Some Geniuses Are Swapping Ford Batteries Into Old Honda Insights To Make DIY Plug-In Hybrids

The Honda Insight was the first hybrid on sale in the US, beating the Prius to the punch by just a few months. Since then, Honda has sold legions of these aerodynamic, fuel-sipping commuter cars. As a result, there is now an aging population of early Honda Insights with good mechanicals but tired batteries. This can leave them weak and feeble under acceleration, but a fresh lithium battery swap can change all that.

Just as gasoline-powered vehicles before them, hybrids and EVs have spawned their own diehard hacker communities seeking better efficiency and performance. Where the ICE world has focused on engine upgrades, when it comes to these cars, the biggest gains to be had are usually at the battery. We’ve seen the Toyota Prius brought back to life with new lithium packs, and feeble Nissan Leafs turned into highway munchers with fat battery upgrades from China. These older cars have been brought into the future by virtue of newer battery tech.

It’s much the same story with the Honda Insight. You could restore your 20-year-old example with a fresh factory battery, or you could make it faster and more efficient with a new lithium pack. If you want to get really creative, you could even swap in some Ford gear and turn it something even more special. Let’s explore how.

New Life

The original Honda Insight landed in 1999. It wasn’t the first hybrid to market, with the Toyota Prius claiming that title, but it was the first on sale in the US. It was a highly unique vehicle in many regards, with its faired-in rear wheels and highly-streamlined 3-door bodystyle.

However, it was the drivetrain where the Insight pioneered the most. Honda combined a 1.0-liter three-cylinder engine with a small electric motor and a small (~1 kWh) nickel metal hydride battery to create a parallel hybrid that aimed to greatly improve fuel efficiency over traditional ICE-powered cars. It could be had with a five-speed manual or a CVT. On launch, it was rated at 65 mpg combined, though modern EPA figures would revise that down to 53 mpg combined some years down the line. It remained the most fuel-efficient gasoline-powered vehicle ever rated by the EPA right up until 2015. This was helped in part due to its sleek design. With a Cd of 0.25, it was the most aerodynamic production car ever built at the time of its release.

While the Honda Insight was a mileage queen on launch, it was no more immune to age than any other car on the road. In fact, owners could expect a significant loss in performance and efficiency as decades passed by and the Insight’s original NiMH batteries wore out. Eventually, their capacity would droop, and they would neither store much energy from regenerative braking, nor supply adequate current to run the electric motor, which Honda termed the IMA—for “Integrated Motor Assist.”

There was an obvious solution for this issue. By the 2010s, a number of companies offered replacement NiMH batteries for the Insight, restoring them to their original performance level. If owners didn’t desire a Honda replacement, they could purchase from companies like GreenTec Auto, Hybrid ReVolt, or a number of others.

Fast forward to today, though, and there are better options available. Why refit your Insight with an ancient, feeble NiMH battery, when you could upgrade it with all the magic of lithium-ion technology instead? Indeed, that’s just what owners are doing—raiding newer vehicles for batteries to give their first-gen Insights a new lease on life.

Enter the LiBCM project. It’s the brainchild of one John Sullivan, perhaps better known as “mudder” on the Insight Central forums. To put it simply, Sullivan created hardware to replace the original Honda battery control module in the first-generation Insight, otherwise known as the G1 models. LiBCM enables owners to swap in lithium batteries instead as an attractive replacement compared to lower-performance OEM NiMH packs.

His motivation was simple. “Battery technology was terrible when the G1 Insight was designed back in the 1990s,” he explains. “The OEM NiMH pack has always been the Insight’s achilles heel… they typically fail one day after the warranty expires.” Unfortunately, replacing a failed pack with one of the same type was not much help. “At this point nearly all cars have had at least one warranty replacement… and probably at least one non-warranty replacement, too,” says John. “Given how cheap these cars are, replacement packs are quite expensive, particularly given that the replacement pack will likely fail after just a few years.” The Insight community had experimented with a wide range of solutions to this problem, but to John, lithium-ion cells seemed to be the real path forward.

The LiBCM module itself is closely integrated with the battery.

John’s initial work started with modifying Nissan Leaf cells, but it wasn’t to be—making them fit in the Insight’s battery bay was a massive haedache. He’d eventually move on to using lithium battery modules from later model Honda hybrids, developing the LiBCM project to make it happen. “We discovered that the G3 Honda Insight’s lithium cells fit perfectly inside the G1 Insight’s battery mechanicals,” he explains. “From there it was off to the races.”

Specifically, Sullivan engineered his replacement battery management system to work with packs from the 2018-2020 Honda Accord Hybrid, as well as Honda Insights built from 2019 onwards. These were termed the “G3” cells, referring to Honda’s third generation hybrid packs. John’s design came to be referred to as the 5AhG3 kit, for its 5 Ah capacity. It operates at a nominal voltage of ~177 V, slightly higher than the stock 144-volt NiMH pack.

