Is anyone using an arc welder with an offgrid system

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hary
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Is anyone using an arc welder with an offgrid system

Post by hary » Sun, 07 Apr 2019, 04:11

Hi to all.

Is anyone using an arc welder with an offgrid system ?

I have a 24V Solar panel/battery/regulator and am currently trying to choose an inverter. (battery is 8S 160Ah LipoFe4 WINTSON cells capable of 1600A for 5s peak at most, 480A for 15min, 80A continuous, so, 38kW for 5s, 11kW for 15min, around 2000W continuous)

I would like to be able to run power tool as grinder or circular saw (2000W nominal, 29A inrush current @230V) which are mostly universal motors and sometime a small compressor (1,5kW) or high pressure cleaner with induction motor.

These tools would be used only sometimes and one at a time, the biggest problem seems being the inrush current at start (I measured 29A@230V).

I would also like to be able to do arc welding but have no idea if a small inverter welder have inrush current and what kind of inverter would be able tu run such a device.

As all appliances inside the house is mostly DC24V (light, laptop . . .), the rest of the time, the inverter will only run a small 120W fridge.

If any experiences and advices, I would much appreciate.

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Re: Is anyone using an arc welder with an offgrid system

Post by coulomb » Sun, 07 Apr 2019, 06:56

I think you'd be better off with an inverter with an old style big low frequency iron transformer in it, like a Victron. They have a better surge rating, and it seems to me that several of your intended loads will have significant inrush current.

It's difficult to measure inrush current, but for most motors, it seems to be some 5x to 7x of nominal current. So I suspect a fair bit more than 29 A peak for a 2000 W motor.

OffgridQld was able to start large motors like a compressor, but that was with a 5 kVA 48 V inverter. I don't think you'll find a 24 V 5 kVA inverter. See early posts in the PIP-4048MS etc topic.

[ Edit: added link. ]
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
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160 W solar, 2.5 kWh 24 V battery for lights.
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Re: Is anyone using an arc welder with an offgrid system

Post by BaronVonChickenPants » Sun, 07 Apr 2019, 07:53

We have an offgrid system using 22s8p LTO cells and a 12kw Low Frequency Transformer inverter from Sacolar: http://sacolar.com/products/info_8_itemid_18.html

We are able to run compressors, welders, radial arm saw and power saws, haven't found anything yet that gives us trouble.

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Re: Is anyone using an arc welder with an offgrid system

Post by smithy2167 » Sun, 07 Apr 2019, 09:00

Would it help to use a Soft Starter, at least for the motorised tools e.g. https://www.jaycar.com.au/soft-start-ki ... s/p/KC5511

It would probably have a heart attack with the welder.

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Re: Is anyone using an arc welder with an offgrid system

Post by offgridQLD » Sun, 07 Apr 2019, 12:05

Welders are less of a issue than starting large motors. With the pip4048 I was able to use a large 16cfm 3 cyl air compressor with 3hp motor. That said it was about the limit for the PIP4048. As in if you had another large load start at the same time it would over load. 200A ac/dc inverter tig welder was fine running from the PIP. Not often your running the welder at full power 100 - 150A was fine.

Though I do agree big low feq inverter is the go for a workshop.

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Re: Is anyone using an arc welder with an offgrid system

Post by hary » Sun, 07 Apr 2019, 17:31

Hi everyone.

And thanks so much for these very helpful response.
coulomb wrote:
Sun, 07 Apr 2019, 06:56
I think you'd be better off with an inverter with an old style big low frequency iron transformer in it, like a Victron. They have a better surge rating, and it seems to me that several of your intended loads will have significant inrush current.
I've been thinking of that. I'll come back later on in this response
coulomb wrote:
Sun, 07 Apr 2019, 06:56
It's difficult to measure inrush current, but for most motors, it seems to be some 5x to 7x of nominal current. So I suspect a fair bit more than 29 A peak for a 2000 W motor.
You might be right and somebody already warned me about that fact.
The 29A I gave were measured with a FLUKE 337 clamp meter which has an inrush function, if that information can help . . .but I understand that the definition off inrush current might differ from place to place (inrush current, surge current, peak current might also be some subtle shading)
[/quote]
BaronVonChickenPants wrote:
Sun, 07 Apr 2019, 07:53
We have an offgrid system using 22s8p LTO cells and a 12kw Low Frequency Transformer inverter from Sacolar: http://sacolar.com/products/info_8_itemid_18.html

