Big Pure Sine Inverters.

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Scott3

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#304166 10-Apr-2023 13:36

Anybody brought one a big pure sine inverter?

The reason, why I ask, is that in recent years they have got to a price point I can more easily justify. And the recent weather events have brought h

The primary application would be to be part of my emergency / power cut kit.

Spouse is extremely attached to her hairdryer - despite having grown up in a poor country with frequent power cuts, she insists she cannot go to be without showing, and having dried here hair with her hairdryer. Low heat would be fine. Assume about 1200W.
For longer power cuts, keeping fridges / freezers cold

+ assorted sundry (charging devices, ONT / router etc)

Secondary purpose will be to run 230v tools away from home. Dremals / sanders / polishers etc. Issue is that I am in the dewalt battery ecosystem. And while good for frequently used tools, it is super expensive vs corded tools for stuff I use infrequently.

Want to be able to run of either car.

Leaf with a 1.7kW (135A) DC- DC converter
Lexus Hybrid SUV which also uses a DC - DC convert to supply 12v. Unknown side, but I assume similar, perhaps a little more given the car is loaded with 12v stuff (amp for sound system under boot floor, power tailgate, powered and heated front seats, heated rear glass and mirrors, Front & rear halogen fog lights, 3x boot lights, mirror lights, doorstep lights).

Thinking of something like the below:

(1500W, 3000W surge $300)

https://nz.adventurekings.com/touring-4wding/electrical/kings-1500w-pure-sine-wave-inverter-safe-reliable-240v-power-in-your-vehicle-campsite.html

Or (3000W, 6000W surge, $400 on special)

https://nz.adventurekings.com/kings-3000w-pure-sine-wave-inverter-remote-compatible-incl-wiring.html

Obviously the latter is kinda massive, and my DC -DC wouldn't keep up if I ran it hard continuously, but it should (drawing down the start battery) have the grunt to start larger devices.

Thoughts? good idea? Bad idea?

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#3061111 10-Apr-2023 17:12

One thing to keep in mind is that if you draw gigantic currents from a car 12V (particularly the leaf as it doesn't charge the battery to a high voltage, but this applies generally too) you'll possibly sag the voltage below the point where the inverter freaks out and cuts power. Every connector and bit of wire adds a couple milliohms, and at 130A+ you'll be dropping volts surprisingly quickly.

That 3000W surge is 250A, at 12V that only gives you 6 milliohms before you hit the 10.5V cutoff limit (at the terminals of your inverter, your big unit spec's 10V +/- 0.5).

Count on making up some leads that are as big as possible and as short as possible, they often come with piddly little input wires.

raytaylor

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#3061112 10-Apr-2023 17:14

In the aftermath of cyclone gabrielle, we had no power at home for about 5 days.

It was an opportunity to jerry rig up some stuff which i found quite fun.

Had a few 12v120ah deep cycle batteries, 4x 280w solar panels and a couple of 500w inverters.

Laid out the solar panels in the driveway and wired them up to a solar controller and batteries, then used a 500w inverter to run the fridge, ont, router, phone chargers.

Filled the fridge/freezer up with bottles of water - they acted as a thermal battery to keep the fridge cold overnight, and would run direct of solar during the day to recharge/recool and effectively bypass the 12v batteries. Before going to bed i would swap some of the water bottles from the freezer compartment to the top of the fridge compartment.

Next day when the sun comes up, i would switch the fridge/freezer back on to recharge itself.

I was able to put an outdoor wifi hotspot on the roof of my house so the neighbors could connect and get internet (cell towers were down for about 3 days).

The flooding dumped heaps of forestry slash up on the beaches nearby so we went with the trailer and got some wood to cut up with the chainsaw.
We heated water on the outdoor brazier in the yard and then used a 12v camping shower that i bought from super cheap auto ages ago which is effectively a small pump that you put into water with a shower head that you stand under.

