Is anyone using an arc welder with an offgrid system

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

Post by hary » Thu, 02 May 2019, 13:19

You should have ask if it has toroid transformer or EI iron core transformer because it can make a big difference in power ability/weight, toroid are supposed being much more better in the ratio power/weight.

Plus one of the problem with all inverter but worst with LF inverter is the no load consumption. It can easily go from 50 to more than 190W for the LF EI style transformer inverter !

I finally got the information from MUST after struggling for quite some time to get the info. Of course, you won't see it in any datasheet !

From the link you provide, we can see some photo of their assembly line where I think we can see transformer (no sure), but they don't look toroid.

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

Post by doggy » Thu, 02 May 2019, 13:39

Hi, the model I am getting has a toroidal transformer.

I am well aware of the differences between transformers, their efficiency and the use of the leakage reactance in the EI transformer models to provide HF filtering plus the losses.

The one I am getting has a standby drain of 1.6 to 2amps. So they say. The inverter will only be on sometimes (in my case) so this really does not bother me.

I found a number of inverters on Alibaba which looked identical to the MUST inverters but I am glad you were able to obtain specs. There are mixed reviews on various YouTube videos. However, quite a percentage of those people do not know what they are doing and have quite primitive electronics knowledge.

Separately, I am buying some big toroids (around 1.5 to 2kVA) and looking at the specs of the even bigger ones (5kVA) they weigh about 35-38kg. So, if my 41kg LF unit does not have a toroid that big, I shall be very suspicious of the real power.

The long thinner LF inverters do not seem to weigh enough to have a decent toroid and quite possibly cannot output the power they claim. This seems to be a common theme on YouTube. People seem to blow up the long thin HF inverters quite regularly.

I have successfully designed inverters to several kilowatts and PWM chargers to 1500W and have certainly blown up plenty of MOSFETS, IGBTs, drivers and so on during development. When you are switching dozens of amps in 10nSecs it does not take much stray inductance to kill a lot of stuff.

Good luck!

Regards,
Dave

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

Post by hary » Thu, 02 May 2019, 19:09

For me, LF inverter are the type to chose when you have big inductive loads like motor.

In that case you mostly need high starting capability, (high surge current) for short time.

Once the device has started, the load goes down back in the inverter's spec.

Plus most of the power tool will run for some minutes only, so a transformer can take bigger load for short period.

I would think : For stable in time load => go for an HF inverter
For short period of high/inductive load => prefer LF inverter

That's what I learned from reading and searching a lot on inverter

What are you up to do with the other toroid transformer you are buying ? Where do you get them from ? Are they new or reclaimed ?

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

Post by doggy » Fri, 03 May 2019, 17:15

This LF beast has arrived.
https://www.alibaba.com/product-detail/ ... 32ecbPxyFR
Standby current 1.3A at 24V (not on eco mode). So 32W pretty good. 35W claimed.
Book is well written and comprehensible.
Has a 75A charger. About 8 battery profiles incl custom. But I will not be letting the charger touch my lithiums other than a bit of gentle testing.
The toroid is massive and at least 37kg of the total 41kg. Toroid 240mm x 120mm.
Internal bus bars are substantial.
Approx 30 MOSFETS of TO220 size on substantial heatsinks.
All wiring nuts and bolts etc neat, snug and tight.
I'll report how it goes and if indeed if it can crank out 5kVA continuously.
I won't be using the charging nor the ATS functions.
Also I probably won't fire up the 200A TIG on it because I am not using it for that wort of work.
It also has a comms interface and remote control but no idea what the comms are or if even operational. At some time I'll do some snooping.
This thing is much bigger and heavier than the long rectangular 5000W LF inverters.
Freq stability good so far. +- approx .01Hz but that is lightly loaded.
My oscilloscope is too far away to check waveforms yet.
Cheers,
Dave

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

Post by hary » Fri, 03 May 2019, 19:32

Could we get some photos of the inside as you already broke the "warranty void if removed" sticker !

