Caring for your batteries, what I have learnt from RC cars!

[whom]

Hi guys

As well as photography, I also like to play with electric toy cars... (4kg, 50mph) The battery technology is the same as that commonly used in DSLR cameras. "Litium-ion polymer" or often called "lipo".

Because of the price of the "lipo packs" needed to power RC cars, and the lack of internal circuitry in these packs, there is a lot of discussion on how best to care for them. There are a few golden rules:

1. Never charge above 4.2V per cell.
The nominal voltage per cell is 3.7, so if your battery says 7.4V it is a two cell battery. Sometimes they sate a nominal voltage of 3.6 (making two cells 7.2).

2. Never discharge below 3.0V per cell.
The batteries used in consumer electronics have circuits inside to automatically cut off power when they get to around this voltage.

(now the most useful one for everyone here)
3. Store at 3.8V (around 50% of full charge)
When stored fully charged the battery will degrade over time. The internal resistance increases. I understand this is partly because the higher voltage leads to an increase in oxidation internally. So it is a bad idea to leave a battery in your bag fully charged for months on end that you never use.

4. Charge at "1C"
Because lipo chargers in the RC world have variable current, this is a guide on what current to use. 1C refers to the capacity, so for a 5000mAh battery, you would charge at 5Amps. This suggests that it should take around an hour to fully charge a battery, the current drops off near the end of the charge however increasing this time.

Here is some more information on looking after lipo batteries:
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

Hope this helps someone.

 

[Deleted member 49549]

Hi Steve, thanks for those. Any tips on how to recover an apparently dead battery?

 

[whom]

Hi Steve, thanks for those. Any tips on how to recover an apparently dead battery?

What do you mean by dead?

If you mean it doesn't hold a charge for long them I am afraid there is nothing you can do. Lithium batteries do not suffer from the "memory effect" like Ni-Cd and Ni-Mh chemistries do so there is no reviving them in that sense.

If you cannot charge it, then it might be that you left it for a while once it went flat, and it has discharged further such that the charger doesn't recognise it. Personally, I would check the voltage with a multimeter across the + and - terminals and if it was over 2.8V (or 5.6V for a two cell) then I would do something stupid. If it was below that I would chuck it in the bin. The something stupid is to get an identical battery that wasn't dead and half charged. Then connect + to + and - to - across the batteries for a minute in order for the battery with a higher voltage to partially recharge the "dead" one. This can be used with Nimh batteries too. Just make sure the voltage difference isn't too high. Then the charger may recognise it.

That is what I would do. Somewhere away from flammable things.

 

[Deleted member 49549]

What do you mean by dead?

If you mean it doesn't hold a charge for long them I am afraid there is nothing you can do. Lithium batteries do not suffer from the "memory effect" like Ni-Cd and Ni-Mh chemistries do so there is no reviving them in that sense.

If you cannot charge it, then it might be that you left it for a while once it went flat, and it has discharged further such that the charger doesn't recognise it. Personally, I would check the voltage with a multimeter across the + and - terminals and if it was over 2.8V (or 5.6V for a two cell) then I would do something stupid. If it was below that I would chuck it in the bin. The something stupid is to get an identical battery that wasn't dead and half charged. Then connect + to + and - to - across the batteries for a minute in order for the battery with a higher voltage to partially recharge the "dead" one. This can be used with Nimh batteries too. Just make sure the voltage difference isn't too high. Then the charger may recognise it.

That is what I would do. Somewhere away from flammable things.

Hi steve, in the absence of a voltmeter, could i just try the 'stupid thing'?

And not sure why the battery (a Nikon EN-EL3e) is dead, it is very likely that it was left a long time without being used

 

[Dave Pickett]

Steve,

Thank you for posting BUT Cameras do not use Lipo batteries, they use Lithium ion Li-ion batteries, the technology and maintenance is utterly and completely different.

What you have posted is correct for our RC car Lipo batteries (I too race RC cars) but irrelevant for camera batteries.

 

[whom]

Steve,

Thank you for posting BUT Cameras do not use Lipo batteries, they use Lithium ion Li-ion batteries, the technology and maintenance is utterly and completely different.

What you have posted is correct for our RC car Lipo batteries (I too race RC cars) but irrelevant for camera batteries.

Hi Dave,

Thank you also for posting.

The technology and maintenance is utterly and completely NOT different actually.

This is a document containing advice on lithium ion batteries that clearly describes the same storage (and more) advice as you often hear for lipo batteries.

http://www.newark.com/pdfs/techarticles/tektronix/LIBMG.pdf

"Charge or discharge the battery to approximately 50% of capacity before
storage."

Whilst some older cameras may use Li-ion, modern batteries are generally Li-ion polymer. Here is some details copy/pasted from wikipedia:

"This type has technologically evolved from lithium-ion batteries. The primary difference is that the lithium-salt electrolyte is not held in an organic solvent but in a solid polymer composite such as polyethylene oxide or polyacrylonitrile. The advantages of Li-ion polymer over the lithium-ion design include potentially lower cost of manufacture, adaptability to a wide variety of packaging shapes, reliability, and ruggedness. Lithium-ion polymer batteries started appearing in consumer electronics around 1995."


