LP-E6 vs LP-E6N vs LP-E6NH self discharge

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jgveill New Member • Posts: 6
LP-E6 vs LP-E6N vs LP-E6NH self discharge
3

Some months ago I bought a new 90D and immediately noted that batteries didn't last compared to my 20D. With my 20D I never encountered any self discharged battery. With the 90D - LP-E6N batteries, after 2 months batteries are drained, in the camera or out of the camera. This doesn't make sense, as good Li ion should self discharge at a rate lower than 2 % a month. I looked at many threads and many people complain about LP-E6N battery life. Li ion battery in my drill lasts forever.

I contacted Canon and they accepted to RMA my camera. After review, they said everything was perfect. Then I started looking at batteries.

In my recent searches, I found a quite interesting post :  "The concrete problem is the LP-E6Ns BMS (Battery Management System) which is a built in electronics in the battery: it manages balanced charging of the 2 cells, provides overvoltage protection and undervoltage protection, etc. It has some current leakage and therefore the cells discharges sooner at an unusual and excessive speed".

Nice to know but there's no way to solve the problem.  It seems that LP-E6 batteries didn't have that problem, but it's not possible to find any today.

The question I have, could Canon have corrected this flaw in their recent LP-E6NH ? Could they have modified the battery internal circuit so that it doesn't drain the battery ? I could not find any thread on LP-E6NH self draining sot that looks good.

To those who own LP-E6NH batteries, did you see a difference with the LP-E6N ?

Canon EOS 20D
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CameraCarl Veteran Member • Posts: 8,070
Re: LP-E6 vs LP-E6N vs LP-E6NH self discharge
1

How authoritative is the source of that quote?  I've got several LP-E6N batteries and have not noticed any appreciable self discharge.

OP jgveill New Member • Posts: 6
Re: LP-E6 vs LP-E6N vs LP-E6NH self discharge
2

No idea but it makes sense, as all battery pack have a circuit for security purpose and to protect the batteries. My 20D batteries never self discharged as the LP-E6N do. I searched the internet  and found many people complaining about that self discharge problem(Dpreview have few threads about that). All batteries may not have the problem but it seems some do.

On my side I got 2 LP-E6N with the 90D and after 2 months fully charged batteries are drained. It does not make any sense. I own a lot of different Li-ion battery and they go with the rule saying that a LI-Ion battery should self discharge at a rate lower than 2 % a month. Many people experience a much higher rate. Why ?  There's not a lot of possibilities : bad batteries or bad electronic circuit in the battery pack or both ?

We can believe or not the explanation, but the question remains : are the LP-6ENH better than LP-E6N for those who experienced self discharge ? With the lot of people having had problems with self discharge, I imagine some of them have tried the new LP-E6NH and  they could compare.

S Castle
S Castle Senior Member • Posts: 1,333
Re: LP-E6 vs LP-E6N vs LP-E6NH self discharge

jgveill wrote:

I got 2 LP-E6N with the 90D and after 2 months fully charged batteries are drained.

Hmm. My 70D uses LP-E6 batteries, of which I own two, one Canon and one 3rd-party. While I can't say for sure I have seen self-discharge, it would explain a couple of issues I have had where I arrive at a photo destination and the battery in the camera is completely discharged -- I always assumed I had left the camera on without checking the auto power-off setting. (Even with auto power-off, the camera may power on if bumped while in a bag or pack.)

Testing this correctly requires charging a battery and then leaving it unused for a while, with a note showing date and time of last charge. I may have to do that.

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OP jgveill New Member • Posts: 6
Re: LP-E6 vs LP-E6N vs LP-E6NH self discharge
1

I got a LP-E6NH and just started doing self discharge test with few fresh fully charged batteries :

- 1 X Brand New LP-E6NH

- 1 X 16 months old LP-E6N in the 90D (everything is off)

- 1 X 16 months old LP-E6N

- 2 X Canon NB-2LH (more than 10 years old)

- I X 18650 Li ion single battery.

I'll be measuring voltage at fix period, so it would be easy to compare voltage drop.

IR1234 Senior Member • Posts: 1,891
Re: LP-E6 vs LP-E6N vs LP-E6NH self discharge
1

We don’t have any NHes but I can assure you all our batteries discharge at a fair rate of knots. Between two locations we probably have 50 LP-E6s and unless they are all used routinely they will discharge. And this happens to Canon and third party batteries.

But here’s the kicker, even if you think they aren’t discharged - they are! What happens is that the discharge internally does not seem to change the output voltage, which is mapped to discharge. So the battery internally is discharging, but when you reinsert the battery it initially registers a higher voltage than the one in the discharge map. So you think the battery is higher than it really is.

Over the next hour the voltage drops rapidly and you watch the bars disappear.

The winter is usually a big problem, we may not shoot for several weeks, when we get going again everyone is taking twice the number of spares to make sure they get through day, and then we start cycling through the batteries again. It can take 3-4 cycles before the battery fully recovers.

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Distinctly Average Senior Member • Posts: 1,209
Re: LP-E6 vs LP-E6N vs LP-E6NH self discharge
2

IR1234 wrote:

We don’t have any NHes but I can assure you all our batteries discharge at a fair rate of knots. Between two locations we probably have 50 LP-E6s and unless they are all used routinely they will discharge. And this happens to Canon and third party batteries.

But here’s the kicker, even if you think they aren’t discharged - they are! What happens is that the discharge internally does not seem to change the output voltage, which is mapped to discharge. So the battery internally is discharging, but when you reinsert the battery it initially registers a higher voltage than the one in the discharge map. So you think the battery is higher than it really is.

Over the next hour the voltage drops rapidly and you watch the bars disappear.

The winter is usually a big problem, we may not shoot for several weeks, when we get going again everyone is taking twice the number of spares to make sure they get through day, and then we start cycling through the batteries again. It can take 3-4 cycles before the battery fully recovers.

The chip in the cell doesn’t have a map. It is in fact quite a simple circuit. You are correct that the initial drop off can happen quite quickly as the voltage drops. The typical discharge curve shows that quite clearly where a cell charged to 4.2v rapidly drops to 3.7v which is the nominal voltage. In the LP-E6 packs there are two cells in series so effectively you can double that voltage and the respective drop. Also, due to the chemistry of these cells when they are fully charged the initial voltage will remain high even after a period of standing, but will drop off a lot faster.

So why do all batteries self discharge? There are a few reasons, chemical parasitic load and electrical load. As I am sure you are aware, there is a lot of energy in lithium cells compared to say an Eneloop type battery. The latter is unlikely to explode in your pocket or suffer massive thermal runaway. A lithium cell however, being highly energy dense requires protection against that. So in the pack is a circuit that protects against a number of things including over charging, discharging below a set threshold, over current protection, cell balancing, thermal protection. It is typically a chip that measures various parameters coupled with a mosfet used to disconnect the cells in the event of a problem. The most basic chips like the DW01 single cell protection IC continuously draws a very low current of about 50Na but that rises when in use. With multiple cells the protection draw when the pack is not in use draws noticeably more depending on the type of protection used. Over temperature protection for instance draws more than many expect. So some draw has to be taken into account there

We also have parasitic chemical discharge. When we charge a lithium ion cell the first 2hrs will see about 5% loss, after that they tend to draw ca4% a month. So after three months we can expect a minimum of 17% best case scenario. It goes further though. Temperature has a big effect on parasitic discharge with a high tem actually being worse. Temperature history has to be taken into account as that too changes the chemistry of the cathode. We also have internal shorts which are often very tiny but increase over usage again increasing parasitic discharge. There are huge white papers on the phenomenon so not worth boring people on here about it all.

What we can say is most lithium ion cells with good protection will loose around 25% of their capacity over three months, often more depending on the factors mentioned above. This is when the battery is not in the camera. If left in a camera drain will be faster depending on the camera and what features are left on. The GPS in the 7D2 was quite notorious for draining a batter even when the camera was off for instance.

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OP jgveill New Member • Posts: 6
Re: LP-E6 vs LP-E6N vs LP-E6NH self discharge
2

I started my voltage measurement and already get something. It's really early but I think it's worth to give your an idea.

