We present an overview of a rather interesting model of a Chinese welding board for batteries. And powered by batteries, and designed to assemble batteries into blocks.

It began with the fact that a lot of 18650 cells were accumulated, suitable for combining into packages, and an appropriate tool was needed. So I looked for a cheap and fast solution that would allow me to do the job. There was no microwave transformer , so such a tempting option was no longer available. After some deliberation, I chose the option with an 8,200 amp MOSFET battery, which in total gives a current of 1600 A from the transistors themselves, because the printed circuit board will not withstand that much.

AliExpress didn’t take too long with the delivery and soon received the package, immediately testing this contraption in operation with a car battery and a footswitch trigger.

Everything turned out to be in full accordance with the description, except that, on the other hand, one more bus and 8 more MOSFET transistors could be installed on the printed circuit board.

Having collected everything together, I proceeded to functional tests. Everything works as described.

The display alternately shows the voltage at the terminals of the welding machine and the set current, or rather the time of the welding process, which theoretically reflects to some extent the energy given off to the working electrodes. This measurement is really very approximate, because the circuit only measures the voltage, and not the value of the current flowing, which is a key parameter for calculating the energy transferred to the electrodes at a given time.

Adjusting the settings is described with the up and down buttons, but there is no fast scrolling of numbers (one click is equal to one value jump). Longer holding of the right button turns off or turns on the device, and pressing the left button turns on the parameters A0 and A1 . These parameters only set the response time of the device after the switch or pedal is activated. Delayed or non-delayed, but the delay parameter allows up to 5 strokes per weld, which occur at intervals of approximately 0.5 seconds.

The undervoltage protection below 10 V also works. Before the transistors fire, the display goes out, which is also correct, because in theory the 1000 uF capacitor should be able to maintain sufficient voltage to control the gates of the transistors during welding, that is, at the moment when the battery voltage can fall below 10 V.

The cross section of native Chinese cables could indicate that they are used not only to power the circuit, but also to limit the pulse current, so I preferred to connect my cables with a cross section of 25 mm2 through an adapter.

I also bought the appropriate crocodile clips for battery terminals, as well as a relatively cheap and durable welding holder. Chinese (printed on a 3D printer) with protruding springs on top of the electrode clamps somehow did not convince.

At the beginning, for tests, I took an old used R20 battery and a piece of a 0.15 x 6 mm plate, which is included in the kit. Set the minimum power ( d01 ). I press the electrodes and there are no traces of melting.

No sign of current flow. It looked as if all the energy that was supposed to be transferred to the electrodes was lost in this supposed 1600 Amp amplifier.

Well, if 1% doesn’t work, then go to the maximum ( d99 ). I press the electrodes and the current strength began to pull the cables – as it should be. But until I disconnected the electrodes, the plate turned red, and a little smoke came out of the power amplifier and the tin melted in some places.

Summing up the welder test

Interestingly, the Chinese, releasing such a miniature called 1600 A, are aware of what the current value is? And in general, what is the formula for the Joule integral? After all, it clearly can not withstand such power!

So is it possible to properly weld lithium cells from a 60 Ah car battery? Of course you can, provided that the power module is 5 times larger. Such modules are not cheap, but they do not have fictitious parameters, and are capable of reaching physical current values ​​of several cloamperes.

It is likely that if the manufacturers used good quality transistors, the device would not burn out, and most of the energy would be transferred to the electrodes. Therefore, if you are going to buy something like this, immediately discard cheap options that are overpriced according to the declared parameters not by 2 (a common thing for the Chinese), but by 5 times.