We are able to run compressors, welders, radial arm saw and power saws, haven't found anything yet that gives us trouble.
That's for sure a big 12kW baby ! Their website and low frequency inverter look a lot like the MUST solar inverter that I've been thinking to get in 24V/6kW version:
https://www.must-solar.com/ep3000-ir-1- ... -inverter/
or
https://www.must-solar.com/ep3000-pro-s ... -inverter/
Unfortunately, SACOLAR make their inverter in 48V and I'm on 24V
smithy2167 wrote:
Sun, 07 Apr 2019, 09:00
Would it help to use a Soft Starter, at least for the motorised tools e.g. https://www.jaycar.com.au/soft-start-ki ... s/p/KC5511

It would probably have a heart attack with the welder.
Some of my power hand tools like circular saw, small angle grinder were purchased already with such a kind device (avoiding any dangerous kickback) and they actually don't show any inrush current. (but maybe peak current on each sinusoid as they seem to be TRIAC angle phase variator, not sure of the translation !)
But the link you give is for 10A only which is very cloth to my needs !
In any case, finding the right device might be a good solution.
offgridQLD wrote:
Sun, 07 Apr 2019, 12:05
Welders are less of a issue than starting large motors. With the pip4048 I was able to use a large 16cfm 3 cyl air compressor with 3hp motor. That said it was about the limit for the PIP4048. As in if you had another large load start at the same time it would over load. 200A ac/dc inverter tig welder was fine running from the PIP. Not often your running the welder at full power 100 - 150A was fine.

Though I do agree big low feq inverter is the go for a workshop.
You end up making me completely lost !
In fact, before coming on this forum, I had selected the MUST 24V/6kW https://www.must-solar.com/ep3000-ir-1- ... -inverter/ or https://www.must-solar.com/ep3000-pro-s ... -inverter/ low frequency inverter and the high frequency (HF) PIP 4024HSP /or MSPhttps://www.mppsolar.com/v3/catalogs/PIP-HSP_MSP24V.pdf

I was more on the MUST solar LF inverter as I could get it from Spain ( I'm from France, Europe), despite having almost no review and feedback, but coming on this forum, I was going to switch to PIP-4024 as the PIP-4048 was well documented and hacked and sold in a lot of various brand.

Plus, the PIP from MPP SOLAR was able to be paralleled is case one is too weak.

The biggest point from now is that I've no feedback from the LF inverter from MUST SOLAR.

If the MPP PIP-4024 and PIP-4048 have the same power output, I would be happy with it, starting 3HP motor and welding 150A, that's not bad at all for what I plan to do !

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Re: Is anyone using an arc welder with an offgrid system

Post by coulomb » Sun, 07 Apr 2019, 18:08

hary wrote:
Sun, 07 Apr 2019, 17:31
The biggest point from now is that I've no feedback from the LF inverter from MUST SOLAR.
The Must brand causes a few of us to bristle, because they were the original illegal cloners of Voltronic Power / MPP Solar products. But their other products may be fine.
If the MPP PIP-4024 and PIP-4048 have the same power output, I would be happy with it...
Not quite, I believe. OffgridQLD's PIP was a 5 kVA / 4 kW model. These have the same real power output, 4 kW. My understanding is that an induction motor starting is a highly inductive load, especially if it has low mechanical load at start up. So you're comparing 5 kVA (22 A) continuous for the PIP-4048 versus what I assume is 4 kVA for the PIP-4024 (they don't specify maximum VA any more, since all the models appear to be unity power factor). [ Edit: I've changed my mind; see the post after next. ]

Both of them presumably have the same 100% overload for 5-10 seconds, enough to start a motor. For highly inductive loads, it's the apparent power rating (VA) that matters. So the PIP-4024 would have about 80% of the motor-starting ability of the PIP-4048. [ Edit: I now believe they're the same, see the post after next. ]
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.