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

Post by doggy » Fri, 03 May 2019, 19:51

There was no sticker.
lf3.jpg
lf3.jpg (1.26 MiB) Viewed 1081 times
lf2.jpg
lf2.jpg (1.44 MiB) Viewed 1081 times
lf1.jpg
lf1.jpg (1007.7 KiB) Viewed 1081 times

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

Post by hary » Fri, 03 May 2019, 20:17

Well, thank you very much for the photos !

It looks a big transformer indeed !

How much did you pay ?
How much for shipping ?

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

Post by doggy » Sat, 04 May 2019, 13:05

It was under $800 incl (free) shipping which was very fast.
I did not buy it from China. I put the photo into "Google Lens" and found a local company "Bit Deals" had them.
I have now tested it on a couple of heaters with fans and motors which turn them. Got it up to 4,900+watts briefly while the heating elements were cold.
I was pulling 200amps DC at that stage.
PF was almost 1 so VA and watts almost identical.
Have not even got it warm yet and air from the fans is not detectably warm.
I have measured the efficiency at 2 and 3.8kW. In each case it was 95%, which is slightly better than the 91% max spec and better than I expected. I was measuring the DC volts at the inverter terminals because I was losing a couple of hundred millivolts through the cables, one of which is crimped and the other soldered. They were getting warm.
AC volts and freq did not budge between no load and 3.8kW nor did freq which was 50.010Hz throughout. Display is pretty accurate. Freq spot on. Voltage display 239 vs 237.6 actual. DC volts about 200mV different. It would be nice if the display showed DC amps but it does not.

The retailer does exclude welders and bore bumps of a certain size even though there is no mention on the OEM site. So I am not going to try it. However I suspect an inverter welder would work just fine. I have seen a YouTube video of a guy welding with a physically smaller but allegedly 5KVA "PowerJack" LF inverter which certainly has a smaller transformer inside (I've looked at the user manual). That device does have the benefit that you can buy replacement boards for it if you blow something up. Apparently earlier PowerJack inverters had a somewhat chequered reputation.

I had a large Victron on my barge in France for 8yrs and so far this thing is performing as well at a fraction of the price. However, there was no doubting the Victron's excellent quality and performance. I had a 200A DC motor-generator-welder on board so I cannot comment on how the Victron would work with a welder. However I had friends who DID use welders on the Victrons without problem.

My next test of this thing is going to be charging my electric car at around 4,800-5,000VA.

Regds,
Dave

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

Post by hary » Sat, 04 May 2019, 15:24

doggy wrote:
Sat, 04 May 2019, 13:05

I had a large Victron on my barge in France for 8yrs and so far this thing is performing ....

My next test of this thing is going to be charging my electric car at around 4,800-5,000VA.

Regds,
Dave
Dave, where are you ? I thought you were from Australia but here you're talking about France. I'm from Perpignan France myself.

Well, at around 4,800-5,000VA for long time charging I guess, you'll see if the thing outputs what it claims !

But would be nice to have some test with power tools like circular saw, compressor, air conditioner that are usually quite hard to start.

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

Post by doggy » Sat, 04 May 2019, 15:45

I am in Australia now.

We owned a small péniche in France for nine years but sold it last year. She was 115 years of age, 38 tonnes, 18metres x 4.4metres with two levels. So plenty of space. We travelled throughout France as well as Belgium, Netherlands and some Germany. We spent approximately 6 months in Australia and 6 months (largely) in France each year. Donc, éte et éte! The Victron inverter ran 24/7, with 1200AH Victron AGM batteries. It ran angle grinders, pumps, pressure washer, large circular saw, orbital sander, belt sander, vacuum cleaners, microwave, washing machine, refrigerator etc. No problems! I would have used an arc welder with it but had no need. It was more robust that the Grid! It also had ATS for shore power and/or generator plus the ability for the inverter to sync with shore power and give us about 7,500W of ptotal ower. It was also possible to set the shore power limit (in amps) with the inverter supplementing the difference and the battery charger using up any spare shore capability to keep the batteries charged. I added solar and MPPTs last year.

