Simple UPS for mostly fridge, lead acid or lithium?

[JosephineFlexton]

Hi all,

Although I live abroad these days my family is still in Joburg, and the load shedding doesn't seem to get any better soon. They're not very technical so often I set up stuff for them when I'm visited, I've already installed a gas cooker on the back porch so they can at least finish cooking when load shedding starts during the afternoon. Also there's one of these Magneto lanterns from Game in each room and so far so good.

No TV etc during load shedding is fine and if they're working from home these days, their laptop battery should be able to last them around 4 hours if its fully charged at the beginning. Only thing now is the fridge and freezer, there already has been some spoilage and it seems that it won't be better soon so when I'm back I want to chuck the freezer on an UPS. Lead acid is a tat cheaper but since I don't see the situation improve in the coming years it might be better to go straight for lithium, it's smaller and more ready for long term operation, so eventually it's perhaps even cheaper?

For a pretty much standard fridge/freezer combo I think those ellies trollies might be a bit overpowered, a 1000W inverter should be enough to deal with compressor startup right? It's a bit hard to judge what is needed and available/already proven from abroad...

[Richard Mackay]

Why do you believe the freezer needs backup power? The ice in the freezer needs to melt first before the temperature gets above 0 deg C (first having to give up its latent heat).

I find during load shedding my freezer hardly changes in temperature. Of course you should refrain from opening the door frequently..

Edited July 30, 2020 by Richard Mackay
grammar!

[___]

8 hours ago, JosephineFlexton said:

fridge and freezer

I'm with @Richard Mackay here on the Freezer. If the Freezer has trouble making it through 4 hours, I would invest in a new freezer. A chest freezer if I can. Those things can go 36 hours before you're in danger of losing food.

With the Fridge, I agree with you @JosephineFlexton. I too find that the temperature rises pretty fast. I mean, normally mine is at 4°C, but it will go to 7°C quite easily during this time. Milk keeps shorter above 7°C. I don't have exact numbers, but fresh milk can last 5-7 days if you keep it at 4°C, but you easily lose a day if you don't keep it there.

Milk is however much cheaper than an inverter... just saying

In any case, yes, a small inverter can often get the job done. It depends on the wattage of the compressor of the fridge/freezer. In my home both have 90W induction compressors, bought specifically for their lower power use. Since an induction motor use 5-6 times its nominal rating when it starts, this puts both my appliances at around 600W (calculated), but more like 450W measured startup power. That means a 1.2kW inverter powers them easily, with spare capacity. Possibly even an 800W unit, though I feel unsafe recommending smaller than around 1kW.

@Jaco de Jongh has built a 1.2kW system recently for a customer, with a singly Pylontech battery module. It works out more than the Ellies trolley though, but at least it's lithium.

[SYC]

FYI Whatever inverter you choose needs to be pure sine wave NOT modified sine wave (as far as I know to run fridge/freezer)

[___]

2 hours ago, Quwatush Shams (Suly) said:

FYI Whatever inverter you choose needs to be pure sine wave NOT modified sine wave (as far as I know to run fridge/freezer)

The price difference between the two has reduced to such an extent that it's no longer really much of an issue.

On the farm, back in the 80s/90s, we ran fridges and freezers of an old MSW inverter for years without an issue. Smaller motors (hair dryers for example) didn't like it as much though.

But given that there is no longer a huge price advantage, there is also no point in taking chances. Rather get the sine wave one.

Also, "pure" sine wave? Yeah I know, marketing speak and all, but that's like when the waiter tells me the sugar is organic

No inverter makes a "pure" sine wave of the hard kind you get from a good grid connection or from a large generator. All of them has a little bit of a steppiness in the waveform, which reflects as a THD (total harmonic distortion) number on the spec sheet. And it doesn't matter... you just have to be close

[introverter]

19 hours ago, Richard Mackay said:

Why do you believe the freezer needs backup power? The ice in the freezer needs to melt first before the temperature gets above 0 deg C (first having to give up its latent heat).

I find during load shedding my freezer hardly changes in temperature. Of course you should refrain from opening the door frequently..

Two reasons I can think of

1) why do we put most things on a load shedding solution? For convenience. If it is running on backup power much less need for "should refrain from opening the door frequently" especially since eskom does not seem to mind switching off the lights while one is preparing dinner or feeling peckish.

