Refrigerator cue 500 watts consumption 70 watts

[frankz66]

Hello everyone I have a 4 kw storage of agm1 c100 110A x3 batteries 12 v

I connected a refrigerator that consumes a maximum of 100 wha. I monitored the consumption, but I realized that every time it attacks only for 1 second I have a cue of about 500 watts that I can barely detect. Immediately after it consumes little about 69 watts for 5 minutes. My perplexity is that at the moment in cut out my batteries report 12.55 therefore very charged, which suggests that during the night I have current left over for the next day. However, my doubt remains and is that if every 15 20 minutes the fridge attaches current and for 1 second I have this cue, if during the night I go down to 12 volts, I would have to find myself for 1 second a drop of 1 volts and then quietly return to 12. This drop that seems normal for lead does not affect the consumption they have accumulated but is only limited to falling physiologically by 1 volts and that's it? I know the question is a bit articulate ...

 

[SamDeleted]

Hi Frank sorry I don't understand the question, beyond me lol. Too late at night or possibly 1 too many beers


But !

Did you know you don't have to run your fridge overnight? You can run them during the day while your panels are making , then turn off 6-8hrs overnight - so it doesn't cycle your batteries

 

[frankz66]

Hi Frank sorry I don't understand the question, beyond me lol. Too late at night or possibly 1 too many beers


But !

Did you know you don't have to run your fridge overnight? You can run them during the day while your panels are making , then turn off 6-8hrs overnight - so it doesn't cycle your batteries

Ok thanks for answering . But can the fridge only be turned off at night without damaging it? It's new, I bought it today, but if in your experience you confirm this, being connected with a smart socket I can turn it off remotely and turn it back on in the morning. It should be off for 12 hours. Can you confirm. Is this if you do this?
I also read this in the features of the fridge:


Power-free runtime 13.5 hours

In short, to make a long way, if you program it to turn it off, will the fridge be damaged or is it a procedure that can be done?

Thank you and sorry if the questions are seemingly silly.

 

[SamDeleted]

Ok thanks for answering . But can the fridge only be turned off at night without damaging it? It's new, I bought it today, but if in your experience you confirm this, being connected with a smart socket I can turn it off remotely and turn it back on in the morning. It should be off for 12 hours. Can you confirm. Is this if you do this?

Yes I've never met a fridge that's damaged by being turned off (but anything is possible?? )

12hrs is a long time for a fridge , you could use a digital (max/min) thermometer over night make sure it's not getting too warm , anything under 8c/9c is fine

Also an external thermostat is much more accurate & efficient then the one built in as standard

If you really want to go to town you can insulated it, the better the insulation, the less power you'll use
(Insulate 3 sides, top and bottom with kingspan/ foam insulation)

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[SamDeleted]

This all applies to freezers just the same

 

[SamDeleted]

Personally I like to put them on a timer cause I'm lazy and have a memory like a sieve

 

[frankz66]

Yes I've never met a fridge that's damaged by being turned off (but anything is possible?? )

12hrs is a long time for a fridge , you could use a digital (max/min) thermometer over night make sure it's not getting too warm , anything under 8c/9c is fine

Also an external thermostat is much more accurate & efficient then the one built in as standard

If you really want to go to town you can insulated it, the better the insulation, the less power you'll use
(Insulate 3 sides, top and bottom with kingspan/ foam insulation)

Digital Max Min Greenhouse Thermometer Garden Indoor Outdoor Wall Room - IN-270 | eBay

It is compact and easy to install on your wall or in any room. Or you can simply place it where you want. Range: -10 to 50°C. All Products Include Two Year Warranty .

www.ebay.co.uk

Inkbird 220V ITC-310T Programmable Digital Temperature Controller Thermostat for sale online | eBay

Find many great new & used options and get the best deals for Inkbird 220V ITC-310T Programmable Digital Temperature Controller Thermostat at the best online prices at eBay! Free delivery for many products!

www.ebay.co.uk

Thank you very much . I will definitely turn it off at night. But if I changed by hypothesis my accumulation, as I would like to do, replacing it with lifepo4 of 300A 12.8, in your experience leaving it on also the situation would change or not?

