A small white work truck sitting on a faded road with trees in the background. In its bed is what looks like an enormous drill battery in an upside down position. The "battery" is black with red and yellow stripes. It has the words "125V, 500 Ah, 52 kWh" and "Mr. G's Workshop" emblazoned on the side.

Kei Truck Looks Like A Giant Power Tool

February 4, 2026 by Navarre Bartz 18 Comments

Kei trucks are very versatile vehicles, but their stock powerplant can leave a bit to be desired. If you need more power, why not try an electric conversion?

[Ron “Mr. G” Grosinger] is a high school auto shop and welding teacher who worked with his students to replace the 40 hp gas motor in this Daihatsu Hijet with the 127 hp of a Hyper 9 electric motor. The motor sits in the original engine bay under the cab and is mated to the stock transmission with a custom adapter plate made from plate steel for less than $150. We really appreciate how they left all the electronics exposed to see what makes the conversion tick.

The faux battery was made by a foam sculptor friend out of urethane foam shaped with a carving knife and then painted. It slides on a set of unistrut trolleys and reveals the 5 salvaged Tesla battery modules that power the vehicle. The fold down sides of the truck bed allow easy access to anything not already exposed if any tweaking is necessary.

We’ve seen a kei truck become a camper as well or an ebike powered with actual power tool batteries. If you’re thinking of your own electric conversion, which battery is best?

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Lumafield battery quality report cover page

Lumafield Peers Into The 18650 Battery

January 31, 2026 by John Elliot V 22 Comments

[Alex Hao] and [Andreas Bastian] of Lumafield recently visited with [Adam Savage] to document their findings after performing X-ray computed tomography scans on over 1,000 18650 lithium-ion batteries.

The short version — don’t buy cheap cells! The cheaper brands were found to have higher levels of manufacturing defects which can lead them to being unsafe. All the nitty-gritty details are available in the report, which can be downloaded for free from Lumafield, as well as the Tested video they did with [Adam] below.

Actually we’ve been talking here at Hackaday over at our virtual water-cooler (okay, okay, our Discord server) about how to store lithium-ion batteries and we learned about this cool bit of kit: the BAT-SAFE. Maybe check that out if you’re stickler for safety like us! (Thanks Maya Posch!)

We have of course heard from [Adam Savage] before, check out [Adam Savage] Giving A Speech About The Maker Movement and [Adam Savage]’s First Order Of Retrievability Tool Boxes.

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Lead Acid Battery Upgraded To Lithium Iron Phosphate

January 23, 2026 by Bryan Cockfield 14 Comments

Lithium batteries have taken over as the primary battery chemistry from applications ranging from consumer electronics to electric vehicles and all kinds of other things in between. But the standard lithium ion battery has a few downsides, namely issues operating at temperature extremes. Lead acid solves some of these problems but has much lower energy density, and if you want to split the difference with your own battery you’ll need to build your own lithium iron phosphate (LiFePO4) pack.

[Well Done Tips] is building this specific type of battery because the lead acid battery in his electric ATV is on the decline. He’s using cylindrical cells that resemble an 18650 battery but are much larger. Beyond the size, though, many of the design principles from building 18650 battery packs are similar, with the exception that these have screw terminals so that bus bars can be easily attached and don’t require spot welding.

With the pack assembled using 3D printed parts, a battery management system is installed with the balance wires cleverly routed through the prints and attached to the bus bars. The only problem [Well Done Tips] had was not realizing that LiFePO4 batteries’ voltages settle a bit after being fully charged, which meant that he didn’t properly calculate the final voltage of his pack and had to add a cell, bringing his original 15S1P battery up to 16S1P and the correct 54V at full charge.

LiFePO4 has a few other upsides compared to lithium ion as well, including that it delivers almost full power until it’s at about 20% charge. It’s not quite as energy dense but compared to the lead-acid battery he was using is a huge improvement, and is one of the reasons we’ve seen them taking over various other EV conversions as well.

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Battle Born LFP Battery Melts With New Problem

January 16, 2026 by Maya Posch 27 Comments

Following up on user-reported cases of Battle Born LiFePO4 batteries displaying very hot positive terminals, [Will Prowse] decided to buy a brand new one of these LFP batteries for some controlled cycle testing.

Starting with 30 cycles with a charging current of 49 A and a discharge current of 99 A, this put it well within the 100 A continuous rating for the battery. There is also a surge current rating of 200 A for thirty seconds, but that was not tested here.

What’s interesting about the results here is that instead of the positive terminal getting visibly discolored as with the previous cases that we reported on, [Will] saw severe thermal effects on the side of the negative terminal to the point where the plastic enclosure was deforming due to severe internal heating.

During testing, the first two charge-discharge cycles showed full capacity, but after that the measured capacity became extremely erratic until the battery kept disconnecting randomly. After letting the battery cool down and trying again with 80 A discharge current the negative terminal side of the enclosure began to melt, which was a good hint to stop testing. After this the battery also couldn’t be charged any more by [Will]’s equipment, probably due to the sketchy contact inside the battery.

