Lipo for kweld/malectrics spot welder

Trying to setup a spot welder for my first battery build.

I can only pickup batteries from this site - https://www.canadahobbies.ca/product/hobby-brands/powerhobby/3s-111v-7200mah-100c-200c-lipo-battery-w-xt90-plug/

I contacted malectrics and they said the battery may work but it also may be too much power "That’s a very strong Lipo battery. The welder is rated for a current of up to 800A welding current. If this battery really can do 200C it would be 200x7000mAh = 1400A. If it does 100C it’s only 700A which would be ok.

The welder will not immediately fail when using a too strong battery but if you do many welds with it the components could fail after a few hundred welds."

waiting for a response from kweld but can anyone reccomend a battery from this page that would work with these spot welders? https://www.canadahobbies.ca/category/lipo-batteries-canada/lipo-3s-batteries/

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I put 2 of these in parallel and it wasnt an overcurrent for the Kweld. Not sure about their C rating, I think its either 20 or 25C.

Could not access CanadaHobbies.Ca from my browser for some reason. Got the same error message thru firefox and waterfox. But what I can tell you is those C ratings are often highly exaggerated. Especially in that case, there is no way a 3s 7,200mah lipo will ever hit 100c for more than a millisecond before turing into a small fire or not so small explosion.

You’ll most likely either be ok with just one of those or you might have to put 2 in parallel like I did to get above the Kweld’s undercurrent rating.

Or just get a larger lipo.

Both vendors had the same issue with accessing the page, You can access it with a VPN.

I’m So ready to pull the trigger on the batteries and supplies i need but this lipo battery situation is turning me off, impossible to find ANYTHING

This is the only battery on there site that comes close to what I need that isn’t 150-190$

So i just buy 1 and hook it up? This is the rest of the message from malectrics:

The welder will not immediately fail when using a too strong battery but if you do many welds with it the components could fail after a few hundred welds. So you could take this battery and test with one weld how much current you really get with it. The welder will display the current if you keep the foot switch pressed after the weld or keep the welding tips at the nickel strip for a few seconds after the weld.

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Um, yeah. I wouldnt listen to that advice, rather heed the instructions given by the manufacturer of the Kweld. If you cant get past the setup and the battery says overcurrent, dont use it. You can damage the Kweld that way.

Is it possible to order from Hobbyking.com? They have both international warehouses and locations in the US and Europe. A 3s 10ah pack would be more than sufficient IMHO.

Now about that Kweld. Heres is a rather lengthy but worth the read thread. The OP is also the guy who designed the product and he checks the forum often for questions. Just make sure to read thru so you’re not asking for info thats already been discussed.

https://endless-sphere.com/forums/viewtopic.php?f=14&t=89039

Also check out the classifieds over on RCGroups.com or maybe post a WTB ad. Just keep in mind that there have been a lot of scammers lately, so beware of any brand new accounts with little activity and no feedbacks. And never do a deal off site or pay thru Paypal using the Friends & Family option.

Shipping LiPOs across the US Canada border is difficult if not impossible these days so be sure to mention that you’re looking for a seller inside Canada.

The battery recommended by kweld and malectrics is " nano-tech 3S/5000mAh/130C " which is sold out at the USA location. If i try to checkout with the in-stock EU i get a dangerous goods message at checkout

Cant afford the kweld but both reccomend the same battery, which is impossible to find. Not sure about using the others on the list, honestly makes me scared to deal with lipos… I also have to find charger.

Kweld reponse to the same question was “Although from the description of the batteries I’ll answer. The first battery is a bit too powerful and you can use it while it’s not completely charged, although I prefer not to risk it. About the second link 3s LiPos will certainly work without a problem”

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Doesnt have to be that exact lipo. Any 3s lipo with a similar capacity in amp-hours will do as long as it has a good actual C rating. Chargers can be found used on the Rc hobby forums for not much money or new if you want.

All the ones ive seen on amazon comes with XT60 instead of XT90 adapters.

I see, upon first searching i was trying to match the C rating with the highest i can find, didnt know more is bad. Alot of ones I think would be a good option are out of stock.

