Hi guys. I need short advice re off-grid inverter.
On my farm, I am completely off the grid. Have a solar and plenty of 24 v lead-acid battery.
But cheapy inverters can not supply juice when needed?
2000W rated when you plug in 500w or more just instantly switch off.What inverter do I need to run something reasonable like a washing machine I( with the) heater off), vacuum cleaner. or,, microwave or inverter welder at low settings - 70A, one the time?

if something like that is going to work or waste of the money again?

I take it back, maybe it is an off-grid inverter.

A 3KA at $350, in sine wave? Sounds way too good to be true.

If they say its off-grid, and rated for what you want, buy one and report back.

I must admit, they look much cheaper than I expected.

Select to expand quote

FormulaNova said..
I take it back, maybe it is an off-grid inverter.

A 3KA at $350, in sine wave? Sounds way too good to be true.

If they say its off-grid, and rated for what you want, buy one and report back.

I must admit, they look much cheaper than I expected.

The problem is that I need to weld something at lower settings. From my 3 generators 650W. 2.4 and 4.5kw only the last one could support inverter welder on the lowest settings. So you have these huge rumblings motors when you just need to stick a few small welds. Ideally, you could run inverter that supports this same welder 70A for a 30 s job, then support battery with the smallest generator ( in needed at all)

You get what you pay for, you can find issues with that brand MPP Solar or re-incarnates of same, capacitors repeatedly blowing on early 4048's etc. Do your research, may of improved, just don't expect it to be great for ever.

If you want it to go the distance, be reliable look or at least compare AUS' Selectronic brand, pricey but you won't buy much better, does far more than invert with PLC input/outputs from memory. Useful for controlling pumps, gensets etc given certain conditions/programing.

Otherwise Victron easysolar models if you want some pretty good kit with minimal install fuss if you are DIY. They too have some good features, remote app, etc.

There is hope for all of us .Lithium battery price is going to drop to the 100 USD per kWh from existing $1000
www.greencarreports.com/news/1126308_electric-car-battery-prices-dropped-13-in-2019-will-reach-100-kwh-in-2023

one may also consider that stationary type for grid/ off-grid should be even cheaper as don't need to meet strict EV criteria and weight doesn't matter as well

Buy some cheap car batteries and work out how to weld directly from them.

Select to expand quote

FormulaNova said..
Buy some cheap car batteries and work out how to weld directly from them.

That is funny because I did think about that too,
I have **** in kw solar panels at no cost at all 250W each ( discarded for solar projects)
I could merge 10 - 30 solar panels to do welding, but only when sun is shining!
I wonder if somebod already tried to weld using solar panels alone !!
My panels range from 28 to 48 V so should suit perfectly for welding.

Maybe and SP Pro Inverter. These are what we install all the time for off-grid. Made in Australia (and exported all over the world). Or for something cheaper (with less grunt?) maybe a Victron. Nothing less than a 7kva genet. With your mix of solar panels you would probably need to DC Couple them to the batteries via a PL60 or something similar. Victron also have a range of MPPTs that would be okay.

Unfortunately 24V batteries are a recipe for disaster. We normally only use 1.2V batteries in series. 12 for 24V installs and 24 for 48V installs. You can still get flooded (open lead acid) but pay the money and get sealed or gel.

Money - there are finance companies who lend money for people installing off-grid. but it would probably have to be installed by a (so called) professional and not a DIY

If you take the step and get a new system, then get new panels, the government rebate makes them quite cheap. Then you could probably do an AC coupled system where the Solar is converted directly to AC (normal house inverter (Fronius or ABB) to be used by what ever load you have and then the SP Pro takes and excess Solar power and charges your batteries.

Use the gen-set for welding. Nothing likes a welder.

You could use oxy - acetylene to weld .
No power required.

Hook up to the grid, fossil fueled power will sort all your problems

Select to expand quote

Macroscien said..
Hi guys. I need short advice re off-grid inverter.
On my farm, I am completely off the grid. Have a solar and plenty of 24 v lead-acid battery.
But cheapy inverters can not supply juice when needed?
2000W rated when you plug in 500w or more just instantly switch off.What inverter do I need to run something reasonable like a washing machine I( with the) heater off), vacuum cleaner. or,, microwave or inverter welder at low settings - 70A, one the time?

if something like that is going to work or waste of the money again?

Read this page about "surge" power , , electric motors that use force or weight cxalled (loading) require usually 5 to 10 times the power for short periods when starting the motor spinning. Because of the load , a motor controller attempts to keep the motor spinning REQUIRING MORE AMPERAGE LET THROUGH.
If an appliance requires to force something then the power required is usually at least 5 times the motor rating.
e.g. 500w washing machine motor requires 2500w contantly so probably 5Kw constant inverter a winch with a 500w motor may need as much as 10Kw , welders usually at least 8Kw , small hobby MIG and arc stick welders around 5Kw.
www.windsolarhybridaustralia.x10.mx/farmingprimaryproduction.html

Select to expand quote

nicephotog said..