It’s clear that the plastic spacer inside the terminal bus bar was once again the primary cause, starting a cascade which resulted in not only the enclosure beginning to char and melt, but with heat damage visible throughout the battery. Considering that the battery was used as specified, without pushing its limits, it seems clear that nobody should be using these batteries for anything until Battle Born fixes what appears to be the sketchiest terminal and bus bar design ever seen in a high-current battery.

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Born To Burn: The Battle Born LFP Battery

December 25, 2025 by Maya Posch 39 Comments

Would you feel confident in buying US-made LiFePO₄ (LFP) batteries? While the answer here is generally expected to be ‘yes’, especially compared to getting an unbranded LFP battery off eBay from a random seller, the outcome may not be that different. Case in point the 100 Ah, 12 VDC LFP Battle Born battery that [Will Prowse] took a look at to see why its positive terminal gets positively crispy.

Battle Born battery positive terminal. (Credit: Will Prowse, YouTube)

Once the lid was cut off, it’s easy to see what the problem is: the positive terminal is only loosely attached to the bus bar, leading to extremely poor contact. It also appears that there’s a plastic spacer which has properly melted already in this well-used battery that [Will] obtained from a viewer.

This overheating issue with Battle Born batteries has been reported for years now, which makes it a great idea to take a good look at any Battle Born LFP batteries you may have kicking around, as they may be plagued by the same design flaw. Trying to make use of the manufacturer’s warranty could be complicated based on the commentators in the DIY Solar Forum thread, as Battle Born likes to claim that the overheating issue is an external problem and not a design flaw.

Either way, it looks like an incredibly sketchy way to design a battery terminal on an LFP battery that is supposed to surge 100+A. [Will] is requesting that anyone affected posts details in the forum or similar to get all information together, as he looks to push Battle Born on this issue.

What makes this issue worse is that shortly after releasing that first video, Battle Born responded to some concerned customers with a response that claims that their terminal design is a ‘thermal fail-safe’, but as can be seen in [Will]’s follow-up video, it absolutely doesn’t look like one.

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That Power Bank Isn’t Quite So Sweet

December 3, 2025 by Jenny List 9 Comments

An unlikely hit of the last few months’ consumer hardware has been a power bank branded by the German confectionery company Haribo. It first gained attention in backpacking circles because of its high capacity for a reasonable weight, and since then has been selling like the proverbial hot cakes. Now Amazon have withdrawn it from their store over “A potential safety or quality issue”. The industrial imaging company Lumafield have taken a look at the power bank with a CT scanner, to find out why.

As you might imagine, the power bank is all battery inside, with pouch type lithium ion cells taking up all of the space. Immediately a clue appears as to why Amazon withdrew them, as the individual layers of the cells are misaligned, laying open a risk of failure. They also take a look at a set of earbuds from the same source and find something even more concerning — torn electrodes. Thus neither device can be regarded as safe, and the backpackers will have to haul around a little bit more in the future.

You’ll not find the Wrencher on a power bank, but you can be sure if you did, we’d make sure there was an element of quality control at play. Meanwhile we feel slightly sorry for the branding executive responsible at Haribo, who we are guessing has had a bad day. We’ve featured Lumafield’s work here before quite a few times, most recently looking at similar defects in 18650 cells.

Expensive Batteries Hide Cheap Tricks

November 23, 2025 by Bryan Cockfield 62 Comments

In our modern world full of planned obsolescence helping to fuel cycles of consumerism, the thing that really lets companies dial this up to the max is locked-down electronics and software. We all know the key players in this game whether it’s an automotive manufacturer, video game console producer, smart phone developer, or fruit-based computer company of choice, but there are some lesser known players desperately trying to make names for themselves in this arena too. Many power tool manufacturers like Milwaukee build sub-par battery packs that will wear out prematurely as [Tool Scientist] shows in this video.

Determining that these packs don’t actually balance their cells isn’t as straightforward as looking for leads going to the positive terminal of each. The microcontrollers running the electronics in these packs are hooked up, but it seems like it’s only to communicate status information about the batteries and not perform any balancing. [Tool Scientist] tested this hypothesis through a number of tests after purposefully adding an imbalance to a battery pack, first by monitoring i2c communications, measuring across a resistor expected to show a voltage drop during balancing, let a battery sit 21 days on a charger, and then performing a number of charge and discharge cycles. After all of that the imbalance was still there, leading to a conclusion that Milwaukee still doesn’t balance their battery packs.

Giving them the benefit of the doubt, it could be that most packs will be just fine after years without balancing, so the added cost of this feature isn’t worth it. This video was put out nearly a year ago, so it’s possible Milwaukee has made improvements since then. But a more realistic take, especially in a world dominated by subscription services and other methods of value extraction, is that Milwaukee is doing this so that users will end up having to buy more batteries. They already make user serviceability fairly difficult, so this would be in line with other actions they’ve taken. Or it could be chalked up to laziness, similar to the Nissan Leaf and its lack of active thermal management in its battery systems.

Thanks to [Polykit] for the tip!

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