Boeing isn’t the only one with Li-ion battery problems. Me too, with my Panasonic shaver!

As I write this, the entire worldwide fleet of fifty Boeing 787 Dreamliner aircraft is grounded thanks to a problem with a Li-ion battery pack in the planes. The planes are grounded because of two incidents where smoke and fire were associated with the batteries. If there are two words you do not want associated with a plane that’s built largely of carbon fiber, those would be “smoke” and “fire.”Here’s an NTSB photo of one of the failed batteries:

Elon Musk has offered to help Boeing. If he does, it will likely be another multi-million-dollar feather in his cap, following Tesla Motors, SpaceX, and PayPal.

I’ve got no insight to reveal here about the Boeing 787 battery problems but I suddenly do have a Li-ion battery story of my own. Although I’ve no design experience with Li-ion batteries, I use several devices containing Li-ion batteries and I recently experienced a failure with one of those devices—my Panasonic ES8077 electric shaver.

I’ve had this shaver for about five years or so. It’s the best electric shaver I’ve ever owned and I’ve had Braun’s, Remington’s, and Norelco’s before the Panasonic ES8077. (The Panasonic cleaning station for the ES8077 shaver, now that’s a whole ‘nother story.)

I change out the Panasonic’s cutter and shaving foil about once a year and it’s kept on doing a great job. It’s always been able to go about a month between battery charges. Two months ago, that period between charges suddenly dropped from one month to three days.

Let me tell you, it’s pretty frustrating when the shaver dies a third of the way into a shave.

The Panasonic ES8077 has a wall charger but it won’t run from the charger. The charger only charges the battery. You can’t switch on the shaver while it’s charging. Imagine that.

Fortunately, I was able to charge the shaver for a couple of minutes and get enough energy into the battery to finish my morning shave. However, a sudden 10x drop in battery capacity from 30 to 3 days indicates imminent battery failure in my book so I figured it was either time to replace the battery or the shaver. For green purposes (and because I’m basically cheap), I preferred to change the battery. Not as easy as you might think.

Curiously, the Panasonic ES8077 shaver has a replaceable AA-sized Li-ion battery that’s not designed to be replaced by the consumer. To underscore that point, try finding a retailer that will sell you a Li-ion battery for this shaver. Even Google has trouble with this task.

The only Li-ion battery vendor I found for my Panasonic ES8077 was an eBay vendor named “softbutton.” Fortunately, softbutton has a 100% eBay feedback rating, which was somewhat encouraging. The cost for a replacement Li-ion battery for my Panasonic ES8077 shaver was $20.47, which includes shipping. For another $3.50, I could get a small vial of silicone grease to reseal my wet/dry shaver after the battery replacement.

Softbutton also conveniently posted a disassembly diagram of my shaver in the eBay listing itself since this too seems to be out of Google’s reach. The assembly diagram wasn’t exactly for my model, but it was close enough:

I elected to spend $23.97 and ordered the battery-replacement kit with the silicone grease. The kit arrived in a few days, packed in a zippered plastic bag. Here’s a photo of what was in the kit:

Notably, the battery has copper-post terminals that I’ve not seen before. Also note that the battery is a generic 3.7V, 1200mAh Li-ion battery made in China. To the left of the battery, you see a microcentrifuge tube filled with silicone grease that cost $3.50 extra. A slick piece of packaging, no? I guarantee you that I’d never have thought of using a microcentrifuge tube to mail small dabs of grease.

With a replacement battery in hand, the next step was to open the shaver and replace the dying battery. Shaver disassembly was easy. One screw holds the plastic bottom cap on the shaver. Then you lift the large, black, rubberized grip from the shaver. It holds tightly to the razor body, so there’s a bit of stretching and tugging needed to free the grip from the shaver. Actually, I had to pry it loose because it was a bit crusty, which you expect from a shaver that’s seen five years of use.

Once you remove the grip, you can back out the four screws and remove the two side clips that hold the two case halves together. Then you pull the two halves apart. This is what my disassembled shaver looked like before I cleaned up the five years of shaving crustiness.

You can see the Li-ion battery in the center of the shaver. It looks like a conventional AA alkaline battery with the exception of the additional terminal posts. The Li-ion charging circuitry is on a board that sits beneath the battery, which you can just see in the photo.

I snapped out the old battery and snapped in the new one. That was the easy part.