2) when the power comes back for 1 minute after scheduled load shedding and then the substation trips and power is off for another 8 hours (follow the City Power twitter account during load shedding  - especially if you live in joburg... the number of "trips" after load shedding should give you nightmares). (not even looking at the scenario of the substation going up in flames because it dislikes being treated like a giant light switch).... and unlike a sometime quoted line from a popular TV series... "summer is coming" so warm ambient temperatures and no electricity are not ideal for food safety.

Possible third reason but may not apply to OP... many fridge freezers are now exactly that...a fridge and a freezer in one unit.

21 hours ago, JosephineFlexton said:

They're not very technical so often I set up stuff for them when I'm visited, I've already installed a gas cooker on the back porch so they can at least finish cooking when load shedding starts during the afternoon. Also there's one of these Magneto lanterns from Game in each room and so far so good..

Good move on the gas cooking. One less thing to have to spec inverter/battery for.

For light we actually use these (ledlenser MT10). It is expensive for a torch but as all load shedding related expenses are grudge purchases for me at least you get more use from this (it doubles as our cycling lights, or just general torch use around the house). ... if you want light during load shedding you adjust the beam to the wide pattern, put it on the medium power mode, stand it upright on the base and the light reflecting off the ceiling and walls lights up a fair sized room sufficiently to easily see the peas rolling towards the mash in your dinner plate. (and if you eat slow it will  probably last 4 or so hours on a single charge). If you want to read... whack it on full power (only going to get about 2 hours of reading quality light though). When you head off to bed, take the torch along (no candles etc. left burning and no need to have inverters wired into the DB to switch on lights). You can also buy some spare 18650 batteries should it be necessary.

21 hours ago, JosephineFlexton said:

For a pretty much standard fridge/freezer combo I think those ellies trollies might be a bit overpowered, a 1000W inverter should be enough to deal with compressor startup right? It's a bit hard to judge what is needed and available/already proven from abroad...

I posted this before: Especially fridge and/or freezers can be sneaky buggers - especially if of the more modern persuasion. One of my upright fridge/freezers when you measure will draw about 15W...open the door...drops to 5W...close the door and some 10 minutes or so later it draws 90W..... but if you wait long enough somewhere during the daily running stages it will draw about 200W for 10 minutes or so. Even with the 200W draw the one thing you do not see is the in-rush current when the compressor starts which for 1/2 a second or so reaches 1800W.

I run two of these (Bosch) fridge/freezers (and some other small odds and ends)  on a 12V Victron multiplus 1200kVA inverter/charger and a mecer 2nd life lithium battery. Based on all indications this setup should run both fridges for 16-20 hours (so when gambling that the local substation won't catch fire I can also run the TV etc. if I can manage to find anything worthwhile to actually watch). The inverter will mention overload alarms in the log when the compressors start - but these are informational they are not yet at the point where it is an actual overload which will cause the inverter to shut down. Barring any unforeseen breakdown this setup should get me at least 3-4 years of service if actually used everyday. So it should get me to the point where either eskom is doing better or I know to get a big hamster and a wheel connected to a dynamo for the future. (I suspect lead acid batteries will be replaced more than once in 3-4 years).

With all of that said, if I had to redo this today I will likely opt for a 48V Multiplus II 3000kVA inverter/charger and associated (pylontech etc.) battery  - total outlay  will be more than for a 12V setup but it represents much better value in my book and leaves room for future expansion - especially if wiring into the DB to avoid trip-and-fall hazard extension leads lying all over.

If wanting/needing to keep budget a bit lower, the ellies/axpert trolley with the 3000kVA inverter could be worthwhile... just ideally with a lithium battery (lots of threads about the lead acid batteries  - deep cycle and what not - just not lasting long). If your parents are unlikely to use solar much, or even at all, you could even hunt around for the Axpert type inverters with PWM solar charge controller (they are a fair bit cheaper that the MPPT versions last time I looked) and have someone  stick it on a trolley (again according to me not lying flat like the ones already made up by all the solar shops), and add a lithium battery. 

[Ingo]

52 minutes ago, introverter said:

Barring any unforeseen breakdown this setup should get me at least 3-4 years of service if actually used everyday. So it should get me to the point where either eskom is doing better or I know to get a big hamster and a wheel connected to a dynamo for the future. (I suspect lead acid batteries will be replaced more than once in 3-4 years).

I agree with this but it could be even less if the environment is not around 25 degrees C. My bank lasted, only just on 3 years in a garage that is +-35 degrees in summer and sometimes less than, and around'ish, 10 degrees C at night in winter so the life expectancy is NOT what the marketing material suggests. I am also making the leap to LiFEPo4.