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Re: Is anyone using an arc welder with an offgrid system

Post by hary » Mon, 08 Apr 2019, 04:20

coulomb wrote:
Sun, 07 Apr 2019, 18:08
hary wrote:
Sun, 07 Apr 2019, 17:31
The biggest point from now is that I've no feedback from the LF inverter from MUST SOLAR.
The Must brand causes a few of us to bristle, because they were the original illegal cloners of Voltronic Power / MPPSolar products. But their other products may be fine.
Would be any feedback, review, fix or hack about the MUST SOLAR ?
coulomb wrote:
Sun, 07 Apr 2019, 18:08
If the MPP PIP-4024 and PIP-4048 have the same power output, I would be happy with it...
Not quite, I believe. OffgridQLD's PIP was a 5 kVA / 4 kW model. These have the same real power output, 4 kW. My understanding is that an induction motor starting is a highly inductive load, especially if it has low mechanical load at start up. So you're comparing 5 kVA (22 A) continuous for the PIP-4048 versus what I assume is 4 kVA for the PIP-4024 (they don't specify maximum VA any more, since all the models appear to be unity power factor). Both of them presumably have the same 100% overload for 5-10 seconds, enough to start a motor. For highly inductive loads, it's the apparent power rating (VA) that matters. So the PIP-4024 would have about 80% of the motor-starting ability of the PIP-4048.
Good point ! I'm a little confused about power factor, kVA and kW. But in the PIP-4024 datasheet they don't actually specify it's PF=1, but still they don't say anything about kVA ! Choosing an inverter, you need to make a lot of guessing . . . !
Even asking, you don't always have a clear answer. From my experience, MUST Solar have been better at answering question than MPP-solar.

I'm still waiting for some info from both provider. I'll see what's coming up.

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Re: Is anyone using an arc welder with an offgrid system

Post by coulomb » Mon, 08 Apr 2019, 08:40

hary wrote:
Mon, 08 Apr 2019, 04:20
Good point ! I'm a little confused about power factor, kVA and kW. But in the PIP-4024 datasheet they don't actually specify it's PF=1, but still they don't say anything about kVA ! Choosing an inverter, you need to make a lot of guessing . . . !

Even asking, you don't always have a clear answer. From my experience, MUST Solar have been better at answering question than MPP-solar.
Yes, this is an area where Voltronic Power and MPP Solar are shooting themselves in the foot. Full information is essential to a happy customer experience, and return or referred sales.

I've changed my mind about what a PIP-4024 corresponds to. On the Voltronic Power website, I can't find a 4 kVA model at all, 24 or 48 V. But there is a 5 kVA 24 V model with PF0.8, so that must be what the PIP-4024 is. I somehow missed the fact that the full model number is PIP-4024MSP; the P indicates power factor PF0.8 (see Weber's excellent Voltronic Zoo of related model numbers post). So it's a 5 kVA / 4 kW model, the same as the old PIP-4048MS (which if they were still manufactured, would now be called PIP-4048MSP). I guess they figure that 5 kW at 24 V (208 A) is just too much to be distributing over PCB tracks (and yet somehow 4000 W at 24 V, 167 A, is ok :| ). So it looks like the PIP-4024MSP will start the same sized motors as the old PIP-4048MS models.
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.

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Re: Is anyone using an arc welder with an offgrid system

Post by coulomb » Mon, 08 Apr 2019, 09:18

hary wrote:
Mon, 08 Apr 2019, 04:20
Would be any feedback, review, fix or hack about the MUST SOLAR ?
I only know of the Must near-clones of Axpert inverters; there have been a few posts about those. I can't immediately find many; "Must" is not a particularly unique search word :(

It's not much to go on, but here are two from the South African PowerForum:
Gennie/Inverter woes
CB Solar - PV1800 5kVA Schematic

I also recall one about a model that is basically a copy of an Axpert, plus grid tie capability.
Must 3KVA PV1800 Solar Charging (so the topic title is wrong, it should say PH1800).
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.

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Re: Is anyone using an arc welder with an offgrid system

Post by offgridQLD » Tue, 09 Apr 2019, 06:37

To add a little more confidence in the PIP4048 units. Over the past year I have had a new offgrid home and workshop built and the PIP4048 was the primary power centre for the build. So it spent many weeks powering the various trades tools. Large drop saws, Air compressors, angle grinders. Some times there where two trades at the same time carpenters using saws and tilers using grinders the inverter never overloaded though I did have the circuit breaker trip once.

