheers

[Guest]

Have you thought about making it a 1 cell option? More less a DNA 40 style. It would be cool to have a micro/mini mod box. It could be set up as a module type mod box to where you buy different voltage battery packs or custom cases. I know my girlfriend would like to have something small and have all the features. It would make for easy production and cost effective.

[Dejay]

Hopefully they make a DNA60 or something that has the same size as the DNA40. But that would be a different board. It would need to be boost/buck voltage again while the DNA200 can only lower the voltage from the battery.

[Guest]

Now if they made a boost/buck DNA 200 v2 with a 3 cell option they could easily flood the market and you would be seeing a lot of custom boxes out there

[John]

We could of course make a 3 cell buck boost DNA 200, but it would be bigger, more expensive, and you can't realistically get more than 80-90 watts out of an 18650 anyway without making the cell life terrible.

[Guest]

Is there a way with the current DNA to have that option and what would the wattage be?ohms law was say at .1 ohms you could get 60w max ideally 40w would suit my girlfriend

[John]

Not with the 200, it needs an absolute minimum of 5 Volta to run. 

[Guest]

Ok, Thanks for the info, I'll just grab some 40's then

[steamer861]

A little confused. Is the diagram in post 66 or 69 correct?

[adski]

They are the same. You can solder pin 2 and 3 On the board or run two wires. 

[Dejay]

They are not the same. And I'm confused as well because John said "it's wired correctly" without referring to the which kind

[adski]

Run a wire from  pin 1 to the positive that you connect to the board at the sled
solder a bridge on the board from pin 2 to pin 3
Run a wire from 2/3 to the opposite end of the sled it does not matter which as they are already connected
run a wire from the negative pin  to the main battery ground that goes to the board at the sled
job done

[BobC]

Brandon/John, though I love the capabilities of the new chip and applaud your achievements, I do hope you realize that many (if not most) of your users do not use or need wattage in excess of 40-50 watts.
Squonkers in particular are quite happy with a single 18650 power supply as the addition of the in-line bottle and feed assembly already add size to a mod.

The chip size itself is not the issue, the size requirements for 2S/3S options with an mah equivalent to a single 2500 mah 18650 is.

I love my DNA40s, but as an alternate metals TC coil user, would love to have the firmware and TCR options contained in the DNA200 with the power requirements of  the DNA40 

[Guest]

That's what I'm hoping for to I'm using a 25 now I bought the 200 cuz of the interface with the PC and for direct wiring to a car if the 40 had interface capability I would get that one to

[John]

I guess the big question if, if you make a DNA 40esque chip with an integrated charger and Escribe, where do you put the USB port and charger? 

[BobC]

John, I`m less concerned about the chip/board size then the power requirements for the unit. It doesn`t have to be the same form factor as the DNA40 for me

[Guest]

John said:

I guess the big question if, if you make a DNA 40esque chip with an integrated charger and Escribe, where do you put the USB port and charger? 

have it to where there's solder pads, then we can solder are own USB to where we want it :-)

[turbocad6]

separate module with 4 wires to the board instead of 2 so it can be placed remotely... 

[John]

Unfortunately USB is a differential signal, it has to be routed with somewhat more care than typical chassis wiring. It would be an absolute minimum of six wires too. 

Not impossible, though. 

[turbocad6]

twisted pair with a ground shield? I really love the dna200 and I can now def see the sense in going 3s, now 2s is awesome too, but a dna40 form factor with escribe functionality sounds like it would be a huge hit, still many, maybe even the majority that are really stuck to the 18650 form factor... 

[BobC]

I second, third and fourth Turbo`s statement