Back up generator advice

[SteamyTea]

5 minutes ago, Iceverge said:

I very much doubt it. 

Question:

Is this pure or modified sine wave?

Answer:

Its modified sine wave. I had to return it as my microwave really didn't like the output
By S R. on 07 July 2020

[Iceverge]

Yes, it's like driving on square wheels I've seen in some comment somewhere. 

[markocosic]

Ouch!

 

Dumb resistive loads? They're fine on anything. Incandescent lamps. Kettles.

 

Switch mode power supplies? They're fine on anything.  (Including DC!) Phone chargers. Computers. Inverter driven motors. That's new fridges for example. Most stuff that's rated for 110/230V is this type.

 

Motors and transformers with lots of iron in them? They don't like modified sine wave (and will run hotter) but can survive. Basic microwaves in this category. Old school fridges included.

 

Choppers? (stuff with semiconductors that switches frequently to control power) They won't like modified sine. Induction hob and speed controlled motors in this category. 

 

Chinesium power supplies? Iffy. Some particularly cheap kit uses things like capacitor resistor droppers that are highly sensitive to anything other than perfection. 

 

 

I hadn't imagined that you'd try to cook on an inverter. Waaay ambitious and over 1 kW. Camping stove for that.

 

The backup power is really for lights, fridge, internets, compute, ventilation

 

 

Cheap LEDs blowing up is a new one on me though. Apologies if this experiment just cost you some fixtures.

 

These probably have "resistor capacitor dropper" power supplies in them. These act as filters to drop a pass a certain power at 50Hz frequency. At higher frequencies they pass more power. Square waves are made of frequencies from the base 50Hz up to "infinity". As you load up a cheapo inverter the waveform becomes more and more square as its power electronics and capacitors can't sustain the modified sine wave. (especially as the input voltage drops which it absolutely will with just 8mm cable at 12V) That'll push more power through these power supplies and overdrive your LEDs these will get dimmer and smellier as they heat up. Hopefully they're not terminally cooked!

 

Suggest not going over 1 kW at 12V and if so only on a "2 kW" + rated inverter unless a decent brand.

 

Xantrex are decent.

 

These probably decent:

https://midsummerenergy.co.uk/buy/sine-wave-inverters 

 

Haven't tried anything like this but as a charger and a potential PV input device for a shed / outbuilding they may make some sense:

https://www.photonicuniverse.com/en/catalog/full/452-Iconica-1000W-12V-hybrid-pure-sine-wave-inverter-with-40A-MPPT-solar-controller-and-20A-mains-charger.html

 

 

 

[Iceverge]

I think it was 16mm2 about 8mm diameter for the DC cables. The whole experiment lasted about 5 minutes so no notable heat appeared in them. 

 

It's all beginning to make more sense. Thanks for your explanations.  As far as I know everything survived to fight another day.  It may have been my Mrs laptops power supply that made the burning smell in the other room come to think of it. 

 

1 hour ago, markocosic said:

I hadn't imagined that you'd try to cook on an inverter.

I was just wondering what would happen, hence the kettle too. Perhaps an ill thought out plan.  

 

I much prefer the idea of just backing the car in bedside the change over switch and plugging in an Anderson connector. It's much cleaner and I'm pretty sure more fool proof than trying to get a small petrol generator going. Especially for the rest of the family if I'm not around on a dark and stormy night.   

 

However the trouble with buying a proper reputable pure sine wave generator is that they cost almost as much as a stand alone generator with greater advertised continuous load. The most reasonable I've been able to find one for sale in Ireland is pictured below.  Would a simple 2800w AVR cheapo generator be more useful considering it might do our heating (1kw) too. Would it avoid all the funny business with the inverter? 

 

 

 

The items we have to power 24/7 are the following. 

