Half Charging Batteries
- Thread starter cavermark
- Start date
AFAIK and a quick search confirmed that the transport rules are based on watt hours (V*Ah). I think you may have got the half charge info from someone who has assumed that the charge given to new batteries is related shipping rules and not related to the optimum charge level for prolonged storage before initial use (40%?).
Les W
Active member
Lost of stuff here.
http://www.candlepowerforums.com/vb/showthread.php?241957-Best-way-to-long-term-store-li-ion-battery-s
Not sure if it is possible to store them that long unless they don't self discharge below protection circuit levels
http://www.candlepowerforums.com/vb/showthread.php?241957-Best-way-to-long-term-store-li-ion-battery-s
Not sure if it is possible to store them that long unless they don't self discharge below protection circuit levels
jarvist
New member
cavermark said:
This is somewhat true for Li-ion / Cobolt chemistries; Li-ion FePO4 chemistries do not care.
Getting them to ~50% depends on the charger. Charging from 80-100% with any half-way decent charger should be much slower, often charger's indicate when they're at 80% (for instance, on my Canon camera charger, the charge light goes from amber -> green @ 80%, but the 'full' light only comes on at 100%). Most chargers are constant current, so if you have some idea of time it would normally take to charge, just unplug them halfway.
Generally take any advice on batteries with a massive pinch of salt; there's more crackpot theories on batteries
All Li-ion batteries will degrade over a few years, unless you are using them heavily (and then if so, why are you storing them?) they will die from old age rather than charge state (just don't flatten them absolutely, and don't store them flattened). Finding a nice cool dry place to store them is almost certainly more important.
korky
New member
I don't think the idea of unplugging the batteries at half their charging time would work reliably for Li-Ion chargers - unless you know that your charger is a really basic one that only carries out constant-current charging. There really aren't many of those about, in my experience.
The majority of chargers will do the constant current charge (and put 75-90% of the charge into the battery), then slip quietly into constant voltage and the charge current will drop off.
The time it takes in each of these stages depends on the power of your charger, the capacity of your batteries, the ambient temperature, when the charger decides the cell is full, the health of the batteries etc. etc.
On a more powerful charger, the constant current charge can be completed in a few minutes; but the constant voltage charge can't really be hurried and can take hours.
On a less powerful charger, the constant current charge will take proportionally longer... but unless there's an indicator, or you're watching the voltage, there's no way of telling...
If I were storing a Li-Ion battery for an extended period of time, I would:
1) Fully charge the battery. 100%.
2) Use about 10% of it's capacity before storing.
The reason I'd use 10% of the capacity before storing is because the life of a Li-Ion is related to how long it spends at it's full voltage. By using just a small proportion of the charge you 'bleed off' the full voltage, yet still have plenty of capacity to be whittled away by self-discharge in longer term storage.
Korky.
The majority of chargers will do the constant current charge (and put 75-90% of the charge into the battery), then slip quietly into constant voltage and the charge current will drop off.
The time it takes in each of these stages depends on the power of your charger, the capacity of your batteries, the ambient temperature, when the charger decides the cell is full, the health of the batteries etc. etc.
On a more powerful charger, the constant current charge can be completed in a few minutes; but the constant voltage charge can't really be hurried and can take hours.
On a less powerful charger, the constant current charge will take proportionally longer... but unless there's an indicator, or you're watching the voltage, there's no way of telling...
If I were storing a Li-Ion battery for an extended period of time, I would:
1) Fully charge the battery. 100%.
2) Use about 10% of it's capacity before storing.
The reason I'd use 10% of the capacity before storing is because the life of a Li-Ion is related to how long it spends at it's full voltage. By using just a small proportion of the charge you 'bleed off' the full voltage, yet still have plenty of capacity to be whittled away by self-discharge in longer term storage.
Korky.
paul
Moderator
I bought a Sten Light in the US in 2006 and at the time also bought a spare battery (Li-Ion). I charged this battery and left it in the fridge since then totally unused.
Just out of interest I plugged the spare battery into my Sten Light for the first time since purchase and it works perfectly. I am now charging it again and will return it to the fridge.
Just out of interest I plugged the spare battery into my Sten Light for the first time since purchase and it works perfectly. I am now charging it again and will return it to the fridge.
This article: http://batteryuniversity.com/learn/article/how_to_store_batteries has:
A) a table showing "Estimated recoverable capacity when storing a battery for one year" - at zero degrees C 98% at 40% charge and 94% at 100% charge
B) a rough guide to establishing 40% charge in a Li-ion cell "The SoC of Li-ion is roughly 50 percent at 3.80V/cell and 40 percent at 3.75V/cell. Allow Li-ion to rest 90 minutes after charge or discharge before taking the voltage reading to get equilibrium."
15 minutes searching Panasonic/Sanyo site produced: "Storing the Batteries. The batteries should be stored at room temperature, charged to about 30 to 50% of capacity. We recommend that batteries be charged about once per year to prevent overdischarge.". So a manufacturer says "room temperature" and not "in a fridge" :-\
A) a table showing "Estimated recoverable capacity when storing a battery for one year" - at zero degrees C 98% at 40% charge and 94% at 100% charge
B) a rough guide to establishing 40% charge in a Li-ion cell "The SoC of Li-ion is roughly 50 percent at 3.80V/cell and 40 percent at 3.75V/cell. Allow Li-ion to rest 90 minutes after charge or discharge before taking the voltage reading to get equilibrium."
15 minutes searching Panasonic/Sanyo site produced: "Storing the Batteries. The batteries should be stored at room temperature, charged to about 30 to 50% of capacity. We recommend that batteries be charged about once per year to prevent overdischarge.". So a manufacturer says "room temperature" and not "in a fridge" :-\