[Anonymous]

I agree go Lifepo4 cost per useable storage vs DOD is cheaper for Lithium than Lead Acid also requires less space.

[Richard Mackay]

6 hours ago, introverter said:

Two reasons I can think of

1) why do we put most things on a load shedding solution? For convenience. If it is running on backup power much less need for "should refrain from opening the door frequently" especially since eskom does not seem to mind switching off the lights while one is preparing dinner or feeling peckish.

2) when the power comes back for 1 minute after scheduled load shedding and then the substation trips and power is off for another 8 hours (follow the City Power twitter account during load shedding  - especially if you live in joburg... the number of "trips" after load shedding should give you nightmares). (not even looking at the scenario of the substation going up in flames because it dislikes being treated like a giant light switch).... and unlike a sometime quoted line from a popular TV series... "summer is coming" so warm ambient temperatures and no electricity are not ideal for food safety.

Possible third reason but may not apply to OP... many fridge freezers are now exactly that...a fridge and a freezer in one unit.

JosaphineFlexton srtikes me as trying to help her family with tried and tested solutions during power outages. 

I think if one can avoid installing an inverter UPS for load shedding one should do so. The batteries cost plenty and before you know it they need to be replaced.

You will not be able to power all electrical loads on the UPS due to limited capacity of the UPS anyway..

[introverter]

11 hours ago, Richard Mackay said:

I think if one can avoid installing an inverter UPS for load shedding one should do so. The batteries cost plenty and before you know it they need to be replaced.

I am definitely a supporter of reduce your loads and be frugal so the cheapest way to cope with load shedding is to do nothing but while at it one can then also ask "If I do not need it for 4 hours, do I need it for 8h, 12h, 24h..... at all?". Using no electricity even when eskom is available should save quite a few extra Rand.  I choose to keep some electricity based convenience and for me, during load shedding, being able to open my fridge without my wife having to run a stopwatch is worth the (extra) cost (powering a hairdryer or TV is not worth the cost for me).

While batteries will obviously need replacement at some point (even if not using the pesky inefficient middleman inverter), the grid state in general but especially following load shedding, may also contribute to whatever appliances are connected to mains needing replacement, so one might have to choose which is cheaper - replacing batteries or appliances.... and the one appliance that is likely running 24/7 on mains in many homes will be fridge/freezers. So to my mind the fridge/freezer on a UPS/backup supply is like the spare tyre in my car - I might not need it but I prefer to have it. In the bigger metropolitan areas the problem is likely also greater than just eskom - a lot of the electricity supply problems are not solely eskom's issue so even if eskom based load shedding ends this year, localised unplanned outages of fairly long duration and unstable/out of spec grid supply will be part of our existence for many years.

11 hours ago, Richard Mackay said:

You will not be able to power all electrical loads on the UPS due to limited capacity of the UPS anyway..

I suspect the size of load (and total duration) is limited only by budget and not some inherent characteristic of UPS/inverter based backup power supplies?

[Anonymous]

Cooper Power Supplies decent pure sine line interactive ups inverters that can handle continuous loads with large battery banks however they only cater for lead acid batteries their internal chargers are high amperage units so the 1000 va unit can have 2x200 amp batteries in 24v as an example. However going with a Solar inverter will not cost a lot more and you can use lithium batteries with the system and add solar panel later if need be. An Axpert type 3KVA inverter is quite cheap the 2.8KW 24 lithium battery is not unless you go for second life or custom built batteries with lower duty cycles the fact is its a mine field because you get Good quality Axpert clones and then you get the bad clones personally I do not like the Axpert type inverters because they are problematic and unreliable where the line interactive ups inverters are low frequency units that can handle 3 x their rating in surge power for a couple of seconds and Axpert type inverters are high frequency inverters that can only handle 2 x their rating in surge for a couple of milliseconds.

The ellies battery trolleys with their little 1200 watt modified sine wave inverters is definately not a great product in my opinion lead acid leasure batteries with very low duty cycles and a modified sine inverter.

However my best advice would be to replace the Fridge freezer with a new A+++ fridge freezer and you will not have defrosting problems also you will save a lot of money on electricity..

[Richard Mackay]

53 minutes ago, SteveFury said:

However my best advice would be to replace the Fridge freezer with a new A+++ fridge freezer and you will not have defrosting problems also you will save a lot of money on electricity..

I totally agree!

This thread is: Simple UPS for mostly fridge. This is a  question about surviving power outages, not about embarking on a RE installation with the ultimate aim of going off grid.

