Author Topic: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply  (Read 25124 times)

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Offline nctnico

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #75 on: September 03, 2016, 10:22:54 pm »
!MAJOR WARNING!
What Dave shows here is really dangerous! Never ever connect a battery to a generic power supply without a series diode! If something goes wrong in the power supply excessive currents may flow back into the power supply. Worse, some power supplies have a crow-bar (thyristor) across their output which gets activated in case of an error (overheating for example) and short the battery. I've seen the damage it can do first hand.
The voltage across the series diode can be compensated by setting the voltage a bit higher but don't overdo it. There is not much extra charge going into the battery near the maximum charging voltage anyway.

Also: when using Lithium batteries always use a UN38 certified pack with an integrated protection circuit against overcharge, undervoltage and current limits.
Always, Never. Typical EU type thinking.  8)
Well one of my ongoing projects involves lithium battery packs so I have seen a thing or two which can go horribly wrong. The certification lab which tests the battery packs used to have the battery testing lab inside the building. They thought it would be good enough to use a heavy duty fire proof cabinet. They where wrong! As a result of a big fire (due to operator error BTW) they moved battery testing to outside units with some distance to the main building.

Also, lets put some numbers in place. A generic 18650 Li-ion cell has an internal DC resistance of about 25 milli-Ohm. At 4V this means it can push 160A into a dead short. In that case the amount of power involved is 640W which is dissipated somewhere. Multiply that 640W with the number of cells in a pack. The problem is that 18650 cells look like oversized C Alkaline cells which are pretty harmless. Li-ion cells however contain a boat load of energy and can release that quickly. In general you really have to be carefull with devices which can hold a lot of energy. Think about something simple like the coil spring in the suspension of you car. When something goes wrong during dissassembly it will snap your arm right off if your arm happens to be in the way.

Also don't assume a high quality power supply can't go wrong. These are typically fitted with a crow bar in order to protect the load against the PSU going bad but when charging a battery you really don't want that. Again, I've seen this go wrong!
« Last Edit: September 03, 2016, 10:25:45 pm by nctnico »
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Offline Kleinstein

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #76 on: September 04, 2016, 02:23:54 am »
Good power supplies often have a crowbar, but they should also have a fuse (or something that acts like it at the output, so the crow bar current will be limited. Still this could end up with a deep discharged cell.

With a series diode, it gets tricky to set the maximum voltage right. Even with an R+D parallel combination the charging will turn to reduced current quite early and take longer.

I would at least add a fuse. With a possibly explosive device it's good to have a fuse. Even old bombs had one.  :-DD
 

Offline nctnico

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #77 on: September 04, 2016, 04:01:26 am »
A fuse at the output of a PSU is a bad idea because it increases the PSU's output impedance which may be bad for other purposes.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline Barny

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #78 on: September 04, 2016, 08:07:02 am »
With a series diode, it gets tricky to set the maximum voltage right. Even with an R+D parallel combination the charging will turn to reduced current quite early and take longer.
With an 4-Terminal measurement of the cell, a diode should not be a problem ;)
 

Offline Someone

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #79 on: September 04, 2016, 09:02:47 am »
With a series diode, it gets tricky to set the maximum voltage right. Even with an R+D parallel combination the charging will turn to reduced current quite early and take longer.
With an 4-Terminal measurement of the cell, a diode should not be a problem ;)
Many power supplies (and other 4 wire measurement devices) have limits on the differential voltage, its not a perfect fix.
 

Online EEVblog

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #80 on: September 04, 2016, 09:20:23 am »
A fuse at the output of a PSU is a bad idea because it increases the PSU's output impedance which may be bad for other purposes.

Err, just put it in series with the battery. No need to permanently modify your supply.
 

