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Battery backup for power cut instead of generator

  • 11-10-2022 3:53pm
    Registered Users Posts: 23,076 ✭✭✭✭

    Is there any reasonable solution for battery backup for powercuts instead of going the generator route.

    Im not talking about fully automated installed battery system, more a diy isolated system that can be plugged into house via changeover switch so should be grid safe etc.

    So im talking about battery and invertor to run house basics for 5 hours or so. We would be looking to run 2 or 3 lights, tv, wifi, heat circulating pump and fridge.

    As a diy effort, what would be required in terms of batteries and invertor and would it be at all cost effective versus generator?

    We already have old style changeover switch installed to switch between grid and generator.


  • Moderators, Home & Garden Moderators Posts: 5,509 Mod ✭✭✭✭graememk

    Depends on how much you want to run.

    As you already have the changeover switch there.. you would know the limits of the generator. Same with any "battery generators"

    All comes down to budget. And knowing your limits..

    If you don't have solar ..

    You could get a ecoflow ,they are about 4k.

    Or something like this : (not a recommendation just a example)

    It can output 1200 w and has about 1kwh of storage.

  • Registered Users Posts: 21,000 ✭✭✭✭ELM327

    What connector has your generator to the house board? Is it a blue CEE plug? If so, get one for a battery generator?

  • Registered Users Posts: 23,076 ✭✭✭✭mickdw

    We have a big blue plug outside the house which was to connect generator to house and then the change over switch too.

  • Registered Users Posts: 21,000 ✭✭✭✭ELM327

    Ok so that's a 32A CEE plug. To use a battery generator (hate that term) you need one that has a 32A CEE output that you can plug in there

  • Registered Users Posts: 2,232 ✭✭✭waterwelly

    Powercuts are pretty rare, I'd say I've had one about every 10 years in a storm and the occasional scheduled outage where we get a notice in the door and can be prepared.

    I'm not really getting the idea of using power outages as a justification to invest in batteries etc., You won't be able to run showers, coolers or heating for long with the battery anyway.

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  • Registered Users Posts: 21,000 ✭✭✭✭ELM327

    Perhaps some people, myself included, are not willing to accept power outages and prep accordingly. I have 20kWh of batteries currently, pretty mad that I have hours and hours of "Base Load" covered in my batteries but the default is to switch off ?

  • Registered Users Posts: 12,000 ✭✭✭✭KCross

    would it be at all cost effective versus generator

    I dont think it would be, for you.

    You already have the wiring and the generator so the only cost you have left is the petrol that you burn for the few hours a few times a year that you need it. Its a miniscule cost going forward so why spend thousands on an isolated battery system.

    Batteries are relatively expensive and they are not designed to be sitting at 100% state of charge for months on end waiting for a power cut. In addition, any reasonable cost battery system you have wont come anywhere close in terms of available power relative to burning a few litres of petrol.

  • Registered Users Posts: 2,232 ✭✭✭waterwelly

    Well if you have the batteries you may as well use them.

    But spending thousands on batteries so you have electricity during a rare outage, is hardly worth it.

  • Registered Users Posts: 1,368 ✭✭✭DC999

    We had a power cut in Dublin 12 the other day. 1st one in 2.5 years of my WFH that I recall (or for more than a few mins). Was out for 80 mins. (ESB site) showed the fault affecting 1400 houses.

    That’s an 'uptime' of 99.994% (30mins downtime a year) 😊. In any cities you won’t claw the money back for adding that failover / redundancy. Assuming of course the outages stay at the same level as they do now.

    My new solution is to let my laptop battery charge all day long so battery is always full (up to now I had it to only charge at times). And I use 4G on phone for internet (which can charge from laptop battery if needed). Fill the flask in the morning for hot water + coffee during the day so could make coffee. I’ve still to dig out the little camping gas stove we've in the shed so could cook and heat with that in a pinch. Runs on the disposable gas bottles. Then we're sorted :)

    Camping stove and gas is maybe 50 quid (heat and cooking). And some sort of battery torch. And some power banks for mobile phone charging.

