Portable Power Stations

[jennyjj01]

My own take: a simple system.
A solar panel to power AA and AAA and Anker power banks.For light,FM/SW radio,and two way radio. If SHTF We’ll feed from the freezers and give it away. That’ll make the neighbours think we have nothing. Low tech , low worry.

Yours is a solid system. Maybe aspiring to run freezers post apocalypse is a bit silly, especially when I have an Electric cooker which would be useless..
Maybe better to plan on just having one working fridge which I could possibly do with a very cheap setup.

I probably have just about enough solar charging capacity to maintain minimal LED lighting and USB charging. But I need to inventory that.

[Rusty74]

as jansman says we would adapt,my grand parents never had freezers they had a cold step and managed and even when my nien(welsh for nanna) had a fridge she would still use the cold step to set jelly etc,some of the old ways are still the best in my eyes and to me as we have progressed we have lost some of them

[British Red]

What size freezers? Chest, large upright?

Two x modern built under integrated ones, one older fridge freezer(50.50) combo and one older small chest freezer about 250mmx500mmx500mm capacity

The modern ones seem happy to start and run on my genny so I assume they are not going to be a problem on an inverter.
The older ones do work off the genny at a pinch. So long as they don't try to start up at the same time, they can all run on boost at the same time on 700W

I'd also hope to run a slow cooker off the inverter.

I know I have to do some maths to figure out what rating of solar panels and batteries I need, but it doesn't help when all the adverts lie.
Doesn't help too that I'd be wrestling with shade on the panels, having to move them around a lot through the day.

It's tricky as that doesn't sound a lot. But let's take your car battery analogy. A simple car battery is about 20 Amp hours (AH). Multiply by the Voltage to get Watt hours. 12V battery gets you 240 Watt hours. If your freezers are drawing the full 700Watts of your generator your freezers would flatten a car battery in about...20 minutes. They probably aren't consistently drawing that but you get the idea

Now a quality rechargeable AA is 2AH and 1.5V So 3 Watt hours. The same car battery that runs the freezers for 20 minutes would charge around 80 AA batteries - you can see why Jansman's approach makes sense.

There are other factors in play. No inverter or AA battery charger is 100% efficient so there is some loss - but I hope the basics make sense.

[Yorkshire Andy]

What size freezers? Chest, large upright?

Two x modern built under integrated ones, one older fridge freezer(50.50) combo and one older small chest freezer about 250mmx500mmx500mm capacity

The modern ones seem happy to start and run on my genny so I assume they are not going to be a problem on an inverter.
The older ones do work off the genny at a pinch. So long as they don't try to start up at the same time, they can all run on boost at the same time on 700W

I'd also hope to run a slow cooker off the inverter.

I know I have to do some maths to figure out what rating of solar panels and batteries I need, but it doesn't help when all the adverts lie.
Doesn't help too that I'd be wrestling with shade on the panels, having to move them around a lot through the day.

It's tricky as that doesn't sound a lot. But let's take your car battery analogy. A simple car battery is about 20 Amp hours (AH). Multiply by the Voltage to get Watt hours. 12V battery gets you 240 Watt hours. If your freezers are drawing the full 700Watts of your generator your freezers would flatten a car battery in about...20 minutes. They probably aren't consistently drawing that but you get the idea

Now a quality rechargeable AA is 2AH and 1.5V So 3 Watt hours. The same car battery that runs the freezers for 20 minutes would charge around 80 AA batteries - you can see why Jansman's approach makes sense.

There are other factors in play. No inverter or AA battery charger is 100% efficient so there is some loss - but I hope the basics make sense.

20ah car battery? What are you driving a micro car or similar even the wife's old matiz was a 60 ah ISH battery

With a flooded deep cycle caravan battery use the (ah*volts) /2 since you will soon kill a deep cycle battery taking it below 50% DOD (depth of discharge)


I've been half looking at the jackery type units when you think the average 110ah 12v battery is 660wh at 50% DOD and costs £85 ISH it's a no brainer to stick with the old basic reliable tech...

That and ive a distrust of larger lithium cells that said some of the power stations are listed as the safer lithium iron cells

[jennyjj01]

I aspire to lash up a solar panel, a few car batteries? and an inverter,...Current recommendations?

(apart from dont be a cheapskate )

I'm currently researching an absolute bare bones solar-battery-inverter system . Forget freezers. Let's consider enough to run a crockpot and one of those cup heating elements they used to sell in Ibiza
I've only just been introduced to the MPPT controller, which seems to be required to match the solar panel to the battery. Prices start at £9 up to god only knows.
I'll come up with my spec and run it by you guys.
Still p1553d at how everyone lies / overstates on ads and specs.

[British Red]

I aspire to lash up a solar panel, a few car batteries? and an inverter,...Current recommendations?

(apart from dont be a cheapskate )

I'm currently researching an absolute bare bones solar-battery-inverter system . Forget freezers. Let's consider enough to run a crockpot and one of those cup heating elements they used to sell in Ibiza
I've only just been introduced to the MPPT controller, which seems to be required to match the solar panel to the battery. Prices start at £9 up to god only knows.
I'll come up with my spec and run it by you guys.
Still p1553d at how everyone lies / overstates on ads and specs.

