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Sneak preview of the new χ1 LiPo battery board

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Sneak preview of the new χ1 Li-Po battery board

Postby amb » June 11th, 2011, 11:45 pm

jerdobi wrote:...embed a DAC and/or dual gain switch on that dual board too.

There is no way to do this in the existing case unless we go to very small SMD parts and very high density board layout (with parts on both sides of the board), but then the amp will become difficult to build for most people. DIY is not commercial production and we need to be mindful of that.
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby linux-works » June 12th, 2011, 6:41 am

you never want to design a DIY item that requires it be sent out to an assembly company... its not DIY then, its BIY (buy it yourself). lol.
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby Shaman » June 12th, 2011, 7:38 am

Thanks for the clarification, MisterX.
You could see my questions as recommendations for x2. :mrgreen:

Btw, the Greek chi (x) and the chinese chi are pronounced in a very different way. Catchy name-play though!

MisterX wrote:
Any chance it could be tweaked to be used with three (and preferably higher mAh) batteries?


The protection and charger controllers are designed to only work with 2 cells.
The max fast charge current supported by the charge controller is 1.2A, the protection circuit's max current capacity is 3 Amps, assuming a 1C charge rate the board should in theory be able to support cell capacities up to 1200mAh but it remains to be seen if it would work reliably (with the thermal demands) at that level.

This could form the basis for a great "universal" LiFePo battery power supply.


This board is not designed to be compatable with LiFePO4 cells.
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby MisterX » June 12th, 2011, 12:09 pm

Unless you have a link to some LiFePO4 cells that fit into the enclosure along with the amplifier it's a non starter.

FWIW the LT3652 is available with a MSOP package and would be much easier to solder then a QFN-20 package. ;)
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby vixr » June 12th, 2011, 5:00 pm

amb wrote:
vixr wrote:will there be any benefits beside faster charging?

Read my intro post above. ;)

wow...I swear I read the whole thing and did not see the huge difference in the run times...sorry for the dumb post... :oops:
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby DorkVader » June 12th, 2011, 9:30 pm

Wow! I've finally gotten a job offer (for the summer, and part time for the next 2 years hopefully) and I've always wanted to build a mini^3. This project is, of course, right up my alley. and I'll finally have a source of income to support my DIY habits.

Does the use of this board necessitate a new or different mini^3 board, or will it work with what's available now? (so we can "easily" upgrade it like a gamma1 -> gamma2) It sort-of looks to me like it "plugs in" to where the to-220 (LM317, I think) would go in a "normal mini^3" so I assume this is the case, but I wanted to check.

What does the board rest on? There's the place is plugs in to the mini^3 board, and I assume it's flush with those capacitors and the DC inlet as well?

An excellent alternative, I think to the normal mini^3 battery design. Both options have their advantages. Thanks for the pictures, MisterX!
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby amb » June 12th, 2011, 9:41 pm

DorkVader wrote:Does the use of this board necessitate a new or different mini^3 board, or will it work with what's available now? (so we can "easily" upgrade it like a gamma1 -> gamma2) It sort-of looks to me like it "plugs in" to where the to-220 (LM317, I think) would go in a "normal mini^3" so I assume this is the case, but I wanted to check.

No change to the Mini³ PCB. You can upgrade an existing NiMH-based Mini³ to Li-Po power by de-populating the original battery charger section and replacing the two tall 470uF caps with shorter versions.

What does the board rest on? There's the place is plugs in to the mini^3 board, and I assume it's flush with those capacitors and the DC inlet as well?

The Mini³ board rides in the bottom slot of the Hammond case as before, and the χ1 board rides in the top slot. The case provides the support of both boards.
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby MisterX » June 13th, 2011, 2:00 am

26 hours.
It was like, geeze... will this battery die already! :D
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby nattonrice » June 13th, 2011, 5:36 am

This is a fantastic upgrade option!
Congrats =)
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby dougigs » June 14th, 2011, 2:10 am

Brilliant design. I built a similar LiPo board about 5 years ago, to power one of Tangent's boards, but it was considerably larger (4-cell battery, not really pocket-sized, proved impractical). This is great miniaturization, ingeniously done. (One thing I did add was a comparator to light on an LED when the voltage dropped below a "needs charging" threshold... I'm not sure if that's possible with these chips or with your extremely limited board real estate).

One question about the design: Is JP1 hooking into the holes from C8- and C4 (which I'm assuming would be replicated on the daughterboard)?
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