💬 Single board computer UPS

[openhardware.io]

https://www.openhardware.io/view/570/Single-board-computer-UPS

[gohan]

Why the 2 batteries?

[kalina]

@gohan said in Raspberry UPS (external):

Why the 2 batteries?

Because each battery has own advantages and disadvantages. I see the next picture:

I think that UPS must support both battery types.

[mfalkvidd]

@kalina does it support connecting both batteries at the same time, giving the lipo priority since it is rechargeable? or does the user choose to connect only one of the batteries?

[kalina]

@mfalkvidd said in Raspberry UPS (external):

@kalina does it support connecting both batteries at the same time, giving the lipo priority since it is rechargeable? or does the user choose to connect only one of the batteries?

Yes, both batteries can be connected at the same time. This is allowed by circuit design - separate channels with MOSFET (see pic below).

One of the tasks is develop the algorithm of functioning (priority and so on ..)

[gohan]

@kalina I have missed the big one wasn't rechargeable

[kalina]

Today I have received a holder for DIN rail and i am trying to apply it for my enclosure now.

[giltesa]

Hello @kalina

It looks very good, but why do not I use a DIN rail box?

For example:
https://www.aliexpress.com/item/1-piece-87-60-52mm-din-rail-plastic-box-enclosure-junction-box-electronics-plastic-control-housing/32848666230.html

[kalina]

Hello @giltesa
I have been looking for an enclosure for this device long time. But i didn't find suitable DIN rail enclosure. At first looks like that this one is suitable, but later one of the sizes does not fit.

[kalina]

I have received pcb from PCBWAY today. 11 pcs were in the box instead 10
As always, quality is excellent for little money! In a few days I'll assembly the boards.

[alexsh1]

Interesting.
I am using one of these

http://pimodules.com/

It is an internal UPS (Hat on), very advanced, very small with multiple settings battery options.

[kalina]

@alexsh1
You share really great UPS! But in my case I need UPS for outdoor usage. I am going to use this UPS on temperature -20 C and lower. As for multiple settings, I put Atmega328p inside, so this UPS will be Arduino compatible and will have multiple settings too.

[kalina]

Some photos of soldered device...

[gohan]

did you hand soldered all those smd components?

[kalina]

@gohan Yes. This first board was soldered manually. But I use the services of soldering in general.

[giltesa]

@kalina
The PCB looks very good.
I thought you soldered the PCBs manually. Where do you order the assembly of PCBs? Price?

[kalina]

@giltesa I order boards assembly in Ukraine. This is a small company that develops and small-scale production of electronics. The price is very different and depends on many factors, such as quantity and size of components, number of devices, etc. All questions are discussed individually.

[kalina]

I tested this device yesterday and found some issues. Now, I want to share results.

1. The analog comparator circuit must be modified. AIN0 should left floating (unconnected) and to this pin need connect the internal 1.1V bandgap reference. The 5V_Fail signal must be connected to AIN1 pin.

2. VD7 must be removed and DC-DC will be works all time except power save mode.

3. Need to add the MOSFET for manage LiPo charger, because this IC interrupts accumulator detecting signal (this signal always near 4..5 volts).

4. Need to add the 5V (external) detecting signal to the microcontroller .

5. Many of the components values should be revised.

All these remarks will be taken into account in the new revision.

Everything else works perfectly!
For the first revision of the device, I'm completely satisfied with the result.

[kalina]

The second revision of "Raspberry UPS" which now called "Single borad computer UPS" was received yesterday from PCBWAY.com

[berkseo]

@kalina
Privet
Great work, I want it (rev2).

[kalina]

@berkseo Hello,
Thanks!
First of all I have to check hardware part, and then i am going to develop software. In my opinion, production will be start in a month. I'll share photos of the soldered device tomorrow.

[kalina]

First soldered device:

And a small test: