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Nisei

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Reply with quote  #1 
Wouldn't it be pretty simple to have the DNA detect input voltage and limit max wattage output accordingly to support single cell batteries (or 2 single cells in parallel) as well?

Board detects a voltage between 3 and 4.5V and switches to 60W (or 50W) max mode
Board detects a voltage between 9 and 16V and switches to 200W max mode

This way the board would be much more attractive to people who rather keep using standard Li-ion batteries.
John

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Reply with quote  #2 
Not really, no. The whole board is built around using a 3s lithium. I mean, sure, we could detect it, but we couldn't... do... anything with it, couldn't charge, etc. 

We COULD conceivably run from 2s in a degraded (probably 120W or so) fashion, but once you go to 2s and taps, there's very little extra cost or difficulty to go to 3. 
Nisei

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Reply with quote  #3 
Thanks for the quick response.
I wonder what you mean with "etc."
I didn't think about charging (probably because I always charge outboard) but that's the only caveat I can come up with.
Otherwise I see no reasons why it couldn't be done.
VapingBad

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Reply with quote  #4 
Quote:
Originally Posted by John
Not really, no. The whole board is built around using a 3s lithium. I mean, sure, we could detect it, but we couldn't... do... anything with it, couldn't charge, etc. 

We COULD conceivably run from 2s in a degraded (probably 120W or so) fashion, but once you go to 2s and taps, there's very little extra cost or difficulty to go to 3. 


Please have a look at this John, people have misread the FAQ to believe 1 x 18650 is going to happen.

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Nisei

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Reply with quote  #5 
Ha ha, yes I saw your post on the other forum [smile]
That's why I posted this here to ask if perhaps it can be done.
I'd really like to know what would be the reason it couldn't be done. Charging could also be done accordng to supply voltage.
My cheap Turnigy LiPo chargers also auto detects how many cells are in a battery and chooses the right voltage to charge with.
I'd love to buy this board but I'm not prepared to convert to Snickers sized batteries just for the features. I don't want 200W
John

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Reply with quote  #6 
The charger only steps voltage up. The board only steps voltage down, and the internal logic needs at least 5v to run. 

If you run from single cell, which is 3-4.2v, the charger will not be able to control charging, because it can put out a minimum of 4.5 volts. The board would only be able to put out 3v, and at any rate neither system would turn on. 

I'm not saying it isn't possible. I am saying this board can't do it. 

The reference design, with a 3s battery in it, is significantly smaller than a classic Hana, so you don't have to get particularly big to get the feature set. You can even turn the max power down and run a 3s battery that is smaller than an 18650 if you are so inclined. You just can't do it from a single cell with this particular board. 
Nisei

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Reply with quote  #7 
Hey thanks again John. That makes it very clear!
My concern with the batteries isn't just size related though, it's shape and connectivity that worries me most.
With most classic designs you unscrew a cap, drop in a battery and pop the cap back on.
Now APV and mod makers are limited by the fact that you have to be able to open it up in such a way that you can connect plugs to connectors.
This has a huge impact on how a device is going to look unless you want people to depend on onboard charging.
John

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Reply with quote  #8 
 There are plenty of drop in connectors and solutions for this type of 3 cell pack. Many brands of power tools now have an option that is 3 18650s with a drop in connector.  Certainly there will be a learning curve, but it is not insurmountable. 


balazsk

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Reply with quote  #9 
Quote:
Originally Posted by John
We COULD conceivably run from 2s in a degraded (probably 120W or so) fashion, but once you go to 2s and taps, there's very little extra cost or difficulty to go to 3. 


John, I think it really would make sense especially in case of 18650. It would be just a good option to use 2x18650 for smaller mods with replaceable batteries.
If you ask me it would worth the effort but of course I can understand that this is opposite of the original concept.

Nisei

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Reply with quote  #10 
Agreed. Also, existing 2x parallel 18650 designs could simply be modified to use 2x 18650 in series without having to start from scratch again.
Bapgood

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Reply with quote  #11 

I'm confused about what in the FAQ's is confusing people about the requirement of having to run a 3S battery?

This is in the FAQ's
Q: What is the battery requirment?
A: Battery needs to be a 3S LiPo/LiFePo4/IMR lithium type battery capable of handling a constant load of the max 23 amps. Having some overhead is always a good thing.

And I just deleted the FAQ entry about charging to 4.1v since its now a feature.

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