So, if I was setting up an off grid system and could afford it, I would buy Victron again.

My car is a Zoe.

Cheers,
Dave

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

Post by doggy » Sat, 04 May 2019, 16:53

Waveform is quite good. I have tested the current waveform at low load, 2.2kW and 4.2kW and briefly 5kW.

There is no visible distortion at zero load, or 1.0kW. There is a tiny amount at 2.2 kW- barely discernible.

There is a small amount of distortion at 4.2kW. Basically a few small artefacts. I would estimate no more than a few percent THD at 4.2kW -> 5kW.

Certainly I have seen much, much worse than this. Indeed, I cannot think of anything that would "mind" the waveform.

Cheers,
Dave

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

Post by doggy » Sun, 05 May 2019, 11:16

Given this is about welding with an offgrid inverter, this is a little out of place.

However I have just completed almost an hour of testing charging my Zoe at 20 and 21 amps. Power factor was very close to 1. The inverter had no problem at 4.8kW nor at 5kW. I ran it at 5.5kW and after half a minute (as predicted by the user manual) I started to get warning beeps about overload. Output voltage and frequency showed no droop.

200+ amps was warming the input cables (35mm2) which dropped about 300mV, so about 32watts per cable. I'll upgrade them to 68mm2. The inverter remained cool as a cucumber.

For interest, it can only maintain 15kW for about 1 or 2 seconds- but useful for motor starting.

So overall I am very happy with this inverter. I measured 93% efficiency at max continuous output, which is 5kW.

The only negative so far is that the fans (which come on at high load) are quite noisy.

I did add a MEN link externally to the output block. By the way, this output block is quite generous and fine with 6.5mm2 wire.

Cheers,
Dave

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

Post by doggy » Mon, 06 May 2019, 16:14

Final test.
Charging.
Set it for Lithium and I was able to set a max voltage which, when reached, stops the charger.
Can also set a low volts value to start charging.
Delivers slightly more than the specs.
Max was a continuous 80amps at 88% efficiency. Claimed max 75A
Efficiency at 55amps was 90% (set for 50amps).
When set on 25amps, efficiency still 90% and actual amps 27.
So, all in all, pretty good.
Regards,
Dave

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

Post by hary » Tue, 07 May 2019, 06:19

Hi Dave

What kind of BMS do you have for your Lithium cells ?

Did you try some inductive load on it ? Like a compressor or high pressure cleaner, something with an induction motor as they seem to be the worst to start ?

I got in touch with a Chinese supplier, the price seem good, but shipping to France with DHL cost a fortune.

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

Post by doggy » Tue, 07 May 2019, 11:50

Hi, I have not tried it with such a load. However they claim you can start a 1.7HP motor without problems. That's a 1.3KVA load with a likely startup of 9kW.

My BMS is my own design. It is running on my other battery which is a 26V 180A CALB bank. The charger is AC with an (almost) lossless ideal diode bridge using big MOSFETs, a 16kg laminated iron transformer, my own (98.5% efficient) buck converter with current and voltage control. This is a three phase unit but I am only running two phases and max 40amps at the moment. If I can get one at the right price, I might replace the transformer with a toroid. However this big one is pretty good with very large and conservative windings and a huge core. I had to put in a slow startup for it as otherwise the startup surge with 160,000uF capacitor bank on the MOSFET bridge pulled a 30amp surge from the mains popping the 20A breaker. So now I turn it on by cycle skipping until the capacitors charge a little.

The unit tracks my excess solar and only charges when there is excess solar and switches on the battery when insufficient solar- to run all the computing equipment including CCTV and servers in my house.