If you mean a slow cooker (Crockpot) they still eat a lot of juice - anything that heats or cools does. A slow cooker uses over 1kWH in eight hours of use - so will totally flatten a large 12V battery. A coil heater isn't as bad but I'd look to something like a Kelly Kettle as a much cheaper and more efficient way of heating water

[Yorkshire Andy]

I aspire to lash up a solar panel, a few car batteries? and an inverter,...Current recommendations?

(apart from dont be a cheapskate )

I'm currently researching an absolute bare bones solar-battery-inverter system . Forget freezers. Let's consider enough to run a crockpot and one of those cup heating elements they used to sell in Ibiza
I've only just been introduced to the MPPT controller, which seems to be required to match the solar panel to the battery. Prices start at £9 up to god only knows.
I'll come up with my spec and run it by you guys.
Still p1553d at how everyone lies / overstates on ads and specs.

My bad I hit edit the button not quote its moved


I'd forget heating off a leisure battery too much loss ...

For slow cooking look at a chaffing pot and gell..


As for the charge controller most are cheap Chinese pwm units which still work ok badged as mttp

[British Red]

20ah car battery? What are you driving a micro car or similar even the wife's old matiz was a 60 ah ISH battery

(Snip)


I've been half looking at the jackery type units when you think the average 110ah 12v battery is 660wh at 50% DOD and costs £85 ISH it's a no brainer to stick with the old basic reliable tech...

That and ive a distrust of larger lithium cells that said some of the power stations are listed as the safer lithium iron cells

20AH Based on the size of one of my jump starters - the other is a 17AH. Small but the maths stands up when using one to run the freezers - even a 100AH isn't going to cut it.

Whilst I do agree on the power station price, those Lithium batteries are a very different animal. That said I would prefer a power bank with Lithium Iron Phosphate technology (LFP) to the Lithium Nickel Manganese Cobalt Oxide (NMC) that Jackery uses. LFP is heavier but takes more discharge cycles and is safer. NMC are lighter and better at extreme temperatures. You pay your money... If I had infinite money, I'd definitely have Lithium batteries - it is much harder to damage and longer lasting - hopefully the price will drop.

[jennyjj01]

I'm currently researching an absolute bare bones solar-battery-inverter system . Forget freezers. Let's consider enough to run a crockpot and one of those cup heating elements they used to sell in Ibiza
I've only just been introduced to the MPPT controller, which seems to be required to match the solar panel to the battery. Prices start at £9 up to god only knows.
I'll come up with my spec and run it by you guys.
Still p1553d at how everyone lies / overstates on ads and specs.

If you mean a slow cooker (Crockpot) they still eat a lot of juice - anything that heats or cools does. A slow cooker uses over 1kWH in eight hours of use - so will totally flatten a large 12V battery. A coil heater isn't as bad but I'd look to something like a Kelly Kettle as a much cheaper and more efficient way of heating water

Good point aboit the kelly kettle. I already have a hobo stove and a rocket stove. I see this is very cheap

I read that a crockpot on high uses 200W, or as you say 1.6kWh over 8 hours.. If we assume a 300W solar generator operating at 50% efficiency for 10 hours of the day that gives 1.5kWh or ALMOST enough to keep the battery replenished.... In the absence of anything else.

I've never tried running my hobo stove or rocket stove for 8 hours, but that might be a PITA and use quite a few twigs

[jansman]

I'm currently researching an absolute bare bones solar-battery-inverter system . Forget freezers. Let's consider enough to run a crockpot and one of those cup heating elements they used to sell in Ibiza
I've only just been introduced to the MPPT controller, which seems to be required to match the solar panel to the battery. Prices start at £9 up to god only knows.
I'll come up with my spec and run it by you guys.
Still p1553d at how everyone lies / overstates on ads and specs.

If you mean a slow cooker (Crockpot) they still eat a lot of juice - anything that heats or cools does. A slow cooker uses over 1kWH in eight hours of use - so will totally flatten a large 12V battery. A coil heater isn't as bad but I'd look to something like a Kelly Kettle as a much cheaper and more efficient way of heating water

Good point aboit the kelly kettle. I already have a hobo stove and a rocket stove. I see this is very cheap

I read that a crockpot on high uses 200W, or as you say 1.6kWh over 8 hours.. If we assume a 300W solar generator operating at 50% efficiency for 10 hours of the day that gives 1.5kWh or ALMOST enough to keep the battery replenished.... In the absence of anything else.

I've never tried running my hobo stove or rocket stove for 8 hours, but that might be a PITA and use quite a few twigs

You’d be better off with a haybox cooker. We used them in the Scouts. I’m thinking of making one ,since re - reading a wartime book ‘feeding poultry and rabbits on scraps’. The haybox was pushed then as a fuel saver. https://en.wikipedia.org/wiki/Haybox

Loads of information out there…