Repairing A Mercedes EQC 300 BEV Battery

April 22, 2026 by Maya Posch 15 Comments

When [OGS Mechanics] got a Mercedes EQC 300 battery-electric car in for repair, it was found to have a bit of a weird issue: after sitting in a garage for a while, its range on battery had suddenly reduced significantly without clear cause. Although the typical response here is to just mark the battery pack as ‘faulty’ and replace the whole unit, [OGS] decided to dig into the pack to see what was going on.

The short version is that this particular battery pack consists of two individual batteries, each with its own BMS, one of which had reported a condition to the master BMS that triggered the ‘replace battery module’ error observed with the scan tool. From this it could also be seen that the first battery was at a 10% state-of-charge (SoC), and the second at 95%, making them incredibly unbalanced. Unfortunately the dealer procedure to rebalance did not work here, with only the second battery wanting to charge even after draining both to the same initial level.

To diagnose the underlying issue in earnest required gently prying open the battery pack like a massive glued-shut smartphone. Going by the theory that it is a software glitch, since the first battery was still at a healthy voltage level, it was decided to manually charge it. With both batteries now fully charged, the BMS for the first battery was then removed to have its memory overwritten with that of a known good BMS module, clearing the ‘replace battery module’ error.

Although in the preview for the next video it’s hinted that there’s also an internal balancing issue in the first battery pack, this could be another symptom of its BMS glitching out. Either way, it would seem that BEVs battery modules are both heavily dependent on software, as well as afflicted by the same throw-away culture that has people just buying a new smartphone when the battery fails.

Continue reading “Repairing A Mercedes EQC 300 BEV Battery” →

Vape-powered Car Isn’t Just Blowing Smoke

March 4, 2026 by Tyler August 12 Comments

Disposable vapes aren’t quite the problem/resource stream they once were, with many jurisdictions moving to ban the absurdly wasteful little devices, but there are still a lot of slightly-smelly lithium batteries in the wild. You might be forgiven for thinking that most of them seem to be in [Chris Doel]’s UK workshop, given that he’s now cruising around what has to be the world’s only vape-powered car.

Technically, anyway; some motorheads might object to calling donor vehicle [Chris] starts with a car, but the venerable G-Wiz has four wheels, four seats, lights and a windscreen, so what more do you want? Horsepower in excess of 17 ponies (12.6 kW)? Top speeds in excess of 50 Mph (80 km/h)? Something other than the dead weight of 20-year-old lead-acid batteries? Well, [Chris] at least fixes that last part.

The conversion is amazingly simple: he just straps his 500 disposable vape battery pack into the back seat– the same one that was powering his shop–into the GWiz, and it’s off to the races. Not quickly, mind you, but with 500 lightly-used lithium cells in the back seat, how fast would you want to go? Hopefully the power bank goes back on the wall after the test drive, or he finds a better mounting solution. To [Chris]’s credit, he did renovate his pack with extra support and insulation, and put all the cells in an insulated aluminum box. Still, the low speed has to count as a safety feature at this point.

Charging isn’t fast either, as [Chris] has made the probably-controversial decision to use USB-C. We usually approve of USB-Cing all the things, but a car might be taking things too far, even one with such a comparatively tiny battery. Perhaps his earlier (equally nicotine-soaked) e-bike project would have been a better fit for USB charging.

Thanks to [Vaughna] for the tip! Continue reading “Vape-powered Car Isn’t Just Blowing Smoke” →

Raising A GM EV1 From The Dead

December 4, 2025 by Jenny List 19 Comments

Probably the biggest story in the world of old cars over the past couple of weeks has been the surfacing of a GM EV1 electric car for sale from an auto salvage yard. This was the famous electric car produced in small numbers by the automaker in the 1990s, then only made available for lease before being recalled. The vast majority were controversially crushed with a few units being donated to museums and universities in a non-functional state.

Finding an old car isn’t really a Hackaday story in itself, but now it’s landed in [The Questionable Garage]. It’s being subjected to a teardown as a prelude to its restoration, offering a unique opportunity to look at the state of the art in 1990s electric automotive technology.

The special thing about this car is that by a murky chain of events it ended up as an abandoned vehicle. GM’s legal net covers the rest of the surviving cars, but buying this car as an abandoned vehicle gives the owner legal title over it and frees him from their restrictions. The video is long, but well worth a watch as we see pieces of automotive tech never before shown in public. As we understand it the intention is to bring it to life using parts from GM’s contemporary S10 electric pickup truck — itself a rare vehicle — so we learn quite a bit about those machines too.

Along the way they find an EV1 charger hiding among a stock of pickup chargers, take us through the vehicle electronics, and find some galvanic corrosion in the car’s structure due to water ingress. The windscreen has a huge hole, which they cover with a plastic wrap in order to 3D scan so they can create a replacement.

This car will undoubtedly become a star of the automotive show circuit due to its unique status, so there will be plenty of chances to look at it from the outside in future. Seeing it this close up in parts though is as unique an opportunity as the car itself. We’ve certainly seen far more crusty conventional cars restored to the road, but without the challenge of zero parts availability and no donor cars. Keep an eye out as they bring it closer to the road.

Continue reading “Raising A GM EV1 From The Dead” →

Thermal Runaway: Solving The Bane Of Electric Vehicles

September 17, 2024 by Maya Posch 86 Comments

Although battery fires in electric cars and two-wheeled vehicles are not a common phenomenon, they are notoriously hard to put out, requiring special training and equipment by firefighters. Although the full scope of the issue is part of a contentious debate, [Aarian Marshall] over at Wired recently wrote an article about how the electric car industry has a plan to make a purportedly minor issue even less of an issue. Here the questions seem to be mostly about what the true statistics are for battery fires and what can be done about the primary issue with batteries: thermal runaway.

