General question for those who have worked in the consumer electronics industry: Are small rechargeable devices (like bluetooth audio devices specifically) designed to fail after a set time to force customer replacement? Is there for instance a mechanism that disables charging once the battery has totally failed or after a certain length of time? I have heard of AC power supplies having lower-rating capacitors or something that will decrease component life and cause earlier failure.

I've experienced this perhaps 3 times:

Somewhat older electronics:

  1. Motorola HT820 stereo bluetooth headphones - model 1 failed after about 2 years. Lights up on connecting charger but will not charge or power on after being on charger.
  2. Motorola HT820 stereo bluetooth headphones - probably different hardware revision - Failed in same fashion after about 1 year.

Recent electronics

  1. Bose QC35 bluetooth noise cancelling headphones - $350 - Failed after 1.5 years. No lights on connecting charger. Will not charge - Details: Battery was definitely almost at end of life. Disassembled to find the lipo battery inside it. Accidentally poked battery releasing a very small spark. Used it next day until battery depleted. Tried to connect charger after that, no lights, no charge. What the heck? Battery might have been failed/dead completely at that point (0 charge due to short I created?).

On the other hand, I had a lipo based Palm Centro that lasted many many years before it started to display random glitches probably caused by hardware. It lasted clear from 2008 (new model) to about 2014-15? I've had a lenovo thinkpad T430 that has been running great since 2011, used daily, but not transported all that much (which I think greatly increases mechanical wear on the circuits). I am only now replacing it because it can't run newer games.

So TL;DR: Do consumer electronics have actual kill circuits that make the device fail when the battery really dies or some other timeframe that makes the customer replace?


closed as off-topic by duskwuff, Elliot Alderson, Chris Stratton, Leon Heller, Dave Tweed Dec 12 '18 at 19:52

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  • \$\begingroup\$ Why bother with a "kill circuit"? If it can't work with a faulty battery then it would be pointless. \$\endgroup\$ – Finbarr Dec 12 '18 at 18:36
  • 1
    \$\begingroup\$ There's no need to intentionally build anything in. All that is required is a marketplace that will refuse to pay twice as much for something that may or may not last ten times as long, but is otherwise exactly the same out of the box. And that marketplace is -- us. \$\endgroup\$ – TimWescott Dec 12 '18 at 18:39
  • \$\begingroup\$ Not exactly a time frame but the chips in toner cartridges that prevent refills do something like that. And my car nags me as the service interval approaches. It doesn't quit if the time is exceeded, but the warranty might be voided. \$\endgroup\$ – Spehro Pefhany Dec 12 '18 at 18:57

I've worked on countless consumer products, and I've never seen a "kill" circuit that intentionally causes the product to fail after some specified period or event.

However, consumer products are designed for a certain lifetime, with a certain number of failures in that lifetime being acceptable. That's just a reality of the reliability of components.

The manufacturer has to balance lifetime and reliability with cost, product size, time to market and other factors. If the product is too expensive or big compared to the competition, no one will buy it. If it fails to early and provides a bad customer experience no one will buy the next one.

So in general manufacturers try to make a product as reliable as possible while meeting all the other product constraints. What you hear about or remember is the time the product failed right after the warranty (or battery or whatever) expired. The hundreds of products you have had that didn't do that don't get any "press".

If a battery is not replaceable even by the manufacturer then it may not make economic sense to make the product reliable enough to outlast the battery by a wide margin.

  • \$\begingroup\$ on the last line .. I felt that my bose headphones, having paid a ton of money for it, ought to last longer than a cheaper set of bluetooth headphones. This is my feeling, and perhaps there are far more expensive headphones out there that do the same thing that are for consumers... \$\endgroup\$ – Shorin Dec 12 '18 at 19:46
  • \$\begingroup\$ After two inexpensive WIFI router radios slowly failed on me on their second year (their range slowly declined until these became unusable), I went out and bough more expensive Apple ones. They have been going for nearly 10 years. Some companies do care about post-warranty lifetime. \$\endgroup\$ – Edgar Brown Dec 12 '18 at 20:55

You cannot just replace the battery, you also have to reset the charge counter chip.

If you want to reach maximum charge over cycles, you should never charge a LiPo battery to more than 90% and never discharge it to less than 10% of the capacity. This measurement accuracy cannot be reached by checking the unloaded voltage of the battery pack, you have to count the charge going in and out the battery.

The downside is you have to reset the chip when you replace the battery. It may seem simple, but as you don't know how much charge is initially inside the new battery when you replace it, what's the value you should set?

If the battery is dead, the charge counter chip is set to a safe value – full – because an overcharged LiPo will catch fire pretty certainly.

  • \$\begingroup\$ I thought Lipo battery chargers switch from CC to CV after it detects a certain condition from the battery... so maybe it can tell when it's fully charged? I am aware of the "gas meter" counting circuits being the usual case, but the CC->CV thing makes me wonder. \$\endgroup\$ – Shorin Dec 12 '18 at 19:49
  • \$\begingroup\$ Certains types do exist. The better ones count the charge. The "certain condition" you mean is upper/lower voltage bounds. But these trigger at 95…100% and 0…5% depending on the battery condition, temperature, charge/discharge speed etc. \$\endgroup\$ – Janka Dec 12 '18 at 19:55

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