 

[SamDeleted]

Thank you very much . I will definitely turn it off at night. But if I changed by hypothesis my accumulation, as I would like to do, replacing it with lifepo4 of 300A 12.8, in your experience leaving it on also the situation would change or not?

That I can't help you with I am sorry

No experience with lithium!

but I realized that every time it attacks only for 1 second I have a cue of about 500 watts that I can barely detect. Immediately after it consumes little about 69 watts for 5 minutes.

It sounds like what you're experiencing here is the startup surge of the compressor motor in the fridge. I would say a temporary 1 volt drop is normal in this situation

 

[frankz66]

That I can't help you with I am sorry

No experience with lithium!






It sounds like what you're experiencing here is the startup surge of the compressor motor in the fridge. I would say a temporary 1 volt drop is normal in this situation

Yes I know it is. but written written before if I get to 11.90 during the night I assume that I have about 1 volts of drop that would lead to 10.80-90 for 1 second and I don't know what can happen as the inverter has a detachment threshold, I think 10.50 (my reverse also provides for soft start ...).

 

[frankz66]

That I can't help you with I am sorry

No experience with lithium!






It sounds like what you're experiencing here is the startup surge of the compressor motor in the fridge. I would say a temporary 1 volt drop is normal in this situation

Anyway, thank you for your valuable information that came in handy. I am at the first experiences so I have to learn a lot of things.

 

[zcskywire2]

Hello everyone I have a 4 kw storage of agm1 c100 110A x3 batteries 12 v

I connected a refrigerator that consumes a maximum of 100 wha. I monitored the consumption, but I realized that every time it attacks only for 1 second I have a cue of about 500 watts that I can barely detect. Immediately after it consumes little about 69 watts for 5 minutes. My perplexity is that at the moment in cut out my batteries report 12.55 therefore very charged, which suggests that during the night I have current left over for the next day. However, my doubt remains and is that if every 15 20 minutes the fridge attaches current and for 1 second I have this cue, if during the night I go down to 12 volts, I would have to find myself for 1 second a drop of 1 volts and then quietly return to 12. This drop that seems normal for lead does not affect the consumption they have accumulated but is only limited to falling physiologically by 1 volts and that's it? I know the question is a bit articulate ...

If that is a compressor driviven fridge, chances are that spike is caused by the compressor starting up. At start up they use a large surge current to start up. Then then ramp down quickly to a typical sustained power draw level. This spike can be as high as 13a on 120v power. It is only sustained for less than a second. This is expected operation. Such a spike could be enough to trigger over current protection on a bms however. Either through over current protection or tripping low voltage protection due to voltage sag. That sag will get worse as the batteries are discharge generally, so you will have more than 1v drop likely as they run overnight. Lfp will have about the same voltage sag as agm, but as the lfp discharges it maintains a much flatter voltage curve. This means that you likely would get a longer run time out of them even at the same capacity, with a given voltage cutoff.

 

[frankz66]

If that is a compressor driviven fridge, chances are that spike is caused by the compressor starting up. At start up they use a large surge current to start up. Then then ramp down quickly to a typical sustained power draw level. This spike can be as high as 13a on 120v power. It is only sustained for less than a second. This is expected operation. Such a spike could be enough to trigger over current protection on a bms however. Either through over current protection or tripping low voltage protection due to voltage sag. That sag will get worse as the batteries are discharge generally, so you will have more than 1v drop likely as they run overnight. Lfp will have about the same voltage sag as agm, but as the lfp discharges it maintains a much flatter voltage curve. This means that you likely would get a longer run time out of them even at the same capacity, with a given voltage cutoff.

