Apple Newton Gets Rebuilt Battery Pack

December 13, 2024 by Bryan Cockfield 12 Comments

We all carry touch screen computers around in our pockets these days, but before the smartphone revolution, there was the personal digital assistant (PDA). While it wasn’t a commercial success, one of the first devices in this category was the Apple Newton. Today they’re sought after by collectors, although most of the ones surviving to this day need a bit of rework to the battery pack. Luckily, as [Robert’s Retro] shows, it’s possible to rebuild the pack with modern cells.

By modern standards, the most surprising thing about these battery packs is both that they’re removable and that they’re a standard size, matching that of AA batteries. The Newton battery pack uses four cells, so replacing them with modern rechargeable AA batteries should be pretty straightforward, provided they can be accessed. This isn’t as easy, though. In true Apple fashion the case is glued shut, and prying it apart can damage it badly enough so it won’t fit back in the tablet after repair is complete. The current solution is to cut a hatch into the top instead and then slowly work on replacing the cells while being careful to preserve the electronics inside.

[Robert’s Retro] also demonstrates how to spot weld these new AA batteries together to prepare them for their new home in the Newton case. With the two rows fastened together with nickel strips they can be quickly attached to the existing electrical leads in the battery pack, and from there it’s just a matter of snapping the batteries into the case and sliding it back into the tablet. If you’re looking for something a bit more modern, though, we’d recommend this Apple tablet-laptop combo, but it’s not particularly easy on the wallet.

Continue reading “Apple Newton Gets Rebuilt Battery Pack” →

Half Power Bank, Half Spot Welder

January 8, 2024 by Jenny List 13 Comments

There was a time when every gizmo on AliExpress also had a big white LED so it could also work as a flashlight, but maybe the power bank is the new flashlight. [Aaron Christophel] has a battery spot welder that costs a not unreasonable 30 euros and can also be used as a novelty power bank. He subjects it to a test and teardown in the video below the break.

First of all, he conducts a few weld tests, and we have to say it seems capable of some reasonable results if its parameters are correctly adjusted. Then the end comes off the extruded aluminium case, and the guts of the device are slid out for a teardown.

The power comes from a pair of Li-Po pouch cells, while on the board, there’s an STM32 clone providing the timing for a set of MOSFETs that do the heavy lifting. There’s a colour display for tweaking the settings. Alongside all this, there’s also a small chip for that power bank functionality. Charging is via USB-C, though, of course, it’s not really proper USB-C but a USB-C socket that expects 5 volts. This is a disappointing trend in cheap electronics that sullys the promise of USB-C.

It seems this spot welder is capable of doing the job, which is pleasing after our previous disappointing look at battery welders.

Continue reading “Half Power Bank, Half Spot Welder” →

An exploded diagram of the spot welder. Shown are the capacitor bank, trigger, 12 V relay, DC power input, power out, step up converter, voltmeter, industrial SCR module, and capacitor bank.

Hackaday Prize 2022: A Not-So-Smart Spot Welder

October 17, 2022 by Navarre Bartz 5 Comments

DIY spot welders often use high-powered components that can be a bit frightening, given the potential for dangerous malfunctions. [Wojciech “Adalbert” J.] designed his capacitive discharge spot welder to be safe, easy to build, and forego the microcontroller.

Many projects work great with just a single Li-ion cell, but when you need more power, you’ve got to start connecting more cells together into a battery. [Wojciech]’s spot welder is designed to be just powerful enough to weld nickel tabs onto a cell without any overkill. The capacitor bank uses nineteen Nichicon UBY 7500uF/35V capacitors, all wired in parallel using solder wick saturated with solder. They sit atop on a perfboard with metallicized holes to carry the high current.

[Wojciech] has detailed every step of building the welder, including changes to the off-the-shelf relay board and adding a potentiometer to the step-up converter board. The level of detail makes this seem like a good starting place if you’re hoping to hop into the world of DIY spot welders. Safe is always a relative term when dealing with high powered devices, so be careful if you do attempt this build!

DIY spot welders have graced these digital pages many times, including this one built with safety in mind, and this other one that was decidedly not.

Building A Spot Welder From 500 Junk Capacitors

August 20, 2022 by Dave Rowntree 5 Comments

[Kasyan TV] over on YouTube was given a pile of spare parts in reasonably large quantities, some of which were useful and allocated to specific projects, but given the given the kind of electronics they’re interested in, they couldn’t find a use for a bag of 500 or so low specification 470uF capacitors. These were not low ESR types, nor high capacitance, so unsuitable for power supply use individually. But, what about stacking them all in parallel? (video, embedded below) After a few quick calculations [Kasyan] determined that the total capacitance of all 500 should be around 0.23 Farads with an ESR of around 0.4 to 0.5 mΩ at 16V and packing a theoretical energy total of about 30 joules. That is enough to pack a punch in the right situation.

