Can I create a UPS with powerboost 1000 and a USB LiIon/LiPo

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Hilton
 
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Can I create a UPS with powerboost 1000 and a USB LiIon/LiPo

Post by Hilton »

LadyADA mentioned a UPS capability with the USB power boost 1000 but wasn't clear how this would be done.
I've found bits and pieces of discussion on the topic of making a UPS in the forum but nothing that gives a concrete solution and how to connect it.

I have a portable media player project with RPi2 + 2TB drive and a 6000mAh battery that I want to have it switch between Battery and external power without rebooting and without a manual switch if possible that also allows charging while connected to mains. (load sharing if possible)

Im looking to mass produce the case and power circuit and may even do a kickstarter for it. This is just the prototype.

I currently have the original battery charging circuit from the original battery booster with the output from the battery charging board (a 2.1A usb output) connected to Pi microUSB power input.

I also have a DC jack for external power going direct to 5V GPIO and both battery and external power are switched via an DPDT On Off On switch.
This works well in practice now to manually switch between external power and battery but I'd like to automate the whole thing and include a script to also allow power off and reboot.

Can this be achieved with the powerboost 1000 and the USB LiIon/LiPoly charger to make an automated UPS? Load sharing for charging and power would be great too but not as critical as having a smooth cutover from battery to power and visa versa. I could live with a separate charging port/circuit to keep costs of the UPS solution reasonable.

Also, could I do something with the current charging board that came with the battery and just add a powerboost? It actually fits my project perfectly apart from not having load sharing. The current charger disconnects the battery from the Pi when power is plugged into it.

The media player case.
Image

The rear panel. Current LiIon charger on the far left. Pi2 above 2TB drive powered directly via Micro USB to USB. (Pi softmodded to allow 1.2A on the USB ports so there's no requirement for a HUB.) Battery sits above the Pi in the HAT position.
Image

A look inside from the rear.
Image

Here's a slightly earlier version of the prototype without the DC power in.
Image

It lives!
Image

Video demo
https://www.youtube.com/watch?v=VLM5V6JLfY8

And a peek inside Video.
https://www.youtube.com/watch?v=2dgkL1ZcBqs

Any assistance greatly appreciated!
Last edited by Hilton on Fri Apr 10, 2015 11:17 am, edited 1 time in total.

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adafruit_support_rick
 
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Re: Can I create a UPS with powerboost 1000 and a USB LiIon/

Post by adafruit_support_rick »

You can make a UPS out of those two components. Just connect the powerBoost to the load output.

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Hilton
 
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Re: Can I create a UPS with powerboost 1000 and a USB LiIon/

Post by Hilton »

adafruit_support_rick wrote:You can make a UPS out of those two components. Just connect the powerBoost to the load output.
Thankyou. A couple more clarifications please. :)

Does it work with the USB/DC Lipo charger or Solar Charger?

If I plug power into the Lipo charger will current still flow to the Pi and charge at the same time or will the Pi shutdown while charging or will most of the power go to the charger?

Will the Pi reboot when power is added or disconnected?

Many thanks!

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Re: Can I create a UPS with powerboost 1000 and a USB LiIon/

Post by adafruit_support_rick »

If your Pi is using all of the available current from your DC power supply, then the battery will charge slowly or not at all. Otherwise, the battery will charge according to its charge limit and how much DC current is available after powering the Pi.

The DC LiPo and the Solar LiPo both use the same charger chip, so they act the same way. We don't recommend connecting the load output to the Powerboost with a solar panel, since the solar panel can go up to 6V. Instead, we suggest connecting the powerboost to the BAT output pads on the solar charger. If you're not going to use a solar panel, then you can use the load output.

As far as I know, there will be no interruption in power when switching between the battery and DC input.

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Hilton
 
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Re: Can I create a UPS with powerboost 1000 and a USB LiIon/

Post by Hilton »

adafruit_support_rick wrote:If your Pi is using all of the available current from your DC power supply, then the battery will charge slowly or not at all. Otherwise, the battery will charge according to its charge limit and how much DC current is available after powering the Pi.

The DC LiPo and the Solar LiPo both use the same charger chip, so they act the same way. We don't recommend connecting the load output to the Powerboost with a solar panel, since the solar panel can go up to 6V. Instead, we suggest connecting the powerboost to the BAT output pads on the solar charger. If you're not going to use a solar panel, then you can use the load output.

As far as I know, there will be no interruption in power when switching between the battery and DC input.
Thankyou very much. That makes things much clearer.