You were very clear !! I ask you then advice: I have three 110 A c100 12v batteries for a total of 4kw. Unfortunately for my inexperience they have a slightly different life or the first one I bought at the end of August 2022, the second end of January 2023 and the third half of February 2023. If I take the fourth battery I'll buy it now so at the end of April 2023 I'll improve the situation or make a mess ?? Thank you and very kind for your clear explanation.

 

[frankz66]

If that is a compressor driviven fridge, chances are that spike is caused by the compressor starting up. At start up they use a large surge current to start up. Then then ramp down quickly to a typical sustained power draw level. This spike can be as high as 13a on 120v power. It is only sustained for less than a second. This is expected operation. Such a spike could be enough to trigger over current protection on a bms however. Either through over current protection or tripping low voltage protection due to voltage sag. That sag will get worse as the batteries are discharge generally, so you will have more than 1v drop likely as they run overnight. Lfp will have about the same voltage sag as agm, but as the lfp discharges it maintains a much flatter voltage curve. This means that you likely would get a longer run time out of them even at the same capacity, with a given voltage cutoff.

I also wanted to add that the problem is only related to the fridge as with the accumulation I have, I can use TV, nvr system, kitchen accessories and the next morning at 12:00 PM the system is in float! They advise me to keep the fridge off at night maybe when the panels are cut out and use it the next day. The house is not inhabited, I use it as a small country house, but I wanted to have all the comforts of the case ....

 

[MrM1]

If I understand correctly your question, and as suggested this is an older compressor driven fridge, what you are seeing is voltage drop in the agm batteries due to start surge. This momentary voltage drop is not a reflection of State Of Charge (SOC)

A batteries SOC from voltage is best determined while resting with no load. The longer it rests, the more accurate the SOC reading from voltage

As the SOC drops over time, each new start up surge (momentary Inrush of current required to actually start the compressor) will cause the voltage to sag just a little more each time. And even though your battery may not be that low in SOC, it will causes your inverted to turn off due to low voltage disconnect prematurely.

Solution options
1. Lower the LVC (low voltage cut off) of the inverter. But not too low.
2. Buy a new fridge with an inverter compressor. This will start much softer. Probably not an option
3. Getting 304Ah Lfepo4 (LFP) cells will make a big difference
- more available energy stored. Usually between 95% down to 15% +/-, compared to AGMs usable of around 50%
- voltage sag from start up surge will be less because LFP cells are more tolerant of motor start up AND are more voltage stable
- down side of LFP, if you DIY, you'll also need a BMS (battery management system). So cost goes up

Hope this helps. If I misunderstood please disregard

 

[RCinFLA]

Three things that need to be considered for peak current on refrig.

Compressor startup surge current, run current, and defrost cycle current.

Compressor startup can be three to five times average run current and last for about 0.5 seconds. Many refrigerators use a positive temp coefficient thermistor to take the starter capacitor out of circuit after startup. They need to have about 30 minutes of cool off time between run cycles to get their resistance back down to re-enable starter capacitor assistance during startup. If you unplug a running refrig and replug it back in within a couple of minutes, before thermistor has cooled off, the startup current can be very high or even have a compressor locked rotor stall that causes thermal overload breaker to trip. If this happens it can take a couple of hours for compressor to cool down and reset overtemp breaker.

Defrost cycle is highly variable depending on particular model refrig. Usually defrost cycle is done every 12-18 hours. Defrost cycle is typical about 15-30 mins long. Some units have high wattage heaters for defroster that has short on-off duty cycles and some units have a low wattage heater that stays on near continuously during the defrost cycle. I have seen as high as 1kW defrost heaters and as low as 200 watt defrost heaters used.

Defrost current is often the cause of problems with too small a wattage inverter. A 1kw inverter size minimum usually has enough margin.

Lead acid batteries have a large overpotential voltage slump for load current. AGM's are a bit better than flooded lead-acid batteries. A fully charged (12.7vdc rested unloaded voltage) flooded lead-acid 100 AH 20hr rate battery will slump to 12.0vdc with a 25-amp load in about 30 minutes. It will recover to about 12.6v (95% SoC) in about 25 minutes after load is removed.