This matters because one is influenced about what to do largely due to your mindset. I presume Introverter's comments are motivated by his particular mindset (and the PV array and inverter + battery banks that he has installed at a substantial cost)

 

 

 

Edited August 1, 2020 by Richard Mackay

[___]

If you have an energy efficient fridge (like the Bosch A++ I have), you could use a Flexopower Lithium444 to get the job done. Small, portable... and comes in around the price of the Ellies trolley, but WITH batteries (The ellies trolley is like 9k, sans batteries).

[introverter]

1 hour ago, Richard Mackay said:

I presume Introverter's comments are motivated by his particular mindset (and the PV array and inverter + battery banks that he has installed at a substantial cost)

@Richard Mackay you seem to have a problem with my (assumed) mindset and posted comments so please be more specific than the thinly veiled reference to the extravagance of my vast solar array, numerous battery banks, gold plated toilets and the fact that I clearly only wear my socks once.  What comment/s do you take issue with?

2 hours ago, SteveFury said:

However my best advice would be to replace the Fridge freezer with a new A+++ fridge freezer and you will not have defrosting problems also you will save a lot of money on electricity..

I agree with the benefits of the high efficiency appliances but it does not necessarily solve all the OP's issues. For how long can the fridge be off before you have a problem? At what ambient temperature? What if the fridge is already A+++ and you still end up with food spoilage related to power outages? What if you need to open the fridge door while the power is off?

1 hour ago, plonkster said:

If you have an energy efficient fridge (like the Bosch A++ I have), you could use a Flexopower Lithium444 to get the job done. Small, portable... and comes in around the price of the Ellies trolley, but WITH batteries (The ellies trolley is like 9k, sans batteries).

think the flexo should run even a less efficient fridge (supposedly can tolerate a 1200W surge) but it requires manual intervention (need to plug it in and out to charge) so you lose the convenience factor of a plug-and-play-and-forget automatic UPS setup and the OP's family is in joburg where I think (scheduled) load shedding is 4 hours and not convinced it will power even an A+++ for that long? I see the flexo people have a bigger option now ... about 2.5 times capacity of the flexo but you guessed it...also about 2.5 times the price.

[Richard Mackay]

4 hours ago, introverter said:

@Richard Mackay you seem to have a problem with my (assumed) mindset and posted comments so please be more specific than the thinly veiled reference to the extravagance of my vast solar array, numerous battery banks, gold plated toilets and the fact that I clearly only wear my socks once.  What comment/s do you take issue with?

I'm not being vindictive. My point is that it's difficult to be objective. If you want to really experience 'confirmation bias' then read some threads on a RE subject like this on MyBroadband.

I reckon this forum is less hysterical but one must tune in to where people who post questions are coming from.

[Johandup]

On a practical side we do the following to extend the low temperature in our Bosch A++ freezer:

Run it on the lowest temp setting (-26C)

We buy the Oasis water sachets (for runners) and freeze these to act as an ice reservoir when the power goes off. We take these with on our Kruger trips. Obviously not now
The kWhr consumption on normal fridge freezer units is so high that it pays for itself when upgrading to A++ equipment. 
I follow these steps even though they are on a good backup system. As we all know backup systems can also trip or fail. 

When the businesses were closed during lockdown we did not have a single power outage. Now that they are open it’s normal again to get outages. 

[introverter]

1 minute ago, Richard Mackay said:

I'm not being vindictive. My point is that it's difficult to be objective. If you want to really experience 'confirmation bias' then read some threads on a RE subject like this on MyBroadband.

I reckon this forum is less hysterical but one must tune in to where people who post questions are coming from.

Oh come on Richard what does mybroadband, or renewable energy (RE?) for that matter have to do with anything that, up until now, was posted in this thread? Maybe you consider an opinion that the electricity grid is not in a good state and putting an appliance like a fridge on a UPS/backup as a sign of RE hysteria ?

[introverter]

Just now, Johandup said:

On a practical side we do the following to extend the low temperature in our Bosch A++ freezer:

Run it on the lowest temp setting (-26C)

We buy the Oasis water sachets (for runners) and freeze these to act as an ice reservoir when the power goes off.

Some of the Bosch fridge/freezers actually have (had?) specific space in the door for the supplied "freezer blocks" with the stated aim to help maintain the temperature in case of power failures.

something I previously read is that a fridge and freezer should also maintain the temperature a bit better the fuller they are (air warming up quicker than the solids) - could help reduce overall electricity consumption and maintain temperature when eskom goes to bed. At one stage I even considered getting some polystyrene blocks to add as the week goes by and the fridge starts looking a bit bare.

