# Please don't trickle



## Beemer (Jun 2, 2011)

I presume your trickle charger did not stop at ~3.3-3.4 volts?

What you explained was identical to overcharging. There is very little to be gained after the cells internal voltage starts to rise. So why go there?


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## Jan (Oct 5, 2009)

As I understand it, thrickle charging is to keep lead accid batteries charged, because the thrickle charge is more or less the same as the discharge rate of lead. Lithium doesn't self discharge. So thrickle charging is just slowly charging, with the possibility to overcharge. Slowly but still the same. Lithium is so much better than lead, but also totaly different.


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## Beemer (Jun 2, 2011)

Jan,
You are on the ball.
Does a trickle charger ever check the return voltage to be within the Lithium cells very finicky Voltage levels before shutting off?

Jack Rickard of EVTV has proved there is no loss of charge. A couple of times. By comparing a "just delivered" cell and having a pure novice open up a box of four cells from their sealed packaging with the paperwork inside dated two and a half years ago. Checking the voltages over the four old untouched cells and the brand new one that was already on the bench, the variance was only a couple of thousandths of a Volt.

There is an exception for example. A BMS with parasitic daughter boards.


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## coryrc (Aug 5, 2008)

Beemer said:


> Jack Rickard of EVTV has proved there is no loss of charge.


So you didn't see this thread by me about high self-discharge in some cells?

http://www.diyelectriccar.com/forums/showthread.php?t=59330

Some were defective, yes, but even the battery charts acknowledge ~10% loss per month for headways and something like 20-30%/year for CALB/TS. I'm not how you can believe there is no loss of charge when the manufacturer (who has every incentive to play it down) also acknowledges the self-discharge.


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## spdas (Nov 28, 2009)

Seems the self-discharge is sooo negligible that you could say there is no self discharge. I charged 23 cells in series to 80v cutoff voltage and let my charger go to "0" amps. I just charged the same cells 2 weeks later and got only 100 watts into the total pack or 23 Calb 180ah cells. The pack was at resting voltage of 77v (3.348v) and I charged the same way to 80v (3.478v) and tapering to 0amps. Since the voltage of my cells are charged at a comparatively low voltage I can even assume the 100watts went into a finishing charge for the first time charge.
To me this is close enuf to "no self-discharge", unless of course you have a problem with a cell or two.

francis


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## Beemer (Jun 2, 2011)

coryrc said:


> So you didn't see this thread by me about high self-discharge in some cells?
> 
> http://www.diyelectriccar.com/forums/showthread.php?t=59330
> 
> Some were defective, yes, but even the battery charts acknowledge ~10% loss per month for headways and something like 20-30%/year for CALB/TS. I'm not how you can believe there is no loss of charge when the manufacturer (who has every incentive to play it down) also acknowledges the self-discharge.


It's an ionic cell. If made correctly there can be no self discharge on or below it's resting voltage.

JR proved utterly conclusively there is no self discharge. He had a complete novice blow the cobwebs off a box, unseal it, prove the date of manufacture by reading the DOM on the bottom of the user leaflet and check the voltages to four decimal places on those four cells that were received nearly three years ago. If your cells were made badly or have been mechanically/electrically damaged then its no fault of the actual cell design.

The self discharge figure was asked for so they pulled one out of the hat to shut the lead acid/NiMH people up. The rate was set to give them cover if any cells were poor. It was never made nor wanted as an offer of guarantee.

Francis seems to be on the ball. Charging beyond the resting voltage appears to be pointless and the more I see, harmful for practically no real gain in AH capacity.

What was your unloaded 'trickle charge' voltage?
Put it this way; How come your good cells ended bad after you charged them?
(http://www.diyelectriccar.com/forums...ad.php?t=59330)

Lead acid chargers don't give a cuss for the voltage. They only supply a slight current to keep them topped up. For instance, I use a cheap wall wart consisting of a tapped transformer to select a range of voltages that leads into a full wave rectifier. I've stuck it onto the top setting of 16V and the limited VA rating of the transformer will only give 16mA into the bike socket when it's laid up.


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## coryrc (Aug 5, 2008)

Beemer said:


> It's an ionic cell. If made correctly there can be no self discharge on or below it's resting voltage.


Welcome to the real world. Things cannot be made perfectly.



Beemer said:


> JR proved utterly conclusively there is no self discharge. He had a complete novice blow the cobwebs off a box, unseal it, prove the date of manufacture by reading the DOM on the bottom of the user leaflet and check the voltages to four decimal places on those four cells that were received nearly three years ago. If your cells were made badly or have been mechanically/electrically damaged then its no fault of the actual cell design.


Ah, what was his control group? If all the cells self-discharged the same amount, of course they'll be identical.
Did he charge or discharge them to measure amp-hours remaining? While the voltage should shallowly indicate SoC, I would be more believing of this if he had done another test and wasn't known for shooting from the hip without sufficient knowledge or testing of the situation.



Beemer said:


> What was your unloaded 'trickle charge' voltage?
> Put it this way; How come your good cells ended bad after you charged them?
> (http://www.diyelectriccar.com/forums...ad.php?t=59330)


3.65V was the maximum any cell saw. Cells were acknowledged by the factory as being bad to begin with.


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## coryrc (Aug 5, 2008)

spdas said:


> Seems the self-discharge is sooo negligible that you could say there is no self discharge. I charged 23 cells in series to 80v cutoff voltage and let my charger go to "0" amps. I just charged the same cells 2 weeks later and got only 100 watts into the total pack or 23 Calb 180ah cells. The pack was at resting voltage of 77v (3.348v) and I charged the same way to 80v (3.478v) and tapering to 0amps. Since the voltage of my cells are charged at a comparatively low voltage I can even assume the 100watts went into a finishing charge for the first time charge.
> To me this is close enuf to "no self-discharge", unless of course you have a problem with a cell or two.
> 
> francis


The problem is you start out with new batteries with low and extremely similar self-discharge. Do you know if the cells will have identical self-discharge as they age? How certain are you that they won't drift apart?

Let's pretend, for a moment, that one cell has 40 microamps of self-discharge and all the rest have 50 microamps of self-discharge. That's 6.72/8.40mAh per week. Essentially "no self-discharge", right?

Except without a BMS, every week, you are over-charging that one cell by 8.40-6.72=1.68mAh. You won't notice it this week or even this year -- after all, it's only 87mAh per year. But how do you know the difference won't double or quintuple in four years? And what happens if that low-self-discharge cell is on the outside of the pack where it is cooler (even lower self-discharge) and the others are warmer (higher self-discharge)?

And what if they are actually the stated self-discharge (which comes out to about 2.2mA for a 100Ah cell when full) and they vary +0/-50%? Then you'll overcharge 9.6Ah per year. You won't notice this month or next month or even possibly this year, but within two years you will.

Or if you want to add more batteries from a different batch...


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## Beemer (Jun 2, 2011)

coryrc said:


> The problem is you start out with new batteries with low and extremely similar self-discharge. Do you know if the cells will have identical self-discharge as they age? How certain are you that they won't drift apart?
> 
> Let's pretend, for a moment, that one cell has 40 microamps of self-discharge and all the rest have 50 microamps of self-discharge. That's 6.72/8.40mAh per week. Essentially "no self-discharge", right?
> 
> ...


There was no self discharge. His benchmark was a brand spanking new 400AH cell that arrived that very day, all on film. This is not the first time he has pulled a cell out of a box to prove this.


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## Beemer (Jun 2, 2011)

coryrc said:


> Welcome to the real world. Things cannot be made perfectly.


Some seem more perfect than others. Your whole thread was based on faulty cells. Nothing to do with trickle charging but Lord knows why so high a Voltage. Its a waste of time. They'll only drop back somewhere around 3.365V afterwards.



coryrc said:


> Ah, what was his control group? If all the cells self-discharged the same amount, of course they'll be identical.
> Did he charge or discharge them to measure amp-hours remaining? While the voltage should shallowly indicate SoC, I would be more believing of this if he had done another test and wasn't known for shooting from the hip without sufficient knowledge or testing of the situation.


You didn't read my first reply. I told you. His "control group" was a spanking new 400AH cell straight off Fed-Ex that very day. Took delivery of near 50 of them.



coryrc said:


> 3.65V was the maximum any cell saw. Cells were acknowledged by the factory as being bad to begin with.


So why bring up a thread with "Please Don't trickle" when you know your cells were bad?

Why you charge to 3.65V and hold it there I have no idea why. A waste of electric bill. The voltage will always drop to nominal levels after a couple of days.

The upper knee is ok to play with for an hour or two if you wish your lower cells to catch up but normally 3.4V should be plenty enough on a normal charge up if you want them to last.

One guy who has bandied a thread on here said he gassed up a prismatic on 3.65V by leaving it at 3.65V all weekend. If 3.65V will eventually boil the electrolyte on a prismatic cell constantly dumping current into it, then its a bad idea. If it really was 3.65V and an honest statement.

Was it you?
Incidentally, are you in the 'BMS' business?


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## T1 Terry (Jan 29, 2011)

I am in the process of experimenting the use of the Winston LYP cells for mororhome/house battery applications. Their light weight and ability to hold terminal voltage down the 80%DoD makes them excellent candidates for lead acid replacement. I have connected the cells in a parallel series combination, 4 x 90ah cells in parallel and 4 sets of these in series giving a battety pack capacity of 360ah if fully charged. 
As Aust has great solar conditions most house battery packs are charged via solar or via voltage sensing relays linking the start battery to the house battery and charging via the alternator when the engine is running. I have found 13.8v works excellent for charging 4 cells (3.45v per cell) as this is at the ase of knee curve indicating the cell is full but not pushing the cell and higher so current flow stops. I have been using a PWM solar regulator to control battery current input and have found that once the voltage is reached, the cells stay at that voltage. Any lower voltage and the cell voltage will creep down over time. To me, this indicates the cells were not full and natural balancing was leading to one cell discharging into another.

Just a side note, charging the cells in 12v packs seems to eliminate the balancing problem to a large degree, to date the cell drift at fully charged, under load and at 80%DoD remains the same at 8milli volts highest to lowest according to the cell log 8 data recorder. 

I don't know if this information is of any help to anybody but it's here anyway.

T1 Terry


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## Beemer (Jun 2, 2011)

Hi Terry, there is no mechanism in Lithium cells to shuttle charge. What goes in comes out.

With this slight exception you are right, holding the Voltage in the upper knee does seem to cause the cells to self top balance to a small degree if other cells are lower down they will take a higher current.

If anything causes an imbalance, (especially over time) it will be your bms thingy.


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## spdas (Nov 28, 2009)

So on a related followup.....

1: if you are charging at 3.500v and amperage tapers off to 0amps and right after you disconnect the voltage is at 3.48 and goes to resting a few hours later to say 3.38v where does the .10 volt go to? ie why is it registering 3.48 when it actually is 3.38v?

2: if you are charging at 3.500 and one cell is 3.500 already and another cell is 3.480, will the 3.5v cell "overvolt" to say 3.55 and the other cell at 3.48 "catch up" to 3.500v and then the both cells rest to say 3.38v? (not taking into account resistance of different cells)

Francis


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## Nathan219 (May 18, 2010)

I started this thread because I read a post about someone who had a cell that was low and took it and placed it on a trickle charger over night. Charging on a trickle charger does Lithium cells no good and will most likely result in cell damage due to electroplating the electrode material. Once these Lithium cells reach their end of charge voltage at 0.3C they are charged. The cell voltage varies and you will need to learn where it is for your cells.
What do BMS manufacture recommend when you are combining different cell chemistries in a pack; both cells are lithium Iron Phosphate but one cell has a 3.6V terminal voltage and another have 3.45V Can’t really treat them the same and top balance them now can you, but bottom balance them and all the cells in the series pack will fill up to their capacity quite happily.


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## Nathan219 (May 18, 2010)

spdas said:


> So on a related followup.....
> 
> 1: if you are charging at 3.500v and amperage tapers off to 0amps and right after you disconnect the voltage is at 3.48 and goes to resting a few hours later to say 3.38v where does the .10 volt go to? ie why is it registering 3.48 when it actually is 3.38v?
> 
> ...


The cell voltage is affected a little by the magnetic field of the current flowing through the cell that is the only explanation that makes sense. And after this current is removed the Ions are able to intercalate into the electrode material wherever they want to. 
Any only in materials science know exactly what is happening inside these cells to explain the drop to resting voltage?


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## Beemer (Jun 2, 2011)

spdas said:


> So on a related followup.....
> 
> 1: if you are charging at 3.500v and amperage tapers off to 0amps and right after you disconnect the voltage is at 3.48 and goes to resting a few hours later to say 3.38v where does the .10 volt go to? ie why is it registering 3.48 when it actually is 3.38v?
> 
> ...


