Power Tank Project

[kz1bob]

Hi All,

I am thinking about a project to build a power tank. Here is my schematic. I can get most of the components off Amazon and the rest from eBay (when finished I will post my shopping list). The cost, including battery and waterproof case, comes in around £90.

My question, for those of you smarter than me, would this be 'safe' to use to power an AZ EQ-5 GT mount and the rest of my gear (GPCAM, Hypercam 178M, dew control system (future addition))? Or, do I need to build in more safety (fuse box for each component)?

The wiring will be 12 gauge, the push in connectors are rated to 24a, and the battery is a sealed Yuasa (though I will be speaking with the battery people to ensure I am using the proper one).

Appreciate any advice/comments.

 

[vlaiv]

I don't really get this diagram (sorry ) - what are those 3/4 port things?.

I was also contemplating my own power tank project, and this is what I roughly came up with, so it might be of interest. My power requirements are as follows (it is imaging rig):

- HEQ5 mount - 12V max 2A, around 1A average in regular use

- 2x Cooling for cameras (If I ever get to point of using dual scope setup) - so it is x2 12V, max 2A, I would say around 1.5A average in regular use (that would actually depend on temperature outside).

- Laptop backup power, that one I would put at max 5A 12V - I think it would be around 3A average, for 5h (3h would be covered with internal battery).

- USB3.0 powered hub, not sure how much current that would need, but let's say it is also rated at 2A, 5V, around 1A average

I plan to run my rig for up to 8h (not fully drawing power, first 2h would be setup, so polar align, building sky model, guiding calibration, etc, but let's design for 8h straight).

So if we add up the numbers:

8Ah for mount, 24Ah for camera cooling, 15Ah for laptop backup power, around 4Ah for USB with 90% step down efficiency.

That gives around 50Ah, so I'll be using 60Ah deep cycle battery. Let's assume that all things can peak at the same time, that would be something like 15-16A, so any battery with 1C rating (or any battery with >0.5C) will be able to provide it.

Parts list would be:

- circuitry box holding everything (will be mounted on a side of battery), battery connector cables

- 20A main fuse, main switch (maybe power on led, or I will choose switch that already has signal light built in).

- Analogue voltmeter to monitor battery state

- 4x cigarette connector (female), 3 will have 2A rating, so probably 3A fuse on each, one will have 5A rating so I'll probably go with 5A fuse there (it might blow out in regular use, if that happens, I'll probably bump it to 6A, but it is not critical if it blows since that is laptop backup power - laptop should be able to run on last few percent of internal battery if I need to replace the fuse).

- 12-5 DC/DC step down converted, and some sort of 5V plug (it will probably be a simple one like 5.5mm jack, or maybe USB type so I can use it to charge the phone, but that power plug will be used for USB hub and that can be used to charge the phone)

My only concern is if power plugs for mount and cooling need to be regulated. I know that laptop will have power regulation in car charger device that will be used with this power bank, and 5V will be regulated with step down module.

 

[kz1bob]

Thanks for the feedback Vlaiv. The 3/4 port things are push in connectors for connecting everything up. I could just as easily wire directly to each component. 

I will work up all the power requirements for each component. This was really helpful. 

[RayD]

Definitely fuse each of the outputs.

It's worth doing a forum search as a number of people, me included, have made their own power/battery box, and there is a lot of really good and useful information.  There are also some good images which may help you to choose how you want it to look.

Look forward to seeing it completed.

[fozzybear]

Hi I use one of these to distribute my power output needs and only £11.67 and comes with a USB output as well, you can change the blade fuses on the rear to what ever you want/need just a thought

https://hobbyking.com/en_us/hobbyking-powerstrip-fuse-protected-power-distribution-board.html?wrh_pdp=1

Regards

[Susaron]

Hi there,

I also have an AZEQ5, think that this mount is power hungry, so the amp rate goes from 2A to 3A. It is best to add a step-up converter to stabilize the output voltaje around 13.5V so the amperage received by the mount is around 2.4A-2.5A in the fastest slews.

I am in the process of finishing my own power bank, in my case I have set up two lighter outputs, both fused, one is for the mount, so previous to the fuse I had inserted the step-up converter. The other one will be for the QHY cooled. An aditional output through a XT60 connector will go to a DIY power distributor I have made to fed up the Arduino focuser, the dew controller, the usb hub and an additional mini-PC, so the distributor will have one input through the XT60 and 4 fused outputs, all with AWG18.

I did use for the main tracks and for the distributor AWG12 wires as they can handle up to 10A, the lighter outputs will be wired with AWG16 wires.

The total power, voltage and amperage is monitorized through a Turnigy Watt meter.

I add some pictures of my PCB distribution unit.

You have to think on the total Amps you will have to handle to choose correctly your wires and connectors.

https://www.volumerate.com/product/iztoss-waterproof-cigarette-lighter-power-sockets-red-voltmeter-451411?utm_source=vr&utm_medium=alsosee&utm_campaign=product

 

[Sunshine]

On 2018-03-17 at 17:41, fozzybear said:

Hi I use one of these to distribute my power output needs

Good that its working well for you, being an RC plane pilot i have purchased many things from hobby king, kind of a crap shoot sometimes with batteries especially as some are duds. i just finished a little project powering my LX200 with a Lipo battery that fits in a pocket but powers my scope like a dream so far, posted results here under DIY astronomer also. 

[Susaron]

Everything in place.