If I use a 4Amp 5V supply, with Lipo/DC charger set at 1A charge and I draw 2A for the Pi (total 3A) will that work? If so I'm sold!

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Re: Can I create a UPS with powerboost 1000 and a USB LiIon/

Post by adafruit_support_rick »

yes, that should work.

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Hilton
 
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Re: Can I create a UPS with powerboost 1000 and a USB LiIon/

Post by Hilton »

adafruit_support_rick wrote:yes, that should work.
Thanks again!

Sorry more questions!

I'm just looking now at what can be done to automate a safe shutdown of the Pi for low battery voltage and control power-on/reboot.
Should I use the LBO from the powerboost or the LBO from the LiPo charger or both?

I already have shutdown, reboot and restart application button scripts working on my prototype but am unsure where to integrate the powerboost and LiPo charger into the loop.
Currently I hold the restart/shutdown switch for varying times; 2secs for restart, 4 secs for shutdown and I have a separate hard reset/reboot button. The script times the button press to pull the GPIO resistor up or down and trigger the appropriate command.

With a poweron / reboot button integrated into the circuit where should I trigger the power on and off from to make sure Im not stuck in an on or off loop?
To disconnect power completely from the battery or external power source where should that be integrated into the circuit?

I note you have a smart power switch, if I was to use that how would that be best integrated given the high current Im using?

The Solar, DC and USB LiPo chargers are all functionally very similar for my use case, however...
Is the MCP73871 from the Solar LiPo charger better for loadsharing than the MCP73833 on the USB LiPo charger?
OR is the MCP73861 on the USB/DC LiPo charger better for loadsharing?

Or is there no functional difference for loadsharing and hotswap of power across all three LiPo chargers?

Sorry for all the questions just want to make sure I can do what I expect before I order!

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Re: Can I create a UPS with powerboost 1000 and a USB LiIon/

Post by adafruit_support_rick »

You're referring to this power switch?
https://www.adafruit.com/product/1400
That's good for 3A. I would put it between the powerboost and the Pi.

The powerboost is the best place to get the low-battery signal from.

I'm not up on all of the esoteric differences between the charge controllers. I'll check with someone else

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Re: Can I create a UPS with powerboost 1000 and a USB LiIon/

Post by adafruit_support_bill »

The Solar version of the charger is the only one that has true 'load sharing' at this time. That one will switch excess input current directly to the load while still providing full charge current to the LiPo. All the others just connect the LiPo and the load in parallel, so they share the charge current.

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Re: Can I create a UPS with powerboost 1000 and a USB LiIon/

Post by adafruit2 »

Yeah for the best "UPS" action, the Solar USB/DC charger is what you want. you do not need the huge capacitor if you are not connecting a solar panel :)
Connect the PowerBoost 1000 to the LOAD pads

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Hilton
 
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Re: Can I create a UPS with powerboost 1000 and a USB LiIon/

Post by Hilton »

Thanks, I suspected there might be some differences!

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Re: Can I create a UPS with powerboost 1000 and a USB LiIon/

Post by Hilton »

Thanks for your help, I've ordered a bunch of stuff including the USB LiPo chargers to test on the prototype until the Solar chargers come back into stock.

I've also ordered a couple of the breakout board 3A power switches. Can you program a delay for the off function to avoid accidental power off?

If not, would it be possible to use just a normal switch on one set of Pi GPIO pins with a scripted delay, that then latches another GPIO pin to complete the switch circuit on the breakout board. Im thinking it may be simpler to just use normal GPIO scripting without the breakout power switch but I it could be useful to have the ability to switch a power load on and off.

Im happy to make use of the switches for other prototyping anyway even if I cant use them with a delay for this project.

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Re: Can I create a UPS with powerboost 1000 and a USB LiIon/

Post by adafruit_support_rick »

You can't program a delay for the off signal on the power switch

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Hilton
 
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Re: Can I create a UPS with powerboost 1000 and a USB LiIon/

Post by Hilton »

Thanks for your help guys!

All working as planned as a UPS! I can plug and unplug power without disruption to the Pi2.
For reference it doesn't seem to charge when the Pi2 is turned on though. Hurry up get the Solar back into stock! ;)

Image

Image

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Re: Can I create a UPS with powerboost 1000 and a USB LiIon/

Post by adafruit_support_rick »

Cool!
Hilton wrote:For reference it doesn't seem to charge when the Pi2 is turned on though.
Maybe there's not enough current available for charging.

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