Investigating Lithium battery generators

[Benjahmin]

Given the increasing possibility of power outages this winter, and possibly beyond, I have decided to start looking at some sort of power backup so I don't loose all the lovely garden produce I've managed to freeze this summer.
Firstly, I'm aware that these things are mis-named in that they are not generators at all but storage devices that can be charged from mains, solar, 12v or, indeed, a generator.
My aim would be to have something that can run two freezers and maybe a light. Also something that can be taken in the camper to run the cool box and maybe charge a bike.
So need to get some maths on the go to calculate needed storage capacity, inverter output and sensible solar array in case of long term rolling blackouts (yes, I lived through the 70's).
Annoying thing is, I have solar on the house but, of course, they will not work during power outages as they don't get an AC signal.

Hope some of you will join me in this hunt and help to trawl through the confusing specs to find a quality product.
Going to the oracle google now to see what I can turn up in an initial foray - see you on the other side !

 

[guerney]

I never knew you grew veg @Benjahmin - Fantastic! Not many on this forum, I think... In previous years, I've only every grown pumpkins because:

1. After growing to about 8 inches in height, their growth can accelerates to outgrow weeds at a rate of 6 inches a day. After that they climb over anything in their path, up to 20ft in all directions but downward. One can grow them vertically, like runner beans.

2. They keep for up to 11 months without refrigeration, if kept in the cool dry dark. I ate some of the last edible pumpkin from my 2021 crop 3 weeks ago, then froze the rest because there was another... but wasn't in time to eat the absolute final one which rotted

It's been a right struggle this year keeping everything watered. My tally will be half for pumpkins, despite all my watering efforts. If this happens next year, I'll start growing prickly pear cactii fruits! I'm on the verge of buying seeds.

This year I've grown a year's supply of fresh herbs, which I've ground using a hand cranked meat grinder and frozen. Also some caulis. Damsons I'm ripening and chomping through - no need to freeze those, or the blackcurrants or Marshmello "Da Von Trooo Straw Bereeeeee!", according to celebrity Chef Raymond Blanc, and he's right! Juicy, soft and wonderful strawberry flavour. They taste more like strawberries than any supermakerket strawberry I've eaten. The best I've ever tasted. Unlike others, Marshmellos produce in two batches, one in June and the other is starting now. Supermarket varieties are selected for long shelf-life, not flavour. And wild strawberries, which also taste fantastic, and produce all year round.

Completely fill freezers. If the freezer is completely full, interior temperature won't increase too much 8 hours or so after power loss imho. Particularly if the space the freezer occupies isn't heated. I may keep it simple and buy a small petrol generator, before power outages happen and there's a rush.

 

[Benjahmin]

Been an epic year for runner beans. Cauli's have been good, just in the process of turning some lovely red cabbages into sauerkraut.

So, back on topic.
I have a tall fridge freezer and a small cube worktop one.
I'm assuming 400w for the big one and 200w for the small (maybe ott but it is old).
So, if both are running, that's 600w. I'm also assuming that they run for 50% of the time.
This is where my maths gets a bit sketchy. Am I right in thinking that this would be 300w/hour, so giving a figure of 7.2kw/h in a 24 hour period. Jeez ! Seems a bit large - am I over assuming or is my maths wrong?

 

[flecc]

This is where my maths gets a bit sketchy. Am I right in thinking that this would be 300w/hour, so giving a figure of 7.2kw/h in a 24 hour period. Jeez ! Seems a bit large - am I over assuming or is my maths wrong?

Sorry no figures, but I'd be surprised if freezers ran 50% of the time, even over 20%. You could use one of the 13 amp plug in current monitoring devices like this one to see what you actually use on each one over time.

Also since you lived through the seventies, you'll remember the two hour programmed regular cut offs of power. I'm sure they'll do the same if major cuts become necessary, meaning emergency freezer supply wouldn't be necessary.
.

 

[jonathan.agnew]

I never knew you grew veg @Benjahmin - Fantastic! Not many on this forum, I think... In previous years, I've only every grown pumpkins because:

1. After growing to about 8 inches in height, their growth can accelerates to outgrow at a rate of 6 inches a day. After that they climb over anything in their path, up to 20ft in all directions but downward. One can grow them vertically, like runner beans.

2. They keep for up to 11 months without refrigeration, if kept in the cool dry dark. I ate some of the last edible pumpkin from my 2021 crop 3 weeks ago, then froze the rest because there was another... but wasn't in time to eat the absolute final one which rotted

It's been a right struggle this year keeping everything watered. My tally will be half for pumpkins, despite all my watering efforts. If this happens next year, I'll start growing prickly pear cactii fruits! I'm on the verge of buying seeds.