The higher Voltage cells get warmer when the voltage rises, they do add a little charge but they are more inefficient at taking that charge. The AH does go up therefore the total SOH is higher.

The higher voltage is shed to standard V like a slightly lossy capacitor. Magnetism be blowed.


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## Beemer (Jun 2, 2011)

Nathan219 said:


> I started this thread because I read a post about someone who had a cell that was low and took it and placed it on a trickle charger over night. Charging on a trickle charger does Lithium cells no good and will most likely result in cell damage due to electroplating the electrode material. Once these Lithium cells reach their end of charge voltage at 0.3C they are charged. The cell voltage varies and you will need to learn where it is for your cells.
> What do BMS manufacture recommend when you are combining different cell chemistries in a pack; both cells are lithium Iron Phosphate but one cell has a 3.6V terminal voltage and another have 3.45V Can’t really treat them the same and top balance them now can you, but bottom balance them and all the cells in the series pack will fill up to their capacity quite happily.


Stick your headlights on for a minute and that 3.65V cell won't be 3.65V no more. You should find the pack will be fairly level.


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## IamIan (Mar 29, 2009)

Beemer said:


> Jack Rickard of EVTV has proved there is no loss of charge. A couple of times. By comparing a "just delivered" cell and having a pure novice open up a box of four cells from their sealed packaging with the paperwork inside dated two and a half years ago. Checking the voltages over the four old untouched cells and the brand new one that was already on the bench, the variance was only a couple of thousandths of a Volt.


My 2 bits ... measuring voltage alone , and basing assumptions on that one piece of information alone ... I think is an obvious mistake.

From my perspective ... the correct way to determine / quantify self discharge rate ( for any rechargeable battery ) is the following:

#1> Determine the discharge capacity in Wh ( not Ah ) of the cell ... ideally by measuring for yourself from more than 3 Discharge cycles of a fully charged cell... not one cycle ... not from the spec sheet.

#2> From a fully charged state let the specific tested cell rest for a given period of time ... x number of months... at a given known temperature.

#3> Re-test the discharge capacity in Wh ( not Ah ) of the cell ... first the Wh it had initially after the x number of months ... and then what it's capacity is after a series of 3 or more cycles to check for changes in cell capacity.

If you wanted to extrapolate out about a specific battery you increase the size of your sample to do several individual cell samples of the same battery type at the same time.

The self discharge rate might be very low ... or so low to not be a concern ... maybe it is as low as 1% every 10 years or less ... but it is a very different thing to say there is none ... or ZERO.


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## Beemer (Jun 2, 2011)

If it is a chemical battery then it will never be zero. That is why many are sold dry.

Li cells are not chemical cells. The major manufacturers of these cells for EV work sell the cells (after the pre-conditioning cycles) to 50% SoC. If there was any fear of these cells self discharging in the real world there would be a notice to top them up at specified dates on the delivery box.

Well JR once again showed there is no discernible self discharge on four 34 month old cells. At 3% discharge and assuming no curve then they will be very dead cells indeed. Not at still fresh delivery Voltages within several decimal places of a volt from new!

Reality stinks doesn't it


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## Nathan219 (May 18, 2010)

As always if you need to charge your cells to 99.99999% you have not designed you pack correctly for your application.


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## Beemer (Jun 2, 2011)

Nathan219 said:


> As always if you need to charge your cells to 99.99999% you have not designed you pack correctly for your application.


There is no 99.99999%. If you work a donkey to 99.99999% it will soon be dead.


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## coryrc (Aug 5, 2008)

Beemer said:


> There was no self discharge. His benchmark was a brand spanking new 400AH cell that arrived that very day, all on film. This is not the first time he has pulled a cell out of a box to prove this.


Cells are not guaranteed to be in any particular state from the factory, so what does that show at all?


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## Beemer (Jun 2, 2011)

coryrc said:


> Cells are not guaranteed to be in any particular state from the factory, so what does that show at all?


Your car fuel tank is not guaranteed to be in any particular fill from the factory either.

However, they have to cycle these cells to condition them, test their internal resistance and capacity.

50% SoC is what they do when they are matched ready for the market. The Goldilocks zone.

