Treat Li-Ion batteries like people to make them last

#1

Post by andyrebele » Thu, Apr 23, 2015, 8:56 PM UTC

Treat Li-Ion batteries like people to make them last
purewatercraft.com

Re: Treat Li-Ion batteries like people to make them last

#2

Post by andmarios » Thu, Apr 23, 2015, 9:26 PM UTC

Or just buy a device with an easily replaceable battery.

Re: Treat Li-Ion batteries like people to make them last

#3

Post by abandonliberty » Thu, Apr 23, 2015, 9:26 PM UTC

This is something people really don't seem to care about. The lack of awareness of how to increase battery life combined with non-replaceable batteries baffles me. Perhaps the effect isn't immediately obvious, or overstated?

Though it's actually best to starve people a little bit. http://en.wikipedia.org/wiki/Intermittent_fasting

Re: Treat Li-Ion batteries like people to make them last

#4

Post by codys » Thu, Apr 23, 2015, 9:28 PM UTC

The article lists percentages of capacity as if every battery (or battery controller) reports the full range of capacity (or allows charging to actual full capacity or discharging to completely empty).

I had thought that many manufacturers (at least Apple) had added things that specifically limit the amount the battery is charged to less that "100%" while (of course) still displaying 100% to the user (essentially, users see the the capacity as dictated by policy, not by physical characteristics).

Is this article only talking about "dumb" Li-Ion batteries? I note it's a "watercraft" related blog, does that mean the same mentioned percentages don't apply to non-watercraft/consumer Li-Ion batteries?

Further, we get some numbers, but we don't get the data those numbers are from. I presume they are just "these seemed to make sense to us from our anecdotal evidence".

Re: Treat Li-Ion batteries like people to make them last

#5

Post by Guvante » Thu, Apr 23, 2015, 9:31 PM UTC

abandonliberty wrote: post #3

This is something people really don't seem to care about. The lack of awareness of how to increase battery life combined with non-replaceable batteries baffles me. Perhaps the effect isn't immediately obvious, or overstated? Though it's actually best to starve people a little bit. http://en.wikipedia.org/wiki/Intermittent_fasting

All of these things are built into consumer devices already.

0% maps to about 5%, 100% maps to 90-100% depending on where in the charge cycle the device is (it will stop charging for a while to discharge some of the battery before starting charging again).

Re: Treat Li-Ion batteries like people to make them last

#6

Post by Guvante » Thu, Apr 23, 2015, 9:32 PM UTC

This is about watercraft, not consumer devices. These kinds of things are managed automatically for you in your phone, tablet, or even PC.

Re: Treat Li-Ion batteries like people to make them last

#7

Post by cabirum » Thu, Apr 23, 2015, 9:34 PM UTC

I think the title should include 'boats' somewhere.

> get the most out of batteries for electric boats > Mostly full is a LOT better than fully full > Don’t leave them full > Don’t empty them all the way

I've been under impression that all modern li-ion batteries are equipped with some kind of controller preventing overcharges and empty batteries, monitoring battery performance, etc. Users can actually leave their devices plugged indefinitely and it won't cause batteries to degrade faster.

Re: Treat Li-Ion batteries like people to make them last

#8

Post by andyrebele » Thu, Apr 23, 2015, 9:39 PM UTC

codys wrote: post #4

The article lists percentages of capacity as if every battery (or battery controller) reports the full range of capacity (or allows charging to actual full capacity or discharging to completely empty). I had thought that many manufacturers (at least Apple) had added things that specifically limit the amount the battery is charged to less that "100%" while (of course) still displaying 100% to the user (essentially, us…

I put a link to Battery University at the end. Some of the numbers came from there. Others come from cell data sheets (best ones from Panasonic). A lot of this is synthesis over many data sheets and white papers, none of which would by themselves be illuminating to the average battery user, because so much of the data would be cell-specific.

You're right that device manufacturers choose what to name "100%". Generally, cellphone makers are most attuned to people running out of power, so their 100% is pretty close to the real top charge level (not overcharge). They are rated and tested and reviewed based on tests like Walt Mossberg's run standard processes and see how long it runs until empty. The incentive provided by such make-or-break tests is to allow users to fully charge and fully discharge.

Better control and information would be provided if you gave the actual voltages and chemistries, but both are beyond what a normal user would be comfortable using on a daily basis. Internally, we almost always refer to state of charge in cell voltage terms.

Tesla and BMW provide the ability for the user to know and adjust the top of the charge. Tesla's approach is fairly user-friendly, and BMW's is a little more powerful, albeit less user-friendly.

Re: Treat Li-Ion batteries like people to make them last

#9

Post by andyrebele » Thu, Apr 23, 2015, 10:13 PM UTC

cabirum wrote: post #7

I think the title should include 'boats' somewhere. > get the most out of batteries for electric boats > Mostly full is a LOT better than fully full > Don’t leave them full > Don’t empty them all the way I've been under impression that all modern li-ion batteries are equipped with some kind of controller preventing overcharges and empty batteries, monitoring battery performance, etc. Users can actually leave their de…

This post was not about boats; it's about li-ion batteries in general. We learned the lessons when developing our outboard motor battery pack, but the batteries we're using are the same cells used in laptops, and the same chemistry as used in cellphones, tablets, etc.

There is no specific charge level at which battery use becomes costly. It's just more costly to charge the higher the voltage to which you charge. Of course, overcharging (over the rated voltage) is extremely costly (and dangerous). Under that level, the device maker has to make an arbitrary choice about how to balance cycle life with calendar life, and that choice is usually near (but not at) top voltage.

Our tests have found that charging a cell to 80% instead of 90% can extend its life by more than 50% under the same conditions of use, sometimes much more (lots of factors: charge/discharge rates, temperature, time between cycles, etc.). I'm sure no cellphone/tablet maker is limiting charge to 80%.