• 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
5v UPS
#21
This is great news! I am concerned about the capacitor choice though. Will there be enough reserve capacity if the pi has all kinds of peripherals? In my case I run three protocol converters, about 10 temperature senders and I don't know what else. If the pi is also heavily loaded with software processes, I would be very concerned about there being enough juice for a full shutdown.
In any case, I am looking forward to your design of a UPS!
  Reply
#22
I would have used at least 2 x 5 F, both to have enough energy, and to be able to draw enough current from the capasitors.

If you buy cheap super caps from China, they may also not have the capacity that they are marked with, or have higher internal resistance, so then you may need even more...
  Reply
#23
https://youtu.be/m20o3P-S5s8

In general Andreas is very busy but I have some contact to help in a project as mentor. It will be around a diesel RPM controlled fuel use measurement. He was one reason I came up with esp8266 and doing some experiments with sonoff.

Gesendet von meinem SM-G900F mit Tapatalk
  Reply
#24
(11-19-2017, 06:13 PM)tocan Wrote: https://youtu.be/m20o3P-S5s8

Although this works, it is not a very robust design:
- Since the capacitor is connected directly on the USB voltage, they are only 4.5 V when he initiates shutdown, and he looses 19 % of the energy.
- He has no boost regulator, so he looses even more energy.
- He does not have any current limit on the charging, which can lead to stress on the supply and the capacitor, reducing the lifetime of both. A simple resistor or a one transistor constant current source would be enough.
- USB power supplies have often 5.5 V to 6 V no-load voltage, and he does not have any over voltage protection.
- He has no voltage balancing, which will reduce the lifetime. An opamp can be used for this.
  Reply
#25
(11-20-2017, 10:46 AM)shipahoy Wrote: - He has no boost regulator, so he looses even more energy.

How can a boost regulator save energy? From my perspective the parts of it create resistance and therefore heat so energy is lost. Well not lost but it'll heat your boat instead of running your pi.

Not a big fan of the capacitor solution either but I didn't get my hands on anything > 1F yet so it's hard to judge. For me personal the safest way is the battery and I really don't want to risk to corrupt my raspbian when I'm on tour.
  Reply
#26
(11-20-2017, 11:23 AM)shark24 Wrote:
(11-20-2017, 10:46 AM)shipahoy Wrote: - He has no boost regulator, so he looses even more energy.

How can a boost regulator save energy? From my perspective the parts of it create resistance and therefore heat so energy is lost. Well not lost but it'll heat your boat instead of running your pi.

Not a big fan of the capacitor solution either but I didn't get my hands on anything > 1F yet so it's hard to judge. For me personal the safest way is the battery and I really don't want to risk to corrupt my raspbian when I'm on tour.

You are right that the energy is not lost, but he is not able to use all the energy stored on the capacitor. How much energy that can not be used depends on the minimum voltage the pi can run on, if a boost regulator is not used.

I do not necessarily mean that a super capacitor solution is bad, but it may not be much simlper or cheaper than using a battery, if you want a reliable solution.

I choose a battery mainly because I wanted to make a litium ion battery charger, which I had newer done before ;-)
  Reply
#27
(11-20-2017, 11:39 AM)shipahoy Wrote:
(11-20-2017, 11:23 AM)shark24 Wrote:
(11-20-2017, 10:46 AM)shipahoy Wrote: - He has no boost regulator, so he looses even more energy.

How can a boost regulator save energy? From my perspective the parts of it create resistance and therefore heat so energy is lost. Well not lost but it'll heat your boat instead of running your pi.

Not a big fan of the capacitor solution either but I didn't get my hands on anything > 1F yet so it's hard to judge. For me personal the safest way is the battery and I really don't want to risk to corrupt my raspbian when I'm on tour.

You are right that the energy is not lost, but he is not able to use all the energy stored on the capacitor. How much energy that can not be used depends on the minimum voltage the pi can run on, if a boost regulator is not used.

I do not necessarily mean that a super capacitor solution is bad, but it may not be much simlper or cheaper than using a battery, if you want a reliable solution.

I choose a battery mainly because I wanted to make a litium ion battery charger, which I had newer done before ;-)

You should take a look to the diypowerwalls forum : -₩)))

Gesendet von meinem SM-G900F mit Tapatalk
  Reply
#28
Hi to all on forum!


This is very interesting topic for me, because, some time ago I was looking for some kind module for automatic power ON/OFF and “UPS” for the Raspberry Pi for use in boat or car.


After some time of searching I decide to do it myself.

My request was:
  • no additional battery, only use the car/boat battery (12V)
  • no additional switch, only automatic power ON and power OFF with an ignition key
  • integrated DC/DC power supply for the Raspberry (5V)
  • same dimensions as a Raspberry Pi for easy mounting (on the bottom side)
and principle of working is:
  • power ON the Raspberry Pi after the ACC/IGNITION is ON for more than 30 seconds (default)
  • properly shutdown the Raspberry Pi after the ACC/IGNITION is OFF for more than 15 seconds (default)
  • power OFF the Raspberry Pi 30 seconds after shutdown start
  • auto cut-off built-in DC/DC step down power supply, so there is no standby current consumption
If this is interesting to someone I can put link here (if it is allowed) with some details of working principle, connection and pictures (I sell some rest of module on link), or you can ask here or on PM.
  Reply
#29
@marko_st: sounds interesting, pls provide more info. Don't think anyone will object if you post your link, as long as its relevant.
  Reply
#30
Hi,
link for explanation working principle and some pictures
https://www.tindie.com/products/picotouc...n-and-off/

Poslano sa mog Redmi Note 4 koristeći Tapatalk
  Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)