Obs power via a battery(s) ?

[fwm891]

Hi,
I'm thinking about powering my observatory kit from rechargeable batteries and those recharged via solar panel(s) but before I jump in I'd like to hear some pro's and con's of running via batteries please.

I would be looking at running:
CEM60 standard mount
ASI 294MC Pro cooled camera + asi120mm not cooled
dew heaters (not got any yet but on this shopping list) 8 inch corrector largest optic to de-mist plus 80mm guider.
Laptop - dimmable screen and runs for 6+ hours on full charge

I currently run from 240 V mains power to the obs.

Francis

[Dr_Ju_ju]

A few thoughts :

Firstly you'll need to calculate the total expected current load for all devices, and those in the future, that will not only include the obvious devices, but also things like lighting, dehumidifiers ?, security, roof-openers etc.

Once you have it then you'll either double, treble or even quadruple the figure depending on how many days you expect to run without being able to charge the batteries. Being Solar charged you are very much prone to the vagaries of the weather, but this can be augmented with mains chargers, which then negates the purpose of the exercise .....  

Once you have your figure, you can then work out the number\type of batteries you require. These could either be deep cycle, lead acid or tracer type (with spares ?), but in any event you will need to then physically find space, securely and safely fit them, together with their charging\control system.

 

[Gina]

I thought about that at one stage but as I recall, worked out that it would need a large and expensive solar panel. 

[Gina]

Why bother if you have a perfectly adequate mains supply?  I have battery backup for power cuts which will run the gear for 6-8 hours.  This is just a standard small car battery of 45AH.  As astro imaging is mostly done during the autumn and winter the available light to run solar panels is rather limited.  It would take years to recoup the outlay for solar panels and deep cycle battery.

[Stu Todd]

So to hop in, how do you wire the batteries into the curcuit Gina, to make the continuous power supply? Does your equipment run off the battery which is connected to a mains charger or something like that?

[Gina]

Edited September 17, 2019 by Gina

[Dr_Ju_ju]

For continuous output, think Uninterruptable Power Supplies (https://www.electricneutron.com/theory/charging-methods-for-ups-batteries/)  but its not a cheap option.....

[Stu Todd]

Thanks for that.

So Gina, your mains to 13.8vdc inverter is wired directly to a switch, on to your battery terminals and onto the equipment supply board?

I'm after a UPS system and have seen similar, but via a charger to the battery. 

Edited September 17, 2019 by Stu Todd

[Gina]

Yes.  Well, via switches and fuses.

Edited September 17, 2019 by Gina

[Carbon Brush]

For what it is worth, here are my thoughts.

It costs a lot of money for solar panels, wind turbines, charge controllers and batteries.
The real world implementation of these is not as well established as the salesmen with their glossy flyers would have you believe.

Batteries have a limited life (particulalry lead acid) and high capital outlay (particularly lithium).

A mains cable is well established technology, not expensive and can outlive the owner.

The only sound arguments for a solar/wind/battery powered observatory are:

1/ A very low power requirement. In other words a simple goto mount. No dew heaters or anything else.

2/ The observatory is hundreds of metres away from a mains supply, making the cable run expensive.

3/ Being prepared for extensive mains power cuts that will remove light pollution at a stroke.

Just my thoughts... David.

 

Edited September 17, 2019 by Carbon Brush

[Moonshane]

I'm fitting an external male caravan connection to sockets inside my obs. Like this

I'll then connect to an external socket in the garden which is already there with a female connector and a standard plug. That way I can have power when I need it but it's cut off when I don't. The wire will be removed when not observing or using the building.

[Stu Todd]

@Carbon Brush yeah, I have always seen the same stuff, enough to be swept along so to speak.

No need to overthink things at all. Back to enjoying the stars, stress free.