To Fully Charge or not to Fully Charge, that is the Question.

[Alexander108]

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I am (was) still struggling to find a way of dealing with my M10/M11 batteries. Keeping them fully charged, which is always advised against, seems not to be an option in an ideal world.  

I tried to find an answer given that I know that you should not store a fully charged Li-Ion battery. But is that the case? So I spent two hours or so to research this. 

Nerdy background:

• The typical Li-Ion battery max voltage is 4.2V per cell for a 3.7V rated battery (8.4V / 7.4V for two cells like Leica batteries). 
• However, a fully charged M10 (BP-SCL5) battery has a rated final voltage of approx 8.25V whereas the rated voltage is 7.4V.
• For some reason, a fully charged M11 (BP-SCL7) battery has a rated final voltage of approx 8.4V.
• Hence, the M10 battery won't be fully charged while the M11 battery will be fully charged.
• Researching some discharge diagrams I found that the M10 battery is charge only up to roughly 90% of the possible max capacity. 

I tried to find evidence of whether or not to store a fully charged camera battery. I found something in a Nikon manual:

• After 6 months of not using a battery: charge it and store it. No word of interrupting the charging process whatsoever. Just fully charge and store.
• Have a fully charged spare battery at hand.
• Have more than one fully charged spare battery at hand when shooting in cold conditions.
• It seems Nikon also pursued the more conservative and practical approach to charge their batteries (at least for that camera) to 90% max.

Leica states it differently in the M11 manual (there is no such comment in the M10 manual):

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To me, this is not a practical approach and I wonder why Leica went from charging to 90% only on the M10 to 100% on the M11. 

Key takeaways M10 batteries: 

• Leica M10 batteries are deliberately not fully charged by their chargers. This prolongs their lifespan.
• Storing a fully charged M10 battery is the way to do it. 
• Re-charge a stored and not used battery after 6 months.
• I will now change my paranoid practice of trying to keep batteries at 50% to 80%. Instead I will store them fully charged. This way I am always ready to shoot. 

Key takeaways M11 batteries: 

• Leica M11 batteries will be fully charged to 8.4V. 
• Storing a fully charged M11 battery should not be done. 
• Re-charge a stored and not used battery after 6 months.
• With M11 batteries I try to store them at 50% to 80%. Less practical but prolongs battery life. 

Is there anything in my thought process that you disagree with? Thank you!

[LocalHero1953]

I suspect some of the difference lies in the word 'storage'. Advice to keep them partially charged might apply only when you put batteries way for a long term. If you use them regularly and rotate them as I do, I see no problem in 'storing' them fully charged for the short term while they wait their turn in use.

Edited November 29 by LocalHero1953

[PhotoCruiser]

I suspect also that importance lies in short term, or better how long short term is.
Having uncountable amount of batteries for many devices i usually charge them full, leave for 6 months to Costa Rica for work and when i returned i recharged them again. Ni-Mh, Li-Io, 12+36V LiFePo and 12V AGM batteries. The only ones who discharged completely and went dead were the 12V wet-cell batteries.
I run refresh cycles some times on A/AA/AAA batteries as their charger could do that.

All others get a full charge and then stored dry and cool for months, half year or even up to a year for some devices i rarely use.

There is probably a measurable higher degrade if fully charged then only 80% but the question is how much this degrade influence battery life.
My iPhone and MacBooks charge to 80% only as i have a setting or software who manage that, but on all other batteries i would need to disconnect them in the to me unknown 80/90% state of charge. The only charger what show SoC are the NiteCore USB chargers but then i would constantly need to check SoC to take the battery out to stop charging.

The only way to know would be to have same two new batteries and charge one to full and the other to 80-90% and then use them over years to check if and if so what charge system leads to longer battery life. That is not very scientific, but show real life battery life depending on charge method.

As most here use the original Leica battery in the original Leica charger and there is no particular complaints about log-term battery life i suspect that the Battery and Charger developer knew what he was/is doing.

