kWeld - "Next level" DIY battery spot welder

[tatus1969]

€7,200 for 2 weeks ? I'm in the wrong business !

That's a 90€ hourly rate for an experienced (26yrs) freelance electronics design service. That's an average to below-average rate, considering that this also includes me running a lab and small-scale manufacturing facilities.

[tatus1969]

Thank you very much for your time, I did not think the redesign could be so expensive. I understand all the work you can have, but that is almost the price of a new 125 ADP (8021€), so it's not worth it.

I will keep you in mind for other projects that can not be obtained directly in the market!

Regards.

I'm with you. When I was writing your answer, it became apparent that this design effort would make sense if the invest can be split across a small series production, but doesn't sum up for a one-off. I'd be happy to work for you in the future. I usually offer three different approaches: 1) fixed price offer like above, which means that the risk of having to solve unforseen problems or to go through necessary redesigns is at my side - and therefore I have to make a conservative work estimate. 2) hourly payment, which can be significantly cheaper if a project runs smooth but requires trust from an existing relationship. 3) if a customer wants me to run series manufacturing of the developed component or unit, and agrees to let me do this exclusively for a certain period, then I'm generally willing to distribute part of the project cost across an agreed number of first units.

[yngndrw]

€7,200 for 2 weeks ? I'm in the wrong business !

That's a 90€ hourly rate for an experienced (26yrs) freelance electronics design service. That's an average to below-average rate, considering that this also includes me running a lab and small-scale manufacturing facilities.

I love your work, have purchased your products and I'm really happy with both how they work and the value of them - But let me just put that design service into perspective.

I'm a Principal Software Engineer (Which is really the same kind of work just in a different industry: A lot of design, research and problem solving) with 8 years of commercial experience plus a load of experience as a hobbyist before that. I also work for a large international company so that changes the figures, but let's talk ballpark here - My hourly pay is about £26 / hour and I thought I was paid reasonably. I appreciate that fee also includes general costs such as national insurance or whatever equivalent you have in Germany and you need to charge extra to ensure that you cover the gaps where you're not being contracted to do any design work, but the components and manufacturing in your quote were separate so it's really just your time that's covered as it is in mine.

So as I say, I really am in the wrong business if that's typical !

[CM800]

€7,200 for 2 weeks ? I'm in the wrong business !

That's a 90€ hourly rate for an experienced (26yrs) freelance electronics design service. That's an average to below-average rate, considering that this also includes me running a lab and small-scale manufacturing facilities.

I love your work, have purchased your products and I'm really happy with both how they work and the value of them - But let me just put that design service into perspective.

I'm a Principal Software Engineer (Which is really the same kind of work just in a different industry: A lot of design, research and problem solving) with 8 years of commercial experience plus a load of experience as a hobbyist before that. I also work for a large international company so that changes the figures, but let's talk ballpark here - My hourly pay is about £26 / hour and I thought I was paid reasonably. I appreciate that fee also includes general costs such as national insurance or whatever equivalent you have in Germany and you need to charge extra to ensure that you cover the gaps where you're not being contracted to do any design work, but the components and manufacturing in your quote were separate so it's really just your time that's covered as it is in mine.

So as I say, I really am in the wrong business if that's typical !

It's not far off.

Admittedly, we have a drives manufacturing company we have worked with before, they contract @ 75 Euros an hour.

If your company was to contract you out to another company, you can generally expect them to charge that kind of rate.

The average machine shop charges around £60 per hour for shop time / engineering hours too, though the employee is going to be paid less, the rest of that goes to the companies profit, the lighting, electric, equipment, insurance etc. etc. etc.

The company would need to have savings, imagine if their place burnt down, they'd be out of business, or say their oscilliscope died, they would have to spend out potentially 10k+ or even more for a new one, let alone P&P  machines / reflow ovens. All that cost goes into covering the cost of the machines, in perspective it makes a lot of sense.

[bernieke]

€7,200 for 2 weeks ? I'm in the wrong business !

That's a 90€ hourly rate for an experienced (26yrs) freelance electronics design service. That's an average to below-average rate, considering that this also includes me running a lab and small-scale manufacturing facilities.

I love your work, have purchased your products and I'm really happy with both how they work and the value of them - But let me just put that design service into perspective.

I'm a Principal Software Engineer (Which is really the same kind of work just in a different industry: A lot of design, research and problem solving) with 8 years of commercial experience plus a load of experience as a hobbyist before that. I also work for a large international company so that changes the figures, but let's talk ballpark here - My hourly pay is about £26 / hour and I thought I was paid reasonably. I appreciate that fee also includes general costs such as national insurance or whatever equivalent you have in Germany and you need to charge extra to ensure that you cover the gaps where you're not being contracted to do any design work, but the components and manufacturing in your quote were separate so it's really just your time that's covered as it is in mine.

So as I say, I really am in the wrong business if that's typical !

There's a few things to cover here:
1) I doubt your £26 figure is the cost-to-company. In my case I receive about 40 euro gross (programmer with 13 years professional experience), which amounts to 24 euro net after taxes, but my employer also needs to pay taxes on top of that, which puts his cost for me to 50 euro per hour.
2) You get paid vacation, holidays and sick leave. Add another 12.5% to cover this. We're up to 56.25 euro per hour.
3) As a short term freelancer you're usually spending about half your time working, and the other half doing administration, looking for work, networking, negotiating, ... So double your hourly wage, and in my case I'd be at 112.5 euro per hour.
4) Office space, desk, chair, computers, office supplies, heating, electricity, hospitalization insurance, ... Let's make it an even 120 euro per hour.

Now if you're going to freelance long contracts (3-12 months with the same employer), that rate will drop a lot. Experienced freelance programmers will usually get around 500-650 euro per day for longer contracts, which amounts to about 60-80 euro an hour depending on experience, specialization and project.

So no, you're not in the wrong business, you just didn't realize the realities of a freelancer

[Terry01]

Pfft!

120 euro an hour.... wouldn't get out my bed for that!           

[Kjelt]

I'm a Principal Software Engineer (Which is really the same kind of work just in a different industry: A lot of design, research and problem solving) with 8 years of commercial experience plus a load of experience as a hobbyist before that. I also work for a large international company so that changes the figures, but let's talk ballpark here - My hourly pay is about £26 / hour and I thought I was paid reasonably. So as I say, I really am in the wrong business if that's typical !

You miscalculate. I have the same job as you with 20+ yrs of experience and get the same salary +/- €30/hour before taxes.
I first was hired through another company that charged €85/hour, I still got €28/hour back then. The calculations you are missing are:
- pension contribution
- taxes ( I pay 45% income tax, in Germany it will be high also, in the UK I believe it is 25% so price yourself lucky)
- insurance (extremely expensive for a single person company so many don't do it)
- risk (if there is no job you need to have some green on the bank)
- time to network, advertising (get new clients)
- location (housing prices etc.)

If tomorrow your boss asks if he can hire you as a private contractor and you do all the math you will also end up in the high €80's.
You can get over 150k$ in silicon valley tomorrow if you are good and want it, but you end up sleeping in a cheesy motel since apt's and houses are not affordable even with that salary.

[tatus1969]

€7,200 for 2 weeks ? I'm in the wrong business !

That's a 90€ hourly rate for an experienced (26yrs) freelance electronics design service. That's an average to below-average rate, considering that this also includes me running a lab and small-scale manufacturing facilities.

I love your work, have purchased your products and I'm really happy with both how they work and the value of them - But let me just put that design service into perspective.

I'm a Principal Software Engineer (Which is really the same kind of work just in a different industry: A lot of design, research and problem solving) with 8 years of commercial experience plus a load of experience as a hobbyist before that. I also work for a large international company so that changes the figures, but let's talk ballpark here - My hourly pay is about £26 / hour and I thought I was paid reasonably. I appreciate that fee also includes general costs such as national insurance or whatever equivalent you have in Germany and you need to charge extra to ensure that you cover the gaps where you're not being contracted to do any design work, but the components and manufacturing in your quote were separate so it's really just your time that's covered as it is in mine.

So as I say, I really am in the wrong business if that's typical !

It's not far off.

Admittedly, we have a drives manufacturing company we have worked with before, they contract @ 75 Euros an hour.

If your company was to contract you out to another company, you can generally expect them to charge that kind of rate.

The average machine shop charges around £60 per hour for shop time / engineering hours too, though the employee is going to be paid less, the rest of that goes to the companies profit, the lighting, electric, equipment, insurance etc. etc. etc.

The company would need to have savings, imagine if their place burnt down, they'd be out of business, or say their oscilliscope died, they would have to spend out potentially 10k+ or even more for a new one, let alone P&P  machines / reflow ovens. All that cost goes into covering the cost of the machines, in perspective it makes a lot of sense.

When you work self-employed in Germany, the goverment takes away roughly 35% of everything that you earn. Health insurance takes away another 750€ every month. Before I decided to start this new journey last year, I was in a leading position at ~45€/hour. It is okay and I don't regret my decision in any way, but we have quite a lot less money now to spend at the end of the day.

[yngndrw]

Sorry to take this thread so far off topic, but it's a really interesting discussion - It's not often that pay is compared across industries, let alone across countries and employment vs self-employment.

For myself, pension and taxes are also taken out of my figure so I'm quite far behind - It looks like I should stop working hard to put money in the pockets of my employers and instead work hard to put money in my own pocket even with the considerations you all raised so thank you for opening my eyes to that one !

tatus1969: Don't feel bad about your health insurance. We get "free" health care (We still pay for it in hidden ways) which is fine if you break your arm while drinking, but if you have a serious condition you often don't end up getting the care you actually need - You get what you pay for at the end of the day and if your health care is anything like you cars, need I say more.

[tatus1969]

Sorry to take this thread so far off topic, but it's a really interesting discussion - It's not often that pay is compared across industries, let alone across countries and employment vs self-employment.

If so, then it was me taking the thread off topic, by answering to the project inquiry here instead of switching to email or pm. But as I thought that this conversation could be interesting for others, I decided to go this way.

For myself, pension and taxes are also taken out of my figure so I'm quite far behind - It looks like I should stop working hard to put money in the pockets of my employers and instead work hard to put money in my own pocket even with the considerations you all raised so thank you for opening my eyes to that one !

The grass always looks greener at the other side of the fence (hope that this German idom translates). It's also hard to see how much money seeps through your fingers every month. That's more hidden when you are an employee. There are other reasons why I made this step.

One is pride. When making and selling your own stuff, you get much more direct feedback and appreciation (if you're doing it well  ). As an employee, I have never felt my monthly salary as rewarding or giving appreciation, and I can count the many times on one hand where my boss came to me and told me that it was great what I am doing. They can't do this because they need to be afraid that you get back on them wanting a salary rise.

Another is freedom. Even though I am mostly working on a contract basis with given timelines, I don't have this feeling anymore that a boss is waiting for you looking at his wristwatch throughout the day. That doesn't mean in any way that I am working less, in fact the opposite is the case, but I don't feel this tension that much.

tatus1969: Don't feel bad about your health insurance. We get "free" health care (We still pay for it in hidden ways) which is fine if you break your arm while drinking, but if you have a serious condition you often don't end up getting the care you actually need - You get what you pay for at the end of the day and if your health care is anything like you cars, need I say more.

I know, and I'm (still) happy with that I get for the money.

[tatus1969]

I've made finally found time to redesign the charger module for the supercapacitor / kCap. (https://www.eevblog.com/forum/projects/guesses-on-what-i-am-attempting-here/375/ - it's a shame but I had to go back 10 pages in this thread.)

