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Apr 12, 2019, 07:48 AM
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LiPo vs lithium polymer in consumer electronics


Is there any difference between the LiPos we use for flying, and lithium-polymer batteries used in newer cell phones and notebooks? Or is this same technology?

Especially what makes me wonder - how could it be, that my notebook is always fully charged and the battery doesn't suffer, while my heli lipos have to be discharged to storage if they are not being used?
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Apr 12, 2019, 08:31 AM
Space Coast USA
hoppy's Avatar
One reason could be is that the comsumer product has a <1C draw on the battery and IR doesn't come in to play where as your helis probably draw in the 20C (or more) range where IR becomes important. Bottom line, increase in IR due to full charge storage is not a problem with consumer products like cell phones.
My guess.
Apr 12, 2019, 08:49 AM
Registered User
Yes - the high C is the difference. I'm sure that all Lipos would last longer if not kept fully charged but the lower C 18650's and consumer cells used in phones don't degrade like our high C lipos do.
Apr 12, 2019, 09:10 AM
Proud to eat Kraut ;-)
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Quote:
that my notebook is always fully charged and the battery doesn't suffer
It does suffer. Not loudly screaming like RC lipos, but with a quiet whimpering.
Apr 12, 2019, 09:55 AM
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Thanks guys, it made it clear. Will still keep my notebook fully charged
Apr 12, 2019, 12:24 PM
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Also the laptop has the capacity for sophisticated intelligent battery-management, starts to go into power-saving modes, throw warnings erc, auto shutdown before LVD is reached, and the incoming "charger" current can just be from a raw PSU.

But yes, use cases with .2C considered "high rate" of discharge results in much more leeway for longevity.

Sure I used to discharge and store my laptop batt in the fridge when not in use for long periods, but that's pretty outlier. . .
Apr 12, 2019, 12:48 PM
Registered User
Also, to clarify

LiPo is = lithium-ion polymer

This does not actually signify a specific chemistry, more a physical "packaging" of the electrolyte in a polymer gel rather than requiring metal, to get to thinner casing, minimizing weight and form factor flexibility.

That said, most lipo is afaict LCO (Lithium Cobalt Oxide, LiCoO2), also for the holy grails of energy density and max C rates, same as with most screen gadgets.
Apr 13, 2019, 03:35 AM
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Ok, so are our lipos somewhat different tech from the beginning, as they have 25c or 45c discharge rates (or more), and for this reason they don't like being fully charged?

Or are they same thing, and all of them collect big IR after being charged for too long time, but it just doesn't matter for laptops at all?
Apr 13, 2019, 09:18 PM
Registered User
The formula tweaking that allows high discharge is proprietary and important for that aspect of performance, but doesn't put them in a whole separate category from a chemistry POV.

Can't believe vendor advertised numbers either, search for user tests in the forums and YT.

And nothing to do with "don't like being fully charged", where did you get that idea?

True for all LI types when longevity is the goal, usually only propulsion use cases push for that extra range performance.

IOW longevity is just as much a result of the care / usage patterns as the chemistry involved.

By avoiding the voltage shoulders and keeping to low C-rates, they can last over a thousand cycles rather than a couple hundred.

But LFP and LTO can be made to last decades, many thousands of cycles maybe tens of thousands, while LCO, NMC etc just a couple thousand is optimistic.

And whether polymer packaging is involved or not is irrelevant.

What is it specifically you are trying to accomplish?
Apr 14, 2019, 03:54 AM
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Quote:
Originally Posted by John61CT
The formula tweaking that allows high discharge is proprietary and important for that aspect of performance, but doesn't put them in a whole separate category from a chemistry POV.

Can't believe vendor advertised numbers either, search for user tests in the forums and YT.

And nothing to do with "don't like being fully charged", where did you get that idea?

True for all LI types when longevity is the goal, usually only propulsion use cases push for that extra range performance.

IOW longevity is just as much a result of the care / usage patterns as the chemistry involved.

By avoiding the voltage shoulders and keeping to low C-rates, they can last over a thousand cycles rather than a couple hundred.

But LFP and LTO can be made to last decades, many thousands of cycles maybe tens of thousands, while LCO, NMC etc just a couple thousand is optimistic.

And whether polymer packaging is involved or not is irrelevant.

What is it specifically you are trying to accomplish?
I'm just trying to understand that. I have now several Lithium-Polymer devices - my smartphone and notebook obviously, but also some battery to run photo equipment in the field - this one I rarely use now, and it wasn't cheap, so I wonder how it should be stored.

It is clear to me that we're using high discharge rates in the hobby and that makes cells wear faster. But we're also not supposed to keep our LiPo's fully charged, as this is very bad for them - so either fly it or discharge it. And this doesn't seem to have anything to do with how fast we discharge it, right?

I once advised to a friend who just bought his first multicopter, that he shouldn't keep he's Lipos charged all the time, but rather charge them before flying. He said why? I have my laptop charged all the time and it's a lipo too. I wish I would have a precise answer in this case. It gets more clear with this thread.
Apr 14, 2019, 07:59 AM
Space Coast USA
hoppy's Avatar
Quote:
And this doesn't seem to have anything to do with how fast we discharge it, right?
Wrong.
The lower the discharge rate the more cycles the battery will deliver.
Apr 14, 2019, 08:01 AM
Registered User
If the other usage factors mean the battery lasts a long time - maybe longer than the lifespan the mfg intends for the gadget - then optimizing how its stored while not in use, is not worth bothering the user about
Last edited by John61CT; Apr 14, 2019 at 08:15 AM.
Apr 14, 2019, 08:14 AM
Registered User
Quote:
Originally Posted by hoppy
The lower the discharge rate the more cycles the battery will deliver.
Well, to a point.

If your usual rate is say .2C, I doubt going down to .1C will give that much longer life.

And even going from .5C down to .2C may not make any difference if say average DoD is very high, or voltage charging is high and current pushed until zero acceptance every time.

Or ambient temps always very high. So many variables, no single one's effects can be predicted except within an unrealistic lab context.
Apr 14, 2019, 08:18 AM
Registered User
And note that an internal hard to replace battery going dead is often the stimulus for the user to buy a whole replacement unit.

If our stuff all lasted decades, many companies would have to change their business model or downsize.
Apr 14, 2019, 11:53 AM
Registered User
Thread OP
Quote:
Originally Posted by hoppy
Wrong.
The lower the discharge rate the more cycles the battery will deliver.
Well, there is no discharge rate at all if you just store it fully charge right?


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