Offline ez24

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #81 on: September 04, 2016, 01:58:42 pm »
chez never would have thought charging one battery would be so controversial.  Dave get the shit flying  - charge two batteries  :-DD :-DD  (I liked the photo of the guy who had hundreds)
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Offline Chipguy

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #82 on: September 04, 2016, 03:43:29 pm »
A fuse at the output of a PSU is a bad idea because it increases the PSU's output impedance which may be bad for other purposes.
Err, just put it in series with the battery. No need to permanently modify your supply.
That's exactly what I proposed. Do not build a fuse into the PSU, connect it in series to the battery. Outside the PSU of course.
And for the higher impedance: All that the higher impedance is going to result in is that the switch-off point will take a bit longer to reach and that the battery will have not quite 4.200V but a few mV less (the voltage drop at switch-off time).
Where is that smoke coming from?
 

Offline Chipguy

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #83 on: September 04, 2016, 03:50:07 pm »
chez never would have thought charging one battery would be so controversial.  Dave get the shit flying  [...]
Yeah I can see now why Dave re-uploaded it. (Twice even?)
Especially that impedance thing would become a  never ending story haunting both, forum and YT comments for eternity

:horse:  <- just had to use that "new" emoticon for the sake of it ;D
Where is that smoke coming from?
 

Offline nctnico

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #84 on: September 04, 2016, 05:37:27 pm »
A fuse at the output of a PSU is a bad idea because it increases the PSU's output impedance which may be bad for other purposes.
Err, just put it in series with the battery. No need to permanently modify your supply.
That is not what Chipguy and Kleinstein suggested in their earlier posts!

The picture from the bench filled with -appearantly- Li-ion cells and heaps of lose wires just makes me cringe. But maybe I'm too old and no longer thrilled by the idea that something I do could set the house on fire and kill the inhabitants. Think about someone who enters the room and somehow causes a short circuit (bumping the table while cleaning, knocking something over, pulling a wire, etc).
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline samgab

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #85 on: September 04, 2016, 05:58:35 pm »
Yeah, that was my thinking too: Just a simple 2 or 3A fuse in line with the wire to the battery holder would be a good safety measure to fend off paranoia in case of an inferior PSU... Then if something goes wrong with the PSU causing a short condition, the fuse would blow, no harm done.
 

Online EEVblog

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #86 on: September 04, 2016, 06:27:32 pm »
Especially that impedance thing would become a  never ending story haunting both, forum and YT comments for eternity

I've noticed this on my previous battery videos (and I have a lot of them). I still get email from 5 year old videos.
i don't know what it is about batteries...
 

Offline ez24

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #87 on: September 04, 2016, 06:35:13 pm »
i don't know what it is about batteries...
batteries, religion, and politics    - what can you do

I know - lets talk about religious politician's cell phones batteries. 
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Offline nctnico

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #88 on: September 04, 2016, 06:50:11 pm »
Especially that impedance thing would become a  never ending story haunting both, forum and YT comments for eternity
i don't know what it is about batteries...
They are a key component for anything which needs power where there is no mains outlet. Add all the different chemistries, sub-chemistries, charge/discharge rate versus endurance and some foolklore to the mix and suddenly you have an interesting subject.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Online tatus1969

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #89 on: September 04, 2016, 08:52:45 pm »
i don't know what it is about batteries...
batteries, religion, and politics    - what can you do

I know - lets talk about religious politician's cell phones batteries.
close enough?

We Are The Watt - Resistance Is Futile!
 

Online tatus1969

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #90 on: September 04, 2016, 09:01:42 pm »
Especially that impedance thing would become a  never ending story haunting both, forum and YT comments for eternity

I've noticed this on my previous battery videos (and I have a lot of them). I still get email from 5 year old videos.
i don't know what it is about batteries...
its not about batteries, its about Lipo/LiIon. From my RC hobby, I already had two Lipos on fire personally, one of them almost burning up my house (ehmmm, should I mention not to charge them unattended...). Teslas on fire, burning iPhones and other gear hurting people, Segways in flames, airplane's possibly going down. A known of mine is selling Lipos, and he told me that he had a brand new Kokam in his stock, never touched or charged it, and it just caught fire in the shelf. Probably manufacturing defect.
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Offline retrolefty

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #91 on: September 04, 2016, 09:57:36 pm »
A fuse at the output of a PSU is a bad idea because it increases the PSU's output impedance which may be bad for other purposes.
Err, just put it in series with the battery. No need to permanently modify your supply.
That is not what Chipguy and Kleinstein suggested in their earlier posts!