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Re: Is anyone using an arc welder with an offgrid system

Post by T1 Terry » Tue, 09 Apr 2019, 12:39

One of the off grid house setups we did powers a stick welder from a 2440 MPP solar inverter supported by 600Ah @ 24v of Winston lithium cells. It has been doing this for a few yrs now.
We had another set up that had a main board fail. It was an intermittent failure, sometimes it would run for days, other times it dropped its bundle after 20 mins, restart and another 20 mins and it would do it again. MPP Solar supplied a replacement board and everything is running fine again.
The biggest we have installed to date uses 2 x 2440 inverters in parallel connected to 1200Ah @24v of Winston cells and 10kW of solar. That powers everything they throw at it and they aren't particularly careful about what they turn on at the same time. It has only pulled the low SOC shutdown once and that was because the young son and his mates went up there and he turned the roof top swappy on full loud for the whole night. The sun was a little too late getting up to help with the load, the generator was out of fuel, so they had no power for breakfast :lol: Put pay to story that swampy air coolers used less power than the new inverter reverse cycle units, the swampy doesn't slow down once it gets temp down :roll: :twisted:

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Re: Is anyone using an arc welder with an offgrid system

Post by hary » Tue, 09 Apr 2019, 13:39

T1 Terry wrote:
Tue, 09 Apr 2019, 12:39
One of the off grid house setups we did powers a stick welder from a 2440 MPP solar inverter supported by 600Ah @ 24v of Winston lithium cells.. . ..

T1 Terry
2440 or 4024 ? What was the exact and complete reference please. PIP-4024 ??

You say you are on lithium WINTSON cells, so I guess LiFePO4, is that correct ?

What BMS (Battery Management System) do you have ? (If any)

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Re: Is anyone using an arc welder with an offgrid system

Post by T1 Terry » Tue, 09 Apr 2019, 15:50

hary wrote:
Tue, 09 Apr 2019, 13:39
T1 Terry wrote:
Tue, 09 Apr 2019, 12:39
One of the off grid house setups we did powers a stick welder from a 2440 MPP solar inverter supported by 600Ah @ 24v of Winston lithium cells.. . ..

T1 Terry
2440 or 4024 ? What was the exact and complete reference please. PIP-4024 ??

You say you are on lithium WINTSON cells, so I guess LiFePO4, is that correct ?

What BMS (Battery Management System) do you have ? (If any)
Yeah, got it back to front, PIP4024MSP. I thought the P stood for parallel capable, not a different power factor. They are sold as 4kW/5kva, 60 amp max 240vac charging, 80 amps MPPT controller with a max open circuit of 145vdc and Vmp range of 60vdc to 115vdc. We also use their MPPT solar charge controllers, all controlled by our own proprietary battery management system that includes low state of charge and cell under/over voltage battery isolation. The management system controls all the charging sources as well, the battery isolation is the last line of defence for the battery, too expensive not to protect ;) 8-) There are audio and visual warnings and a constant display of cell voltages and battery parameters on any smart phone via Bluetooth.

T1 Terry
The Winston cells are LYP chemistry, lithium yttrium ferrous phosphate. They sell the LFP cells under the Thundersky brand, must be something to do with the financial settlement between Winston Chung and Sinopoly because Winston had sold the Thundersky name to Sinopoly a while back for an alarming sum of money. I think they believed they were going to get the LYP chemistry and the exclusive rights to its use and that didn't happen.
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Re: Is anyone using an arc welder with an offgrid system

Post by hary » Tue, 09 Apr 2019, 19:15

T1 Terry wrote:
Tue, 09 Apr 2019, 15:50

Yeah, got it back to front, PIP4024MSP. I thought the P stood for parallel capable, not a different power factor. They are sold as 4kW/5kva, 60 amp max 240vac charging, 80 amps MPPT controller with a max open circuit of 145vdc and Vmp range of 60vdc to 115vdc. We also use their MPPT solar charge controllers, all controlled by our own proprietary battery management system that includes low state of charge and cell under/over voltage battery isolation. The management system controls all the charging sources as well, the battery isolation is the last line of defence for the battery, too expensive not to protect ;) 8-) There are audio and visual warnings and a constant display of cell voltages and battery parameters on any smart phone via Bluetooth.

T1 Terry
The Winston cells are LYP chemistry, lithium yttrium ferrous phosphate. They sell the LFP cells under the Thundersky brand, must be something to do with the financial settlement between Winston Chung and Sinopoly because Winston had sold the Thundersky name to Sinopoly a while back for an alarming sum of money. I think they believed they were going to get the LYP chemistry and the exclusive rights to its use and that didn't happen.
Could you point me out to your proprietary BMS please.

