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Power cut backup?

RPackman

Member
Joined
1 May 2021
Messages
60
Location
Oxford
Hi all,

Having had a recent power cut of several hours and having to abandon my tanks to the clueless but well meaning family to sort out, and working long shifts away from home, the news of further potential power cuts and brown outs has me thinking about this again. There have also been several short power cuts if the oven clock is anything to go by, but no idea how long they were. I’d like to have an automatic back up, I’m assuming with something like a car battery and inverter like my friend has on their sailing boat, but I am completely clueless about this. Is anyone able to point me in the right direction for advice/how to guides! A quick look either seems to be over my head or not detailed enough to follow.

I’d be looking at something that could live with the tank and take over automatically if there was a power cut, keep charging the rest of time (without using too much power - £!). I am out of the house for 14-15hrs a day/night and worried about missing one!
 
What do you want to keep going during an outage? The more equipments you need to keep going the more expensive it gets. A cheaper battery backup wont deliver much in terms of run time, but it's by far the easiest to implement and can possibly keep basic filtration going for several hours.

Cheers,
Michael
 
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Hi,
You first need to establish what wattage your tank is using, eg heater, pumps etc, but excluding lighting which do not need to be run on backup.
Easiest way is to use a power meter, but if you add up all the devices wattages manually and say divide the heaters wattage by 4 , you will get a rough guide.
That will then give you some idea of what battery power is needed. Ideally use Leisure batteries designed for such use , not Car ones.
 
It's not looking to good as far as winter (UK)is concerned ,there may be power cuts and the powers that be won't admit . The best thing is try to keep you aquarium room as warm as possible keep the heat in. Curtains drawn ,door seals, the good tip from
@dw1305 polystyrene or similar around 3 sides of the aquarium if possible . A case of maintaining the warmth ,hoping for a mild winter
 
Thanks for your replies.

I would want to keep my 2 filters going definitely. At max that would be 50w according to the internet (my Eheim pro5 seems to have a variable wattage). If I wanted to include the heater that is 210w extra.

I’ve done some research and it looks like I need something like this, but I don’t understand how the inverter would come on automatically if there was a power cut, and turn off when the power comes back on, and that is what I need. Does all power run through the battery/inverter at all times (so probably quite wasteful of power) or does it somehow come on when the power is off? Is anyone able to help me understand this?

I also struggle to figure out what size of inverter I would want.
 

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I also struggle to figure out what size of inverter I would want.

Not an easy question to answer. Ultimately you are wishing to go DC to AC with all the inefficiency involved.

BRStv Investigates ran some testing:

 
I’m still considering a manual backup system at the moment. The reason for this is that I might decide to use it with a variety of equipment.
I’m looking at a a 1000w pure sine wave inverter and a 12V 100-120 Ah Deep Cycle AGM battery. I already have a suitable charger for the battery.
 
I'm not very electronically minded but could you wire in a relay

So under mains power ON you'd have:
Battery charger on > battery charging > open relay switch powered by mains, switching battery output off.

Under mains power OFF the relay would close and you'd have:
Battery charger off because no mains supply > battery > closed relay switch turning on battery output.

That way there's nothing to do when power is off or on. The relay will either be open or closed depending on if it's getting a source of mains power.
 
I’d like something simple and flexible. I doubt they’ll be cutting the power overnight as they’d not gain much by doing that. I think it more likely I’ll be around at the time and I’d like the flexibility of plugging in what I want as I need it. I read online the likelihood of power cuts this winter has increased from about 4% to nearly 12% so it’s something to consider. If they stick to the suggested 3 hours at a time it won’t be too bad I suppose, unless your mobile devices need charging or you want to turn the heating on.
This looks quite easy simple.
 
What you need, if your battery pack/UPS doesn't support switch over is one of these.

Automatic Power Transfer Switch

These automatically switch to battery power if the mains in fails. More importantly they prevent back feeding of your battery fed mains back into the incoming supply which as well as being extremely dangerous (for electricity company employees who think power is off) is also illegal.

Personally I would not trust too much these Amazon ones and get a reputable make from a reputable supplier, as safety is a major concern here.

Also when working on these, be very very careful as you may think mains is off BUT these things could/can switch mains back on when you are least expecting it.

These are used a lot to switch in generators/solar cells/batteries when in coming mains fails.
 
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