The picture from the bench filled with -appearantly- Li-ion cells and heaps of lose wires just makes me cringe. But maybe I'm too old and no longer thrilled by the idea that something I do could set the house on fire and kill the inhabitants. Think about someone who enters the room and somehow causes a short circuit (bumping the table while cleaning, knocking something over, pulling a wire, etc).

Lets face it, different people have different attitudes about their personal risk aversions with the actions they take with the hobbies and work they do. I know that probably driving is the biggest personal risk I face but I accept the randomness of the universe I find myself in.  :-DMM
 

Online tatus1969

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #92 on: September 04, 2016, 10:16:58 pm »
A fuse at the output of a PSU is a bad idea because it increases the PSU's output impedance which may be bad for other purposes.
Err, just put it in series with the battery. No need to permanently modify your supply.
That is not what Chipguy and Kleinstein suggested in their earlier posts!

The picture from the bench filled with -appearantly- Li-ion cells and heaps of lose wires just makes me cringe. But maybe I'm too old and no longer thrilled by the idea that something I do could set the house on fire and kill the inhabitants. Think about someone who enters the room and somehow causes a short circuit (bumping the table while cleaning, knocking something over, pulling a wire, etc).

Lets face it, different people have different attitudes about their personal risk aversions with the actions they take with the hobbies and work they do. I know that probably driving is the biggest personal risk I face but I accept the randomness of the universe I find myself in.  :-DMM
As long as we are talking about hobbyist things done at home I agree. But as soon as we are spreading this information, like us posting and Dave blogging, we implicitly take a certain responsibility.
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Offline nctnico

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #93 on: September 04, 2016, 10:48:20 pm »
Lets face it, different people have different attitudes about their personal risk aversions with the actions they take with the hobbies and work they do. I know that probably driving is the biggest personal risk I face but I accept the randomness of the universe I find myself in.  :-DMM
I had a feeling someone would come up with this comparison but it doesn't hold up because (in most countries) you need a license to operate a car (or any motorised vehicle) in order to become aware of the dangers and (re)act accordingly.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline Scottjd

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #94 on: September 04, 2016, 11:37:25 pm »
Especially that impedance thing would become a  never ending story haunting both, forum and YT comments for eternity

I've noticed this on my previous battery videos (and I have a lot of them). I still get email from 5 year old videos.
i don't know what it is about batteries...
its not about batteries, its about Lipo/LiIon. From my RC hobby, I already had two Lipos on fire personally, one of them almost burning up my house (ehmmm, should I mention not to charge them unattended...). Teslas on fire, burning iPhones and other gear hurting people, Segways in flames, airplane's possibly going down. A known of mine is selling Lipos, and he told me that he had a brand new Kokam in his stock, never touched or charged it, and it just caught fire in the shelf. Probably manufacturing defect.
And let's not forget the timing of Daves most recent video just a couple days before the new Samsung galaxy Note getting recalled world wide being a hot (no pum intended) topic in the media now. Good timing Dave :)
The media spreads the news, and miss information for drama effect  :wtf: about these recalls on devices people have in their homes and carry in their pockets. A lot of people that don't understand or even do electronics as a hobby.
Then questions come up like: if the phones are made with different manufactured batteries,then why recall them all.mWhy not only recall the ones with that one manufactured battery? Samsung said it was the battery, not the charging circuit. If it's just battery then the company should have a list of serial numbers affected and not have to recall every phone.
Or is Samsung and other companies not telling us the truth? Don't they care about the safety of the customers? What if this happens with all cell phones? Don't batteries get tested and certified for safety?