I have 1 x LP-E6NH ; 2 x LP-E6N (16 months old only 200 shots taken) ; 2 x NB-2L (16 y old and 10 y old for Canon PowerShot camera) and I took a 18650 battery to not have any type of protection (3 years old).  All of them were fully charge the same day.  Note that by default my Fluke is 4 digits below 6 volts and the first days I forgot to force it 4 digits for higher voltages.

.003V lost with a bare 18650 compared to a .039V lost on a younger LP-E6N (that's 13 times worst than the bare battery) and .026V for a brand new LP-E6NH which is 9 times worst than the bare battery.  The old NB-2L were certainly less protected being only 5 times worst than a bare battery

So battery packs circuits matters and we will see what happens on long term.

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Andy01 Veteran Member • Posts: 4,704
Re: LP-E6 vs LP-E6N vs LP-E6NH self discharge
1

Be aware that voltage is NOT a good indicator of capacity with lithium batteries (unlike NiMH or NiCd). In general, the discharge curve of lithium batteries is very flat.

For example a 2s (2 cell) lithium is something like 2x 4.2V when absolutely fully balance charged and brand new. The "working" voltage drops quite quickly to something like 2x 4.1V, and then slowly drops to 2x 3.7V at which point they are almost fully discharged (maybe 10-15% charge left), and the last 5-10% drops off VERY quickly where the voltage plummets to 2x 3.0V. If the voltage of any cell drops below 3.0V the charger often struggles to start a charge, so it is not advisable to discharge this low. Fortunately the camera and/or battery circuitry should prevent this happening.

If I had to guess (because I have never measured it) a camera battery might drop from something like 4.2V/cell to 4.05V/cell and only lose around 10% of capacity.

I only have LP-E6 and LP-E6N batteries (no NH), and do not notice an abnormally fast self-discharge.

In general, storing fully charged lithium batteries in very warm conditions is not recommended as it can cause them to die quite rapidly - increased self discharge, dramatically shortened battery life (both per charge and number of charge cycles), and ultimately puffing of the batteries where they swell to the point of being too tight for the battery slot in the device.

I have some very large high voltage (25V 5,000mAh 6s) LiPo (lithium polymer) batteries for my remote controlled helicopters, and I store them in the freezer.

Colin

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OP jgveill New Member • Posts: 6
Re: LP-E6 vs LP-E6N vs LP-E6NH self discharge
1

Thanks Colin,

Sorry for the long post ... but I got results ...

Battery self discharge can be assessed in two ways : Open Circuit Voltage (OCV) and Potentiostatic Measurement. OCV is self explanatory but requires time (at least weeks) and a good DMM. Potentiostatic is done by injecting a very small current (10's micro amps) in a battery so that the battery voltage does not change.  The injected current is then the Self Discharge Current.  This can be done in 2 hours but requires very expensive equipment with many decimals for voltage and current. No need to say almost nobody other than battery manufactures are so equipped to qualify their batteries.  So, I have to rely on OCV but there are ways to get good results.

For OCV method, we first have to know that we cannot measure self discharge right after charging because other factors impacts voltage drop. After being charged, a battery must "relax" and it generally takes 8 days or less. Then, voltage drop should be coming only from self discharge current unless there's something else in the battery pack that takes energy, that's what I'm looking for.

I would not qualify Li Ion discharge curve as flat as we can see in the following curves. This are really typical Li Ion battery discharge curves.

3 - 3.2 v are the safe cut-off voltages. 2.5 v discharge voltage is playing with fire, as it can permanently damage batteries but it's generally how capacity is measured as shown here.

Temperature as well as SOC (State Of Charge) also affect self discharge. That's why you will see voltage going up with my 18650 batteries (4.091v after being 4.090v). As you mentioned the higher the temp, the higher the SOC, the higher Self discharge is. Few degrees around 25C does not change data too much on a longer period of time. To us, who do not have controlled environment, that means we have to wait more time to measure significant self discharge effects that surpasses temperature effects. Now my  8 days are over and I should soon be able to get a good idea on the Self Discharge Rate in the next days.

Here's the updated data for my batteries.

Li ion, typical 10-20 micro amps self discharge current does not drop voltage very rapidly.