You put some charge in. You take some charge out. in, out, in, out, you shake it all about........... Waaay! That's how they do the hockie cokie. 

You can throw all that conditioning away if you wish to wire in parasitic circuits, overcharge, over discharge ad nauseum.


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## coryrc (Aug 5, 2008)

Beemer said:


> Some seem more perfect than others. Your whole thread was based on faulty cells. Nothing to do with trickle charging but Lord knows why so high a Voltage. Its a waste of time. They'll only drop back somewhere around 3.365V afterwards.


My comments have nothing to do with trickle charging, only addressing your faulty statement of LiFePO4 having "NO self-discharge". If you had said "Thundersky cells have, in my experience, negligible self-discharge during the timespan I have used them and the conditions I have placed upon them" then I wouldn't even have bothered posting. But I've demonstrated some LiFePO4 have significant self-discharge, which negates your broad statement of "NO self-discharge".



Beemer said:


> Why you charge to 3.65V and hold it there I have no idea why. A waste of electric bill. The voltage will always drop to nominal levels after a couple of days.


We charged to 3.65V because we were charging many cells in parallel and the voltage drop of the conductors meant the outside cells filled up to 3.65V while the middle ones were still in the mid-3.3xV. Besides, you seem to admit charging beyond some point doesn't add any more charge so how could we have been wasting electricity if they weren't actually being charged? Once all of them just-about reached 3.65V current had dropped to negligible levels overnight (somewhere less than a milliamp per cell) when we went over to shut it down in the morning.



Beemer said:


> The upper knee is ok to play with for an hour or two if you wish your lower cells to catch up but normally 3.4V should be plenty enough on a normal charge up if you want them to last.


Our normal charge voltage is 3.52V without issue.



Beemer said:


> One guy who has bandied a thread on here said he gassed up a prismatic on 3.65V by leaving it at 3.65V all weekend. If 3.65V will eventually boil the electrolyte on a prismatic cell constantly dumping current into it, then its a bad idea. If it really was 3.65V and an honest statement.
> 
> Was it you?


Nope.



Beemer said:


> Incidentally, are you in the 'BMS' business?


Ah, let's get ready for the ad-hominen attacks. My clients/customers require 100% battery use, without tinkering, for a warranty period of ten years. So, yes, of course I put a BMS on their system.


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## coryrc (Aug 5, 2008)

Nathan219 said:


> What do BMS manufacture recommend when you are combining different cell chemistries in a pack; both cells are lithium Iron Phosphate but one cell has a 3.6V terminal voltage and another have 3.45V Can’t really treat them the same and top balance them now can you


Err, why not? Why can't you "top balance" one cell to 3.6V and the other to 3.45V?


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## coryrc (Aug 5, 2008)

Beemer said:


> If it is a chemical battery then it will never be zero. That is why many are sold dry.
> 
> Li cells are not chemical cells.


Yeah, there are certainly no CHEMICALS like Lithium-Iron-Phosphate or Graphite or various organic solvents like ethylene with LiPF6 or LiB4 in a LiFePO4 battery.


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## Beemer (Jun 2, 2011)

I live with the irony of the BMS boys wrecking so many cells. Off topic? Yes.

Your replies previously show us you have not listened to a word I have said and what you have read, give no credence when ultimate proof has been handed to you. We'll all have to presume you think guys who disprove you simply don't exist or are conjurers and tricksters.

So the only point here to make is don't bother trickle charging faulty Li cells.

I'm done.


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## Beemer (Jun 2, 2011)

coryrc said:


> Yeah, there are certainly no CHEMICALS like Lithium-Iron-Phosphate or Graphite or various organic solvents like ethylene with LiPF6 or LiB4 in a LiFePO4 battery.


The charge discharge is not due to a chemical reaction. It's an ionic charge. Didn't you know this basic fact?


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## Beemer (Jun 2, 2011)

coryrc said:


> Err, why not? Why can't you "top balance" one cell to 3.6V and the other to 3.45V?


The wizards of the LiPo: De-Walt. Have patented bottom balancing.


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## MN Driver (Sep 29, 2009)

Beemer said:


> The wizards of the LiPo: De-Walt. Have patented bottom balancing.


DeWalt packs, with LiFePO4, not LiPo cells, are A123 to be exact. They have a BMS and balance taps to each cell. Where are you getting the idea that they are bottom balancing?


