Power Supply with UPS

Posts: 19
Joined: Sun Aug 02, 2015 12:41 am

Power Supply with UPS

Postby iot » Sun Aug 02, 2015 1:10 am

Hello guys,
Thanks for this nice UniPi-board (v1.1).

Question: If there is a power loss we would only power the RPi2 with UPS, not the UniPi and not the 4AO-extension.Therefore J1 is opened. Are there problems for the RPi if it is the only part which is powered (overload on RPi...) by a mini-UPS? Because power loss will stop all pumps and mixers it wouldn't make sense to backup UniPi too.
On the UniPi we find out, that +5V is going directly to the relays. So if the 5V fail due to power loss, no relay (with 80mA current @5V = 0,4W/relay) would work. At the manual you can find the hint, that powering the UniPi only with RPi isn't recommended. We think, it's meant with closed J1, power on the Pi and no power on the UniPi, right?

What about this scene?
Do you have expieriences? Should we really power RPi and UniPi on different times (with opened J1)? Is this state possible if RPi powers down with the "halt"-command?

Thanks for answering
With best regards
Site Admin
Posts: 298
Joined: Wed Oct 29, 2014 9:56 am

Re: Power Supply with UPS

Postby tomas_hora » Mon Aug 03, 2015 2:03 pm


it should cause no troubles to UniPi or RPi. By removing the pwr from UniPi the relays would turn off and also the I2C ICs. The only think that will keep working will be the digital inputs.

Posts: 19
Joined: Sun Aug 02, 2015 12:41 am

Re: Power Supply with UPS

Postby iot » Mon Oct 19, 2015 10:28 pm

after weeks of testing we now have finished a stable RPi2-System with mSATA-SSD (120GB) on a USB to mSATA-converter and a really unexpensive UPS / USV with open source software. Now we are ready for programming, because hardware works absolutely stable (no SD-Card problems, no fear about power fails).
The UPS with 6Ah gives power for about 3,5 hours (very conservative) and will soft shutdown after this time. When power comes up it starts automaticly and a small script restarts the EVOK-daemon for reusing the UniPi. For more details look @ the UPS-software.

We choosed a divided powering:
a) RPi2 + USB/mSATA-conv. + 120GB -Intel-mSATA-SSD (in summary max. 3,5W => UPS protected)
b) UniPi + 4-AO 0-10V extension (power usage depends on your devices => not UPS protected)

The main problem was finding a suitable Powerbank. We ended with "Tecknet iEP360 with 6.000mAh". Also an "Easyacc U-Bright 9.000mAh" should work. The clou is the software, which you can find here (very difficult to find) - many thanks to this guy!!!:
The powerbank is driven by the powerful DR15-5 power source from Meanwell (You can buy it on UniPi - thanks for that.)

Here are some snapshots of our UPS-system which should drive a heat pump in future. It is mounted on top of a "4-AO 0-10V extension" because of less space in case. Therefore we used a small selfmade adapter of wood (safes the money for a good 3D-printer :-) and fixed it with 1 cable tie.

Here are some snapshots:
https://drive.google.com/open?id=0B6lNU ... 09TUW5haTg
https://drive.google.com/open?id=0B6lNU ... 2NpVm9iWTg
https://drive.google.com/open?id=0B6lNU ... jZmNVFHczg

Hope it will help and many thanks to the UniPi-team for creating this "superboard" and all the useful 1-wire extensions. Nevertheless we will post some optimizing features for the next version of UniPi to make it the first choice on the market.

with best regards

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