Zdobienie / Decoration

PERUN – mobile power bank for Astrophotography

Zdobienie / Decoration

PERUN – mobile power bank for Astrophotography

   You can find many different power banks on the market. Unfortunately, none of them met my personal expectations in terms of available power, mobility and small size. Especially in the context of the possibility of taking the power bank on board plane.

Perun - 3D model
Perun – 3D model

I’ve searched the Internet for known solutions. On the Astropolis forum I’ve found a thread, where one of the users developed a solution based on NP-F / FW / FM batteries and he had a working solution. This example inspired me how to construct my own better solution, better suited to my needs, based on the available batteries model: NP-F970.

   I decided to implement my vision from scratch and in a 3D software. I designed a prototype model, which I printed with my 3D printer.

   About 6 months passed from the idea to the implementation of the prototype, which was already able to handle my functional requirements. During this time, three copies were made. First two were suitable only for garbage. The third was what I expected and met my minimum requirements.

Perun - prototype
Perun – prototype with batteries full load

   For almost a year I’ve tested my prototype and noted in details the discovered defects, shortcomings as well as a huge amount of new ideas, for improvements and modifications for existing prototype. I used the prototype as I wanted, it traveled everywhere with me. I used it at PTMA astronomical meetings and on trips abroad. It worked in all conditions, from minus temperatures of around -10C degree to warm nights in the summer season and during the day when I watched the Sun. In humid and very dry climates. At an altitude of 1.5 km above sea level as well as at the seaside.

Perun - testing period
Perun during tests with below 0 C degree

It has never let me down, I have never run out of energy during my longest astrophotography nights in Namibia – 9-10 hours catching of light with my CMOS RGB camera.

It has proved its functionality and design itself in 100%.

After nearly 18 months from the idea on paper (I like to draw an idea on paper before I materialize it and it will see the light of day) to the end of the tests, time comes to make a new, better, more functional and user-friendly version of my mobile power bank.

This is how “Perun” was created, which I am pleased to present below.

PERUN - the body
PERUN – the body

Why “Perunname? It is the god of thunder and lightning of the ancient Slavic religion. The name reflects the nature of this project and a large amount of energy that has been accumulated in a really small volume of Perun.

Perun - Slavic god of thunder
Perun - Slavic god of lightning and thunder
Perun - ancient symbol
Perun - ancient symbol god of thunder and lightning

Let’s take a look to the topic a bit closer.

 

How PERUN was born

Purpose

  • Power source for selected devices in the field, without access to a permanent power source,

  • Possibility to take Perun on board the plane,

  • Using a Perun as a counterweight to the assembly with mount.

 

Specification

In use of 6x batteries, model: NP-F970can be bought in any photography and video equipment market.

NP-F970 - bottom view
NP-F970 – bottom view

Battery technical specifications for model NP-F970:

  • Lithium-ion battery,

  • 7.2 VDC voltage,

  • 8600mAh capacity,

  • Equipped with a chip, compatible with InfoLithium,

  • Standard warranty – 12 months,

  • Free from memory effect,

  • Requires an NP-F standard charger

NP-F - battery charger
NP-F – battery charger
  • Power summary with full load of six pcs: 371,5 Wh

 

Tested and proven devices in cooperation with PERUN

  • Lacerta MGen2 + kamera CCD (guider)

  • Omegon Pro CCD (guider camera)

  • CMOS ATIK Horizon RGB camera

  • ASI 2600MC Pro camera

  • Rasp Berry PI 4 (Astroberry)

  • Asi Air (with maximum power requirements 5A)

  • Asi Air Plus (with maximum power requirements 5A)

  • Parallactic mount CEM25p

  • Parallactic mount CEM26

  • Parallactic mount HEQ5

  • Parallactic mount NEQ6Pro

  • 2x USB heater

  • Power source for mobile phone

  • Power source for other mobile power banks charged with USB port

 

As a power bank:

  • Input current filtering

  • Filtering the output current

  • Over-voltage protection on power ports

  • Filtering out electromagnetic interference on power ports

  • Filtering out electrical noise on power ports

  • Dedicated power switch for each power port

  • Dedicated LED signaling of the power status of each port,

  • Possibility to take on board the plane

  • About 9-10 hours of continuous shooting

  • Perun itself is a counterweight to the devices mounted on the astronomical mount.

 

Electronics – Perun’s equipment

The power source are batteries with a voltage of 7.2 VDC each. Connected in parallel.