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## Beemer (Jun 2, 2011)

MN Driver said:


> DeWalt packs, with LiFePO4, not LiPo cells, are A123 to be exact. They have a BMS and balance taps to each cell. Where are you getting the idea that they are bottom balancing?


Sorry, my fault, you are dead right LiPoFe4.. I left out the rust.

I don't get idea's. I read a lot.

http://www.google.com/patents?id=1G...ook_result&ct=result&resnum=1&ved=0CCgQ6AEwAA


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## IamIan (Mar 29, 2009)

Beemer said:


> The charge discharge is not due to a chemical reaction. It's an ionic charge. Didn't you know this basic fact?


Correction.

The energy stored in the rechargeable battery is chemical energy ... to charge 1mWh of energy in is a chemical reaction converting electrical energy into chemical potential energy ... this happens by producing a reversible chemical reaction where the electrical current is used to move the reactants into a higher potential energy state ... 

To discharge 1mWh of energy out is a chemical reaction converting chemical potential energy into electrical energy ... the electrical energy produced comes from the chemical reactions that result in lower potential energy states ... the difference in energy states is the energy the electrochemical reaction produces ... some of that energy is electrical energy ... but not all of it.

Significant amounts of ionic charge is only seen in devices like some capacitors that store energy just in the ionic charge itself... think static electric charge ... not all capacitors ... some today make use of chemical reactions instead.


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## Beemer (Jun 2, 2011)

IamIan said:


> Correction.
> 
> The energy stored in the rechargeable battery is chemical energy ... to charge 1mWh of energy in is a chemical reaction converting electrical energy into chemical potential energy ... this happens by producing a reversible chemical reaction where the electrical current is used to move the reactants into a higher potential energy state ...
> 
> ...


Correction. I will repeat.

It is an ionic reaction, not a chemical reaction.


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## frodus (Apr 12, 2008)

Beemer said:


> It is an ionic reaction, not a chemical reaction.


[citation needed]


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## Beemer (Jun 2, 2011)

frodus said:


> [citation needed]
> 
> Last


Good idea Frodus!

http://en.wikipedia.org/wiki/Lead–acid_battery
http://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery

Note the tables of chemical reactions on LiFePo4 cells.
Not.


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## MN Driver (Sep 29, 2009)

Beemer said:


> Sorry, my fault, you are dead right LiPoFe4.. I left out the rust.
> 
> I don't get idea's. I read a lot.
> 
> http://www.google.com/patents?id=1G...ook_result&ct=result&resnum=1&ved=0CCgQ6AEwAA


Ok, so it appears they do have a patent for that. Not sure if its to lock in an idea or if its actually for use because when I pulled apart and played with the BMS and A123 M1 cells from a Black and Decker pack back when you could get them for almost nothing off of eBay, I never saw this behavior as the BMS would drop current to prevent the lowest voltage cell from dropping too far in voltage but never saw the whole pack at the same voltage at the end yet when charging they were fairly consistent towards the end of their charge. Just my observation on the matter, could be true that they've changed processes either before or after the pack that I bought but I didn't see that behavior.

"_Sorry, my fault, you are dead right LiPoFe4.. I left out the rust._"

Iron is not rust. Rust is Iron Oxide. You still have it wrong too, it's not lithium polymer iron(4). It is Lithium Iron Phosphate, Li*FePo*4. Lithium Polymer is a different type of cell than the Thunder Sky, Sky Energy, Headway, HiPower, A123, etc type cell that most people are using.



> Correction. I will repeat.
> 
> It is an ionic reaction, not a chemical reaction.


Intercalation and deintercalation is an electrochemical reaction. Overcharge and overdischarge create different and undesirable electrochemical reactions in a cell as well.


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## frodus (Apr 12, 2008)

electrochemical reaction occurs in both Lead Acid and Lithium Ion.
http://en.wikipedia.org/wiki/Lithium_ion_battery#Electrochemistry


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## MN Driver (Sep 29, 2009)

Well, if you want to start posting Wikipedia entries you can always look at this and look for *electrochemistry* It actually shows the reactions that you are saying doesn't exist.

http://en.wikipedia.org/wiki/Lithium_ion_battery

...Frodus beat me to it!