And then people start to worry and thing about all the devices in the home that has a Li-Ion battery in the house and panic and think the worst because the media makes it look like that, and it feeds fuel to the fire.
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Offline Scottjd

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #95 on: September 04, 2016, 11:45:31 pm »
Lets face it, different people have different attitudes about their personal risk aversions with the actions they take with the hobbies and work they do. I know that probably driving is the biggest personal risk I face but I accept the randomness of the universe I find myself in.  :-DMM
I had a feeling someone would come up with this comparison but it doesn't hold up because (in most countries) you need a license to operate a car (or any motorised vehicle) in order to become aware of the dangers and (re)act accordingly.
Interesting thought, but in the US the drivers licenses with most states don't teach anything about the dangers of gas being flammable to get a license. You can buy an electric car not knowing anything about the battery that powers the car. Consumers assume it's safe, the DOT (department of transportation) allowed it so it must be ok. So if the government allows it, the it must have been tested. OR the legal disclaimers in small print in the manual (that no one reads) covers the companies @$$ so they are not responsible the the consumer assumes all risk. So what does the license teach about dangers of driving in your country? Does it cover different gas mixes like ethanol and battery dangers?
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Offline nctnico

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #96 on: September 05, 2016, 12:30:06 am »
Well over here you learn things like not hitting other cars, take a turn slow enough, how far a load may extend at the front & rear of a car, put a net over a load in a trailer and that sort of stuff which make driving safer for you and others.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Online Fungus

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #97 on: September 05, 2016, 12:35:40 am »
If it's just battery then the company should have a list of serial numbers affected and not have to recall every phone.

Do they have a list of names and addresses of people who bought those particular phones?  :popcorn:

(And they're probably doing some ass-covering as well, just in case. You know how the press loves these stories)
 

Offline Scottjd

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #98 on: September 05, 2016, 01:37:59 am »
(And they're probably doing some ass-covering as well, just in case. You know how the press loves these stories)
True, I think Samsung mobile sit started to turn a profit again and now this.
I did notice some countries had the Panasonic cell, and then they changed it to some other cell for other country releases. I guess it wasn't tested enough. I also noticed the top charge voltage was 4.4V and not 4.2V, and the nominal voltage was 3.85V and not 3.6V. I guess companies are under pressure to provide the most battery life because that as what people want. They want something to run all day and not have to charge it. I've only seen one like this were they are trying to push the capacity further in Li-Ion cells. You can see this on the iFixit tear down.
It brings up a separate topic also about how tech companies these days are so much in a rush to be the first to release the latest tech that the consumer becomes the beta tester. They figure these days they can fix the bugs later with software updates and firmware and people accept this as OK. Not when I was growing up, maybe because companies couldn't push firmware updates like they can today?
I'm slowly still waiting for the MS surface pro 4 to get all the bugs worked out that I've owned for a few months now.
It's anoying, and probably for another topic but I just had to rant, but does kind of have to do with the recall also because I wonder if Samsung wasn't in such a rush to beat apples new cell phone release date then maybe this would have never made it into the hand of people buying them.
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Online Fungus

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Re: EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
« Reply #99 on: September 05, 2016, 02:47:12 am »
True, I think Samsung mobile sit started to turn a profit again and now this.
I did notice some countries had the Panasonic cell, and then they changed it to some other cell for other country releases. I guess it wasn't tested enough. I also noticed the top charge voltage was 4.4V and not 4.2V, and the nominal voltage was 3.85V and not 3.6V. I guess companies are under pressure to provide the most battery life because that as what people want. They want something to run all day and not have to charge it. I've only seen one like this were they are trying to push the capacity further in Li-Ion cells. You can see this on the iFixit tear down.

I'd prefer a choice of charging options in the phone config menu:
1) Charge to 4.2V - get maximum time between charges
2) Charge to 4.1V - get maximum battery longevity

eg. My phone used to run for 10+ days when it was new. Two years later and it's down to 5 days.


(Yeah, I'm not one of those people who checks his Facebook page every ten seconds {or whatever it is all those people are doing all day long on their phones :-// }, my vice is EEVBLOG forums between compiles).

 


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