FNIRSI SWM-10 Spot Welder Review/Teardown

[@Ohm7111]

As Julian Ilett mentioned, the power bank function is probably not intended for use as a power bank, but rather as an easy way to discharge the battery to an optimal voltage for storage.

[@LawpickingLocksmith]

Pretty neat. Love the way you keep your 2 cells at exactly zero volts.

[@barryobrien1890]

You forgot the most important resistance measurement, the actual nickel and steel resistance. If that's zero, you will weld nothing as no heat will be generated. For maximum power transfer, the nickel and steel should match the system internal resistance, so the actual maximum welding current is about 600A. You will also have some resistance in the lugs and busbars etc. One thing they are missing is voltage protection on the fets. The inductive kick when the current is switched off due to lead inductance can stress the fets over time which can lead to failure, especially if the user adds longer leads. Overall they did a nice job. Great quality leads, heavy busbars and good quality components. For occasional small battery repair, this is an excellent design. Great review as usual.

[@pault6533]

I believe "charging" simply means the powerbank feature is activated in either manner, charging internal device or charging external device. I suppose this is simply to alert you that welding is not advised. Manual says "soldering while charging is not recommended, as it is easy to damage the charging chip."

[@Phyllis-Watson]

Fantastic information and presentation, thanks.

[@georgefrancis6195]

Would love to see tests on .1, .15, .2 nickle strip and a nickle copper sandwitch

[@silvostraser5268]

Great presentation. Thank you.

[@arekx]

Watched with FF sometimes, so I could miss that data - how long it will keep its charge when not used and laying on the shelve? (The worst thing with these kind of devices is that they are needed rarely, in my case, and when they are, they are often discharged).

[@KerryWongBlog]

I only had it for a few weeks, so far it looked ok. I didn't notice any significant self-discharging. But I will let it sit there for a month or two and check again.

[@jaro6985]

Yeah looks exactly the same as one I had that died after a year, waste of money. Just being discharged would be fine, but the cells die.

[@KaterinaAndersen]

If not used for some time, it would probably be a god idea to use it as powerbank, to discharge the battery to storage voltage, LiPos dont like to be stored fully charged.

[@jheissjr]

Let us know if the manufacture responds about the wrong pulse output values.

[@barrygreengrass3379]

Are the batteries LiHv?

[@norbertrittel1]

Does it charge with a C-to-C cable? It looks like the two necessary 5.1 kOhm pull-down resistors are present on the PCB, but you will certainly be able to confirm from your testing. As we still have way too many (new) devices out there that violate the USB-C specs it's always a good idea to check and mention this in any review.

[@KerryWongBlog]

Yes, it charges with either A-to-C or C-to-C cable.

[@andymouse]

I would like one but it's not urgent, This would fit the bill I feel, thanks Kerry.

[@barrygreengrass3379]

Are the batteries LiHv? when my unit is fully charged it charges to 4.35volts

[@Ohm7111]

My unit sometimes charges the battery to 4.2V and sometimes to 4.35V. I have no idea why.

[@therealspixycat]

Are you able to measure the claimed 1200A?

[@techguy666]

Is there any way to measure the actual current pulse and show it on the oscilloscope? maybe a high current clamp that can handle up to 2000A, but do they make such a clamp for scopes?

[@KerryWongBlog]

TBH, I haven't seen any current clamp for oscilloscopes that can measure above a couple of hundred amps.

[@simontay4851]

Why don't they use a big capacitor for the high current discharge.

[@KerryWongBlog]

More expensive I guess? There are super cap based spot welders out there, they are just more pricey

[@KaterinaAndersen]

I bought one for testing. Unfortunately it is more of a toy than a useful tool for battery welding😮 The interface is one of the best, but unfortunately it has not power enough to weld anything more than very thin NiPlated Steel, Pure Nickel dont give good results. Also you need to charge it after 10-15 welds...and the charging is quite slow.😢

[@martinho53]

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