This year I've grown a year's supply of fresh herbs, which I've ground using a hand cranked meat grinder and frozen. Also some caulis. Damsons I'm ripening and chomping through - no need to freeze those, or the blackcurrants or Marshmello "Da Von Trooo Straw Bereeeeee!", according to celebrity Chef Raymond Blanc, and he's right! Juicy, soft and wonderful strawberry flavour. They taste more like strawberries than any supermakerket strawberry I've eaten. The best I've ever tasted. Unlike others, Marshmellos produce in two batches, one in June and the other is starting now. Supermarket varieties are selected for long shelf-life, not flavour. And wild strawberries, which also taste fantastic, and produce all year round.

Completely fill freezers. If the freezer is completely full, interior temperature won't increase too much 8 hours or so after power loss imho. Particularly if the space the freezer occupies isn't heated. I may keep it simple and buy a small petrol generator, before power outages happen and there's a rush.

This is genuinely useful info (I have a biggish garden, but am unwilling to sacrifice space). Does it mean its possible to espalier pumpkins (like apple trees) and are growing them low maintenance (other than water, I live on an aquifer, chalk stream)? Many thanks

 

[jonathan.agnew]

Sorry no figures, but I'd be surprised if freezers ran 50% of the time, even over 20%. You could use one of the 13 amp plug in current monitoring devices like this one to see what you actually use on each one over time.

Also since you lived throughthe seventies, you'll remember the two hour programmed regular cut offs of power. I'm sure they'll do the same if major cuts become necessary, meaning emergency freezer supply wouldn't be necessary.
.

But could it become cost effective to connect a few 340w solar panels to a deep cycle 12v and inverter and power a freezer that way instead of mains?

 

[oyster]

Scratching around for even tiny fragments of good news or humour:

Survation has released some new polling this morning suggesting that Labour has a 10-point lead over the Conservatives – but that if respondents are told Keir Starmer is the Labour leader, and Liz Truss the Tory leader, the Labour lead rises to 17 points.

 

[guerney]

This is genuinely useful info (I have a biggish garden, but am unwilling to sacrifice space). Does it mean its possible to espalier pumpkins (like apple trees) and are growing them low maintenance (other than water, I live on an aquifer, chalk stream)? Many thanks

They attempt to secure themselves to objects as they grow, and if that object is a polypropylene net held vertially, the vines can be moved to the nets and they will grow upwards. You'll need to support pumpkin weight (also tie vines), bit of a pain tbh.

https://www.reddit.com/r/SquareFootGardening/comments/otd4nr
The yield however, will be somewhat lower than if you leave them to wander freely. Left to grow without interference, they'll make best use of available sunlight to produce as many pumpkins as possible. They are one of the lowest maintenance plants for growing food, they outgrow weeds by a massive margin. Sunlight, water (vertical nets would make them higher maintenance) and the big secret is the application of tomato feed - at the same concentration and frequency of application as for tomatoes - this will result in huge growth, bigger pumpkins, more flowers and high yields.

I live on an aquifer, chalk stream)? Many thanks

Gosh that's handy! Unless you live in a Borrower's scale houseboat.

 

[guerney]

Scratching around for even tiny fragments of good news or humour:

Survation has released some new polling this morning suggesting that Labour has a 10-point lead over the Conservatives – but that if respondents are told Keir Starmer is the Labour leader, and Liz Truss the Tory leader, the Labour lead rises to 17 points.

From my point of view at least - that's great news! Unless Starmer turns out to be a Blair clone, or genuine slightly lefty centrist (highly likely inmh). Leads seem to halve at elections.

 

[guerney]

Been an epic year for runner beans. Cauli's have been good, just in the process of turning some lovely red cabbages into sauerkraut.

Runner benas are very generous plants, they keep on giving! The more you pick, the more you get. Quite low maintenance too. Haven't grown any for three years though, but two of my neighbours who did have had a horrible time - night time temperatures haven't been low enough to trigger flower growth. They open windows or pump in cold air to do that for plants in commercial greenhouses. Tomato feed really does the business on to increase runner bean yield.

I must get into pickling - how much salt do you use?

So, back on topic.
I have a tall fridge freezer and a small cube worktop one.
I'm assuming 400w for the big one and 200w for the small (maybe ott but it is old).
So, if both are running, that's 600w. I'm also assuming that they run for 50% of the time.
This is where my maths gets a bit sketchy. Am I right in thinking that this would be 300w/hour, so giving a figure of 7.2kw/h in a 24 hour period. Jeez ! Seems a bit large - am I over assuming or is my maths wrong?

People are often shocked at how much electricity their fridges and freezers use. Maybe scour the net for manuals and power ratings? They wouldn't be on for as much as 50% of the time, unless they have very poor insulation.

 

[Benjahmin]

After a quick scoot around some forums I'm getting a surprising answer. There is a repeated theme of newer fridge freezers working 80-90% of the time, whilst older ones run 50%. How they get to A rated energy if that's the case, I don't know.
Anyway, this would put things in the 7-8kwh/24hr area.

