Big Pure Sine Inverters.

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richms

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#3061340 11-Apr-2023 10:10

johno1234:

Regarding "pure sine wave" inverters - what kind of loads care if it is a pure sine wave?

I would have thought anything with a DC power supply, i.e. electronics wouldn't care as the rectifier and capacitors are dealing with it?

Old active PFC power supplies hate non sinewaves and will often fail to get anywhere near their rated outputs.

Motors are noisy on it

transformers are noisy on it.

the sharp RF from the steps travels straight thru the RF supression caps in switch mode supplies onto the DC side making anything have horrid 100/200/400Hz and up interference from the steps on their supposidly clean DC side ground.

Richard rich.ms

Scott3

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#3061342 11-Apr-2023 10:25

Ge0rge:
Scott3: Spouse uses her 2200W hairdryer for 40mins+

Say again? Per session? Because your batteries _really_ aren't going to like you...

I swear she is addicted to white noise, and at least half that time is ineffective while she watches video's on her laptop... But here we are.

I have told her, that the inverter will only run the hairdryer on low heat, I assume roughly 1100W (half of the full power).

Given the DC-DC in the leaf is 1.7kW, it should be able to keep the 12v battery fully charged, putting that load onto the traction battery, which is good for 80+ kW loads when driving.

If the above is still too much, we can break out the lower powered travel hairdryer.

Scott3

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#3061343 11-Apr-2023 10:28

johno1234:

Regarding "pure sine wave" inverters - what kind of loads care if it is a pure sine wave?

I would have thought anything with a DC power supply, i.e. electronics wouldn't care as the rectifier and capacitors are dealing with it?

Have run my laptop on a modified sine inverter before. Touchpad went absolutely crazy, but other than that it was fine.

Anything with an induction motor will run very hot on a modified sine wave.

neb

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#3061372 11-Apr-2023 11:51

richms:
Old active PFC power supplies hate non sinewaves

To understand what you're actually getting when you buy a modified sinewave inverter, you need to mentally map "modified sinewave" to what it actually is, "pulsed square wave". You're feeding a noisy pulsed square wave into whatever you're powering.

neb

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#3061374 11-Apr-2023 11:54

Scott3:
I have told her, that the inverter will only run the hairdryer on low heat, I assume roughly 1100W (half of the full power).

That's not quite correct, you need to break it down into its component parts.

What was said was "You need to be careful running your hair dryer from the inverter because it can't reliably supply the full power load it needs, nor can the battery sustain that level of drain for any amount of time, so just run it on low heat and for short periods".

What was heard was "Quack quack quack quack quack quack quack hair dryer quack quack quack quack quack quack heat quack quack quack".

Sidestep

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#3061581 11-Apr-2023 17:17

neb:

That's not quite correct, you need to break it down into its component parts.

What was said was "You need to be careful running your hair dryer from the inverter because it can't reliably supply the full power load it needs, nor can the battery sustain that level of drain for any amount of time, so just run it on low heat and for short periods".

What was heard was "Quack quack quack quack quack quack quack hair dryer quack quack quack quack quack quack heat quack quack quack".

Haha! Not necessarily.. we have a 2500W Nomad Power Systems inverter in the Wagon for no shore power or gen times.

(it's older and a beast, would recommend even though I don't think they make that model now)

Got back to find the Ladies (wife and daughters) getting ready to go out, shower had been running continuously, hair dryer for long enough to heat up the inside of the motorhome. House batteries depleted, inverter ready to fry eggs on...

Said spiel as above..

Hair dryer was turned off.. steely eyes fixed on your truly.. "well that's not acceptable, if they can put men on the moon you'll be able to sort this out.."

Hair dryer restarted..

Thinking of replacing our AGM batts w/ Lithium. It's all priorities..

MichaelNZ

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#3061667 11-Apr-2023 22:20

If you want to do this properly a 48V Outback inverter + Mate 3 controller is as good as you can get.

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Zeon

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#3061683 11-Apr-2023 23:16

If you have an EV or PHEV with a CHAdeMO connector you can get these units which connect directly into the traction battery. Obviously far better than trying to run through the 12v and they can theoretically be rated for probably more than you could ever even get from the grid (I think most houses in NZ top out at 63A so ~15KW?) as those traction batteries are meant to power big EV motors. These units are pricey though:

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SomeoneSomewhere

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#3061950 12-Apr-2023 17:57

Cunning plan. Is reverse power a guaranteed feature of the charging standards, though? I could see some vehicles being programmed with a reverse power or no-charging-happening detection and tripping.

I would be leery of relying too heavily on an EV. Two things spring to mind:

the 12V step-down converter is probably not intended for continuous flat-out use, especially when there's no airflow (stationary) and coolant pumps might not be running because the main parts aren't hot.
In an emergency, having the car actually charged and ready to travel a long distance is a nice safety net.

Apparently there exist butane-powered cordless hair dryers but actually finding one for sale is hard.

neb

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#3061951 12-Apr-2023 18:01

SomeoneSomewhere:
Apparently there exist butane-powered cordless hair dryers but actually finding one for sale is hard.

That's because most people just DIY them.

Scott3

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#3063720 14-Apr-2023 18:21

Well the inverter turned up yesterday. In short, it's a beast - I knew it was big from the dimensions, but there is nothing quit like picking it up to drive the point home.

Tested it out on my hybrid SUV. Monitored voltage at battery terminals.