Im finding some 6000mah/100c but they are all out of stock. my only choice was the 100c-200c i initially linked for $128

These are the only ones i can find on canadahobbies https://imgur.com/a/NLDp3Sf

Would the car battery be a better option?

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75C or better is plenty as those C ratings are typically exaggerated. In the real world if you hook up a battery tester like this one:

you’ll find they have a real world C rating of maybe 25 to 35C, tops.

While a car battery would work, keep in mind they only last a few years and the ones that arent sealed put out fumes when charging and need to be stored and charged in a well ventilated area.

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Thanks for the info.

going off the math 7200mah x 75c = 540A, malectrics’ exact wording ‘should be able to supply around 600A of current.’

Really my option out of those 4 is the first image; 7200/75c

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That one might be ok. But I dont want to say go ahead and get it just to have it end up being sub-par. Have you researched what packs other people are using for the Malectrics spot welder? I’m not familiar with that one, just the Kweld.

The first 4 comments say it all but this whole thread and others like it are worth reading. I’d consider a larger capacity (amp hours) pack even if you have to buy one used.

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I haven’t as i just been looking for vendors that have lipos in stock, then narrowing down exactly what I need to find.

https://malectrics.eu/v4-lipo-battery-bundle-assembly-instructions/

Quickstart - Arduino Spot Welder Quick Start Guide V4 - Malectrics

  • Lipo battery: 3s 5000mAh with minimum 60C (Hobbyking Lipo or SLS Lipo)
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Oh, well in that case go with what the manufacturer recommends. Sorry but my head is stuck in Kweld world and that single 3s 7200mah pack I mentioned did give me an undercurrent warning. So I had to fab up a parallel harness and use 2 of them.

I really hope they ease up on the cross border restrictions soon. Its silly that we can mail batteries all across our own countries but not over a somewhat imaginary line on a map. I get it that just one lipo out of 100s of thousands going up in flames while on a cargo plane can become a huge problem really fast, but we should have ground shipping options across the border.

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I may actually pick up a 2nd hand kweld instead.

i was recommended this battery? https://hobbyking.com/en_us/graphene-5000mah-3s-75c.html?queryID=ad41839bde7a382da70ebcaa04e202d4&objectID=75672&indexName=hbk_live_products_analytics

Same 75c but lower mAh than the this one i was lookin at

Also what is the cheapest charger I can get away with? All these chargers mention XT60 but my lipo uses a XT90, im confused as they’re all made like this?

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Thats just the charge adaptors, they’re all banana plugs on the charger side. New (and used) chargers should come with at least a few of each of these to get you started. I just make my own since I’m handy with a soldering iron.

https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Fimages-na.ssl-images-amazon.com%2Fimages%2FI%2F71u1yVMiYBL.SL1500.jpg&f=1&nofb=1

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Was recommended this charger for that battery.

I assume this has the required adapters to hookup the XT90 ?

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I see. i always need stuff in hand to figure it out but thanks for the confirmation

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I only see an XT60 in that squid connector. So either buy an XT90 charge adaptor or chop off one of the plugs you wont end up using like the Tamiya plug and solder an XT90 on.

Protip: get the anti-spark XT90s or the regular XT90s with the 1/2 cups on the ends and the bullets already installed. Then when you go to solder make sure you’ve got both a male and female connector (not connected to a battery, lol) connected together so the heat from the soldering iron doesnt deform the plastic housing making the connectors more difficult.

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This was in my cart of stuff i was buying

https://www.amazon.ca/gp/product/B074PTHZ3M/

Thats what I had in mind but didn’t think it was safe since im putting on a connector that draws more power?

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Its not the connector that draws more power. You could put an XT150 on there and it wouldnt change the amount of watts or amps your system uses.

Just to dive into electrical engineering though, wires and connectors do act as capacitors so if you were using some huge 2 gauge wires (thick as your thumb) when you connect them they would have to fill with current and that would make a slightly bigger spark.

+1 for anti-spark connectors. Your speed controllers will live longer. Hopefully. :slight_smile: