Odd Dyson fault

[Brian Gaff (Sofa 2)]

So you need a hair extraction tool! Brian

[Pamela]

The issue is not safety as lithium ions batteries and chargers are usually well protected but that the battery is stressed when it contains a full charge. I'm told it also physically swells.

Those smartphone users trying to conserve lithium ion batteries will not charge above 80% or so. A Dyson doesn't offer the same degree of control but leaving it on charge the whole time continually keeps topping up in the most stressful way.

[Pamela]

As I understand it, manufacturers design the charging cutoff to allow the maximum charge in order to satisfy consumers who demand the longest runtime possible.

[T i m]

I don't, mine went years ago. ;-)

Daughter is pretty good at getting hair off the rollers but hadn't really looked past the external bits and the filter.

Cheers, T i m

[T i m]

Yes, except manufacturers of EV's and (some that I know of) laptops ... and who knows what else?

My point here is that unless we know what's going on behind the scenes, we can only assume how the charging is managed.

I'm currently working on a Samsung laptop for a friend and I noticed that has an option in the BIOS to limit the maximun charge to 80% to prolong the battery life. How many other laptops (or phones etc) may also give you the option or do it by default?

I think Tesla will sell you a replacement EV battery at a much reduced cost if you are able to get the existing one up to a specific number of miles / years. To do this the owner would have to manage the battery carefully and that might include ensuring the max and min charge levels are not exceeded. Obviously they want owners to get the maximum lifespan out of their batteries as it looks good on their PR and is likely to reduce any warranty claims (compared when the battery is used 'hard').

Cheers, T i m

[Scott]

I thought the software took care of that by its definition of 100%.

[Pamela]

Quite true. We can only guess at how the charging has been designed. My guess is that smartphones are manufactured to be as short-lived and battery life largely ignored.

Here are a couple of interesting articles on preserving lithium ion life which seem well informed:

[newshound]

Citation? I don't doubt that the wall-wart feeding the bracket is very basic, but doesn't the clever control stuff live inside the battery?

[Pamela]

I'm no expert but as I understand it, lithium ion is so prone to overheating and catching fire that there's safety protection against dangerous overcharge in both cell and charger.

However overcharging stress occurs long before dangerous overcharge, especially if temperature rises, and affects cell life more than safety.

There are mixed messages on how adverse this is. There's better agreement that low discharge is even worse.

[Pamela]

Cites with breaks for clarity:

Lithium-ion operates safely within the designated operating voltages; however, the battery becomes unstable if inadvertently charged to a higher than specified voltage. Prolonged charging above 4.30V on a Li-ion designed for 4.20V/cell will plate metallic lithium on the anode.

The cathode material becomes an oxidizing agent, loses stability and produces carbon dioxide (CO2).

a Li-ion battery cycled within 75%-25% SoC (blue) would fade to 74% capacity after 14,000 cycles.

If this battery were charged to 85% with same depth-of-discharge (green), the capacity would drop to 64% at 14,000 cycles,

and with a 100% charge with same DoD [depth of discharge] (black), the capacity would drop to 48%.

For unknown reasons, real-life expectancy tends to be lower than in simulated modeling. Environmental conditions, not cycling alone, govern the longevity of lithium-ion batteries.

The worst situation is keeping a fully charged battery at elevated temperatures. Battery packs do not die suddenly, but the runtime gradually shortens as the capacity fades.

...

Environmental conditions, not cycling alone, govern the longevity of lithium-ion batteries. The worst situation is keeping a fully charged battery at elevated temperatures.

[Scott]

I'm no expert either but I thought the purpose of the battery management was not optimise the battery, not just to prevent dangerous overcharging.

Again, no expert but I thought battery life was defined by the number of charge/discharge cycles and therefore if you kept topping up, the battery would wear out more quickly.

[Andy Burns]

Pamela quoted:

Assuming a charge cycle per day, I probably wouldn't care whether a battery had 74%, 64% or 48% capacity left after 14 years ...

[Pamela]

I think that's the very point here: a lithium ion battery left on charge the whole time lost most of its capacity prematurely.

Entirely depends on the depth of discharge and what state of charge. I believe satellite batteries are optimised for longevity by avoiding extreme charge and discharge to such a degree that they are designed to work only within a narrow band of charge.

[Andy Burns]

sorry 14 thousand on the brain ... make that 38 years.

[Pamela]

As mobile phone users know only too well:

For unknown reasons, real-life expectancy tends to be lower than in simulated modeling. Environmental conditions, not cycling alone, govern the longevity of lithium-ion batteries.

There's a brisk trade in replacement batteries for phones only a few years old which have lost a lot of capacity. Mine lost 10% capacity in 9 months from new.

[Scott]

Exactly that.

Which is the mail filter? Is it the one at the top or the one at the back?

How do you take the canister off?

Thanks

[Scott]

Unfortunate typo. I meant to say that the purpose of the battery management was *TO* optimise the battery, not just to prevent dangerous overcharging. Are you sure it is left 'on charge'? I thought it was cut off by the management software once it reached its optimum level..

I thought it depended on both factors.

[Scott]

Well, most of my batteries have exceeded expectation (one lasting over five years). I generally let the phone become quite well discharged before putting it on charge. I am not convinced that an apparent full discharge does any harm at all, as I assume the phone will shut down before any harm comes to the battery.

Is that abnormal? What do you believe the design life of a battery is?

[Andy Burns]

I think the last phone I bought a replacement battery for was a Sony K800i.

My previous phone ran out of updates after google's 3 years, was still getting a day and a half per charge, dad's still using it over a year later.

The phone before that only lived just over a year, but that was due to interaction with a washing machine ...

[Pamela]

I expect my phone will become obsolete in pitifully few years. That's why I don't expect its battery charging is designed to last for 14 or 38 years or anything like that. My pattern of use (watching movies, etc) doesn't help and I got only about half a day out of a full charge even when it was new.

My phone also has Qualcomm's aggressive Quick Charge which should serve to further accelerate loss of battery capacity. Shame to see mobile phones designed to be almost as disposable as Bic Biros.