Chris

 

[intangiblethings]

If digital Ms are never a “forever thing” I’m also not going to go through these steps to prolong my battery life.

It seems fairly good and affordable third-party M10 batteries have entered the picture which make me want to prioritize “grab and go” more than anything. 

[pgk]

I store and use my batteries as I need them. Some M8 batteries are still working after all this time. Life is too short to worry about the state of charge of batteries. When you need them they need to be charged. Best advice is simply to use them.

[marchyman]

9 hours ago, Alexander108 said:

To me, this is not a practical approach

May I ask why?  A calendar reminder to put your unused batteries on the charger for 15 minutes once every 6 months does not seem onerous.  That is the rule for unused batteries, i.e. batteries you are storing for the long term (many years) not batteries in use.

When I have multiple batteries that I rotate between I  charge them until full when I swap them out of the camera.  Will that give me maximum potential battery lifetime?  Probably not.  It's not something I tend to worry about.

 

[Alexander108]

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vor 1 Minute schrieb marchyman:

A calendar reminder to put your unused batteries on the charger for 15 minutes once every 6 months does not seem onerous.

That is not a problem as every battery will be used within 6 months. 

It is storing batteries at 50% and not being able to just grab the camera w/o charging first. 

I think the approach with the M10 battery with a maximum capacity of 90% seems most practical.

Although not ideal, leaving a 90% charged battery alone for 12 weeks does way less harm than with the 100% charged battery of the M11.

But I need to figure it out. The best approach I have seen were the DJI drone batteries. They automatically discharged to 80% or so after a few days. Recharging did not take long and the battery could barely be damaged. Those batteries were much larger, though. 

[Kiwimac]

With the M11, since charging is in camera and they no longer give you an actual charger (and yet the price remains the same. Just saying. ) a firmware update could include an option not to exceed 80% I presume. 

[Tseg]

I have 2 and rotate them after each cycle.   I typically use down to 25% then change to somewhere near full in camera, then swap out for what was the previously charged battery.  So good going on a year.  I don't think either of my batteries has sat for more than a month without use.

[jaapv]

1 hour ago, Kiwimac said:

With the M11, since charging is in camera and they no longer give you an actual charger (and yet the price remains the same. Just saying. ) a firmware update could include an option not to exceed 80% I presume. 

In-battery electronics will cut off charging at 80 % or thereabouts. 

[Kiwimac]

20 minutes ago, jaapv said:

In-battery electronics will cut off charging at 80 % or thereabouts. 

Strange since the camera always reports 80% as 100% if that is so. 

[jaapv]

It does. It does so on all electronic gear using LiIon batteries. Max charge 80% min charge 10% approx of theoretical capacity. 

[DenverSteve]

Charge your batteries fully.  Then, if you're not shooting regularly (for some crazy reason) number and rotate your batteries so they all get equal time.  If you only have one battery it shouldn't be an issue. Use it regularly.

Edited November 30 by DenverSteve

[jakontil]

I wouldnt worry too much about fully charging and storing the battery as i always do.. i worry more about using it to the fullest below 20% before recharging..that’s my habit since i get to know lithium battery the first time

[Alexander108]

I thought about it a bit more. My typical use case is: I mainly use my cameras on vacation. I have a 50h/w job and barely find time to do photography on weekends, let alone during the week. That means sometimes my batteries sit fully charged for weeks. This may work but common knowledge is that this is far from ideal. Storing batteries with 80% is much better. When I come home from vacation most of my M10, M11 and DL8 batteries are fully charged.

As I love tinkering I came up with the idea to build a discharging station. It was supposed to be a rather simple Arduino sketch but I ended up with >300 lines of code that deals with everything including the ability to adjust the discharge voltage between 8V and 7.4V.

