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Sneak preview of the new χ1 LiPo battery board

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Re: Sneak preview of the new χ1 Li-Po battery board

Postby MiniMe » June 10th, 2011, 1:59 pm

-nevermind- I see it now
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby amb » June 10th, 2011, 2:06 pm

flynhawaiian wrote:I was just about ready to purchase the m3 board. Glad I waited a bit. If you need a beta tester let me know :D

In case you're not aware, and Mini³ are different beasts.

MiniMe wrote:Am I seeing it right in that the rear LED is replaced with one to indicate charging status?

Yes, see the intro post of this thread.
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby flynhawaiian » June 10th, 2011, 3:38 pm

I was just thinking, since you are basically going to have a 2-cell lipo battery, have you installed a "balancer" on the charging circuit to balance the batteries? I know lipos are really really picky about that kinda stuff.

Also, just something I was thinking about... Looking at the design, wouldn't it be better to use a "camera" battery? I was thinking since they are "contained" versus the 650mah batteries. I would also suspect they are made to be "beat up" more as well. And I believe they have an overload protection. Something to think about, since they are 1000mah and wouldn't require people to solder wires on lipo batteries. Not trying to criticize the design at all, just wondering if you have thought about this as an alternative. Keep up the good work!

http://cgi.ebay.com/NB-6L-BATTERY-CANON ... 2349wt_910
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby mattcalf » June 10th, 2011, 10:35 pm

Looks really good, thanks misterx and amb.
Just checking if it will fit into the oringal mini3 bom hammond case?
amb wrote: Like a pure class A amp should, the maximum heat dissipation occurs when the amp is idle. It will actually run cooler when playing loud.
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby amb » June 10th, 2011, 10:59 pm

mattcalf wrote:Just checking if it will fit into the oringal mini3 bom hammond case?

Yes. The enclosure will be packed full like a jar of olives. ;)
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby mattcalf » June 10th, 2011, 11:06 pm

Wouldn't be fun otherwise.

Thanks!
amb wrote: Like a pure class A amp should, the maximum heat dissipation occurs when the amp is idle. It will actually run cooler when playing loud.
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby Shaman » June 11th, 2011, 1:20 am

Great work, as usual!
Any chance it could be tweaked to be used with three (and preferably higher mAh) batteries?
This could form the basis for a great "universal" LiFePo battery power supply.
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby MisterX » June 11th, 2011, 2:14 am

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.
1352.5 and counting.
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby amb » June 11th, 2011, 5:20 am

flynhawaiian wrote:I was just thinking, since you are basically going to have a 2-cell lipo battery, have you installed a "balancer" on the charging circuit to balance the batteries? I know lipos are really really picky about that kinda stuff.

The charging chip and the protection chip we selected are designed to support two cells. There is no need to add any external balancer.

Also, just something I was thinking about... Looking at the design, wouldn't it be better to use a "camera" battery? I was thinking since they are "contained" versus the 650mah batteries. I would also suspect they are made to be "beat up" more as well. And I believe they have an overload protection. Something to think about, since they are 1000mah and wouldn't require people to solder wires on lipo batteries. Not trying to criticize the design at all, just wondering if you have thought about this as an alternative. Keep up the good work!

http://cgi.ebay.com/NB-6L-BATTERY-CANON ... 2349wt_910

Amongst other things, we have to consider the below requirements:
- Size of battery (it has to fit the the Hammond 1455C80x case, in the space that originally held the 9V NiMH battery)
- High energy density (as much mAHs as we could find to fit in the space we have)
- Availability (whether the battery is commonly and easily available)
- Price (so you don't get gouged)
- Connectivity (must have wire leads -- the camera battery you linked require special spring contacts which is unfeasible for our application)

We researched many different battery types and narrowed down to just two, and then to one. It meets all of the above requirements, and since it's made for RC helicopters, it's just as robust (if not more so) as a camera battery.
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby jerdobi » June 11th, 2011, 6:48 pm

A dual board design is definitely a future generation of the Mini3 design and supporting a Lithium battery is the a natural next step. That said, what comes to my mind as the next generation of the Mini3 would be using a single or dual iPod classic 6th generation batteries (easily available), embed a DAC and/or dual gain switch on that dual board too.
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