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## Beemer (Jun 2, 2011)

MN Driver said:


> Ok, so it appears they do have a patent for that. Not sure if its to lock in an idea or if its actually for use because when I pulled apart and played with the BMS and A123 M1 cells from a Black and Decker pack back when you could get them for almost nothing off of eBay, I never saw this behavior as the BMS would drop current to prevent the lowest voltage cell from dropping too far in voltage but never saw the whole pack at the same voltage at the end yet when charging they were fairly consistent towards the end of their charge. Just my observation on the matter, could be true that they've changed processes either before or after the pack that I bought but I didn't see that behavior.
> 
> "_Sorry, my fault, you are dead right LiPoFe4.. I left out the rust._"
> 
> ...


Rusty humour my man, rusty humour. Besides, its not chemical, its ionic. What they dope 'em with is how they perform.

Bottom balance "BMS" on discharge... Good idea! Why didn't the BMS'ers here think........... of that.

Not that I see the point


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## IamIan (Mar 29, 2009)

Beemer said:


> Correction. I will repeat.
> 
> It is an ionic reaction, not a chemical reaction.


No matter how many times you repeat it ... it is still wrong... it is a chemical reaction.

Look closer at your own example of Lead Acid ... even from Wikipedia ... as weak of a reference as that is ... it disagrees with you... and even your own Wikipedia reference lists the chemical reactions that are happening for you for the anode and the cathode ... they even give you easy to follow pictures.

Changing PbO2 to PbSO4 is a chemical reaction ... changing PbSO4 to PbO2 is a chemical reaction.



> *Initial Charge*
> 
> 
> Cathode is oxidized
> ...





> *Discharge
> *
> 
> 
> ...





> *Recharging
> *
> 
> 
> ...


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## Beemer (Jun 2, 2011)

IamIan said:


> No matter how many times you repeat it ... it is still wrong... it is a chemical reaction.
> 
> Look closer at your own example of Lead Acid ... even from Wikipedia ... as weak of a reference as that is ... it disagrees with you... and even your own Wikipedia reference lists the chemical reactions that are happening for you for the anode and the cathode ... they even give you easy to follow pictures.
> 
> Changing PbO2 to PbSO4 is a chemical reaction ... changing PbSO4 to PbO2 is a chemical reaction.


READ MY POSTS!
I added in Pb cell to show THAT is a chemical reaction.
There is no chemical reaction in a Lithium cell of any sort I know of.

I was taught all about Pb cells in 1975 and for about a decade afterwards could recite the reactions off by heart!
That was in the days of irate half informed punters arguing they wanted pure sulphuric acid in their cells for more power and they were being ripped off on a mass con.

Such fun, nothing changes.


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## spdas (Nov 28, 2009)

Youse guys is trying to confuse the hell utta me. There are strong opinions on both sides, is there some truth here? I see

In a lithium-ion battery the lithium ions are transported to and from the cathode or anode, with the transition metal, cobalt (Co), in Li_x_CoO2 being oxidized from Co3+ to Co4+ during charging, and reduced from Co4+ to Co3+ during discharge.

Is it transportation of lithium ions or is it a chemical change of Co? Or both, so is the discussion a draw?

francis


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## IamIan (Mar 29, 2009)

Beemer said:


> READ MY POSTS!


I and others have ... you're wrong.... we've been trying to educate you , despite your resistance.



Beemer said:


> The charge discharge is not due to a chemical reaction. It's an ionic charge.


Ionic charges = Static electricity.

Batteries do not hold static electricity to charge or discharge with ... they are chemical reactions... some capacitors hold Ionic Charges ... but not Lead Acid and not LiFePO4.



Beemer said:


> I added in Pb cell to show THAT is a chemical reaction.


Then I misunderstood you when you referenced both as a your citation for batteries not having chemical reactions... I request in the future you state this when you give the reference to avoid confusion.



Beemer said:


> There is no chemical reaction in a Lithium cell of any sort I know of.


The chemical reactions you do not know of , people have been trying to educate you on... despite your resistance.

frodus already linked to the Wikipedia page showing you the chemical reactions that happen in a Lithium cell.