Well, so my battery cells must be LYP, so LiFeYPO4 instead of LiFePO4 ! I didn't notice that myself !

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Re: Is anyone using an arc welder with an offgrid system

Post by T1 Terry » Wed, 10 Apr 2019, 07:54

The BMS we use for systems we install as off grid and grid back up. These go in houses, houseboats, caravans and motorhomes. We don't really sell them as a separate item usually, but if you go to the T1 Lithium web site I think Margaret (my wife and her business) could have some information and photos etc. It isn't particularly pretty looking in the commercial sense because we never intended to use it on anything but our own installs.

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Re: Is anyone using an arc welder with an offgrid system

Post by Richo » Wed, 10 Apr 2019, 12:54

Sorry if this is not the right place for my question.
Is there anything bigger to make it "like for like" so around 22kVA going off grid?
I'm sure there is a limit on what western power provide as 3-phase to a residential house.

Even with 3 separate circuits this is still 10kVA per inverter.
Double what has been suggested for an inverter.
So the short answer is NO but the long answer is YES.
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Re: Is anyone using an arc welder with an offgrid system

Post by hary » Wed, 10 Apr 2019, 19:24

As I am in contact with both MPP SOLAR and MUST SOLAR to make the choice about my inverter;
again MPP SOLAR are very confusing not directly and accurately answering my question.

I asked them if the PIP-4024 could start the same inductive load as the PIP-5048 (considering what said offgridQLD) and they're turning around asking me what are my loads when I already told them.

In the opposite, MUST SOLAR are giving me all detail, even if they're not nice, like the no load consumption of 192W (which seems terrible) , but I think I'll go with them with the PV3000MPK 24V version.

It's a ridiculous solution since I need the invereter mostly to run the 120W fridge, and very seldom for some workshop tools.

I'll try to find a way to control the ON/OFF of the inverter only when needed from a microcontroler device or so.
So the inverter would start only when the fridge would ask, and stops at the same time the fridge stops.

What do you think ?

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Re: Is anyone using an arc welder with an offgrid system

Post by coulomb » Thu, 11 Apr 2019, 06:48

hary wrote:
Wed, 10 Apr 2019, 19:24
the no load consumption of 192W (which seems terrible) , but I think I'll go with them with the PV3000MPK 24V version.
192 W is more than your fridge!
It's a ridiculous solution since I need the invereter mostly to run the 120W fridge, and very seldom for some workshop tools.
It seems to me with your very different load requirements that you might be better off with two inverters. One small and efficient one for the fridge and perhaps some lighting, and a beast for power tools.
I'll try to find a way to control the ON/OFF of the inverter only when needed from a microcontroler device or so.
So the inverter would start only when the fridge would ask, and stops at the same time the fridge stops.
Those sorts of things are often a lot harder than they first appear.
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160 W solar, 2.5 kWh 24 V battery for lights.
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Re: Is anyone using an arc welder with an offgrid system

Post by hary » Thu, 11 Apr 2019, 13:45

Hello Coulomb.

Being a specialist (if not THE specialist) of the MPP-SOLAR inverters, for my needs, and from your point of view, would you go for the HF MPP-SOLAR PIP-4024 or the MUST-POWER PV3000MPK 24V/6kVA.

The prices seems to be almost the same.

About your previous post, I think yes, the solution will end by getting a small HF inverter and a big LF inverter.
But again, one DC24V circuit for light and laptop and everyday small appliances, plus one low power 24/24h "HF" AC230V for fridge and soup mixer, plus one high power occasional use "LF" AC230V for hot water cattle and toaster and power tools..... I'm afraid to drive my wife crazy with all of these procedure to respect ! We already have so many water pipes/hoses and valves ! :shock:

Living OFF GRID is not an easy way ! :twisted:

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Re: Is anyone using an arc welder with an offgrid system

Post by coulomb » Thu, 11 Apr 2019, 14:17

hary wrote:
Thu, 11 Apr 2019, 13:45
HF MPP-SOLAR PIP-4024 or the MUST-POWER PV3000MPK 24V/6kVA.
Sorry, I don't know the Must model at all.
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.