“The goal was to create a replacement battery module that didn’t require any modifications to the IMA system,” Sullivan tells me. “That’s a tall order because you’re stuffing a modern design into a 25-year-old car, whose computers are expecting an old busted NiMH pack.” However, with perseverance and smart engineering, he was able to prevail. “In the end, my 5AhG3 LiBCM product is 99% drop-in; you have to tap into a single wire in the IMA wire harness,” says John.

Through his business, Linsight, Sullivan began selling “near drop-in lithium battery” conversion kits for the Insight, using this configuration. It’s still very much in beta, and requires regular firmware updates as Sullivan continues to develop the project and iron out the bugs. There’s a lot of moving parts to make it all work, with the LiBCM hardware responsible for spoofing multiple signals between the new battery and the stock Honda hardware to make everything work. Also worth noting is that if you buy a kit from Linsight, you get the necessary upgrade parts, but it doesn’t come with the batteries themselves.

A modded Insight with Honda G3 cells. The driver notes a welcome boost in performance from the upgrade.

You might imagine that this swap requires hunting through junkyards for the correct battery modules. You can certainly go that way if you’re so inclined. However, there is an easier solution to get yourself the right cells. Companies like GreenTec will sell you the necessary modern Honda batteries, or you can even buy a complete LiBCM and battery kit, ready to install. A full swap kit costs just under $3,000. It’s an achievable sum if you really love your Insight and want to restore it to something greater than its former glory.

Funnily enough, the 5AhG3 setup, which has a capacity of 887 Wh, does not outright hold more energy than the original NiMh pack, which comes in at 936 Wh. However, as explained by Sullivan, the newer lithium-ion cells that Honda used are able to operate safely over a wider range of state-of charge. Thus, you can use more of the energy in the pack—666 Wh for the lithium-ion setup, versus 515 Wh for the original NiMh pack.

Sullivan’s install instructions include a guide on how to boost the IMA power with the popular “current hack” mod. 

The lithium-ion cells have other benefits, too. Most specifically, the lithium-ion cells sit at a higher voltage and are much more capable of delivering high current. As explained by Linsight, this provides a performance boost when it comes to the IMA—the Insight’s electric motor. As stock, it can deliver 16 horsepower at most, powered by the NiMH battery. Upgrading to the higher-voltage lithium-ion pack boosts the motor’s output to 24 horsepower.

You can go further, too, by throwing in a current hack PCB that enables the motor to draw yet more current, as we’ve explored previously. This will allow the IMA to briefly deliver up to 32 hp, albeit under specific conditions and with the use of a special manual controller for the motor. This is only for five-speed manual models; those with the CVT can expect 28 hp at best. Still, as a further bonus of the lithium-ion swap, a complete pack weighs just 62 pounds, compared to 73 pounds for the original NiMH battery.

Gray25xt has performed the lithium-ion upgrade, and shares their experience above.

Added performance is great, and the IMA boost can really wake up a decades-old Insight, which would take around 10.4 seconds to hit 60 mph as stock. You can drop that to 8.9 seconds with a lithium-ion swap, according to YouTuber gray25xt, who performed the swap on his own blue first-gen Insight. Indeed, John appreciates the upgrade, too. “In my real-world testing, I’ve achieved ~100 horsepower in an LiBCM-equipped Insight, versus the stock 73 horsepower,” he explains. “At lower rpm the  power and torque difference is incredible, due to the electric motor’s flatter profile across rpm.”

However, what many Insight owners are also concerned with is fuel economy. Gray25xt has found it to be quite rewarding. He found that a brand-new NiMh battery got him 77 mpg over a full tank, and was good for about 700 miles of range. With the lithium-ion swap, he hit 81 mpg on a whole tank, which scored him 800 miles on the stock 10-gallon tank.

Of course, enquiring minds might wonder as to the difficulty of such an install. It’s more complicated than swapping out your regular car’s starter battery, but it’s not outside the capabilities of an attentive backyard wrencher, either. Sullivan states on the Linsight installation guide that a first-timer should expect to take a full day to do the job, while subsequent installs might be as quick as four hours. Ultimately, the smaller size of the battery means that you’re not facing the same size job as swapping out a traction pack in a full EV like the Nissan Leaf.

The main thing for the home gamer is to observe the proper safety precautions when working with high-voltage batteries. While the Honda packs (and the lithium-ion replacements) will only just crest 200 volts when 100% fully charged, that’s still plenty enough to cause harm. To that end, Sullivan provides videos on the correct safety procedures as well as the install instructions themselves.

Sullivan provides video instructions to those pursuing the lithium-ion upgrade.