 

[flecc]

There is a repeated theme of newer fridge freezers working 80-90% of the time, whilst older ones run 50%.

Maybe the experienced users having learnt not to keep opening the door and leaving it open while they choose what to eat that day.

Anyway, this would put things in the 7-8kwh/24hr area.

That is insane consumption. I have separate fridge and freezer, both A rated and my home is all electric for lighting, cooking, water heating, frequent boiling kettle and home heating, no gas supply here. In the summer months my electricity usage drops to 9 kW per 24 hours for everything !! My on-all-the time 90W heated towel rail alone uses 2 kW per 24 hours since it's not thermostatically controlled.

For example, July 274 units (= 8.84 kW per day), August 284 units (= 9.16 kW per day) for everything.

The fridge and freezer must only be a fraction of that.
.

 

[Benjahmin]

I agree, bloody insane. I have access to a power logger, I'll get hold of it and try to wiggle the fridge/freezer out so I can get at the socket. Better take all the liquids out first I guess .

 

[Benjahmin]

Looking around there seems to be a lot on the market, but a lot of them are small battery capacities, making them expensive for what they can do. There also seems to be a mismatch in many where the solar charge is concerned. For instance I was just looking at a Hyundai unit. Looks like a quality piece of kit, sensible amount of outlets (some are way over the top), with a 1080Wh battery. At £1080 (£1/Wh ?) seems OK, but then it's offered with a solar panel for another £300. It's specced as a 60W solar panel. So, assuming clear blue sky, that would take 18hours to fully charge and probably wouldn't keep up with what you're taking out of it. Overly optimistic (perhaps opti mystic) which would lead to disappointment and flat batteries for those who don't understand the technology.
Got the power logger, just got to get the fridge out now. Then I can start to understand more precisely what I need.

 

[Nealh]

1080wh is only 45ah assumming a 24v set up.
One needs to work out the daily take the white goods will use.

My pair of freezers are in the garage and I have been pondering (as they are some of the the larger powerusers in the house on a constant daily basis) in an off grid battery array soley powered by solar for powering these all year around. I just need to do the figures to see if it is worth the while or even viable given the later months sunlight.

I would install the system if viable myself.
lifep04 battery 3v modules would need 8 to make a 24v battery but whether I would have enough wh is another thing esp Sept to April.
One can buy 8x modules for a 105ah/2520wh 24v battery for £532 or a 280ah/6720wh 24v for £1080.
Easy enough to add a BMS and then a case of all the other ancillary items needed such as charge controller,inverter and panels etc,etc to have a viable small off grid system. Issue is how much power to the battery will panels produce esp Sept to April.

 

[Nealh]

My 252L chest freezer is A+ rated and uses 248 kw/h p.a. or 20.6 kw/h per month. That alone accounts for approx 10% of the leccy used p.a.
My smaller freezer I will have to see if I can work out as well as the TD and WM usage.

 

[Benjahmin]

Grey day panel power is very low and short days make it worse.
I have a 1.75Kw array on my roof and I've seen as low as 40w on the inverter display, shooting up to 4-500w as clouds pass over.
I think to run freezers only on solar would be a big ask and battery would need constant monitoring.
Did an experiment a few weeks ago. Bought a cooler box for the van and a 40w panel. We were camping in the height of the heat, so bright and long days . I was able to orientate the panel to early and late sun. After 2 days my van battery was down to a measured 9v. What I hadn't taken into account was that the cooler runs 24/7 on 12v, there doesn't appear to be a thermostat, so it was running all night. It's rated at 48w, result flat battery. Fortunately the panel recharged the battery over the next 18 hours or so and I was able to run the cooler from mains hook up.
I'm realising that we simply do not appreciate how much power we unthinkingly use.

 

[Nealh]

One needs the battery storage to run some off grid so a 6000kwh battery should cope with a few days bleak weather, all about doing the sums to see what may work and how many panels to keep said battery ticking over at above 60% imv.

A 40w panel is never going to be enough for somthing drawing greater energy then it can supply.

My house lays East /West aspect, from research I have done laying panels back to back on E- W orientation is more effiecient and produce more energy then a pure southerly aspect. Also the research says for this type of array the most effiecient angle is 10 degrees.
I have 6m x 3m garage roof I could easily lay a couple of 24v 400w panels to charge a battery set up just for garage use.

I hoping my house roof is going to be tyveked ,re- battened and new pointing done next year so I can't think of using any solar on the house roof until this work is done.

 

[WheezyRider]

Bear in mind the compressor is an electric motor and will have a higher start up power than running power, so the inverter needs to cope with start up. Also, I think motors need a pure sine wave inverter for efficient operation. Modified sine wave inverters lead to a lot of heating in motor applications.

In terms of power consumption, a decent large freezer I bought 12 years ago uses 1 kWh/day.

 

[Nealh]

My A+ rated one works out at 0.68kwh per day.