 

1. An electric fence energiser (50w) to prevent our beasties from escaping.

2. A borehole pump. Not sure of the power requirement of this, worst case 700w intermittent. 

3.  Internal lights, mostly LED's, say 150w total max. 

4. 2 x laptops (90w each) 

5. A TV (60W) to which we have handed over the duty of rearing our children! 

6. Mobile phone chargers (10watts) 

7. Internet router (5 watts) 

8. MVHR (40 watts) 

9. Fridge about 125W? 

 

Nothing hectic overall. Well below 1000w on average.

 

We plan on getting solar at some stage and maybe a battery. Maybe this could be integrated. Now my head is becoming fried and disappointingly the mains power is still on despite our neighbours being in total darkness. 

 

I'll give more thought to it in the morning! 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Edited December 8, 2021 by Iceverge

[JohnMo]

Been following this topic with interest.

 

So if I purchased one of these.

 

https://www.photonicuniverse.com/en/catalog/full/452-Iconica-1000W-12V-hybrid-pure-sine-wave-inverter-with-40A-MPPT-solar-controller-and-20A-mains-charger.html

 

Some solar panels and batteries.

 

Configured it to charge batteries by utility and/or solar.

 

So when I get a power cut, I switch main breaker for supply to house and other large loads.

 

From there how do I get to use the battery power and also if I wanted to connect a car to keep charge in the batteries, do I just connect to batteries as you would if jump starting a car?

[ToughButterCup]

From memory @Jeremy Harris has written about this issue in some detail (link to follow if I can find it)

In summary: don't worry about the issue: the average outage is less than four hours, so go and eat out, dig out the camping stove if you like, and put another dog on the bed if you are cold. The vast majority of us will not suffer greatly, so there isn't a good business case for the necessary investment in infrastructure.

 

I sympathise greatly with those who have suffered recently, my heart goes out to them. 

This (below) isn't the post I was thinking of , but its close enough

 

 

Edited December 8, 2021 by ToughButterCup

[SteamyTea]

39 minutes ago, JohnMo said:

So if I purchased one of these.

That looks a good bit of kit.

Assuming it can take around a kW of PV added to it, as an inverter it is not stupidly expensive.

[epsilonGreedy]

On 30/11/2021 at 07:51, SteamyTea said:

There is a 130 Ah on on ebay for 77 quid.

 

 

A word of warning about high loads on a lead acid battery. A draw of 20% of headline capacity is considered to be a high load. Also the effective capacity of a lead acid battery is about 50% of what is says on the tin.

 

Given 10% loss at the inverter that eBay battery would contribute ( 130Ah x 0.2 ) x 0.9 x 12  =   280 watts for 2.5 hours to the house. Subject to that sort of duty cycle it would fail far sooner than you expect.

 

Battery based mains power is now feasible with Lithium batteries and live aboard boaters will spend £10,000 on this type of setup. Their battery banks are typically over 1000Ah. 

[epsilonGreedy]

51 minutes ago, JohnMo said:

From there how do I get to use the battery power and also if I wanted to connect a car to keep charge in the batteries, do I just connect to batteries as you would if jump starting a car?

 

 

Don't do it unless you think multi hour power cuts will be a monthly event.

 

Drawing 1000 watts from a battery bank requires seriously thick cables and special connection clamps. You will need 300 to 500 amp hours of battery capacity for a working winter solution to cover a 3 hour power cut and best buy a low power kettle as well. If you cannot afford to buy a lithium battery bank the array of lead acid batteries will need to be in a vented housing. The batteries will need topping up with electrolyte and will consume power to maintain a full state of charge.

 

1000's of people have thought their way through this off grid challenge, most buy a 1 to 2 Kw generator for occasional use or spend £10K on a lithium + PV solution. A few die hard survivalists types build a large lead acid battery room coupled to a high quality Victron type inverter.

 

The notion that a UK household can get through a > 30 minute winter power cut by hooking up cheap batteries via jump start cables to a 2Kw cheap inverter is just plain daft.