If you still disagree, please let me know and any references would be appreciated.

 

[whom]

Hi steve, in the absence of a voltmeter, could i just try the 'stupid thing'?

And not sure why the battery (a Nikon EN-EL3e) is dead, it is very likely that it was left a long time without being used

You could try the stupid thing. It is probably dead though. Personally I would just buy a cheap 3rd party battery with good reviews. EG:

http://www.amazon.co.uk/Lig0sh-Capa...3?s=electronics&ie=UTF8&qid=1333794598&sr=1-3

 

[Dave Pickett]

mmmm

Well Li-ion batteries do not do this:

http://www.youtube.com/watch?v=ixIOEPnsgbI&feature=related

And also the chargers we use for RC cars are far more sophisticated than the ones supplied with cameras and other consumers devices, so its not really possible for to maintain them in the way you suggest.

I have recovered a Lipo battery as you have suggested by connecting to a NIMH charger for a short time, to bring the voltage up and yes it worked, but anyone looking to do this (which may or may not work with LI ion) should watch that video again and be careful.....

That is why Li ion batteries are used in cameras mobile phones etc, and Not Lipos. You may be aware that the BRCA (Rc cars governing body) insist that Lipo batteries are charged in a Lipo sack, and at many events battery voltages are checked at full charge and no car is allowed to start if the voltage is above 4.2volts/cell.

I will leave it to forum members reading this thread to decide whether the two types of battery really are the same!!!!

 

[whom]

mmmm

Well Li-ion batteries do not do this:

http://www.youtube.com/watch?v=ixIOEPnsgbI&feature=related

And also the chargers we use for RC cars are far more sophisticated than the ones supplied with cameras and other consumers devices, so its not really possible for to maintain them in the way you suggest.

I have recovered a Lipo battery as you have suggested by connecting to a NIMH charger for a short time, to bring the voltage up and yes it worked, but anyone looking to do this (which may or may not work with LI ion) should watch that video again and be careful.....

That is why Li ion batteries are used in cameras mobile phones etc, and Not Lipos. You may be aware that the BRCA (Rc cars governing body) insist that Lipo batteries are charged in a Lipo sack, and at many events battery voltages are checked at full charge and no car is allowed to start if the voltage is above 4.2volts/cell.

I will leave it to forum members reading this thread to decide whether the two types of battery really are the same!!!!

Dave, I think you are mistaking the key difference to be the battery chemistry when really it is the internal circuits. Consumer electronic batteries have in built protection preventing over discharge or over charge. This is why they often have four pins and not two. When you check the extra pins you will find that they are not "balance pins".

The batteries used in cameras and mobile phones are usually, as I previously stated, lithium polymer. Just search for pictures of ipod batteries.

They are hidden away inside so don't need to be made to look pretty like removable batteries.

Granted, it is not possible to charge a battery for 50% on a normal camera charger but it is easy to guess, or half use it and then store it. I have charged my camera batteries on my RC charger with lipo mode to get a capacity value.

Regardless of the type of lithium chemistry, you cannot argue that they require different care. I noticed you stepped away from that argument after my previous post. Therefore my original advice IS relevant either way.

 

[Dave Pickett]

Thanks for posting the picture of a battery in an ipod.

It clearly states li-ion

Ok just seen the Lithium polymer at the top, BUT just check any of your camera batteries as I just have and they are Li-ion

 

[whom]

Thanks for posting the picture of a battery in an ipod.

It clearly states li-ion

Are you blind? It says Li-ion Polymer Battery.

Please stop wasting my time with your pathetic arguments. You've made a complete mess of this thread and achieved nothing but embarrass yourself.

 

[Mikesphotaes]

Interesting information but keeping a spare battery in my bag, only half-charged, is just not going to happen for me and I suspect more than a few others here.

 

[whom]

Interesting information but keeping a spare battery in my bag, only half-charged, is just not going to happen for me and I suspect more than a few others here.

Yeah I understand that. Me included!

But if you have half a dozen batteries you use when you go away on your annual holiday, but only one in your bag the rest of the year, then this could be relevant. It also applied to old mobiles, laptops, ipods etc etc.

 

[gblades]

If you want to keep a spare battery but want to keep it topped up as you don't know when you are going out then keep the battery in the fridge as they self discharge less when cold.

Anyone know what cathode type the camera batteries use. iPods etc... use cobalt but there is also magnesium. Magnesium is much safer but heavier and lower capacity for a given size. They are often used in power tools and electric cars.

 

[Splog]

If you want to keep a spare battery but want to keep it topped up as you don't know when you are going out then keep the battery in the fridge as they self discharge less when cold.

Really!

 

[whom]

Yes, the some experimental results can be seen on the link on my first post.

0 degrees = 6% in a year
25 degrees = 20% loss in a year

To be honest, if there was any chance that I would not be using a battery for more than a couple of months I would leave it half charged. It only takes half an hour to fully charge it if I go out.