Advice on best inverter solution for my needs

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ros_b

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I live in a complex. Putting solar panels onto my roof is not an option. I live alone, and can quite happily get by for 3 hours with no backup system at all. My laptop runs for 3 hours, my Wifi is provided by a 4G modem whose battery seems to cope fine for 3 hours. I don't watch TV so can watch stuff on my laptop. Light is provided by a rechargeable lamp. I have one of those little butane stoves to boil water for coffee or heat up food. So it's only Stage 5 or worse that is an issue, and my main concern is my fridge and then running my laptop and wifi modem for maybe an hour or two. My fridge says its power consumption is 263 kWh/year. It's a Defy D210, so smallish, with a little two-shelf freezer compartment above the fridge. Please can you helpful folk advise on my best option. Thanks!
 
Sounds like 2kva would do you fine... Or preferably a 3kva Axpert type trolley with lithium.
 
Question is, do you want hard wired with auto switch over or manual switch over? I'd get a trolley wired to the circuits you need.
 
lkpat said:
Question is, do you want hard wired with auto switch over or manual switch over? I'd get a trolley wired to the circuits you need.
Click to expand...
I'd prefer manual switchover, I think, so I can control my use? For example, I might want to alternate between powering the fridge for 2 hours, then powering the laptop for 2 hours. How would that work if it was hardwired in?
 
ros_b said:
I'd prefer manual switchover, I think, so I can control my use? For example, I might want to alternate between powering the fridge for 2 hours, then powering the laptop for 2 hours. How would that work if it was hardwired in?
Click to expand...
You could most likely get by with a 1kw unit

The reason i would not go for such a low unit is more to do with the charge rate to get the battery full again

ie normally they are 12v units with a 10A charge capacity

So at best can only recharge 500wh in the 4hrs we have power

Stepping up to 24v turns that 10a into 1kwh recharged in 4hrs

You can get a charger to help top up the battery if wanting to stick with 12v single battery

Naturally if you can get a 12v unit with a 20a charge rate you should be able to recharge 1kwh if your load fits that

You do have to get a pure sine wave for the fridge though

So an axpert type that is 20a charge capable should work fine, as long as you know you won't expand to need more than the 1kw output ie never need to use kettle or microwave a step up to 2400w or 3000w unit should open up those options but add battery cost ie needs 2 batteries for 24v
 
OK, next question: I'm in Joburg (Randburg) - where's the best place to go shopping, or should I just order something online? In which case.. best place?
 
ros_b said:
I'd prefer manual switchover, I think, so I can control my use? For example, I might want to alternate between powering the fridge for 2 hours, then powering the laptop for 2 hours. How would that work if it was hardwired in?
Click to expand...
Seems like you only need a portable power station.
 
The problem i have with most cheap portable units is the 10a charging so if your total usage over 4hrs is 500wh yes it can recharge that but if more it is just a problem

The last thing you want is to not be able to run the stuff you want because you could not fully recharge the batteries


This unit has a nice ac charger that can put back all you take out of the battery and if ever you decide to expand batteries it can cope with that



www.electromannsa.com

SUN NM-2000-12 2KVA 12v Pure Sine Wave Hybrid Solar Inverter

SUN 2KVA 12v Pure Sine Wave Hybrid Solar Inverter 24V to 230V with 80A MPPT Charge Controller and AC Charger (10005952) Package Contents: 1x Hybrid Inverter 1x User Manual 2x DC Battery Cables
www.electromannsa.com www.electromannsa.com
 
ros_b said:
I live in a complex. Putting solar panels onto my roof is not an option. I live alone, and can quite happily get by for 3 hours with no backup system at all. My laptop runs for 3 hours, my Wifi is provided by a 4G modem whose battery seems to cope fine for 3 hours. I don't watch TV so can watch stuff on my laptop. Light is provided by a rechargeable lamp. I have one of those little butane stoves to boil water for coffee or heat up food. So it's only Stage 5 or worse that is an issue, and my main concern is my fridge and then running my laptop and wifi modem for maybe an hour or two. My fridge says its power consumption is 263 kWh/year. It's a Defy D210, so smallish, with a little two-shelf freezer compartment above the fridge. Please can you helpful folk advise on my best option. Thanks!
Click to expand...

Dont need anything for the fridge/Freezer

Tests show that mine takes 8 hours to drop from -25 to -5 and another 4 hours to go over 0. <-- This changes when you open the door.

I am using

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to monitor

You can use the poor man method as well to freeze a cup of water and place a coin ontop. If the coin ever gets to the bottom you know you have a problem ;)

For backup in case my power is off for longer than a day I did buy a Kool 1KW 50ah to add cooling if needed and it can easily be transported to recharge if needed.

Also is great if I need to charge a phone or such.