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Re: Is anyone using an arc welder with an offgrid system

Post by T1 Terry » Sat, 13 Apr 2019, 13:37

One solution may be to use a smaller inverter with an auto switch through when a stable 240vac supply is sensed on the mains input. That way all the low power devices can run on the smaller more efficient inverter and the bigger draw items powered by the big mother inverter as well as a supply to the small inverter. The switch through is as close to instant that appliances don't see the switch, so the big inverter would power everything when you switched it on ready to power the big loads and the small inverter would automatically switch back in when the big inverter is switched off. We use these in the 12v version for the 12v RV installs that have limited battery capacity and area for solar https://www.ebay.com.au/itm/PROJECTA-PU ... Sw8f9b271r The eco mode switches down to almost zero draw when it no longer senses a load, but a few of the really soft start gear can't bring it back on line, so something to keep in mind. The standby current for the 12v units is only around the 10w mark, but they don't list the standby current for the 24v unit, only the eco mode at 10ma

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Re: Is anyone using an arc welder with an offgrid system

Post by hary » Sat, 13 Apr 2019, 14:58

T1 Terry wrote:
Sat, 13 Apr 2019, 13:37
One solution may be to use a smaller inverter with an auto switch through when a stable 240vac supply is sensed on the mains input.
Do you mean "when a stable load is sensed on the line" ?
T1 Terry wrote:
Sat, 13 Apr 2019, 13:37
That way all the low power devices can run on the smaller more efficient inverter and the bigger draw items powered by the big mother inverter as well as a supply to the small inverter.
Do you mean supplying the line with the big inverter instead of the small one ? That would imply a kind of relay NC/NO switching the loads from the small inverter to the big one and being absolutely sure the 2 inverter are not feeding the line at the same time !
T1 Terry wrote:
Sat, 13 Apr 2019, 13:37
The switch through is as close to instant that appliances don't see the switch, so the big inverter would power everything when you switched it on ready to power the big loads and the small inverter would automatically switch back in when the big inverter is switched off.
T1 Terry
[/quote]

Are you sure the switch from one source to the other (small to big inverter or opposite) can be done without any synchronisation ? I wonder what happen if the switch is made when inverter are not in phase (not same sine wave position at switch time) , don't know if I clear enough ?

One other point to think about is not forget to switch the big inverter when using a big tool. Otherwise, as you have 230V from the small one, you just forget, plug in the big saw and burn the small inverter !!!!

By the way, any idea where I could get review or people that have experienced using the LF MUST inverters.

T1 Terry
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Re: Is anyone using an arc welder with an offgrid system

Post by T1 Terry » Sat, 13 Apr 2019, 15:44

Never heard of the MUST inverters so no information or experience with them. The Projecta intelligent inverter checks the incoming 240vac wave form to ensure it is clean and the correct frequency and voltage. It will test load it and see if it can supply the required load while maintaining the clean wave form, frequency and voltage. Only then will it switch the power through and stop being an inverter. It constantly monitors the incoming supply and if it isn't happy with it the inverter switches back on and the supply ignored. At the same time it switched the earth/neutral link off if it senses an earth/neutral link on the supply to prevent any upstream RCD's from tripping.
As far as the big inverter trying to power the high loads, they are wired on the supply before the small inverter, if the big iverter is not switched on then they will have no power supplied to them.
Very smart pieces of equipment, the price reflects that, super reliable, well the 12v units have been anyway, never had one fail and they often get an accidental overload when the hot water is switched on and a second high draw load is added, the RCD on the supply trips because of the over load and the inverter tried to carry the load, it screams an alarm but if it is within its 100% overload limit it will power it for a while, then shut down if the overload is not removed. They will start up and run the roof top air con units fitted to caravans where a Honda IE2.0 won't and power a 2400w kettle till it boils, but it does sound the alarm after a few mins.

T1 Terry
Green but want to learn

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Re: Is anyone using an arc welder with an offgrid system

Post by doggy » Thu, 02 May 2019, 07:35

If you look on AliBaba, I am quite sure you will find inverters that look identical to the MUST inverters.

I have been snooping around LF inverters and am buying a 5,000W/VA unit with claimed 15kW surge capability. This is the RP5000 unit. I believe it uses a toroid rather than iron core xformer. It must be quite large because the weight is around 40kG. I am quite prepared for it to be a dud but might be pleasantly surprised.

I'll let people know how it goes but mainly want it for charging Zoe from 24V AVASS battery set up and my own BMS/Charger.

But I am not sure I am going to try it on my 200Amp TIG welder which can pull 4kW on max.

https://www.alibaba.com/product-detail/ ... 32ecbPxyFR

Cheers,
Dave

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