If an appliance requires to force something then the power required is usually at least 5 times the motor rating.

In such case whole inverter rating is a bit misleading. Something is rated 3000W but all you could draw is 1000W.
My existing inverter 24v is rated 1500w but I am worry to exceed 500W. Now I received link to such Australian supplier but I am still not sure if any of those will run what I need. One may think that inverter could be designed in such way to limit max current and supply amount of power advertised.
For example 3000W inverted should stick to 3000W and no more but keep working, not switch itself in first second. Even those induction motor pump may then "soft start" at this limited power without the need for sudden surge. For some experimental use I like to draw power directly from solar panels . You could short 300W solar cables and you know that current will not exceed nominal.I am not electronics expert but designer of inverter could also incorporate Supercapacitor to handle initial shock of turning on devices on limited battery power.
www.elinz.com.au/buy/pure-sine-wave-power-inverter-2500w-5000w-24v-240v/INTP24V2500



Anyone used one of those on their caravan or off grid?

There is another idea worth testing.
If we could somehow limit to max power, or current that deviced could draw during start up, then we could overcome cheap inverter shutting off.
www.ebay.com.au/itm/231698915873?ViewItem=&item=231698915873

It may not be exactly what is advertised, but something of this sort is needed here.If we have inverter 2000W lets limit power drawn from any device plug in to max 2000W and not any more.In such case we don't need inverter that could supply 10,000W for few seconds or miliseconds required for pump or compressor to start up. Motor could then start softly with 2000W power given, no more.

Lets imagine scenario where we do have solar panels 2000W as energy source and very simple generator- DC to AC converter without any protection circuits. All we could draw from this solar panels is 2000W regardless how big start up current or power may be required. So our pump should theoretically start softly while drawing no more then generator could supply, without the shock of 7x .The same should apply to standard inverters to limit max power output not to try match max requirement and then shut off when not able to comply with required power.

Select to expand quote

Macroscien said..
There is another idea worth testing.
If we could somehow limit to max power, or current that deviced could draw during start up, then we could overcome cheap inverter shutting off.
www.ebay.com.au/itm/231698915873?ViewItem=&item=231698915873

It may not be exactly what is advertised, but something of this sort is needed here.If we have inverter 2000W lets limit power drawn from any device plug in to max 2000W and not any more.In such case we don't need inverter that could supply 10,000W for few seconds or miliseconds required for pump or compressor to start up. Motor could then start softly with 2000W power given, no more.

Lets imagine scenario where we do have solar panels 2000W as energy source and very simple generator- DC to AC converter without any protection circuits. All we could draw from this solar panels is 2000W regardless how big start up current or power may be required. So our pump should theoretically start softly while drawing no more then generator could supply, without the shock of 7x .The same should apply to standard inverters to limit max power output not to try match max requirement and then shut off when not able to comply with required power.

First, when some type of electrical device is made and approved it has a "rating".
e.g. a 3000w inverter is rated at 3Kw so it will handle current draw constantly up to 3Kw, the trouble is that to 'do work' = "use energy to motivate" it must use more energy the heavier the load. so if you needed a 500w rated electric motor to move under load in a washing machine, a 300w motor can also do that but would burn out extremely quickly.
When an electric motor is switched on it is motionless until the current controller that watches the RPM understands it is not spinning at the speed it must try to always spin, it then lets in more and more current until that speed is reached, However, when a huge load of work is weighing against it, the motor controller will continue to allow current draw far above the rating level at e.g. 4kw because it needs energy to spin against the load weight of washing and water.
A 3000w inverter will only allow maximum of 6Kw surge power for 1 second then the circuit breaker will trip to swtch off and protect the inverter from overload. (inverters are usually twice the constant power rating).
There is in some manufacturers a heavier inverter type that will allow the surge power to continue for 3 to 5 seconds similar to the standard power supply invertes.

Select to expand quote

Macroscien said..
There is another idea worth testing.
If we could somehow limit to max power, or current that deviced could draw during start up, then we could overcome cheap inverter shutting off.
www.ebay.com.au/itm/231698915873?ViewItem=&item=231698915873

Good. Let me know how the testing goes and it will contribute to the group knowledge.

You are a thinker from the future, so make sure you don't get stumped on this one.

Select to expand quote

Macroscien said..
Hi guys. I need short advice re off-grid inverter.
On my farm, I am completely off the grid. Have a solar and plenty of 24 v lead-acid battery.
But cheapy inverters can not supply juice when needed?
2000W rated when you plug in 500w or more just instantly switch off.What inverter do I need to run something reasonable like a washing machine I( with the) heater off), vacuum cleaner. or,, microwave or inverter welder at low settings - 70A, one the time?

if something like that is going to work or waste of the money again?

Washing machine my a@@hole
Dude, you live on a farm, grow outside ;)