The packs have the benefit of being smaller than full-size EV batteries, making them easy to install by hand.

Going Plug-In

While the later-generation Honda cells are a nice upgrade, so much more is possible. It’s a much more experimental swap, but Sullivan has been exploring the use of Ford’s lithium-ion batteries to produce battery packs for the original Insight with far greater capacity. It’s still very much in development, but these larger packs give the Insight altogether greater capabilities, almost turning it into a plug-in hybrid with the addition of a grid charge feature.

Sullivan and Linsight refer to this as the FoMoCo swap. It relies on LX68 lithium-ion modules produced by Ford for cars like the Ford Escape PHEV and Kuga Hybrid. However, they’re also found in other vehicles like certain years of the Jeep Wrangler 4xe and the Audi Q5 PHEV. With four or five of these FoMoCo modules, it’s possible to put together a pack containing a total of 48 or 60 individual lithium cells with 8 or 10 kWh of capacity, respectively. That’s not far off from the size pack you might find in a mainstream PHEV like the Dodge Hornet.

According to John, it’s got 12 times more capacity than the OEM NiMH pack. What does that mean in the real world? “You can drive 40+ miles fully electric with this product,” he says. With a caveat, though. “The gas engine still rotates—but doesn’t consume gasoline—as the electric motor is permanently attached to the flywheel,” he explains.

As an experimental offering, Sullivan is only offering the FoMoCo LiBCM kits to Insight Central forum users on a special-order basis. The install is significantly more complicated than the 5AhG3 swap, as it requires the use of a custom aluminum battery tray to hold the Ford cells. It also requires modification to the IMA motor enclosure and the wiring harness, as well.

You also need to find a source for the right cells; Sullivan has supplied some to eager swappers, but shipping these cells is prohibitively difficult and expensive. Despite the challenges, he’s already found several customers, having shipped 40 kits to date.

The key benefit of the FoMoCo swap is the sheer capacity of the battery. The Linsight kit pairs the larger pack with a grid charger, which allows you to juice up the Insight just like a plug-in hybrid. You don’t need to plug it in, but that’s kind of the whole point of the swap—that you can juice up the battery so you can drive on more electric power and less gas.

Unfortunately, you can’t really naturally drive the Insight in a pure-electric mode like a modern PHEV, due to limitations baked into the original hardware. However, with a manual controller for the IMA motor, it’s possible to spend a lot longer driving on solely electric power, as Sullivan demonstrates in the YouTube video below. He has his Insight set up with a small hand control to vary the amount of electric assist or regen from the IMA. It’s a weird way to drive, but Insight hackers aren’t afraid to get into the nitty-gritty to juice the most out of these first-gen hybrids.

Sullivan demos the Honda Insight driving with a 60S pack built with FoMoCo cells. 48S and 60S refer to the number of individual lithium cells in series—48 or 60 in series (S), respectively.

Even the large 60S FoMoCo pack is still small enough to charge quickly in a few hours with a simple 240V grid charger.

Kits aren’t readily available off the shelf. They’re built as Sullivan finds the time, and you really need to be on the forums and in the Insight community to gain access. Still, based on the Linsight website, pricing lands somewhere around $4000 for a 60S kit with the fastest grid charger and a manual controller for the IMA motor.

If you are brave enough to pursue the FoMoCo install, though, you’ll still find plenty of resources. The Insight Central forums play host to a long-running thread on LiBCM developments, and Sullivan has provided detailed videos for those pursuing a DIY install at home. But make no mistake—you need to wade deep into the world of Insight forums and hackers if you want to tread this path. Expect to spend a long weekend on the install, John tells me.

If you’re even more daring, you can go off-book and figure out how to use your own cells. “The core technology should work with any lithium cells.  Doing so takes a couple of days, as you need to gather charge/discharge data from each new cell type, and then modify the firmware slightly based on that data,” notes Sullivan. It’s not for the faint of heart, and you’ll really need to know what you’re doing. Still, it’s entirely possible. “Two customers have achieved this with different lithium modules,” he explains.

There is a bit of wiring to do if you want to run a Ford-based pack.

Ultimately, Insight owners are a niche bunch. The broader population of car owners probably aren’t rushing to purchase an aging 25-year-old Honda just to have fun throwing in some pricy new batteries. This kind of thing is not mainstream, and probably won’t ever be.

At the same time, it goes to show just how daring and innovative members of the car community can be. Just because the cars are different these days, doesn’t mean that modding spirit has gone out the window. New generations of enthusiasts are pulling apart hybrids and EVs, and making them faster and more capable—and they’re having a great time doing so. As long as the car exists, don’t expect that to stop.

Image credits: John Sullivan via YouTube screenshot, GreenTec, Honda, gray25xt via YouTube screenshot