Pi UPS

Looks ok to me, if all you want is a power bank controller that can charge and discharge at the same time. You might find you can buy a complete power bank (including the Li cells) for about the same price if you shop around. My local computer store was selling Romoss Sailing models on sale for ridiculously low prices recently.

To be a useful, general purpose UPS though, it needs to be able to output a signal to tell the load (Pi) that it's about to run out of juice so that the Pi can shut down cleanly and go into a low(er) power state, all without corrupting the SD card.

Assuming you can figure out how to derive such a signal (e.g. by monitoring cell voltage, or by starting a timer when the charging input fails), I guess you could try to couple it to something like this:

"It watches the state of BCM pin 17 and, when pulled low (pressed), it initiates a clean shutdown. Last thing, just before your Pi shuts down, BCM pin 4 is pulled low to completely cut power to your Pi."

Allan

Perhaps you don't recall the difficulty people had finding a power bank that would work like a UPS where it could provide power all the time and only drain the battery when the power failed.

Ideally such a controller would actually be smart enough to periodically run the batteries down a bit, but not all the time. Still, this is pretty good for a COTS board.

I have thought of a number of devices I would design if I could tap into the whole manufacturing/sales thing you see on eBay. I mean I don't touch the units or even the orders. I develop a manufacturable design and get a royalty off the sales. But I guess that just doesn't happen with eBay sort of stuff. I guess I could be in the loop somewhere, but I've yet to figure out how to get access to the low cost manufacturing and get the devices sold all without ever leaving Asia.

Anyway, this would be one of them. Something that integrates well with the rPi and doesn't cost as much as a rPi. That's one of the sad parts of the rPi, accessories cost more than the CPU board.

--

Rick C 

Viewed the eclipse at Wintercrest Farms, 
on the centerline of totality since 1998

The particular range I mentioned (Romoss Sailing) can do that. The datasheet calls it "synchronous charging," and states explicitly that it can charge itself and provide power to a load at the same time. It doesn't say whether there's an internal direct input to output bypass circuit, but at these prices, do you care?

Disclaimer: I haven't tested one to verify how well it works in practice.

BTW, the sale's over now.

Allan

Am 15.10.2017 um 02:18 schrieb rickman:

Look at this:

It's not so cheap as yout found device but it works perfect with the RasPi.

There's

who have an open source PCB fab - you upload an open source design, people can buy as many as they want from their website, they handle logistics.

They also have a manufacturing arm, and a library of standardised components to reduce BOM complexity. I think someone can order one of the open source PCBs and they will assemble.

They have a more traditional contract manufacturing section as well. That might work more on a for-profit basis, but you'd probably have to stump up the cash first.

I'm not sure what the volumes are like - ie can they 'print-on-demand' or do you need to commit to making a certain volume, that they hold in stock until they sell?

No personal experience.

Theo

Uwe K. wrote on 10/15/2017 5:18 AM:

My dear GOD! Could they have made the page any more difficult to read? Reminds me of the hackaday site, but worse because they don't even use white lettering, it is *grey*!!! Grey text on a dark grey background is idiotic! I might be willing to produce a competing product just so I can compete them out of business!!!

Also my scroll wheel won't work on their page and I think the product is not all that great. The battery is only 300 mAHr which would give less than an hour run time even for a pi zero. They make it way too hard to find out just what the various versions do with vague descriptions, "includes useful and innovative additional functions".

This is literally one of the worst web sites I've ever seen for selling products.

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Rick C 

Viewed the eclipse at Wintercrest Farms, 
on the centerline of totality since 1998

While I agree with everything you say about their web pages, their product looks good, if not cheap.

If all you want is a UPS with clean shutdown if the power doesn't return within 20-30 mins, 300mAh is fine. But they also offer the same board with a 3000 mAh external battery for either extended UPS or for portable use of the RPi, i.e around 5 hours plus or minus a few hours: this looks reasonable to me.

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martin@   | Martin Gregorie 
gregorie. | Essex, UK 
org       |

But you said it, the PRICE! I don't expect to pay as much for the USP as I do for the pi or many times more if this is holding up the pi Zero!

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Rick C 

Viewed the eclipse at Wintercrest Farms, 
on the centerline of totality since 1998

Indeed. But I might expect to pay *as much* or even a bit more (plus battery) if it does what this one does. Why? Because production volume and its effect on price.

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martin@   | Martin Gregorie 
gregorie. | Essex, UK 
org       |

??? And what is their production volume? If they sell a good (or even OK product) at a good price it will sell in volume. There are lots of applications where people want their pis to stay up 24/7. Before I bought this thing, I'd buy a proper UPS that will also power other devices. This also isn't exclusive to the rPi. It can work with any embedded system.

