feature article
Subscribe Now

The Anti-Tesla

Tiny Bumblebee Batteries Replenishes Hybrid Car Battery Packs

“If the car feels like it’s under control, you’re not going fast enough.” – Mario Andretti

Electric cars have been around since the 1830s. That’s more than 175 years of progress, from the early Davenport autocar to the Tesla Model S, BMW i8, or Karma Revero. Hybrid cars – that is, ones that combine both an internal-combustion engine and an electric motor – are a much more recent development. Hybrids are popular these days. Toyota says it’s sold almost 6 million of them worldwide – a popular model by any standard.

The charm of a hybrid is that it’s a half-step. It’s part familiar, part Space Age. It runs on gasoline most of the time, but uses stored electricity to boost fuel economy a bit. You don’t have to worry about running out of juice (“range anxiety”) any more than you do with any normal gas-powered car.

The downside is, hybrid cars carry a lot of extra weight – sometimes hundreds of pounds of it. Those batteries are heavy, and ironically, it’s their extra weight that prevents hybrid cars from achieving even better gas mileage. It’s like driving around with a couple of sacks of concrete in the back seat, all the time.

The other problem is that batteries eventually die. As we’ve all learned from our cell phones, laptops, flashlights, and smoke alarms, even rechargeable batteries eventually lose the will to live and have to be discarded. For AA cells, that’s no big deal. But what do you do when you’ve got a few hundred half-dead NiCads weighing down your family hauler? Doesn’t that defeat the purpose of buying a hybrid in the first place?

Hybrid automakers – Toyota, Honda, Ford, et al. – provide a warranty on their batteries, along with some vague wording about their expected lifetime. Most hybrid cars haven’t been around long enough to have their batteries die of old age, but we’re getting there. When your hybrid’s batteries eventually do tap out, where do you go for a replacement?

If you’re a Honda Insight owner, you probably make a phone call to Portland, Oregon. Tiny Bumblebee Batteries has just six employees, and all they do is remove, replace, and recondition battery packs for the first- and second-generation Honda Insight hybrid car. It’s a bit of a cottage industry, but one that’s growing along with the popularity of the cars themselves.

In the US, Honda’s Insight is the second-most-popular hybrid vehicle, after the ubiquitous Toyota Prius. Insight owners tend to be fiercely loyal, pointing out that the Insight beat the Prius to market by several months, and that it gets better gas mileage. First-generation Insights were kind of funny looking, however (so were first-generation Priuses, it must be said), and the car never sold as well as its national rival. Still, there are tens of thousands of Insights on the roads, and their batteries aren’t getting any younger.

Honda is happy to sell you a new battery pack. But Bumblebee can do it cheaper. And, according to the company, its batteries offer more power. It’s the modern equivalent of souping up the old roadster with an aftermarket carburetor.

Bumblebee buys brand new batteries from the Asian manufacturer, has them shipped to Portland, and puts them through a series of incoming inspection tests using instruments, test beds, and software that were designed in-house. The test equipment has a Wi-Fi interface that beams data across the shop floor to a central server, which (among other tasks) retains records of every cell in every battery pack.

Testing batteries is not terribly straightforward. They’re inherently analog devices, and chemical ones at that. Each car has about 120 batteries (it varies with model year) arranged in “sticks” of six batteries each. Individual batteries are almost (but not quite) the same size as conventional D cells, and they’re welded end-to-end to create a stick. First-generation Insights are powered by 20 sticks, arranged in a rough cube that fits in the trunk.

The whole assembly is controlled by Honda’s two onboard power-management computers, neither of which the Japanese company is willing to open up to outsiders. So Bumblebee had to reverse-engineer Honda’s firmware before figuring out how best to manage the battery pack’s charge/discharge cycles.

Testing batteries can be downright dangerous, too. A full pack of rechargeable cells puts out a nominal 144VDC, sometimes more, with enough current to vaporize heavy-gauge wire. In the car, an Insight will draw up to 12KW from its pack – nearly 100A under heavy boost. You don’t want to test these batteries by putting your tongue on them.

Also, seemingly harmless items can be a danger. Honda mounts its batteries on black rubber spacers, to minimize vibration. Rubber is an insulator, naturally, but it’s commonly colored with carbon, making the spacers into high-value resistors. They’re conductive enough that, with dozens of volts across them, the spacers can heat up and melt, causing a big gooey mess. Bumblebee routinely removes the offending spacers as part of its rebuilding process.