While the Wired article references a study by a car insurance company about the incidence of car fires by fuel type (gas, hybrid, electric), its cited sources are dubious as the NTSB nor NHTSA collect statistics on these fires. The NFPA does, but this only gets you up to 2018, and they note that the data gathering here is spotty. Better data is found from European sources, which makes clear that battery electric vehicles (BEVs) catch fire less often than gasoline cars at 25 per 100,000 cars sold vs 1529/100k for ICE cars, but when BEVs do burn it’s most often (60%) from thermal runaway, which can be due to factors like a short circuit in a cell, overcharging and high ambient temperatures (including from arson or after-effects of a car crash). Continue reading “Thermal Runaway: Solving The Bane Of Electric Vehicles” →

From Nissan ICE Pickup To BEV With Nissan Leaf Heart

June 11, 2024 by Maya Posch 8 Comments

Last year [Jimmy] got a request from a customer ([Dave]) to help convert a 1998 Nissan Frontier pickup into an electric drive vehicle, with a crashed 2019 Nissan Leaf providing the battery and electric motor for the conversion. He has documented the months-long journey with plenty of photos, as well as a series of videos over at the [EVSwap Conversions] YouTube channel. While the idea sounds easy enough, there’s a lot more to it than swapping out the ICE with an electric motor and sticking some batteries to the bottom of the car somewhere with double-sided tape. The pickup truck got effectively stripped down and gutted, before the 110 kW (150 HP) motor got installed using an adapter plate.

The donor Leaf’s battery pack came in at a decently sized 40 kWh, which should give the converted Nissan Frontier BEV a range of easily 100 miles. This pack was split up into two packs, which got put into a custom aluminium battery box, each mounted on one side of the driveshaft. The charging port got installed on the front of the car, next to the logo, discreetly behind a panel. The front of the car had much of the openings that were needed for the ICE’s radiator sealed up for reduced air friction, along with the new low-friction tires that got installed. Although this converted car still has a radiator, it only needs to assisting cooling the motor stack (including inverter and charger) when driving slowly or charging, making it far less demanding and thus allows for a more sleek front.

As a bonus, the car still has the manual 5-gear shift, just without a clutch, and the pickup bed can now also tilt, albeit with hydraulics (so far). Considering that it started with a decent 1998 pickup and totaled Nissan Leaf, this is among the cleanest conversions we have seen, not to mention a good use of a crashed BEV.

Thanks to [JohnU] for the tip.

Continue reading “From Nissan ICE Pickup To BEV With Nissan Leaf Heart” →

A black PCB with a cellular modem board piggy backed on top. It has a micro-USB and DB-type connector on the end facing the camera.

Open Vehicle Monitoring System Is The Window To Your EV’s Soul

January 25, 2024 by Navarre Bartz 14 Comments

Electric cars have more widgets than ever, but manufacturers would rather you don’t have direct access to them. The Open Vehicle Monitoring System intends to change that for the user. [via Transport Evolved]

As car manufacturers hoover up user data and require subscriptions for basic features, it can be a frustrating time to make such a big purchase. Begun in 2011, OVMS now interfaces with over a dozen different EVs and gives you access to (or helps you reverse engineer) all the data you could want from your vehicle. Depending on the vehicle, any number of functions can be accessed including remote climate start or cell-level battery statistics.

The hardware connects to your car’s OBDII port and uses an ESP32 microcontroller connected to a SIMCOM SIM7600G modem (including GPS) to provide support for 3 CAN buses as well as Wi-Fi and Bluetooth connections. This can be particularly useful for remote access to data for vehicles that can no longer phone home via their originally included cellular modems as older networks shut down.

Do you wish EVs weren’t so complicated? Read our Minimal Motoring Manifesto.

Can A $3200 Kit Convert Your Car To Electric Power?

October 15, 2023 by Jenny List 114 Comments

Whether hardcore petrolheads like it or not, we appear to be living through the final years of the internal combustion engine. In many countries there are legislative timetables in place for their eventual phasing out, and even those which remain in production are subject to ever more stringent emissions legislation. If there’s a problem with the EVs with which we’re expected to replace our fossil fuel vehicles it’s the cost, those things are still very expensive. An Aussie student has an interesting idea that’s won the James Dyson Prize: a low cost conversion for existing vehicles that bolts onto their rear wheel hubs.

Electric conversion of fossil fuel cars is nothing new, indeed we’ve brought you news of units designed to replace the original engine and transmission. Neither are wheel hub motors new, but the difference with this system is that it doesn’t require significant mechanical modification to the vehicle. It retains the old engine, and this motor sits inside each rear wheel.

It almost seems too good to be true, but a closer reading shows the rotor bolted on one side to the old wheel hub and on the other side to the wheel. The stator meanwhile is bolted to the existing brake caliper mountings. This would lead to a slightly wider track and a greater unsprung weight, but we can see that it would work. Besides the motor there’s a battery pack for the spare wheel well and a set of electrically-powered systems to supply the brake servo vacuum and other services. The idea is that this whole kit could be fitted for 5000 Australian dollars, which is somewhere south of $3200 USD. It’s not perfect and it still involves hauling around the dead weight of an unused engine, but we can see it might still have a niche. If, and that’s a big if, it ever makes it to market, that is.