This is the approach (for those who are as "Monk-ish" / nerdy as I am):

• Discharge the battery with a rather moderate load that can be easily accomplished. I opted for a 0,5W Power LED that is fed by a 100mA constant current circuit when discharging.
• Every minute of discharging the LED will be switched off and after 2s the no-load voltage of the battery is measured. 
• If the measured battery voltage is lower or equal the entered discharge voltage, the discharging process is stopped.
• There are three independent channels. I printed battery bays for the M10, M11 and D-Lux 8 batteries. As this is exchangeable I could also print a second M10 bay so I can discharge two M10 batteries at the same time.
• Measuring the voltage with an Arduino is relatively simple. With two resistors a voltage divider is built that brings the max. 8.4V down to 5V which is the max voltage an Arduino can deal with in the analog input pin. I checked my calculated voltage with my rather expensive Fluke multimeter and it works surprisingly well. 
• Switching the LED on and off is simply done with a 2N2222 transistor. Why the 2N2222? Because I have a box with 200 of them lying around.

This is my (very crude) diagram:

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And this is how my little device looks like:

To change the discharge voltage threshold you just push the knob. Then the voltage in line 1 starts blinking and by turning the knob it can be adjusted in 0.05V steps up and down.

Discharging with 100mA only obviously takes a while. The M11 battery has 1800mAh. Draining from full down to 80% (360mAh) will take roughly three and a half hour which is reasonable.

Conclusion: 

Was it necessary to design and build such a device? Of course not!
Was it fun, challenging, and pleasing writing the code, designing the parts in Fusion 360 and eventually build everything? Absolutely!

It is so rewarding watching the device doing what I wanted it to do.

Nerdy greetings
Alexander

[Derbyshire Man]

Great work!
 

Whatabout something similar where you could set the charge target maxima, eg 60% with a daily steady state check?

[Alexander108]

vor 10 Stunden schrieb Derbyshire Man:

Great work!
 

Whatabout something similar where you could set the charge target maxima, eg 60% with a daily steady state check?

Thank you. Charging is a very different animal. If you don't want to design a charging circuit yourself (which I cannot do with my limited electronic capabilities) that does the CC/CV approach you need to rely on charging boards from China. I would not be able to identify if these charging circuits are working properly or not. You need a rather precise voltage measurement in the CC phase and clearly identify when the target voltage is reached.

For me topping up this is not an issue at all as I now charge fully and then discharge down to 78% - 80% and use the battery within the next 4-6 weeks latest. Batteries won't sit long in the shelf. 

[Stuart Richardson]

Micromanaging this seems to be a waste of precious time and enjoyment for photography as a hobby, or efficiency in a career. Batteries are a consumable, but one that lasts a very long time. Leica gives instructions, and presumably they are what they think is the best practice. They may be different than Nikon's battery or charger design. The thing I find the most interesting, however, is that it seems like you all believe the charger percentage given is some kind of reliable and accurate indicator to the battery's charge state. There are so many variables at play: temperature, battery age, charge rate, demand of the camera changing in different use patterns, how often and how much it is charged etc. It is better now than it used to be, but older batteries would routinely say they were more than half full and then just die completely. The battery in my Panasonic S1 would just completely charge out in camera over a week or two, so had to be kept outside the camera. In the end it really seems like the best option is to charge the batteries when they need to be charged, and replace them when they no longer reliably work (which is likely to be longer than 5 or even 10 years in digital Leicas, at least in my experience). 

[Alexander108]

vor 18 Minuten schrieb Stuart Richardson:

Micromanaging this seems to be a waste of precious time and enjoyment for photography as a hobby

Could be. But you wouldn't believe how rewarding and joyful it was to build this little device. I do this as a hobby. I just cannot consider this a waste of time. YMMV and from the perspective of a professional photographer, not taking into consideration that programming and designing such a device is an unnecessary wate of time, you are right. 

Edited 4 hours ago by Alexander108

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[Stuart Richardson]

Yes, I am sure it was rewarding for you to design that, and it seems that is also a hobby for you. I just mean in general for people whom electronics is not a hobby, it probably makes sense to just charge the batteries as Leica recommends, and store them slightly discharged if you don’t plan to use them for many weeks.