The hard part was getting the shaver back together. I applied some of the silicone grease to the recessed waterproof gasket in one of the case halves using a toothpick and then smoothed the grease with my finger. You only need a thin film for sealing. The two case halves then rejoined with no problem but replacing the grip proved a problem for me. The grip incorporates a mechanical switch that locks the shaving head in place. It does so by moving a small black lever back and forth to actuate a plastic head-locking mechanism.

The problem was that there’s nothing in the grip design to retain that locking switch so of course it fell out while I was fiddling to expand the grip to fit it around the shaver body during reassembly. Worse, the switch fell down onto the carpet after it popped free. A bit of searching on my hands and knees located the switch and I was ready to try again. This time, a small white plastic insert in the switch fell out and onto the floor. I needed a flashlight to find it.

I finally managed to retrieve the plastic insert but unfortunately, I had not snapped a photograph of that assembly so I had to figure out how everything went back together. Take a tip from me: use your digital camera to record the disassembly process in detail so you can get things back together after the repair, no matter what product you’re repairing.

Another ten minutes of trial-and-error fiddling and I had the shaver back together. I switched it on and nothing happened. (Cue the chirping crickets.) At this point, I hoped the battery was completely flat. Otherwise, I was out $23 and change and it was time for a new Panasonic shaver.

I charged the shaver for just one minute and pressed the soft on switch. The shaver started up. Success! I finished the button-up by replacing the bottom cap and let the shaver charge in its cradle overnight. There’s a simple 4-bar LED charging graph on the shaver’s handle so I could see that it was charging. According to the bar graph, it was fully charged after just a couple of hours in the charger.

In this era of greener design when we’re trying to give consumers every opportunity to recycle, it seems like a good idea to engineer products with replaceable batteries. The battery inside of the Panasonic ES8077 shaver is indeed replaceable.

However, not easily so.

First, it’s hard to find a replacement battery for this particular Panasonic shaver model. It doesn’t appear to be that hard to find an AA-sized Li-ion battery, although I’ve certainly never seen one before, but finding a battery with those little copper end posts was fairly difficult. If only one eBay vendor carries a product, that’s a pretty rare product in my book. The $20 Li-ion battery from softbutton on eBay is the only one I found from a US vendor although there’s an eBay vendor in Slovakia selling them too at slightly higher prices and presumably longer lead times. Through Google, I also found the Li-ion replacement battery offered by a vendor in the UK for £14.50, which is a bit more than $20 and didn’t include shipping. I don’t even know if the UK vendor ships to the US.

I presume that the Panasonic Li-ion shaver battery is hard to find because Panasonic didn’t engineer the ES8077 shaver to allow for consumer replacement of the battery. The shaver is somewhat hard to disassemble and you need to use silicone grease to reassemble it if you want to preserve the shaver’s wet/dry capability. Most people don’t have a vial of that stuff lying around either.

The company obviously planned for the shaver to be re-celled by a technician if it was to be repaired at all. However, that seems to be a very unlikely scenario for a consumer product like an electric shaver with a replacement cost that’s less than $100. What consumer is going to try to find someone still engaged in the dying art of shaver repair? There used to be shaver-repair stores in the occasional strip mall but these have disappeared, like VCR repair stores.

Even if you do manage to find someone who repairs shavers and other low-cost consumer electronics, what business can afford to charge less than $50 to replace a $20 battery? At that point, you might as well toss out the shaver and buy a brand new one. I consciously make this choice each year when considering the $30 cost for the Panasonic replacement blade set. Still, it seems a shame to consign the shaver to the landfill without trying to repair it if you have the skills.

So the next time you design a battery-powered product, give a lot of thought to the ease of battery replacement. If you possibly can, use a battery that people can purchase from “normal” retail vendors and provide an easy way to access the battery. If the unit needs to be waterproof, take a cue from other vendors that have managed to design accessible battery compartments in waterproof designs. Fluke DMMs are a good example to learn from. The examples of good green design are out there, if you look.


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2 Responses to Boeing isn’t the only one with Li-ion battery problems. Me too, with my Panasonic shaver!

  1. Steve,
    Great seeing you at DesignCon. Interesting story. We have a story about Li0Ion batteries that relates toe electric vehicles at The Connecting Edge. Guess which battery photo starts it off?

  2. Philipb says:

    I think this is exactly my problem i.e. my Panasonic shaver only gets warm when I charge it – no lights, no flicker when I press on? How can I check it is the battery prior to buying a new one?



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