[SteamyTea]

https://uk.renogy.com/12v-100ah-smart-lithium-iron-phosphate-battery-pre-order/

 

If you have a spare grand for a couple of them.

Edited December 8, 2021 by SteamyTea

[Iceverge]

7 hours ago, ToughButterCup said:

 the average outage is less than four hours

 

But my livestock would be over the hills and far away at that stage! Also unfortunately/fortunately they aren't allow in the pub so need borehole water to quench their thirst. 

 

Being rural, during hurricane ophelia we were without power for a almost two weeks. My parents were 16 days. 

 

6 hours ago, epsilonGreedy said:

The notion that a UK household can get through a > 30 minute winter power cut by hooking up cheap batteries via jump start cables to a 2Kw cheap inverter is just plain daft

 

 I don't think people are aiming for the whole Banana here with electrical consumption, and as you stated and I proved yesterday it's completely impractical to heat stuff with a car battery and inverter. 

 

However running low wattage essentials seems to work ok. 

 

I dismantled the cheapo inverter from my Skoda today, attached it to ye olde tractor and plugged it into the electric fence energiser. 

 

After finding all the moomoos and cajoling them back to their designated grazing area I assessed the electric fence using the "stand on one leg and grab it really tight" method. 

 

It plused away at its regular 60 or so Hz but wierdly about one in 7 pluses disappeared. Not precisely 7 though, sometimes maybe only one in as many as 13. For periods the pluses were of regular strength then occasionally stronger and sometimes progressively weaker.  Very unusual. 

 

Anyway I turned off the tractor after about 15mins and restarted 3hrs later with no issues to recharge the battery. That was about lunchtime. I might stroll over and have a look again later. I have a multimeter somewhere so I can look at the battery voltage before and after. 

 

I'm coming to the idea a pure sine wave inverter and a leisure battery may work very well. 

 

I'll keep updates coming on this voyage of electrical discovery. 

 

 

 

[JohnMo]

We are blacked out, been an hour so far.  Fourth in 4 days.

 

So back to my question

7 hours ago, JohnMo said:

Been following this topic with interest.

 

So if I purchased one of these.

 

https://www.photonicuniverse.com/en/catalog/full/452-Iconica-1000W-12V-hybrid-pure-sine-wave-inverter-with-40A-MPPT-solar-controller-and-20A-mains-charger.html

 

Some solar panels and batteries.

 

Configured it to charge batteries by utility and/or solar.

 

So when I get a power cut, I switch main breaker for supply to house and other large loads.

 

From there how do I get to use the battery power and also if I wanted to connect a car to keep charge in the batteries, do I just connect to batteries as you would if jump starting a car?

 It would be great to have a few lights on and a water lift pump that worked, so we had water etc.

 

Not looking to put on the immersion heater, or kettle, etc, hence the 1kW.  Possibly AGM batteries

 

Not looking to power whole house from batteries or PV, just charge the batteries when the sun is out and if required hook up the van to charge the batteries when there is a power cut.

[TonyT]

Fit the changeover switch.

 

with it you can then power the house it via generator or inverter..

[Bozza]

Thanks everyone for the replies and ideas.  A few boffins amongst you for sure   If budget was unlimited there’s lots of great solutions, some which would put me well off grid.  I did look into the car battery / invertor issue, only problem with that being if the cars are not at home

 

Something that interests me is the idea of battery storage but the costs seem prohibitive - £thousands. That said I was wondering about linking car batteries, on mains charge, and utilising an invertor (I have a suitable outbuilding).  To keep me going until I need to use a genny, to run the essentials.    Any thoughts on that as a solution?  
 

I suppose it comes down to risk and returns of any financial outlay.  Anything over a grand just probably isn’t worth it.   As I live ten mins from the city so plenty of cheap hotels, even factoring cost of freezer contents.  
 

 

[epsilonGreedy]

13 minutes ago, Bozza said:

 

Something that interests me is the idea of battery storage but the costs seem prohibitive - £thousands. 
 

