Home » This Startup Has A Clever Idea To Easily Retrofit Old Cars Into Hybrids

This Startup Has A Clever Idea To Easily Retrofit Old Cars Into Hybrids

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Here’s the thing about mass electrification of the global automotive fleet for environmental benefit: logistically, it won’t be perfect. Last week, a study from Polestar and Rivian said that even if the world’s supply of cars goes fully electric in the next few years and those cars are powered by fossil fuel-free energy, it still might not be enough to keep temperature increases in check. Plus, that’ll likely never happen anyway — not for decades. And as things stand right now, we can’t make every single car electric. In fact, doing that would introduce all sorts of associated problems and resource issues and would be massively wasteful, considering the world is filled with over a billion cars.

What actually would help more is if there was some way to make a significant portion of the current global car fleet burn less fuel most of the time – I say this not because I’ve crunched all the numbers, but more because I know that a rapid switch to 100% electrification is effectively impossible, and doing something is much better than doing nothing. It doesn’t need to be perfect, just better.

Plug-in hybrid combustion-electric vehicles are an ideal solution here because they can be completely electric for the short trips that form the bulk of how we use cars, but at the same time be able to use a combustion motor for longer trips and recharging, avoiding the need to build a staggering amount of EV chargers.

A startup called BlueDot Motorworks seems to get this idea and is developing an interesting and pleasingly basic-seeming universal unit to retrofit pretty much any car into a plug-in hybrid.

Will this actually happen? Who the hell knows, but let’s look at what they’ve got.

Oh, and it appears that their prototype unit has been fitted to what looks to be a 1997-2001 Jeep XJ Cherokee:

That video, which makes the case quite well for the need for retrofitted partial-EV solutions instead of trying to re-make the whole automotive landscape as pure EVs, shows their prototype driving around, a battery pack with what looks like fake taillights hanging off the trailer hitch of the XJ. I can’t tell if the system, which they call the Narwhal, is actually providing motive power or how that power would be moving the Jeep’s wheels, but you can at least get a general sense of what they’re going for.

Their website provides a couple of diagrams that provide a bit more insight:


Their planned line of cetacean-named add-on-hybrid kits actually has two entries: Narwhal, which we saw in the video in trailer hitch mount form, is for solid-axle vehicles and somehow connects to the rear differential to provide power from a co-axial motor/clutch system.

The other version is the Humpback, which can also mount the battery pack off the rear bumper, presumably via a similar trailer hitch-type mount, but provides power via what looks like a pair of external motor units that connect to the rear wheel’s mounting bolts/nuts.

This is an interesting if clunky way to accomplish this, and I suspect would be best used on FWD cars, of which there are plenty. It looks like the sort of thing an owner could install in their driveway in an hour or so, which is fantastic. Oh, also interesting: the SUV that they’re using in that image is a Mahindra XUV500, an unexpected but very cool choice for their diagram here. I bet they chose it in the hopes that it would be unrecognizable to most non-Indian readers, but they didn’t count on us, did they?

The graphic also notes they’re planning on an EV-only range of 30 miles, with “up to 200 hp” from the EV motor. My guess is that these are just target numbers, but as far as targets go, they make sense. A 30-mile range would, on average, cover most Americans’ daily commuting distance, and around 200 hp would be enough for that sort of commute, too, easily.

For me, the big appeal of Blue Dot’s solution is the simple straightforward, even almost crude design. These seem like plausible ways to cheaply add hybrid functionality to just about anything. They remind me of some goofball ideas I had back in 2012 for clamp-on motor units (the drawings show a gasoline version but I played with electric options, too) that would help push a broken car back home:

Myoldideas Assist

The notion of a completely separate, independently-contained power and energy storage unit means that it really can be applied to just about any car, even the old vintage heaps I gravitate to. Now, I’m not sure about the implications of a lithium iron phosphate battery effectively replacing your rear bumper, so that would likely take some figuring out and destructive crash testing, but I feel like there must be some solution there.

Of course, there are more issues involved in a system like this, too, which our resident suspension engineer Huibert Mees lays out for us:

I reached out to BlueDot for some answers to these questions, and heard back from their CEO and founder, Tom Gurski, who told me this:
We are targeting a nominal weight for a 15 kWh pack of approximately 250 lbs. Using the wheelbase and weight of our XJ test vehicle, if a vehicle started with 50% of the weight on the rear axle, our system would increase that to 56%. While this will have some effect on at-the-limit handling, it will be a second-order effect as the increased lateral load is offset by increased traction. This is completely in line with many currently accepted practices, such as a hitch cargo carrier or the tongue weight of a trailer. There is also the option of mounting the pack inside the vehicle, which, especially for pickup trucks, will be preferred by many customers.
The anti-sag is an additional spring that is connected from the hitch to the axle by either an arm underneath (Narwhal) or by the external swing arms (Humpback). The preload is adjustable so normal ride height can be achieved.
The normal use case would be to use the system until the battery is depleted and then turn on the engine. We do not anticipate frequent switching back and forth, and may actually include a timeout function that prohibits this.
Okay, these seem pretty reasonable; I’m not sure that the problems are so much solved as it seems the company has decided that the tradeoffs are acceptable, given the expected use cases. I mean, engineering is all about compromise, so perhaps they’re right.
A large-scale, any-car retrofit solution like this really doesn’t have to do all that much to make a significant impact: about 30 miles of electric-only range, able to hit at least 65 mph or so, and that would cover most daily commuting needs, and that alone, at scale, would make a big difference.

Will these guys actually get a product to market? I have no idea. But, I hope that someone will get into the business of easily and cheaply adapting conventional combustion cars into some sort of plug-in hybrid. Plus, it could also be a great limp-home solution the next time one of my shitboxes has some stupid failure of some part I’ve neglected for years!

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55 Responses

  1. I think your design with the janky wheel hanging off the back is actually more practical.

    How the heck does it attach to the differential? With like 40 universal joints?

  2. The battery for my Prius, which gives you maybe a couple of miles of pure EV driving if you baby it, weighs over 100 pounds. I’m dubious they can get 30 miles from 250 lbs of battery that won’t be anywhere near as efficiently integrated as the Prius one is.

    Still, I don’t hate the idea. It’s less wasteful to retrofit existing cars than to build completely new ones and scrap the old ones.

  3. Hi friends, Goldie Wilson III for Wilson Hybrid-Conversion Systems. You know, when my grandpa was mayor of Hill Valley, he had to worry about emissions problems. But now, you don’t have to worry about emissions! I’ll hybrid-convert your old ICE car into a electric hybrid. For only $39,999.95. So come on down and see me, Goldie Wilson III, at any one of our 29 convenient locations. Remember, keep ’em clean.

  4. This is akin to the people that buy into the idea of mounting an alternator on the fender and driving it off the wheels and thinking they would have a perpetual motion machine. This is a simple idea with bad execution that would not work.

    I suppose if they integrated the battery into the truck space and replaced the rear rums with regen brakes/hub motors, you could in effect make a passive hybrid. if you could perhaps charge the smallish battery and turn off the engine altogether an still safely drive the old thing that would be a plug in hybrid. But I cannot see this as being an inexpensive option that would likely only sort of OK for most people.

  5. It’s like a hinkier version of betting all your chips on fleet electrification, when what is an order of magnitude (scientific eye-squint) more effective is reducing use and reliance on individual cars.

  6. Jeebus, that is one bad idea!
    I’d much rather have glass solar roads (how retro..) or one of those stupid luckily-nonexisting high centre of gravity 3D-rendered VW bus boats from Instagram!

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