We got a 200L drum of water, stood it up on some cinderblocks and wrapped a coil of water pipe around the chimney of the brazier and it heated the drum of water quite nicely. After about an hour of heating, the water was warm enough for 4 people to have a 3 min shower if the garden hose was also keeping the drum of water topped up.

My parents didnt have any LPG for their BBQ but my stepfather has a 2kw inverter on his work van which he uses for his microwave and coffee machine. (yes he has a cafe-style coffee machine in his work van, they are obsessed with coffee).

So they had to wait for a fuel station to start serving up LPG which took a couple of days - there were big queues so we each went and filled up a bottle then went to their house to eat.

I had dehydrated camping meals which just require adding boiling water to for a few days.

Mum was able to use a long extension cord into the house and run her hair dryer off the inverter in his work van, and they used it to keep their fridge cold too.

I didnt have to start up my generator - didnt want to because fuel stations that were able to pump on generators were running out of fuel quite quickly and it took a few days for some to open, and the fuel trucks to get in to the city with the bridges closed. Thankfully the port was able to move one of their generators down to the fuel tank yards and fuel near the port was able to be released to stations so the shortage didnt last long.

So i felt quite lucky compared to the neighbors.

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Rikkitic

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#3061131 10-Apr-2023 18:44

My story isn't nearly as fancy. When I noticed the fridge melting, I remembered an inverter generator that had been sitting unused in a closet for years. I dug it out, studied the manual, and fired it up just inside a big open garage away from the house (it was raining, of course). It is a petrol generator but fortunately I had a supply for the lawn mower. I ran some tests to make sure everything was stable and plugged the fridge into a long extension cord from the generator. It worked fine and I was even able to plug in the laptop to charge it. The generator hummed away all afternoon, the fridge cooled, and then the power came back on! It was an interesting experiment and now I know what to do the next time.

Plesse igmore amd axxept applogies in adbance fir anu typos

richms

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#3061212 10-Apr-2023 20:53

If you are using an inverter to its limits, do not connect devices you care about to it at the same time as a large load like a saw or other motors. They do nasty things to protect on overloads and that can kill electronic loads.

Richard rich.ms

neb

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#3061213 10-Apr-2023 21:07

Rikkitic:
My story isn't nearly as fancy. When I noticed the fridge melting,

... I realised that maybe I needed to go on different meds?

Rikkitic

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#3061218 10-Apr-2023 21:27

neb:
Rikkitic:

My story isn't nearly as fancy. When I noticed the fridge melting,

... I realised that maybe I needed to go on different meds?

You are supposed to supply the missing words yourself.

Plesse igmore amd axxept applogies in adbance fir anu typos

Scott3

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#3061225 10-Apr-2023 22:48

mkissin:

One thing to keep in mind is that if you draw gigantic currents from a car 12V (particularly the leaf as it doesn't charge the battery to a high voltage, but this applies generally too) you'll possibly sag the voltage below the point where the inverter freaks out and cuts power. Every connector and bit of wire adds a couple milliohms, and at 130A+ you'll be dropping volts surprisingly quickly.

That 3000W surge is 250A, at 12V that only gives you 6 milliohms before you hit the 10.5V cutoff limit (at the terminals of your inverter, your big unit spec's 10V +/- 0.5).

Count on making up some leads that are as big as possible and as short as possible, they often come with piddly little input wires.

1500W comes with 16mm^2, and 3000W comes with 32mm^2, bolt terminals.

But it would be very convenient if I could run crocodile clips. Below are 1000A rated, but I don't know how much resistance they would add.

https://www.mrpositive.co.nz/1000a-lead-acid-battery-crocodile-clip-red

But yeah, get your message. Current drawn by those big inverters is kinda epic. The 3000W unit quoted 284A (on 12V at rated load). Even with say 100A of that being fed by the DC-DC, and assuming the low voltage cut off is not triggered, I would only have about 6min before the 12V battery hits 50% depth of discharge (Assuming roughly 20Ah available).

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Scott3

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#3061234 10-Apr-2023 23:03

richms:

If you are using an inverter to its limits, do not connect devices you care about to it at the same time as a large load like a saw or other motors. They do nasty things to protect on overloads and that can kill electronic loads.