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Rick C 

Viewed the eclipse at Wintercrest Farms, 
on the centerline of totality since 1998

Sure, but that is still a lot less than the number of Pis sold, most of which have owners or users (especially the latter) who don't give a monkey's whether its shut down safely or not.

I'd be surprised if even 1% of RPis are owned/used by people who understand why they shouldn't just turn off the power whenever they want or care about what it may do to their data - until their bum is bitten.

I don't use a UPS for my RPi, but I'm in a country with reliable mains. In the 3 - 4 years I've had a UPS on my main Linux PC, which runs 24x7, I've had one mains drop-out - and that didn't last long enough to force a shut-down. Since my RPi is only up a few hours a week I've not yet judged it worth the effort to plug it into the spare sockets on the UPS and to configure the UPS to shut it down if the UPS batteries get drained.

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martin@   | Martin Gregorie 
gregorie. | Essex, UK 
org       |

While not wanting to contradict you in the main, you're wrong in one central point. A web page only defines its contents. Everything about its form and look are mere suggestions and it's up to you and your browser to accept those or not. I have set mine to use fixed colours for font and background, not to show background patterns and to impose a sensible minimum font size. Most browsers have placed these settings within easy reach from the main menu and for good reason.

OTOH this self defence was installed in the browser wars of the nineties and the newest browser versions are hiding these settings again and are making them harder to find. It's our web, our computer and our choice of browser, let's make it.

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/ \  Mail | -- No unannounced, large, binary attachments, please! --

That would still be 10's of thousands of units. The few who do know and care about shutting them down safely are likely using more than one unit. In fact, that is one of the requirements for using the rPi commercially, that it doesn't self destruct just because power glitched.

A "country"??? Mains reliability is related more to where you are in relation to other people. If you are in a city, your power only goes out when a power transformer blows up. If you are rural there are many more issues that can cause power glitches. One of my places gets power glitches every time lightning strikes nearby. I have a proper UPS on my networking equipment so that doesn't glitch. My laptop takes care of itself. The lights flicker and go out for seconds sometimes, minutes or hours less often. It has nothing to do with the "country" I am in. If I wanted to run a pi 24/7 and it wasn't near the UPS, I would need one of these units. I am looking into boards similar to these because I am working on a design that will simply use battery power and I saw that some of the boards available would work as UPS for the rPi.

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Rick C 

Viewed the eclipse at Wintercrest Farms, 
on the centerline of totality since 1998

Pi Hut and others sell the AdaFruit PowerBoost 1000 board that can do what you want.

It's more expensive, but proven for this sort of application. You need a

3.7V Lithium or Lithium polymer battery as well as the board.

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Cheers, 
 Daniel.

Similarly, I'm working on a project which will use a portable RPi as a control box for a much smaller/lighter Picaxe airborne unit, so fitting the RPi with something like this would be a good idea.

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martin@   | Martin Gregorie 
gregorie. | Essex, UK 
org       |

That looks very useful, and cheaper than the S-usv equivalent. Thanks for posting.

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martin@   | Martin Gregorie 
gregorie. | Essex, UK 
org       |

If the Pi pulls BCM pin 4 low to cut power (I assume on the power source) how does the circuit get powered back up? Once power is cut, pin 4 won't be pulled low anymore. I guess it has to be a momentary input controlling a state on the power controller. Then something else has to change the state and turn power back on?

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Rick C 

Viewed the eclipse at Wintercrest Farms, 
on the centerline of totality since 1998

Thanks. This shows there is a market for the product. It has some shortcomings though. Like many small units like this it only charges at 1 A rate which can be below the power needed by a pi if peripherals are attached. I'm not certain as I have not looked at the circuit, but while the output uses an inductive boost circuit, I believe the input has a simple dropping regulator to charge the battery. So the 1 A input will only be about 1 A * 3.7 V / 5.0 V = 0.74 A output without accounting for the efficiency of the boost circuit. Use more on average than that and the battery won't hold charge.

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Rick C 

Viewed the eclipse at Wintercrest Farms, 
on the centerline of totality since 1998

As part of installing it, you solder a momentary contact switch to the board. Pressing it powers the RPi up if its off and shuts it down if its on. There is control software associated with the board. It will power up without it, but the software must be installed on the RPi for shutdown to work.

Or so it says on the referenced Pimoroni page.

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martin@   | Martin Gregorie 
gregorie. | Essex, UK 
org       |