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5v UPS
#11
Well, it was pretty easy to test if I can do charge/discharge at the same time with this particular power pack. I'm sure different power packs have different characteristics. I just plugged the little power pack I had in to see what would happen. Initially, the power pack wasn't charged, and as a result the PI didn't start due to low voltage, or so I thought. I put it on charge for an hour and then plugged in the PI, and it appears that too much current is being drawn, the main voltage goes down to 2.9V and the PI still doesn't start. I tried another power pack with two batteries and the voltage only reached 4.6V. I suspect if a buck converter were introduced this problem could be resolved - clearly this little cheap power packs don't have this sort of thing.

So, I guess the take-away from this is that whatever is applied as a UPS needs to be capable of 2 amps or so at a steady 5V, even if it is for a short period. I still believe this may be the start of something that could work. While I know that others have done this with capacitors, I'm concerned that full shutdown might not be complete before the capacitors were fully discharged. This would be particularly an issue in my case, as I'm using an SSD for storage, which takes a good deal of current.
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#12
(11-13-2017, 09:06 AM)shark24 Wrote: Unfortunately most of the UPS solutions won't work for me. On the boat the pi is fed by the 12v system and should be shutdown when I kill the main power. After the shutdown the pi needs to be cut of the UPS's battery because it won't turn off completely. The pi still sucks some current in shutdown and fires the GPIO pins so the UPS wouldn't last very long. I haven't figured out yet how to detect whether the pi has finished the shutdown completely. Because of that i need some sort of timer like shipahoy wrote. First I was going for a NE555 and a relay but recently I've tested a MOSFET and a capacitor at the gate. I'm a total newbie when it comes to electronics and I'm trying to figure everything out by myself and not follow some DIY-guide. I hope I'll have a working solution in the next weeks. Currently I'm waiting for the delivery of last parts from china.

For the parts you are describing, you might find it easier to deploy an Arduino Pro Mini, and just do the appropriate programming to detect voltage states, do timing, etc. You'll probably find that the actual board real estate required for something like that would be less than a 555, capacitors, etc. It's also a lot easier to implement some logic in that configuration.
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#13
You got me wrong. I'm not using an ne555. Besides I want to keep the power consumption as low as possible. I would safe a mosfet and a 50uF capacitor and get a micro controller instead. I don't see the benefit in that.
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#14
I like to mention that Adam did make an update video. I follow his and his friends videos since a long time. So was not surprise I did ask him for a 3,0 Amp solution. I prefer for shutdown in the moment a solution with capacitors and the method of Spies the man with the swizz accent

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#15
Can you please give us some details tocan. I know Andreas's video but I have some concerns regarding the super capacitor solution. 
I hook up different stuff to my Pi and won't know which capacity to choose. What capacitors are you using?
Are there any problems regarding the balancing of the capacitors or are you using a single one?
How much current sucks the capacitor in the beginning? I'm concerned whether my power supply (2.2 A) can handle it.
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#16
I did exact how Andreas did describe. And I bought the same. I like this super capacitors stuff in general. It's in parts useful if you run solar as well. For my 30 years old engel fridge what have 24 Volts I use up step converter and I support with super capacitors the start. Most knowledge was from Adam and from Iulian and I did start also with some stupid unpacking videos as you mentioned before. Super caps take what they need and get but raspi keep it. Did not got failure. But it's only for save shutdown. And supercool are wonderful to help starting a diesel engine. Here I did test with a small battery agb type 20 Ah but in general a 30 watt panel and a 6 pack 500 F super caps is enough to guaranty a smooth start. Can also be done with some Lipos. And if all runs dirty with batteries and solar in general you can start by hand with dynamo and a simple handweel...

Anyways with the diy power walls we do at the moment with raspi and influx and grafana a raspberry build. So also the epever will be included. And from China I got for inverters the modus protocol will soon be translate in next week's. And for final I will not care much failures of the raspi because plan b is the discussion of today to use in such case complete android as server. With opencpn I can not something back because of Kap files so I have to focus to pure tiles of openseamap or use navionics.

Just look how it works Julian did just did a postbag video with supercaps. They are to big for the raspi but Andreas did explain what is good to use. Read just the coments and look the postbag videos.

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#17
Yes, I did misunderstand your setup for shutdown. The reason I was thinking that a microcontroller might be good is when I was thinking through the logic of when a clean shutdown might be required. For example, I might want my pi to ride through a momentary power loss of a few seconds, and then if the power loss persists, send a shutdown signal via GPIO. Also, it might be useful in extreme cases to have a power switch that would allow me to initiate a clean shutdown with a single momentary press, and a forced power off when the button is held for 10 seconds, like on a PC.

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#18
(11-18-2017, 10:09 AM)abarrow Wrote: Yes, I did misunderstand your setup for shutdown. The reason I was thinking that a microcontroller might be good is when I was thinking through the logic of when a clean shutdown might be required. For example, I might want my pi to ride through a momentary power loss of a few seconds, and then if the power loss persists, send a shutdown signal via GPIO. Also, it might be useful in extreme cases to have a power switch that would allow me to initiate a clean shutdown with a single momentary press, and a forced power off when the button is held for 10 seconds, like on a PC.

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You can implement all of this logic in the pi.
Connect your main power to a gpio pin (keep in mind the max. voltage of the gpio and besides that use a pull down resistor). Set up an interrupt handler for the pin. If pin is low (means main power is out) start an timer. After your selected time is up start the shutdown.
A shutdown button can be arranged aside of that pretty easily. But there is no forced shutdown possibility like in your desktop PC. This forced shutdown is executed by the mainboard and there is no similar function for the pi. All you can do is cut off the power.
If you got a ups that tries to shutdown the pi, waits for a minute and kills the power afterwards, you won't need to worry about the shutdown. 
Just get a switch for the main power. If its switched the pi tries the clean shutdown. In case off a system crash the power gets cut by the ups anyway.
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#19
What a interesting thread

We are working on 3 stackable hats for openplotter Smile
The first one is about to be sent to production, I will introduce it in few days.

One of them is an UPS with voltage conversion from 9V to 32V to feed the raspberry. We are still on concept stage on this one but I think we will go with the capacitors option, no batteries.

Please keep sharing your impressions on this.
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#20
(11-19-2017, 08:30 AM)Sailoog Wrote: One of them is an UPS with voltage conversion from 9V to 32V to feed the raspberry. We are still on concept stage on this one but I think we will go with the capacitors option, no batteries.

A 5 F capacitor charged to 5 V, and connected to a boost converter that works with 2-5V input, should be able to provide 1A for 10s.
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