DC-DC can keep up fine with No, Low, or medium heat on the hairdryer (battery terminal voltage above 13v). Hairdryer ran fine on max (2200W per label, didn't dig out my AC power meter to get actual number), but it was clearly stressing the 12v system. Battery voltage dropped well below 12v, and after a while a alarm came on from the inverter (assume low voltage alarm). Noting cut off, but I figured I had stressed the system enough, so didn't push to find where the actual low voltage cut out was.

Took quite a few minuets with the hairdryer on medium for the cooling fans to even turn on.

Started anything I threw at it without issue:

1500W Lawnmower (brushed motor)
2300W leafblower (2 speed, brushed motor)
500W Insinkerator (induction motor)
600W drill press (induction motor)

Few area's of concern:

Inverter is massive, going to be a bit of a pain to store, transport etc. 32mm^2 wires are stiff etc.
The manual advised a direct connection to the battery, but this is contradicted by a note on the bottom of the unit saying to use a suitable fuse. Appears to be no fusing on the unit itself (didn't open).
On disconnecting, I let the trailing wires touch and there was a massive crack, and there is now a scorch mark on the metal rings. Must be some big caps that are connected to the 12v side of the inverter. Might need to get a resistor to safely discharge them quickly for storage.
Bolting on to battery lugs is inconvenient. Going to find some massive battery clips.
Would be nice if it had a display. Input voltage, and output power.

Not really sure if I made the right decision going with the 3000W unit vs the cheaper, smaller 1500W unit, given limitations on the DC side. (if there had of been a 2000W, I probably would have got that instead). But this unit sure passed my testing without breaking a sweat.

On direct access to the HV battery of the Leaf. Obviously this is a technically superior soultion. But it is a non starter as such units cost several thousand dollars, rather than $400. Also it would only be compatible with my Leaf (and other CHAdeMO fitted EV's), and hence not my other car.

SomeoneSomewhere:

Cunning plan. Is reverse power a guaranteed feature of the charging standards, though? I could see some vehicles being programmed with a reverse power or no-charging-happening detection and tripping.

I would be leery of relying too heavily on an EV. Two things spring to mind:

the 12V step-down converter is probably not intended for continuous flat-out use, especially when there's no airflow (stationary) and coolant pumps might not be running because the main parts aren't hot.
In an emergency, having the car actually charged and ready to travel a long distance is a nice safety net.
Apparently there exist butane-powered cordless hair dryers but actually finding one for sale is hard.

I haven't done a deep dive into cooling, but I think it is likely both of my cars will fire up the coolant pumps, whenever the car is on and something needs to be cooled. Slow moving heavy traffic can be some of the most onerous times in terms of car cooling in general.

Also (beyond the testing I did), I don't intend to max the system out.

In terms of emergency, we would make an assessment of what is important at the time (perhaps refrigeration, Comm's and device charging is important, but not hair drying). Should note that this is more about comfort & convenience than lifes true essentials (that said keeping food safe to eat, and being able to power out ONT / Router / Devices if the cell network, but not UFB goes down would be very nice)

With regards to my particular circumstance:

We live in the inner suburbs of Auckland (and the suburb has apartments with elevators), so baring an issue like the 1998 Auckland power crisis, outages are likely to be fairly short.
The leaf has a range of about 90km so is not really suitable for long distance travel anyway, especially in an emergency.
If we want to conserve battery power in the leaf, I can use the hybrid SUV to power the inverter instead. I usually keep 45L of fuel on hand + what ever is in the tank of the SUV (which I fill before storms). Obviously, we would need to weigh the availability of fuel, with a potential need for travel.
Have family in cities a few hours north and south of Auckland, so in the event roads are open, and Auckland is seriously messed up, we likely head out in fairly short order.
In the unlikely event that Auckland is poked, and the roads look to be closed for some time, and the BOP is Ok, I rate my chances of leaving by sea. Either by walking to the Marina / Ramp, and talking out way onto a boat (I have done a bit of coastal sailing, am an engineer etc), of if we have comms by asking a family member to come pick us up on his trailer fishing boat.

The intent is for the inverter to do all sorts. Hairdryer is largely to get wife approval.

gzt

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#3063759 14-Apr-2023 20:20

A 12v hair dryer in the glove box for emergencies might be useful and efficient.

Scott3

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#3063779 14-Apr-2023 23:10

gzt: A 12v hair dryer in the glove box for emergencies might be useful and efficient.

Sadly commercially available 12v hairdryer's are about 100 Watt. Haven't actually tried one, but suspect they are next to useless.

Frankly I think it is a bit of a pitty there isn't a wider range of 12v appliances.

Something like say a 600W 12v hairdryer would be fairly cheap to mass produce, and would get the job done more efficiently, and without the bulk of weight of a inverter. Power draw would be in the same general area as a big 4x4 tire compressor.

But sadly I think the business case for investing in 12v appliance grows weaker by the day. Inverters are so cheap these days most people who really wants a hairdryer, blender, breadmaker, coffiee machine in their boat / camping rig is just going to pony up for one and use standard AC appliances from the local store, rather than seeking out one of the limited and often weaker & more expensive 12v versions.

Anyway, the hairdryer isn't the sole reason for doing this. If it was i could have gotten away with the smaller, cheaper 1500W inverter (given I knew the 12V system couldn't keep up with much more than that for more than a short period of time), and I likely could have gone modified sine too.

Being able to run tools in the feild / boat yard (heat gun, dremmal etc), has value for me too. As does running fridges, freezers, and IT gear in an extended blackout.

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