A PCB was constructed to wire 168 of the little cans in parallel, with hefty wide traces, reinforced with multiple strands of 1.8mm diameter copper wire and a big thick layer of solder over the top. Three such PCBs were wired in parallel with the same copper wire, in order to keep the total resistance as low as possible. Such a thing has a few practical uses, since the super low measured ESR of 0.6mΩ and large capacitance makes it ideal for smoothing power supplies in many applications, but could it be used to make a spot welder? Well, yes and no. When combined with one of the those cheap Chinese ‘spot welder’ controllers, it does indeed produce some welds on a LiPo cell with a thin nickel plated battery strip, but blows straight through it with little penetration. [Kasyan] found that the capacitor bank could be used in parallel with a decent LiPo cell giving a potentially ideal combination — a huge initial punch from the capacitors to blow through the strip and get the weld started and the LiPo following through with a lower (but still huge) current for a little longer to assist with the penetration into the battery terminal, finishing off the weld.

[Kaysan] goes into some measurements of the peak current delivery and the profile thereof, showing that even a pile of pretty mundane parts can, with a little care, be turned into something useful. How does such an assembly compare with a single supercapacitor? We talked about supercaps and LiPo batteries a little while ago, which was an interesting discussion, and in case you’re still interested, graphene-based hybrid supercapacitors are a thing too!

Continue reading “Building A Spot Welder From 500 Junk Capacitors” →

Cheap Spot Welder Teardown

March 16, 2022 by Al Williams 16 Comments

It used to be hard to dump enough electricity through two pieces of metal to meld them together. But a lithium-ion battery can do it. The question is, should it? [The Signal Path] takes a cheap battery-based spot welder apart to see what’s inside and tries to answer that question. You can see the teardown in the video below.

The cheap welder has some obvious safety problems so the first thing was to trim down some wires and also retinning some of the PCB traces to ensure they are the lowest possible resistance. Of course, the less resistance in the wiring, the more current is available for welding.

Continue reading “Cheap Spot Welder Teardown” →

Robert Dunn holds a button in his hand for controlling a spot welder

Gorgeous Battery Welder Hits The Spot

September 14, 2021 by Ryan Flowers 32 Comments

Raise you’re hand if you’ve ever soldered directly to a battery even though you know better. We’ve all been there. Sometimes we get away with it when we have a small pack and don’t care about longevity. But when [Robert Dunn] needed to build a battery pack out of about 120 Lithium Ion cells, he knew that he had to do it The Right Way and use a battery spot welder. Of course, buying one is too simple for a hacker like [Robert]. And so it was that he decided to Build a Spot Welder from an old Microwave Oven and way too much mahogany, which you can view below the break.

A Battery Cell with a spot welding tab attached — Spot Welding leaves two familiar divots in the attached tab, which can be soldered or welded as need.

For the unfamiliar, a battery spot welder is the magical device that attaches tabs to rechargeable batteries. You’ll notice that all battery packs with cylindrical cells have a tab with two small dimples. These dimples are where high amperage electricity quickly heats the battery terminal and the tab until they’re red hot, welding them together. The operation is done and over in less than a second, well before any heat damage can be done. The tab can then be soldered to or spot welded to another cell.

One of the most critical parts of spot welding batteries is timing. While [Robert Dunn] admits that a 555 timer or even just a manual switch and relay could have done the job, he opted for an Arduino Uno with a 4 character 7 segment LED display that shows the welding time in milliseconds. A 3d printed trigger and welder handle wrap up the hardware nicely.

The build is topped off by a custom mahogany enclosure that is quite a bit overdone. But if one has the wood, the time, the tools and skills (and a YouTube channel perhaps?) there’s no reason not to put in the extra effort! [Robert]’s resulting build is almost too nice, but it’ll certainly get the job done.

Of course, spot welders are almost standard fare here at Hackaday, and we’ve covered The Good, The Bad, and The Solar. Do you have a battery welder project that deserves a spot in Hackaday’s rotation? By all means, send it over to the Tip Line!

Continue reading “Gorgeous Battery Welder Hits The Spot” →

Review: Battery Spot Welders, Why You Should Buy A Proper Spot Welder

June 16, 2021 by Jenny List 64 Comments

Making battery packs is a common pursuit in our community, involving spot-welding nickel strips to the terminals on individual cells. Many a pack has been made in this way, using reclaimed 18650 cells taken from discarded laptops. Commercial battery spot welders do a good job but have a huge inrush current and aren’t cheap, so it’s not uncommon to see improvised solutions such as rewound transformers taken out of microwave ovens. There’s another possibility though, in the form of cheap modules that promise the same results using a battery pack as a power supply.

With a love of putting the cheaper end of the global electronic marketplace through its paces for the entertainment of Hackaday readers I couldn’t resist, so I parted with £15 (about $20), for a “Mini Spot Welder”, and sat down to wait for the mailman to bring me the usual anonymous grey package.

Continue reading “Review: Battery Spot Welders, Why You Should Buy A Proper Spot Welder” →