I have just ordered components and boards to make test builds, and if I don't find any new mistakes I will run a first production batch.

The solution is very powerful and charges the ultracapacitor module with 70A, which allows for a very high welding rate. This might be overdone (and overpriced) for people who only use the welder casually, and prefer to use a weaker charger and accept longer recharge time. Therefore I'm thinking to split this into three different variants:
a) (65€) full power version with 70A (peak) output current. You need a specific HP server supply to power it (~20€ used at ebay)
b) (41€) low-cost version with reduced 35A (peak) output current, and without mating connector for the HP supply. This model is to be used with a standard 12V PSU.
c) (17€) optional heat sink kit. This is not included above, and allows a much higher continuous current.

I have to take measurements with the final design, but I think that the heat sinks won't be necessary for operation with kCap, as the average current draw is much lower than 70A even with intense high-energy welding.

Guys, please let me know what you think about it.

[carracing111]

It's great news  As soon as the  first production is finished, two for me, a) + c)

Finally I bought a Miyachi Unitek 100ADP at a good price (used), but I will also continue working with Kweld. Please, let me know when the Kweld software is modified to be able to use the delay function in manual mode, it would be very helpful!

Regards

[tatus1969]

It's great news  As soon as the  first production is finished, two for me, a) + c)

Finally I bought a Miyachi Unitek 100ADP at a good price (used), but I will also continue working with Kweld. Please, let me know when the Kweld software is modified to be able to use the delay function in manual mode, it would be very helpful!

Regards

I would be interested to know how kWeld holds up against this pro machinem, especially regarding weld consistence. Two-pulse-constant-timing versus energy-metering.

Please check the attached firmware, I just had to comment one line to make that work. It's now using the auto trigger delay in manual mode as well.

[carracing111]

Thank you 
Of course, when I have the new welder running we can compare results, if I can do some concrete test, you just have to tell me!
The biggest difference seems to be in the welding time, the 100ADP machine welds at a lower voltage, in a shorter time and at a higher current.

Regards

[tatus1969]

Thank you 
Of course, when I have the new welder running we can compare results, if I can do some concrete test, you just have to tell me!
The biggest difference seems to be in the welding time, the 100ADP machine welds at a lower voltage, in a shorter time and at a higher current.

Regards

I was a bit too quick with my firmware mod, this new one should work.

What I am most interested in is how my energy metering approach holds up against a professional system with fixed timing, with regards to weld consistency.

[oPossum]

kWeld assembly and use video by HB Powerwall (not me)

"This is by far the best 18650 spotwelder I've used to date, fast doesn't get too hot and consistent welds.  The end result would have looked much cleaner with new cells rather than recycled - but recycled cells works for me."

[Terry01]

kWeld assembly and use video by HB Powerwall (not me)

"This is by far the best 18650 spotwelder I've used to date, fast doesn't get too hot and consistent welds.  The end result would have looked much cleaner with new cells rather than recycled - but recycled cells works for me."

Well cool video buddy! 

[tatus1969]

Hi guys,

I've got some important news:
- I was out of stock during the last weeks - new boards will arrive tomorrow (I'll only add stock in the shop after I've actually got them though.)
- a customer reported to me that he was having trouble with arcing, and that he got damaged cells from that. The problem with arcing is that, even though kWeld still makes sure that the deposited energy stays constant, the accelerated electrons in the ionized gas will collide with the positive pole and work their way through the material there. Arcing only happens when there is a bad electrical contact and/or not enough mechanical pressure, but I found a way to reliably detect this by software. The new firmware below will instantly stop a pulse when the electrical current falls below 800A. This is a reliable indicator for arcing, as the ionized gas has a much higher electrical resistance than the direct contact.
- I got a few customers who reported poor response of the dial knob. I found that there is a lot of production variation of the rotary encoder regarding the amount of grease that they fill in, which leads to contact noise. The firmware has always included contact debouncing, but it was not matching the noise characteristics that the encoder exibits. This has also been improved in the attached firmware.

p.s. this was my "test bed" for my arcing experiments. The new firmware caught every single case in the end, no matter what I did  I think that this feature is again unique among all spot welders operating with DC current.