 

[MrM1]

Also, can you please list what inverter you have?

What solar charge controller (SCC) if external from the inverter

Amp hour of batteries, number of batteries in parallel, and system voltage?

 

[MrM1]

Disregard most of my 1st comment, @RCinFLA is here ?

 

[Leeds]

As others have said, inductive loads have inrush currents that exceed their runtime draw. LRA stands for "Locked Rotor Amps" and you need to allow enough power to overcome that.

In the case of an AC inductive load you need an inverter with a large enough capacity to ride through the spike (that's what the big capacitor(s) in the inverter are for). If you're using some sort of a DC fridge then you need your actual battery bank to supply that surge.

 

[zcskywire2]

You were very clear !! I ask you then advice: I have three 110 A c100 12v batteries for a total of 4kw. Unfortunately for my inexperience they have a slightly different life or the first one I bought at the end of August 2022, the second end of January 2023 and the third half of February 2023. If I take the fourth battery I'll buy it now so at the end of April 2023 I'll improve the situation or make a mess ?? Thank you and very kind for your clear explanation.

Will it improve the situation? Yes it would have an improvement. However this may not solve the issues you are having with the solar setup. As suggested by the poster above. Moving to a Lithium iron phosphate setup would work much better for you needs. In addition it what the poster above said, a lithium iron phosphate system, will likely be lighter and smaller for the same AH. It will also last much longer especially at deeper draws. The AGM batteries are rated 500 cycles at 50% discharge, a Lithium iron phosphate pack would do easily 2000 cycles at 100% discharge.

 

[frankz66]

If I understand correctly your question, and as suggested this is an older compressor driven fridge, what you are seeing is voltage drop in the agm batteries due to start surge. This momentary voltage drop is not a reflection of State Of Charge (SOC)

A batteries SOC from voltage is best determined while resting with no load. The longer it rests, the more accurate the SOC reading from voltage

As the SOC drops over time, each new start up surge (momentary Inrush of current required to actually start the compressor) will cause the voltage to sag just a little more each time. And even though your battery may not be that low in SOC, it will causes your inverted to turn off due to low voltage disconnect prematurely.

Solution options
1. Lower the LVC (low voltage cut off) of the inverter. But not too low.
2. Buy a new fridge with an inverter compressor. This will start much softer. Probably not an option
3. Getting 304Ah Lfepo4 (LFP) cells will make a big difference
- more available energy stored. Usually between 95% down to 15% +/-, compared to AGMs usable of around 50%
- voltage sag from start up surge will be less because LFP cells are more tolerant of motor start up AND are more voltage stable
- down side of LFP, if you DIY, you'll also need a BMS (battery management system). So cost goes up

Hope this helps. If I misunderstood please disregard

Complimenti per la tua spiegazione tecnica che mi ha fatto capire sempre più ( sono alle prime esperienze ) . Il frigo l'ho comprato perchè in offerta e vedendo il consumo ho pensato

Also, can you please list what inverter you have?

What solar charge controller (SCC) if external from the inverter

Amp hour of batteries, number of batteries in parallel, and system voltage?

Congratulations on your technical explanation that made me understand more and more (I'm at my first experiences). I have 4 180 watt 12v panels in 2s2p configuration , an SCC Epever 4210AN , an edecoa 1000w 2000 w pure wave inverter , 3 batteries in parallel AGM1 110 A c100 12v .

I also respond to what you have explained to me technically, and what I can say as a beginner and that I made the mistake of not calculating the startup cue as it is not present in the label. I was thinking of buying a lifepo4 battery of the qeen power 12.8v 300 amper BMS 200 A . But being not very competent, I thought that perhaps this battery might not solve the problem at all, but perhaps it could with consumption precautions, cope with this situation. It's been 1 year since my PV experiences, at the moment maybe like everyone else I paid for my mistakes out of my own pocket . https://amzn.eu/d/28PuIZ4