 

The raw numbers are sobering when you dig into the details. For example that 130Ah battery mentioned earlier would weigh around 50kg and would hopefully come with carrying handles. Despite its mass it could only deliver about 0.7 of a kWh in total to a home before it requires a deep recharge.

 

During a winter evening a home could easily be consuming 5kW of electricity per hour if heated with an ASHP. Just makes me realise how much energy each house draws from the grid when 24 hour of grid consumption is converted into car batteries, off the top of my head I think we are talking around 120 car batteries to keep a house powered and warm up for a day.

 

26 minutes ago, Bozza said:

I suppose it comes down to risk and returns of any financial outlay.  Anything over a grand just probably isn’t worth it.   As I live ten mins from the city so plenty of cheap hotels, even factoring cost of freezer contents.  
 

 

It helps to define the problem that an offgrid solution will solve.

 

The subject that interests me is national grid instability (energy security) in the mid 2020s. The problem definition that I will design for is scheduled area blackouts of 4 hours on 2 to 3 days each year when the UK cannot generate enough electricity because of a global shortage of natural gas combined with little wind across the UK, the loss of half our present nuclear capacity and the dismantling of our last few GWs of coal power..

 

I have a 900w suitcase generator left over from my boating days, for the minimal effort of fitting a master switch to isolate the house from the grid and running an armoured cabled from the consumer unit to a remote corner of the garden I will be able to keep the lights on for about £5 per blackout.

[SteamyTea]

37 minutes ago, Bozza said:

car battery

Not car batteries.

They are designed to deliver huge amounts of power over a very short time frame.

Nickel iron may be a suitable option.

But which ever way you cut it, no option is going to be cheap.

[epsilonGreedy]

3 minutes ago, SteamyTea said:

Not car batteries.

They are designed to deliver huge amounts of power over a very short time frame.

 

 

That's true, car batteries have multiple thin plates to deliver high starter motor amps.

 

I used the size, weight and typical amp hour capacity of a car battery because it is familiar unit of measure to most here.

[SteamyTea]

Man makes his own lithium ion battery pack with a BMS.

 

 

[Bozza]

Sooner than expected we experienced another 24 hr power cut due to storms.  My newly purchased wee inverter generator performed perfectly for our needs.  Having gone down a rather simplistic and cost effective route of running extension cables around the house to the required appliances,, this required the power lead from the generator coming through an open window, which is not ideal in a storm.  So what I would like to do is to have an exterior hook up socket to supply a dedicated internal socket entirely independent of the house circuits.  Though there are plenty of industrial wall mounted sockets, I’d much prefer to have some sort of waterproof enclosure but these are designed for standard external sockets and I cannot identify anything suitable.  I did briefly consider utilising a standard enclosed external socket and running a cable from genny to it, with male three pin plugs both ends but I’m pretty sure that’s unsafe in many ways.   I’ve seen caravan style hook up sockets with flaps, but unsure if that’s suitable in stormy rainy conditions as they don’t seem to create a watertight seal.   Any suggestions / knowledge very welcome.

 

 

 

 

 

 

Edited January 30, 2022 by Bozza

[joe90]

Yes I was thinking “caravan hook up socket/plug, you could always build a small enclosure to keep the worst off it.https://www.screwfix.com/p/abb-16a-2p-e-surface-socket-250v/1858F?tc=SB6&ds_kid=92700055281954493&ds_rl=1249401&gclid=EAIaIQobChMIwO_JkI3a9QIV5ejtCh3FpgCeEAQYASABEgKXavD_BwE&gclsrc=aw.ds

[TonyT]

I have this

https://www.tlc-direct.co.uk/Products/CGM125CS.html

 

with a 230 volt commando plug in the garage

 

generator plugs into this and sits outside garage

 

1.9kW generator powers whole house, sensible loads only

[Bozza]

Thanks chaps