Charging time

[andwhyisit]

What would the charging time of the Pyra's battery be?

 

[levi]

It will depend what current your charger puts out, but it's a 6000mAh (at 3.3V I assume) battery. That's 19.8Wh. Your charger will put out 5V, so if it puts out 2.1A, that's 10.5W, so will take at least 19.8/10.5=1.89 hours. I practice given the Pyra will need some juice to run and will lose some power when converting from 5V to whatever voltage is needed to charge the battery, and on my Pandora it currently takes about twice the time it should theoretically to charge. The Pyra will probably take longer than twice the theoretical time to charge though, as my Pandoras received a lot of patches to reduce idle power usage recently, while the Pyra will probably be slurping a lot more juice to run to begin with.

 

[Djoga'Ro]

Adding to @levi: The recommended - if not dictated? - charging scheme for LiIon-batteries is controlling the voltage to have the current constant at the set value till the voltage reaches the target voltage for the battery (with LiIon typically 4.2 V) and then holding that voltage. In the second phase the current will decrease constantly. When it reaches a certain threshold you're done. So you won't hold the nominal current of your setup through the whole process. This is why it takes longer, than what you calculate, @levi.

 

[levi]

Yes, I understood the first phase required the input power to be converted to constant current, by modifying the voltage as the load changes. I don't know how common charge circuits actually do that - if the voltage needed is above the input voltage, I don't even really understand how you do that without a transformer, but either way I assumed there was some power loss involved in doing that, which combined with the system load seems to mean charging takes twice as long as it should assuming perfectly efficient charging (and preteding the CPU doesn't need any power to work).

But my experience shows that charge time is roughly proportional to charger current, and I believe that if the Pandora had a battery smaller or larger then proportionally the charge time would also change, more or less. But that shows how little power the CPU takes on the Pandora compared to any of my chargers I guess.

 

[Grench]

So, cutting the science out and going for round numbers: Around 5-6 hours if you aren't using it while charging and 10+ hours if you're trying to play intense games while 'charging' - put in quotes because under 'heavy use' it could very well balance to 0 or even discharge still if under heavy load - which could include USB devices drawing power as well. There are a lot of variables involved and it has a very large capacity battery - triple the capacity of many phones.

 

[Djoga'Ro]

I too don't know how to up the voltage without a transformer - maybe having capacitors; feeding them in parallel and draining them in series, then switching between those quickly? just a wild guess.
However, with 5 V from the USB port and charging LiIon-batteries with no more than 4.2 V such sophistication isn't needed.

 

[Grench]

So - I started wondering... The Pyra is capable of charging/powering through either the microUSB charge port OR through the microUSB 3.0 OTG port. USB 3 allows for negotiation to higher current flows. Would there be any advantages to charging via a microUSB 3.0 cable fed from a 3A+ USB3 power brick? Does charging via one port or the other have any theoretical advantages to max current draw?

There is some limitations to what could flow into the battery itself and heat in general, but would a higher amperage source enable faster battery recharge times while the Pyra is being heavily used?

Just theory and curiosity.

 

[pmprog]

I practice given the Pyra will need some juice to run

Hmmm, meant to ask this. Will the Pyra fully boot when charging, like the Pandora? It's one feature of the Pandora I don't really like.

 

[TrashyMG]

Hmmm, meant to ask this. Will the Pyra fully boot when charging, like the Pandora? It's one feature of the Pandora I don't really like.

From early claims I've heard it won't, it can charge with the system off.

 

[Kippykip]

I believe ED? said at one point that it can run without a battery, I'm not sure if it will work through the USB port though if that's the case.

 

[levi]

I believe ED? said at one point that it can run without a battery, I'm not sure if it will work through the USB port though if that's the case.

How else will the system get power if it doesn't have a battery in? The Pyra won't have a charge port like the Pandora does.

 

[Amnykon]

I too don't know how to up the voltage without a transformer - maybe having capacitors; feeding them in parallel and draining them in series, then switching between those quickly? just a wild guess.

Yes, this is the way to increase voltage (at the cost of current)

http://electronicdesign.com/power/charge-pump-option-ldo-and-inductor-based-regulators

 

[ible]

@levi I can confirm @Kippykip in that ED said you can run the pyra without a battery. that is what he planned anyways for the traveling Pyra, since it's less expensive to ship without a battery.

 

[Grench]

@levi I can confirm @Kippykip in that ED said you can run the pyra without a battery. that is what he planned anyways for the traveling Pyra, since it's less expensive to ship without a battery.

At some point someone is going to connect a Pyra to a cheap 100mA USB charger and pop the charger - then complain.

 

[ible]

can't please everyone all the time

 

[Kippykip]

At some point someone is going to connect a Pyra to a cheap 100mA USB charger and pop the charger - then complain.

Well if they don't know the difference between certain USB chargers, they shouldn't be buying a linux handheld in the first place.
Just you wait though, that'll probably actually happen.

 

[levi]

I've used a 500mA USB charger to charge my Pandora in the past. It wasn't that cheap though - it came with a ~$200 GPS sports watch a good few years ago. I know my Pandora will gladly suck up over 2A through that same port if it gets the opportunity, but even the Pandora's charge chip seems to be clever enough to know not to keep sucking current when the voltage in starts to drop and instead increase the resistance.

 

[Ligachamp]

I've used a 500mA USB charger to charge my Pandora in the past. It wasn't that cheap though - it came with a ~$200 GPS sports watch a good few years ago. I know my Pandora will gladly suck up over 2A through that same port if it gets the opportunity, but even the Pandora's charge chip seems to be clever enough to know not to keep sucking current when the voltage in starts to drop and instead increase the resistance.

So no random USB-C device burning behavior on Pyra? :/ Like always, we seem to be unable to keep up with all this modern top of the art features...