With only 2 valid days, data does not look good at all for the newer Canon Battery packs. The 18650 stand alone Li Ion data has a very low drop.  Total drop (10days) as well as last 2 days drop makes sense. I will need much more time to measure self discharge rate for this battery.

The old NB-2L battery design already shows significant drop in the last 2 days.  That means high Self discharge or circuit taking energy. These are 10 years + old batteries and age could explain the result.

LP-6EN drop (total so far or last 2 days) is much higher than 18650. These batteries are almost new (200 pictures taken with these 2 batteries so far). Self discharge cannot explain such a voltage drop. Bad batteries or circuit taking energy.

LP-6ENH looks better than LP-6EN but is much worst than the old Canon battery design with the NB-2L.

So far, data shows that I will get stupid Self Discharge Current indicating that something else is discharging the batteries. The 2 last days drop demonstrates there's something else than Self Discharge current specially if you compare with the stand alone 18650. 10 times higher Self discharge current !

To get a real % power drop I have to have a curve like the ones shown before for each battery. To do, I will fully charge the battery and discharge it with 0.2C (for a 1800 mah this is 0.36 amp  discharge current) and store this data. With the data, and 2 voltages measurement some days apart, I will be able to compute the power % drop in that period of time.

I'm losing my time to compute this power drop. The drop I got so far with the last 2 days is way too high for Self Discharge Current only.  Storing the cells in the freezer could probably be the best thing to do to avoid Self Discharged Batteries but not for a circuit stealing energy from the battery.  I never had to consider doing this with the NB-2L and with the 20D batteries.

OP jgveill New Member • Posts: 6
Re: LP-E6 vs LP-E6N vs LP-E6NH self discharge

After some days I needed some batteries so I had to use some. Here's the voltage drop. I kept only data after 8 days to have "relaxed" batteries.

It's quite clear,  a 18650 (no protection) has .001v drop in 8 days so about .09% voltage drop per month. More time is required to have a valid measurement, but we see self discharge is really low, much lower than what initial Li Ion battery that were close to 2 % a month.

The old NB-2L loss is about .60 % per month.  The internal circuits has an impact for sure. The LP-6EN is just over 2.8 % per month. Internal circuit has more impact.

Canon, please look at your battery pack internal protection circuits, it eats power !  Protection should be active when battery is used, not when stored.

Next test, having a battery in the freezer. Li Ion self discharge is much much lower in cold weather.  I'm quite sure that Canon battery pack voltage would continue to drop at the same rate as the culprit is the internal circuit and this circuit should not be slowed down  by cold temperature.

Distinctly Average Senior Member • Posts: 1,209
Re: LP-E6 vs LP-E6N vs LP-E6NH self discharge

jgveill wrote:

After some days I needed some batteries so I had to use some. Here's the voltage drop. I kept only data after 8 days to have "relaxed" batteries.

It's quite clear, a 18650 (no protection) has .001v drop in 8 days so about .09% voltage drop per month. More time is required to have a valid measurement, but we see self discharge is really low, much lower than what initial Li Ion battery that were close to 2 % a month.

The old NB-2L loss is about .60 % per month. The internal circuits has an impact for sure. The LP-6EN is just over 2.8 % per month. Internal circuit has more impact.

Canon, please look at your battery pack internal protection circuits, it eats power ! Protection should be active when battery is used, not when stored.

Next test, having a battery in the freezer. Li Ion self discharge is much much lower in cold weather. I'm quite sure that Canon battery pack voltage would continue to drop at the same rate as the culprit is the internal circuit and this circuit should not be slowed down by cold temperature.

No, protection needs to be active all the time there is power in a cell. You have to realise just how much potential energy is in lithium based cells. It is not trivial in any way. Things like thermal runaway can be disastrous. What can be done though is a design that has less drain in standby mode. That is something that can be done. However, regulations in certain locales require different specifications and that is where things get complicated. Japan has especially stringent laws these days for this kind of cell. If you look at the average mobile phone or most ot her mass market device with a cell pack you see similar monthly drain in some part because of these rules.

Oh, and single cells, like the 18650 vs a pack with more than one cell have different laws. Single cells rarely require protection by law, a pack does.

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