Perun - 3D model - present version
Perun – 3D model – present version

To obtain a voltage of 12VDC for powered astrophotography devices, it is necessary to use a DC → DC Step Up converter.

AsiAir – due to the high current requirements of 3.5A to 5A peak current, requires a dedicated converter with a dedicated power port. The additional Step UP converter is not installed in the standard configuration – an option to buy.

I assumed that Perun should be equipped with a converter with a maximum power of 6 A. This will fully satisfy the needs of most connected devices, which in a very short time they need a little more than 5A of supply current – e.g. during start-up.

PERUN - LED status active
PERUN – LED status active

Without load, the Step Up inverter generates no heat. It heats up slightly during load, therefore does not require active cooling.

Voltage has been set at the output of the Step Up converter to 12.9VDC

The Step Down converter 12VDC → USB 5VDC has two ports. USB ports can be load with a current of 3A, so you can power or charge any device powered by a USB port in an accelerated mode.

Perun has three 12VDC power ports. Each power port has a current protection of 6.3A. The Step Up converter is able to handle momentary currents greater than the nominal operating current. However, the Step Up inverter itself and the connected devices, must be protected against damage.

During operation, the voltage automatically drops to slightly more than 12 VDC, which the powered devices have the nominal voltage provided.

 

Included

Bodysix ports for a battery model: NP-F950 / 960/970, batteries with a charger must be purchased separately,

PERUN - the body
PERUN – the body

Two locks securing the batteries against uncontrolled sliding out of the port – in the case of reverse mounting on the counterweight rod.

PERUN - battery locks
PERUN – battery locks

Spare fuse

Spare fuse
Spare fuse

One dedicated power cord of the selected device (to be agreed), non-standard power plugs may require an additional fee,

PERUN - example pwr cord
PERUN – example pwr cord

Two plugs for power ports for self-use with self made power cord.

PERUN - pwr plugs
PERUN – pwr plugs

Two bolts locking the body on the counterweight rod,

PERUN - lock bolts
PERUN – lock bolts

Counterbalance rod diameter reducer for mounts equipped with a counterbalance rod diameter less than 19.9mm, e.g. mounts: EQ, HEQ, NEQ (tested).

PERUN - Rod adapter
PERUN – Rod adapter
PERUN - Rod adapter set
PERUN – Rod adapter set
 

Optional

Covers for batteries model: NP-F970, with an additional fee.

 

PERUN - Battery cover in use - example
PERUN - battery covers - example
PERUN - Battery cover - example
PERUN - battery covers - example

Comparison to other solutions

Alternative solution, no longer available (checked 06/11/2022) with non valid price: https://www.ioptron.com/product-p/8128.htm

Let’s compare

PowerWeightTM CW Battery – iOptron – has a maximum power of 96Wh with the price of 158 USD (old price from 2020, customs and vat tax excluded), which can be taken on board the plane.

In order to get the amount of required power comparable to what offer us a Perun, you need to purchase 4 pcs. PowerWeightTM CW Battery, which gives us cost:

4x96W = 384Wh, cost 4×158 USD = 632 USD Gross, price 1Wh = 1,65 USD Gross

Perun oraz PowerWeightTM CW Battery
Perun and PowerWeightTM CW Battery on one counterweight extended rod

4 pcs of PowerWeightTM CW Battery you can’t put as counterweight on the rod. Even if I use the counterbalance rod extension, we can fit a maximum of 2 pcs on it.

It only gives me half of the power I need to run my astrophotography setup, during the entire night (8 hours average of collecting lights).

PERUN – has maximum power 371.5Wh with price 347,26 USD Gross. Cost of 1Wh = 0,93 USD Gross

Perun volume shape, it takes less space than 1 pcs of PowerWeightTM CW Battery !

Therefore, it is possible to add one more Perun as a counterweight on rod, which will provide a total of 743Wh of power! If you could fit 3 pcs of Perun, you would have to change the Watt unit to kW! of power, on a piece of iron rod as a counterweight to my assembly.

Perun is an uncompromising and unrivaled solution that guarantees me a power reserve for use in the field without access to a permanent power source.

If you are interested in to buy PERUN, please contact me. The e-mail address you can found in the footer of the page. You can also contact me via Messenger.

 

ATTENTION! – the prices given are indicative (with high accuracy). The final price valuation may differ slightly due to the inflation increase in the prices of components needed to build PERUN and their availability or availability of replacements and local TAX applicable.

 

1.0 – 27.8.2022 – Public version

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