So how does this massive battery pack get into and out of a customer’s car? Most owners handle it themselves, though the less technically inclined can have a Honda mechanic effect the swap for them. In most cases, Bumblebee ships a new battery pack directly to the customer, along with a how-to video. That keeps the car on the road while the batteries are in transit, and allows the owner to drive the car to the mechanic’s shop, if desired. Once the swap is complete, the owner ships the old pack to Bumblebee, where its structural frame and wiring harness are reused, but the original batteries are discarded.

Most installations go smoothly, which is remarkable given the natural variety of Insight owners and the Gaussian distribution of their technical skills. One owner who’d evidently just bought his first voltmeter complained that his replacement battery pack was dead on arrival and demanded a replacement. Bumblebee ships all of its batteries discharged, for safety, but the customer was not to be denied. A second pack arrived, also discharged. Again, he complained and again, Bumblebee shipped him a third battery pack. After much cajoling, the owner agreed to charge the batteries first (i.e., start the car) before measuring the voltage. He emails back to say they’re the highest-capacity Honda batteries he’s ever seen. Thank you, sir.

Bumblebee seems content to handle Honda hybrids for now, but is considering branching out into Toyotas in order to serve the large audience of Prius owners. The batteries aren’t the same, and the battery-management computers are certainly different, but the market opportunity seems too enticing to pass up.

The challenges aren’t all technical, either. Sometimes it’s a simple matter of economics. Some hybrid vehicles depreciate faster than others, and owners aren’t always willing to spend $2000 for new batteries when the entire vehicle is worth only $4000. Since any hybrid will run just fine with no batteries at all, it makes more sense to simply continue driving it as a conventional gas-powered car. Ideally, you’d remove the batteries to save weight, but that’s a whole different DIY project.

Bumblebee Batteries provides an interesting juxtaposition: a small startup company with limited resources participating in the vastly more complex market for hybrid vehicles. Honda, Toyota, Ford, GM, and other car companies have collectively spent billions of dollars on research and development. Designing hybrid vehicles is complex stuff – really complex stuff. Yet here’s a six-person operation funded with little more than pocket money playing a vital role. Without Bumblebee, a lot of Honda owners would be selling their cars, scrapping them, or driving them in non-hybrid mode. Or just paying more for factory Honda replacements. It’s nice to see that garage-based technology startups still happen.  

Leave a Reply

featured blogs
Apr 11, 2021
https://youtu.be/D29rGqkkf80 Made in "Hawaii" (camera Ziyue Zhang) Monday: Dynamic Duo 2: The Sequel Tuesday: Gall's Law and Big Ball of Mud Wednesday: Benedict Evans on Tech in 2021... [[ Click on the title to access the full blog on the Cadence Community sit...
Apr 8, 2021
We all know the widespread havoc that Covid-19 wreaked in 2020. While the electronics industry in general, and connectors in particular, took an initial hit, the industry rebounded in the second half of 2020 and is rolling into 2021. Travel came to an almost stand-still in 20...
Apr 7, 2021
We explore how EDA tools enable hyper-convergent IC designs, supporting the PPA and yield targets required by advanced 3DICs and SoCs used in AI and HPC. The post Why Hyper-Convergent Chip Designs Call for a New Approach to Circuit Simulation appeared first on From Silicon T...
Apr 5, 2021
Back in November 2019, just a few short months before we all began an enforced… The post Collaboration and innovation thrive on diversity appeared first on Design with Calibre....

featured video

Meeting Cloud Data Bandwidth Requirements with HPC IP

Sponsored by Synopsys

As people continue to work remotely, demands on cloud data centers have never been higher. Chip designers for high-performance computing (HPC) SoCs are looking to new and innovative IP to meet their bandwidth, capacity, and security needs.

Click here for more information

featured paper

Understanding Functional Safety FIT Base Failure Rate Estimates per IEC 62380 and SN 29500

Sponsored by Texas Instruments

Functional safety standards such as IEC 61508 and ISO 26262 require semiconductor device manufacturers to address both systematic and random hardware failures. Base failure rates (BFR) quantify the intrinsic reliability of the semiconductor component while operating under normal environmental conditions. Download our white paper which focuses on two widely accepted techniques to estimate the BFR for semiconductor components; estimates per IEC Technical Report 62380 and SN 29500 respectively.

Click here to download the whitepaper

featured chalk talk

How Trinamic's Stepper Motor Technologies Improve Your Application

Sponsored by Mouser Electronics and Maxim Integrated

Stepper motor control has come a long way in the past few years. New techniques can give greater control, smoother operation, greater torque, and better efficiency. In this episode of Chalk Talk, Amelia Dalton chats with Lars Jaskulski about Trinamic stepper solutions and how to take advantage of micro stepping, load measurement, and more.