I also only recently noticed how much our existing kitchen layout probably makes life very difficult for the fridges... fridges are backed to a western wall that bakes nice and warm in the afternoon sun... the eye level oven is also positioned 90 degree to the side of the fridges and vents all the hot air towards the fridges 

[Johandup]

2 minutes ago, introverter said:

also only recently noticed how much our existing kitchen layout probably makes life very difficult for the fridges... fridges are backed to a western wall that bakes nice and warm in the afternoon sun... the eye level oven is also positioned 90 degree to the side of the fridges and vents all the hot air towards the fridges 

So true. 
One needs to make proper provision for air circulation. 
To push them against a wall is not the way to go. 

[introverter]

10 hours ago, Johandup said:

We buy the Oasis water sachets (for runners) and freeze these to act as an ice reservoir when the power goes off. We take these with on our Kruger trips. Obviously not now

Btw, even though it won't help much for load shedding and fridges, something that I found made a very big difference to "mobile cold transport" (i.e. trip to Kgalagadi/Kruger etc.) is to put a space blanket inside the coolbox almost forming a big bag in which you place all food/ice packs etc... fold remaining bit of space blanket over the top of the contents before closing the lid. Unlike normal aluminium cooking foil the space blanket allows much more for forming around weird shapes and angles without tearing, and withstands repeated folding and unfolding also better than aluminium foil... and adds no weight.... you also KNOW when someone is digging around in the coolbox with all the "ge-ritsel" ...I did this with normal coolboxes but I think it should even help with camping fridge/freezers to reduce consumption from the battery system.

Normal addis plastic coolbox also seemed much improved by drilling a couple of holes in the lid and filling the lid with expanding PU foam and later sealing the holes with some silicone (to help keep moisture out of the foam which may contribute to funky smells at some stage).

The plastic fillable ice cube packets also are handy as double purpose (keep contents cold and have ice for drinks), they also allow for a degree of shaping around some of the contents but they do tend to leak when defrosting even slightly, so putting them inside a ziplock bag helps keep dry what is preferred dry.

enough off-topic from me...

[introverter]

adding to the "how crazy is it to stick a home fridge on a UPS/backup power supply?" topic... my position in favour of doing it is also influenced by the following... (I decided to try harder to reduce my wordy posts ... so the kids can help if the adults struggle):

                        ?   ?  

[Jaco De Jongh]

2 minutes ago, introverter said:

so the kids can help if the adults struggle):

                        ?   ?  

Thanks, you made my day...

[___]

I think the usual bickering about a more efficient DC setup can be skipped. The OP said she (if it be fair to guess the pronoun in this internet age) wanted the fridge and freezer on there. Those things have induction motors, which means you need AC, which means you need an inverter. The end

Edited August 2, 2020 by plonkster

[introverter]

2 hours ago, Jaco de Jongh said:

Thanks, you made my day...

the internet voted and it was my turn 

[introverter]

For those battling to decipher my complex code or just missing over-elaborate posts: 

 "how crazy is it to stick a fridge on a UPS/backup power supply?" ... I prefer, as much as possible, not to buy any temperature sensitive produce during load shedding so I try to stock up a bit in my continually working fridge during the first day  - since load shedding is seldom a one day affair anymore. Even if the temperature in my very efficient fridge with all the nice stars and incredible annual kWh consumption sticker on the door,  does not shoot up the moment the electricity goes off, the same is not necessarily true for my local supermarket. Many stores now have generators etc. but I also frequent stores where the load shedding solution consists of big pieces of flattened card board boxes over the freezer contents..... the dairy section with the nice upright open display fridges are often left to the mercy of the elements..as are the meat/poultry... anyone up to buy chicken that has been to room temperature and back a couple of times...?

Therefore I have my fridge/freezers on a UPS/backup supply....I dislike food poisoning that much. (I am not referring to simply having "the runs"... more the lying in the foetal position next to the toilet kind because no amount of buscopan seems to do anything for the cramps... whether it goes up...or down...it looks the same....but you are convinced what went down can't taste worse than what went up... you for the first time understand why the "Hotel Formula 1" group practically put the toilet IN the shower....and when the worst is over three days later you go to check whether the wall paint or tiles discoloured because the odour emanating from your body's equivalent of input and output terminals created an environment suitable only for NASA to conduct testing on survival in atmospheres consisting solely of sulphur....