I am building a second charger which will work the same way, will add the third phase and use a toroidal transformer giving me 55-60A into my AVASS battery bank which is 26V x 460AH. I am currently waiting for new BMS boards which are identical to the ones I made for the CALBs but I had to shorten them to fit the different cell spacing on the new cells. I have also changed the bleed resistor configuration to give me 2 amps versus 1.2A for the CALBs. The AVASS batteries are from the failed electric bus project and you can read about them elsewhere in this forum. I'll not be using the inverter charger because even though you can change the max output current in 5A increments, there is no comms interface which I would need to automate the process and track the solar. This unit will only run when the first system is at maximum and there is further excess solar. The 9pin connector on the inverter does not seem to be connected and I think there might be a separate optional PCB for this.

Regards,
Dave

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

Post by doggy » Tue, 07 May 2019, 19:24

Hi Hary,
The other problem you have is import duties, tax and handling fees. I spent half of each of the past 8 years in France and twice imported things and the additional costs (on top of DHL) were a real killer. Have you tried a photo of the inverter using Google Lens to see if someone in France might be importing them (in quantity, by ship) thereby significantly reducing the on-costs? That's what I did in Australia because the DHL cost would have been very high even to Australia.
Cheers,
Dave

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

Post by hary » Wed, 08 May 2019, 00:20

Hi Dave.

No I didn't try google lens. I didn't even know about !

I tried to figure out how to use it but didn't yet understand if I can use it from my laptop or if I need an Android phone to use it. It's very unclear !
I have an Iphone but need IOS11 I think and I'm on version 8. Then I must upgrade the phone from Itunes by connecting the Iphone to a computer, but my computer runs linux ! So now I'm trying to run Itunes with Wine or PlayOnLinux.

Are you still satisfied with the inverter ? Today I've been in touch with a Sumry sales man.I need to check once more what has been said, but I might make my mind to buy it.

He said the 6000W model would start a 4.5HP air conditioner. Deduction from that they made a 1.5HP air conditioner start on a the 2000W version.

Have you an idea what is the chip on the controller board ? Maybe a 8010 chip on an EGS002 control board ? Or a uC STM32..... something ?

I sometime got away from custom duties with some product from China, but you never know ! And when they catch you, it's very expensive.

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

Post by doggy » Wed, 08 May 2019, 03:47

Sorry, I use Android and Linux.

Also, I do not know what microprocessor they use. I would have to take out more boards to see and I do not want to do that.

I agree the 6kW unit might be best for your needs. It is not available in Australia but I would have bought it if it was available. I assume you are using 48volts? I am at the limit of my lithium cells (with 220amps) and my 26V bank and need 65mm2 cable and every connection very solid.

I am still happy with my unit. The only negative is that the fans are very loud when they run so mount it where the sound will not worry you.

Best Regards,
Dave

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

Post by hary » Wed, 08 May 2019, 05:51

I'm on 24V, 8x160Ah WINSTON LiFeYPO4 cells with Electrodacus SBMS http://electrodacus.com/

For best temperature, I have the battery in the house, and to get as short cable as possible to the inverter, I'll probably install the inverter also in the house.

But I should only need the inverter when working with power tools, so, not so often. Maybe 15 minutes from time to time.

Most of the house is on 24V (light, internet box, laptop ....)
I think the 5kW would be enough for my use.

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

Post by doggy » Wed, 08 May 2019, 10:14

Hi Hary,
Sounds good.
I have 35mm2 cabling at the moment but am upgrading it to 75mm2 because 220amps is a bit much for 35mm2. This is to feed the inverter.
Cheers,
Dave

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

Post by hary » Wed, 08 May 2019, 15:26

Well, 220A on 35mm2 cable means 6.3A/mm2, not so bad, but of course in 24V, if you have some distance, it can still have drop in voltage.
Of course the bigger the better.

Do you have a mechanical power ON/OFF switch on the inverter ? So it can easily and remotely be controlled by paralleling the switch to another place or even with a uC control device ?

Do you have any safety protection on your input circuit ? Circuit breaker or fuses ?
I'm not used to these big current ! 200A at full power, maybe 600-800 or even more with high inrush current / inductive loads !
I'm even more afraid with these very low internal resistance lithium battery !