Thanks for the heads up.

A bit torn on the two inverters I listed above.

Big one should be well oversize for what I need, so should start motors without too much issue. But is massive (590 x 240 x 110mm, and heavy at 7.2kg)

Small one might struggle to spin stuff up, but is a somewhat better match for my cars electrical system. And both cheaper and smaller / lighter (
320 x 220 x 75 mm / 4.8kg)

Some of the stuff in the manual is a bit scary too. Casing reaching 60deg C at max load etc. Might be better with the oversized unit so say a 1200W hairdryer on low is a walk in the park for it...

[edit] not a big deal for my use case, but idle load is less than 0.7A for the small unit, less than 2A for the big unit, so quite a big differnce.

neb

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#3061238 10-Apr-2023 23:34

Scott3:
Big one should be well oversize for what I need, so should start motors without too much issue. But is massive (590 x 240 x 110mm, and heavy at 7.2kg)

Small one might struggle to spin stuff up, but is a somewhat better match for my cars electrical system. And both cheaper and smaller / lighter (
320 x 220 x 75 mm / 4.8kg)

Size and weight is a good thing here. I'd be pretty nervous about running a continuous 1500W through something weighing a paltry 4.8kg. To put things into perspective, even the much bigger 3kW 7.2kg inverter is less than half the size and weight of a 3kW SMA inverter, and that's intended for wall mounting with active convection cooling.

raytaylor

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#3061241 11-Apr-2023 00:04

Oh oh oh something else to look into...

The warehouse around 2005 sold a range of butane cartridge powered hair styling appliances of the Conair brand.

But i see you can also now get battery powered hair dryers too.

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Scott3

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#3061242 11-Apr-2023 00:10

I purchased the big one. Figured for the sake of $100, it was best to go with one that is the least likely to have issues starting stuff (baring issues with dragging down the 12v system).

Also means the likes of a hairdryer on half (say 1200W), will have the unit cruising along at 40% of it's capacity, as opposed to 80% for the 1500W inverter, meaning stuff like cooling should be less of an issue.

neb:
Scott3:

Big one should be well oversize for what I need, so should start motors without too much issue. But is massive (590 x 240 x 110mm, and heavy at 7.2kg)

Small one might struggle to spin stuff up, but is a somewhat better match for my cars electrical system. And both cheaper and smaller / lighter (
320 x 220 x 75 mm / 4.8kg)

Size and weight is a good thing here. I'd be pretty nervous about running a continuous 1500W through something weighing a paltry 4.8kg. To put things into perspective, even the much bigger 3kW 7.2kg inverter is less than half the size and weight of a 3kW SMA inverter, and that's intended for wall mounting with active convection cooling.

I guess you are right. With the big inverter, there is no way I can max it out for any length of time due to limitations with the car 12v systems, so everything should stay somewhat cool etc.

Regarding the SMA (solar?) inverters, these are in quite a different class to the cheap 4x4 / camping inverters, so I am not surprised they are a lot heavier as they would be designed with the components better cooled and less stressed.

Scott3

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#3061245 11-Apr-2023 00:24

raytaylor:

Oh oh oh something else to look into...

The warehouse around 2005 sold a range of butane cartridge powered hair styling appliances of the Conair brand.

But i see you can also now get battery powered hair dryers too.

Found the Conair "thermocell" Curling iron - Not really much use for our application

On battery hair dryers, the linked one is unlikely to be of any use for us. It advertises as being 400W, and a run time on hot of 15mins. Spouse uses her 2200W hairdryer for 40mins+

But I am a but surprised to see that cordless battery hairdryers are becoming a thing. The below one is rated 4 stars from 321 reviews on amazon:

https://www.amazon.com/Lylux-Cordless-Rechargeable-Brushless-Attachments/dp/B0B6FXCJW5

They do put a lot of effort into stressing that no hot mode is available, only Warm & Cold.