[FredNuno]

Hi Frank, I'm trying to update "181205_kweld_release_r2_6.zip" firmware but no avail.
I lunch PuTTY, choose COM21 at 115200, Serial, Open. On black screen I type "k" (small letter) and nothing happens. See my screen shot attached.
At lower left side you can see "Offline". Could you explain me what I can do to have this "Connected"?
Thank you in advance.
FredNuno.
 

[tatus1969]

Hi Frank, I'm trying to update "181205_kweld_release_r2_6.zip" firmware but no avail.
I lunch PuTTY, choose COM21 at 115200, Serial, Open. On black screen I type "k" (small letter) and nothing happens. See my screen shot attached.
At lower left side you can see "Offline". Could you explain me what I can do to have this "Connected"?
Thank you in advance.
FredNuno.

I think that this "offline" status refers to ancient dialup modems. If the window is opened without an error, then you are connected to the device. Please try the following:
- It can sometimes be tricky to find the right port, depending on what else you have in or at your computer. I use to have the device manager open, and plug/pull the tool to watch which of them appears and disappears.
- Have you set the jumper on the red board to 3.3V? (The inputs are 5V tolerant though, a wrong setting doesn't damage anything.)
- Have you made sure that CAPS LOCK is off? The device does not accept capital letters.

It could also be a driver issue. Please try the following:
-   download and unzip the latest driver from this page: https://www.ftdichip.com/Drivers/VCP.htm
-   start the Windows device manager
-   remove the malfunctioning device (right click on it -> “Uninstall” -> make sure to click the “Remove drivers” in the following prompt)
-   unplug it
-   restart the computer
-   plug in again
-   in device manager, select “Update driver”, then enter the path of the above driver

[FredNuno]

Hi Frank, thank you for your response.
I have tried everything you posted, but no avail, until now. But I'm over this matter and I will solve this problem, I'm sure. From the begin I have choosen 3,3 V. I have read the manual.
FredNuno.

[tatus1969]

Here's again a new firmware, this one allows to alter the minimum current threshold through the menu. I realized that this would be important for users with weaker batteries who like to keep their system as it is. They wouldn't be able to use the welder anymore otherwise. And I had also the request to raise the threshold. If your battery delivers 1400A, then setting the minimum to e.g. 1200 might further improve the arcing detection sensitivity.

[tatus1969]

p.s. new kWeld electronics just arrived and can be ordered through the shop 

[tatus1969]

I've been firefighting during the last days, after an increasing number of kWeld users reported me that the rotary encoder on the board had become unreliable. It turns out that it is a huge quality problem with the component itself. There are tiny plastic elements inside that break loose and end up blocking the contacts. The kWeld production test couldn't catch this, because this only happens after using the part for a while. It's even more annoying because I deliberately use quality brand components only for the entire design, in this case a Bourns PEC12R-4220F-S0024.

We are busy replacing the rotary encoders on the entire current production batch with this new component: EN11-HSB1AF15 (Digikey 987-1186-ND). I have disassembled one of these, their internal construction is way better. The only drawback is that they count in opposite direction, which is why I had to update the firmware again. This version has a new menu item "Encoder" that allows you to select "normal" and "reverse" counting direction.

If any of you guys are having problems with your welder, then please let me know. I'll do what I can to resolve this issue for you.

[EV]

I updated the FW to r2.8. No problems!

I also tried to weld with 0.0J energy! It is not 0.0J! It was very big, the electrodes got very hot and burned hole to nickel strip! When setting to 0.1J the energy level is correct.