By any chance, as an experienced man, have you ever had to deal with solar water pumping ?
I'm seeking a DC24V, low power, low flow, 30m lift reliable water pump.

For some year, I've been going with some brushed DC diaphragm pump like this one :
http://www.seaflo.com/fr-fr/product/detail/5550.html
but they are not reliable for continuous duty cycle.

I'm thinking going with one of these kind of brushless DC screw pump :
https://fr.aliexpress.com/store/product ... c22RaH7bq
Of course they are well pump, which is not the best for me as I'm pumping in a shallow creek !

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

Post by doggy » Wed, 08 May 2019, 15:54

Hi Hary,
35mm2 is okay but gets quite warm.
I have a 200A contactor between the inverter and battery. This is controlled from a FET in my BMS. Uses about 200mA when on. The BMS will cut off the inverter if any cell goes too low ( at the moment I stop at 2.9V but I might reduce that to 2.7V under load).
I also have a 250A breaker with mechanical switch between the battery and the inverter.
I have 10A fuses to other switched, low power, 24V equipment.
I have a quick blow fuse between my ideal diode rectifier and the triphase buck converter.
I have a slow blow fuse on the transformer.
I have another overall slow blow fuse on the overall AC mains input.
I have a 32A Triac on the AC input to the transformer with full wave triggered control.
I have two uPs watching over everything, with watchdog timers. Both monitor voltage. Most of the A/Ds are 12bit so lots of precision with precision voltage reference chips and dividers.
If either uP stops hearing from the other one or from the BMS modules on the cells or voltages or currents are wrong or inconsistent then things shut down. There are two ways to shut down loads and two ways to shut down charging so that is all reasonably failsafe.
I do cycle stealing/dropping when I turn on the transformer. Something like one cycle on, three off, one on, two off, two on, one off then all on. This stops big startup surges.
I also have a fast blow fuse on the Buck drive-current supply.
The BMS modules run off the cells. All the other logic runs off 240V but I have a switch to run everything off the battery if there is a power failure.
Regards,
Dave

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

Post by doggy » Wed, 08 May 2019, 16:21

Sorry, no experience with solar driven pumps. For my solar hot water (32 evacuated tubes) I use a small 30W 240V pump. Also have a big several HP Grundfoss to lift water from a 5,000litre tank to the top of our property (about 30meetre lift).
The Aliexpress pump looks nice.
Cheers,
Dave

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

Post by hary » Thu, 09 May 2019, 01:57

doggy wrote:
Wed, 08 May 2019, 15:54
...
I have a 200A contactor between the inverter and battery. This is controlled from a FET in my BMS. Uses about 200mA when on. The BMS will cut off the inverter if any cell goes too low ( at the moment I stop at 2.9V but I might reduce that to 2.7V under load).
...
Dave
Do you cut off the inverter from the 200A contactor ?
Is there not a power ON/OFF switch on the inverter you could "hack" ?
I wonder if this 200A contactor will resist ? In case the contact got welded, you'll have no control on load and might deplete and destroy your battery !

You say there are 2 ways to shutdown. One is the 200A contactor. What is the other ?

When you say transformer, are speaking about the ZOE's charger ?

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

Post by doggy » Thu, 09 May 2019, 05:36

I will normally use the inverter switch on its remote control. This also has a simple set of contacts which I can control from a small relay without touching the inverter itself. However I am not doing this now. You could do it very easily if you get one. The remote control gives access to the contacts without undoing anything.

The contactor is there as a safety device, not to normally turn the inverter on/off. That is, it is to isolate the battery when the inverter is not needed.

I also have Triac control on the mains input.

The transformer I mention is on my lithium charger- nothing to do with Zoe.

By the way, in France, I built a slow start box for use with my Victron. I had a big 3.5HP vacuum cleaner which the Victron would not start- it would pop the breaker or suffer an overload fault. The slow start box contained a uP which drove a phase controlled triac and gave a 6secs startup. I used it for 7 years and the new owners are still using it. Good for motors but not good for transformers.

Regards,
Dave

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