Let's design our own UPS

Total cost excl labour?

So that's a tricky one... the short answer is: R30K
But, I was sent the wrong battery, I paid and ordered a 50Ah 48V pack but received a 100Ah 48V pack.

So technically I paid about R15K less than I should have.
Bought some tools with the money I saved... like a proper brushless drill, heavy-duty battery cable crimping tool etc.
 
That looks awesome. Did you take it for a spin? What what the max wattage that you pulled form it?

So I couldn't really push it hard enough yet without having to run extension leads all over the place.
The most I could do was run a 700Watt charger on my electric bike while plugging in a hair dryer at full blast.... but that got me to 2.1Kilowatts.

Enough though for my mum to run the TV, fridge, lights and use a hairdryer at the same time at least.
 
Might need a new thread, not sure.

Lightning just nuked my inverter, and long story short, I now have a 12v 1kwh battery that's going to be gathering dust unless I repurpose it. I bought an Ecoflow as a replacement and the old battery isn't going to fit in with the new system.

My internet routers are all 12v though. In principle the battery should keep them running for a loooooong time. What's the easiest/cheapest way to charge the battery without having to manually switch the power over when loadshedding hits?
 
Might need a new thread, not sure.

Lightning just nuked my inverter, and long story short, I now have a 12v 1kwh battery that's going to be gathering dust unless I repurpose it. I bought an Ecoflow as a replacement and the old battery isn't going to fit in with the new system.

You can always use the 12v battery to charge the EcoFlow but it will only charge it at around 100w.

You'll need an external charger to charge it thought. I have one that looks like this:
 
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My internet routers are all 12v though. In principle the battery should keep them running for a loooooong time. What's the easiest/cheapest way to charge the battery without having to manually switch the power over when loadshedding hits?


Use an old laptop charger (18-19 V) to power one of these set for a float voltage e.g. 13.6 for lead acid.


Put that on the output to get constant 12 V.

You will have a nice on-line UPS with zero transfer time and several days runtime.
 
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Use an old laptop charger (18-19 V) to power one of these set for a float voltage e.g. 13.6 for lead acid.


Put that on the output to get constant 12 V.

You will have a nice on-line UPS with zero transfer time and several days runtime.
Battery is LiFePo4. Got a laptop charger, but not a spare laptop charger, so will need an alternative.
 
Battery is LiFePo4. Got a laptop charger, but not a spare laptop charger, so will need an alternative.

How about a spare phone charger, plus this:


It'll probably be a slower charge than discharge rate but it's certainly a cheap option.
 
How about a spare phone charger, plus this:


It'll probably be a slower charge than discharge rate but it's certainly a cheap option.
I think I'm gonna get the sort of charger Park recommended.

I've got a small backup power unit that can run a router for a few hours, it takes 12v dc in and the input also suggests it will accept a solar panel. if the power goes, it automatically keeps everything going. So in principle if I'm looking at a longer outage, I could probably just plug the battery into the backup power unit to keep it charged. I don't particularly mind faffing about and swapping stuff around, so long as I don't get disconnected at the time when the power dies.
 
My power trolley/hand truck build is finally done.
Even managed somehow to get this Rentech battery BMS chatting to the Growatt inverter.

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Smart man!

What is the weight of this setup?
I'm thinking that I can do more or less the same to my inverter setup, should I need to move it.
You could also add a earth rod with a flylead that you can poke into the earth somewhere and have a proper earth when not plugged in.
You thought about adding a EL to the output of the inverter? Should one have a device that is faulty, that it can properly go to earth (earth rod) and not through you and trip the EL.

I imagine it should not be that hard? You get these Din rails that you can cut a section off and poprivet it on that alu bar you have on there.

Where did you get the trolley?
 
Smart man!

What is the weight of this setup?
I'm thinking that I can do more or less the same to my inverter setup, should I need to move it.
You could also add a earth rod with a flylead that you can poke into the earth somewhere and have a proper earth when not plugged in.
You thought about adding a EL to the output of the inverter? Should one have a device that is faulty, that it can properly go to earth (earth rod) and not through you and trip the EL.

I imagine it should not be that hard? You get these Din rails that you can cut a section off and poprivet it on that alu bar you have on there.

Where did you get the trolley?

Thanks man.

Yeah, so this was quite a while ago. My mom is still depending on this thing... however, a few months ago they had a severe lightning strike in the area and she didn't unplug the inverter from the grid, it fried that Growatt inverter but it was replaced with a new one and now it's kicking perfectly again. They're still not using solar panels with it but I suspect that might become necessary in the near future. Earthing it would be a good idea.

I never weighed it but it's quite heavy, you definitely need the hand truck effect to move it around. My guess is it was probably around 50-60 Kg's... but the fact that the weight of the inverter is at the top created a very nice lever effect so it was easy to move around despite the weight.... and after you place it in the position you want it it's easy to just pop off the wheels and place them in a cupboard somewhere, it looks pretty nice and not out of place.

I haven't built another one since but I've been itching to do so ever since I built it, just because it works so well and I know many people who can benefit. It looks like it could also work with those "lemoen" batteries you find locally these days. It would definitely be less expensive to build one now.

Here's the link of the hand truck I used. Jees, I see the prices on those things have increased, still worth it though since it really was the perfect fit and haven't seen any similar hand trucks out there that would work this well.

 
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