    Am not trying to be dismissive or divisive here. Just saying what is relevant for our house + family. Granted it's easier in the city for sure (as less outages). Or for older, more vulnerable people it’s more serious of course. Someone from Meath was telling me it’s a lot more common for them.

  • Moderators, Home & Garden Moderators Posts: 5,509 Mod ✭✭✭✭graememk

    Having some backup is nice even if it's just a power bank.

    OP has all the hard work done, and if they already have a generator, just stick with that.

    To be filling a flask every morning could get tedious though.

    Being up in the north west, I have often found bad weather doesn't really effect our power as much.

    Survival of the fittest maybe, often have high winds etc so the infrastructure is sort of "used " to it.

    Where as the places that don't get much wind a big storm takes a lot out.

    There was a massive upgrade of the power lines up here about 15 yrs ago now.. ESB didn't have to collect the old poles either, they were quickly claimed by the landowners. Not good enough for electric poles but will last a long time as gate posts.

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  • Registered Users Posts: 21,000 ✭✭✭✭ELM327

    Yes if you have the batteries but don't do anything else, you can't use them in an outage. You'd need some sort of changeover.

  • Registered Users Posts: 1,548 ✭✭✭victor8600

    I think it would make sense to have batteries changed from a solar cell array, and to use the power from the batteries as much as possible. This way batteries pay for themselves.

  • Registered Users Posts: 801 ✭✭✭Boardnashea

    If you're not interested in going the solar route, you could get a day/night meter, or bite the bullet and go for a smart meter and use the off peak charges to load up your batteries to use during the day when rates are significantly higher - load shifting. If you don't fully discharge your batteries you should be able to keep a basic level that would keep things going during a powercut.

  • Registered Users Posts: 12,000 ✭✭✭✭KCross

    Someone from Meath was telling me it’s a lot more common for them.

    Its a rural problem, primarily.

    Alot of city power infrastructure is underground or is shielded by buildings and has lots of redundancy built in where power can be diverted from other places if one sub station gets hit in some way.

    In rural scenarios you are alot more exposed to outages as there is little redundancy and everything is above ground in open fields and gets the brunt of all weather. We get power cuts of varying degrees most years. Anything from a few minutes to a day. "Beast from the East" had us out for 5 days!

    Rural folk also have the downside of their running water being driven by an electric pump in their own well, so once you lose power you lose running water so toilets become an issue! Again, not an issue for city dwellers, the water still runs when the power is out.

    After the 5 day outage a few years back I put in backup generator. I wasn't going to get caught with that again and I dont think the storms are going to stop anytime soon! 😀

    I'm all for backup generators in this scenario, but having a dedicated battery backup doesn't make any sense. Its not designed for this rural scenario.

  • Registered Users Posts: 1,368 ✭✭✭DC999

    Wow, 5 days of no power for the 'beast from the east' is very real + scary. Plus it was freezing cold at same time of course to add to it all!! Granted that was maybe 11 years ago, but was still a hard + scary time for many affected. Fair point that outside the city it needs more thought!

  • Registered Users Posts: 1,308 ✭✭✭denismc

    It depends where you live, we get 2-3 a year, and they can last for several hours.

    Most modern fridges are insulated enough to last several hours without electricity.

    With regards to power outages, some EVs, come with a V2L option which allows you to run some household appliances from your car, something to consider if changing car.

  • Registered Users Posts: 6,160 ✭✭✭Ubbquittious

    Ideally you'd have both. Batteries won't really fill much on a day like today. Small generators only last abou 500 hours before the engine is completely fcuked (no oil filter & other manufacturing shortcuts = short life) and also need a supply of fuel.

    Don't forget to fill your scullery with tinned/long life food or you will be one of those many people looking to turn electricity into food during the impending nuclear apocalypse

  • Registered Users Posts: 21,000 ✭✭✭✭ELM327

    I have a 7kVa diesel 3 phase generator, which has oil filters etc..

    As it's diesel I coudl run it on kerosene, agri, or any other lubricant - adding some white spirit to thin in winter.