That said there are some complaints on the unit if you wanna use it as a perm on (UPS) solution see:

Mecer SOL-I-BB-M1L Inverter Trolley

Has anyone used this inverter? https://www.firstshop.co.za/products/mecer-1kva-1kw-lithium-battery-inverter-trolley-with-50ah-lithium-ion-battery-and-820w-mppt-controller-sol-i-bb-m1l-158799 I wanted to find out how noisy it is when charging, and when it is discharging? And I'm hoping it isn't...
mybroadband.co.za mybroadband.co.za
 
leon.davibe said:
The problem i have with most cheap portable units is the 10a charging so if your total usage over 4hrs is 500wh yes it can recharge that but if more it is just a problem

The last thing you want is to not be able to run the stuff you want because you could not fully recharge the batteries


This unit has a nice ac charger that can put back all you take out of the battery and if ever you decide to expand batteries it can cope with that



www.electromannsa.com

SUN NM-2000-12 2KVA 12v Pure Sine Wave Hybrid Solar Inverter

SUN 2KVA 12v Pure Sine Wave Hybrid Solar Inverter 24V to 230V with 80A MPPT Charge Controller and AC Charger (10005952) Package Contents: 1x Hybrid Inverter 1x User Manual 2x DC Battery Cables
www.electromannsa.com www.electromannsa.com
Click to expand...
Maybe I misunderstood the OP. But he seems to only want to charge his laptop or run the fridge on occasion only. A portable emergency power station will work just fine.
 
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Dan C said:
Maybe I misunderstood the OP. But he seems to only want to charge his laptop or run the fridge on occasion only. A portable emergency power station will work just fine.
Click to expand...
agreed but a device that can only recharge 500wh is realy limiting
if spending this amount of money it is a good idea to have a bit faster charge rate for the perfect storm days

and that is guaranteed to be able to handle a lithium
ie other threads on here where a guy had bad experience with a lithium on an rct


the kool/mecer units the the 50ah model actually fits this bill nicely
or an axpert 12v + 100ah will be just a bit more expensive than the trolleys with a lead acid

and you already have a lithium
this combined with the inverter i postted earlier or has wingnuts new batteries arrived
ie https://www.bobshop.co.za/item/5840...YHrUbCxj69V4gczBagByp1SXVglISSphoCvDgQAvD_BwE
 
leon.davibe said:
agreed but a device that can only recharge 500wh is realy limiting
if spending this amount of money it is a good idea to have a bit faster charge rate for the perfect storm days

and that is guaranteed to be able to handle a lithium
ie other threads on here where a guy had bad experience with a lithium on an rct


the kool/mecer units the the 50ah model actually fits this bill nicely
or an axpert 12v + 100ah will be just a bit more expensive than the trolleys with a lead acid

and you already have a lithium
this combined with the inverter i postted earlier or has wingnuts new batteries arrived
ie https://www.bobshop.co.za/item/5840...YHrUbCxj69V4gczBagByp1SXVglISSphoCvDgQAvD_BwE
Click to expand...
Yeah good solution. But it still does not make sense for the OP. He has everything covered besides maybe charging his laptop for an hour. Oh and maybe top up his fridge which as mentioned not sure why :p
 
AlphaJohn said:
Dont need anything for the fridge/Freezer

Tests show that mine takes 8 hours to drop from -25 to -5 and another 4 hours to go over 0. <-- This changes when you open the door.

You can use the poor man method as well to freeze a cup of water and place a coin ontop. If the coin ever gets to the bottom you know you have a problem ;)
Click to expand...
So this is the freezer you're talking about? It doesn't defrost completely, but there's this effect where things slightly defrost and then freeze again when the power comes back, and I end up with bits of ice in my frozen veggies and ice buildup in the freezer compartment.

Also, I've had milk go off sooner than usual, and for the first time ever had to throw out an unfinished cucumber because it was getting mouldy. Maybe I just took longer than usual to use the milk and the cucumber, but I don't think so. So sure, the fridge, mostly stays cold, but it would surely gain a bit of heat over 2 hours, certainly over 4 hours, and then the cumulative effect of this, day after day after day, is that food would go bad a bit quicker than before, no?

And yeah, if I didn't plan ahead and take some milk out of the freezer for coffee, then I could be forced to briefly open the door over a 4-hour stint.
 
leon.davibe said:
The problem i have with most cheap portable units is the 10a charging so if your total usage over 4hrs is 500wh yes it can recharge that but if more it is just a problem

The last thing you want is to not be able to run the stuff you want because you could not fully recharge the batteries
Click to expand...
The unit you suggested is called a "hybrid solar inverter". What does that mean? Is it possible to get a portable solar panel to hook up to the unit so I can recharge it via the sun on my balcony during the day (I read some references to that in the other thread someone linked to here)? I do that with a rechargeable lamp that I use.
 
ros_b said:
I'd probably open it once or twice through the 4 hours. But I find the freezer starts defrosting a bit, I get ice build-up.
Click to expand...
Make your running temperature lower, so you built yourself a buffer
 
think about it a trolley with 10A charge means all that is usable is 512wh that is all you can charge back
so you pay R8k for a lead acid battery and slow charge so even if you add a lithium later you just have a reserve tank but if you can never refill it it is a one time reserve tank

ie if really using next to nothing i would say these two badly matched devices is still better than a trolley as long as you never pull more than 500w as you still only have the 500wh capcity for the same price but limited on peak output by bms in battery 50a, later if you add extra battery parralel you can use 1kw if needed

but then you have a lithium for the same price


www.electromannsa.com

SUN NM-2000-12 2KVA 12v Pure Sine Wave Hybrid Solar Inverter

SUN 2KVA 12v Pure Sine Wave Hybrid Solar Inverter 24V to 230V with 80A MPPT Charge Controller and AC Charger (10005952) Package Contents: 1x Hybrid Inverter 1x User Manual 2x DC Battery Cables
www.electromannsa.com www.electromannsa.com

 
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