- - - - - - - - - 



spdas said:


> Youse guys is trying to confuse the hell utta me. There are strong opinions on both sides, is there some truth here? I see
> 
> In a lithium-ion battery the lithium ions are transported to and from the cathode or anode, with the transition metal, cobalt (Co), in Li_x_CoO2 being oxidized from Co3+ to Co4+ during charging, and reduced from Co4+ to Co3+ during discharge.
> 
> Is it transportation of lithium ions or is it a chemical change of Co? Or both, so is the discussion a draw?


Sorry for the confusion Beemer's mistake is causing you.

The charge in a Lithium battery is chemical stored energy ... not ionic energy ( aka static electricity )... and there are chemical reactions... despite his resistance to admit his mistake.

Oxidation is a chemical reaction ... even when it happens in a battery ... even when it happens in a lithium battery.

Where is the energy coming from to move that ion in the battery during discharge ?? ... the correct answer is a chemical reaction during discharge.... as the chemicals drop to a lower energy state and release some of that energy as electrical energy... these are chemical changes ... it is not static electric ( aka Ionic charge ) energy storage.


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## Beemer (Jun 2, 2011)

IamIan said:


> I and others have ... you're wrong.... we've been trying to educate you , despite your resistance.
> 
> 
> 
> ...


Ok, my (also) pedantic friends, there is a chemical reaction in the form of a simple toggle Lithium ions do settle between the plates and the electrolyte from discharge to charge. However it's barely a true chemical reaction until damage is done on the cell.

I also did not see Frodus' link. My fault when he didn't supply one?

Meanwhile back at the ranch this whole thread was based on telling people not to trickle charge duff Headway cells to 3.65V. How good cells became self discharging after charging well into the knee I can leave to you 

In this blog, a reasonable lecture on the innards of Lithium cells. I'll go see it again 
http://media2.evtv.me/chargecar.mov


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## Beemer (Jun 2, 2011)

spdas said:


> Youse guys is trying to confuse the hell utta me. There are strong opinions on both sides, is there some truth here? I see
> 
> In a lithium-ion battery the lithium ions are transported to and from the cathode or anode, with the transition metal, cobalt (Co), in Li_x_CoO2 being oxidized from Co3+ to Co4+ during charging, and reduced from Co4+ to Co3+ during discharge.
> 
> ...


The last numbers i.e. "3+" and "4+" is the number of ions. Nothing to do with any chemical reaction in that laptop/phone battery type cell.


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## frodus (Apr 12, 2008)

relinking this for Beemer since he didn't see it.



frodus said:


> electrochemical reaction occurs in both Lead Acid and Lithium Ion.
> http://en.wikipedia.org/wiki/Lithium_ion_battery#Electrochemistry




From what I'm reading, it's still a chemical reaction, although it's using intercalation. The big thing here, is that it's a reversable reaction to a point, Unless you overcharge, then you start getting Lithium Oxide. Lets just let this argument die Beemer, since you're getting hung up on details but technically you're both right. 

*Back to the OP.*

I've left plenty of Headway batteries on power supplies set to 3.65V and let them sit for days. Once the voltage between the two is the same, there is little or no current flow between the power supply and the battery. I've had no issues. They charge/discharge just fine, and show no degredation between discharges. They measure almost exactly the same amount of Wh discharge every time. 

For me, the big thing is, Do not overcharge (overvolt) the batteries. Keep them at or below the charge voltage, but don't charge at the nominal voltage, or you won't pull any amps. The higher the voltage differential between where the cell sits and what the power supply is set to, the more amps you will draw. If you have them essentially at the same voltage, little or no current is drawn, and either it won't charge, or it'l take forever.

But I'm with Beemer. I'm wondering Why you'd trickle charge a Li-Ion cell to begin with, when it has such a low (if even measurable) self discharge?


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## Beemer (Jun 2, 2011)

frodus said:


> relinking this for Beemer since he didn't see it.
> 
> [/COLOR]
> 
> ...


Yes, dead right on hung up, lol
Lithium chemistry, once battered by over or under charging does wreck the cell. There is no chemical reaction, lol. The numbers after the molecule are ions!
The Video I provided provides total proof on what I'm saying. It's a good bit of reference mat'l from the horses mouth.

http://media2.evtv.me/chargecar.mov

But I can back you up on cell charging even though I'm happier at the bottom of the knee and/or as soon as the current starts to drop and/or the temperature rises. After its settled can always turn the charger back on to check its SoC..

Andrew


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