    I'm turning into a real doomsday prepper in my old age. I've just ordered a stove top kettle and coffee pot!

  • Moderators, Home & Garden Moderators Posts: 5,509 Mod ✭✭✭✭graememk

    You could nearly run a combined heat and power from that? (Unless it's air-cooled!)

    Plumb the cooling from it though a coil in a buffer tank, hot water and power!

  • Registered Users Posts: 288 ✭✭JL555

    Not sure what you could get to plug into your blue socket. In my case, on the south coast when we get a storm I'm out for an average of 24hrs. I invested in solar power back up batteries. You can get them from a few hundred watts to about 2kw power storage. They're small and very handy to have. Can power TV, (better for a small TV not your big 55")- Modem (FTTH), lamps with LED bulbs, charge the laptop a few times, keep devices charged etc. I don't use them for much more than that, Freezer keeps the stuff ok for long enough, I have 2 stoves in the house, so can keep the family warm.

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  • Registered Users Posts: 23,076 ✭✭✭✭mickdw

    To clarify. I don't have a generator currently as it no longer works. That's why I'm looking at other options but doing my own research from the replies here, batteries don't appear to be at the races at all cost wise versus generator.

    The generator I had was very basic and wasn't suitable for fine electronics so maybe i should just invest in a good generator.

    I'm in rural mayo and get regular outages and am expecting alot more this winter.

  • Registered Users Posts: 21,000 ✭✭✭✭ELM327

    It's peak 7kva but I wouldnt want to run it at full tilt for hours. Plus it's not really off grid if you're running generators.

  • Moderators, Sports Moderators Posts: 18,470 Mod ✭✭✭✭slave1

    Cheapest option is a double socket off the EPS on inverter/battery pack and just run an extension lead to power my router, laptop, stove pump and mini-oven, not ideal but would keep me going with heat, internet access and be able to WFH.

    I also have a sine inverter I could hook up to either EV that would give an additional boost.

    This is not a comprehensive solution but by far the cheapest and most DIY

  • Registered Users Posts: 253 ✭✭SodiumCooled

    Interesting to come across this as I recently came across portable power stations (solar or mains charged battery packs) thanks to facebook advertising. I am currently building and adding a changeover switch is a definite.

    Like the OP I'd like to just be able to plug in at the change over switch rather than power off the sockets on it. This caught my eye for example

    Could one of these be rigged to plug into the change over switch (assuming heavy loads like heat pump etc were disabled (at the breaker) and just essentials like lights, fridge/freezer, internet, tv/work screens etc enabled?

    We also have a shed that has no power away from our house and with the cost of the standing charge + connection fee alone we are looking at ways to power it (lights for at most a few hours or less a few times a week in winter, power tools occasionally and if possible mobile BB and a security camera if power can be supplied at all times). Something like the link above looks ideal with a solar panel to charge as just the socket could be rigged to power a few led lights but to double up for use at the house being able to connect into the house would be very desirable rather than having a generator.

    Our area was without power for nearly two weeks a few years ago and power gone for a few hours or most of a day happens with enough regularity that I want to plan for it even if its a few hours once a year and I or my wife have an important work call etc its worth having.

    Post edited by SodiumCooled on

  • Registered Users Posts: 1,368 ✭✭✭DC999

    Hey, any chance you could send on the link to the sine inverter you bought to hook up to the EV? I did look before but got confused with options.

    And what else do you need for that? Crocodile clips to battery (or do they come with that?), and just a long extension reel then back into the house? I know you've to keep it under the max output of the sine inverter, which I would. Would get us out of a hole if it was down for many hours.

    How would you keep it somewhat waterproof? Could leave the sine inverter and plug for extension reel under the bonnet wrapped in something? There's no moving parts in the engine when it's stationery afaik so nothing to get caught

  • Registered Users Posts: 6,160 ✭✭✭Ubbquittious

    A lad in the boating forum bought one of those. You are paying a big premium for the portability & nice package

    Inverters quickly struggle with inductive loads like fridges. So if you had 2 come on at the same time or you have a bit of load on it already and a fridge tries to switch on it might conc.