Do all batteries have a memory effect?

[Special K]

I realize there is already 1 active battery thread in HT, but since this is a different question I felt it was deserving of its own thread.

Basically I want to know if one should follow different charging/recharging procedures in order to maximize the lifetime of different types of batteries.

For example, I have heard that NiCd should always be drained all the way before being recharged, but with Lion batteries, this is never an issue and you can charge/recharge at any time with no negative effects.

 

[Aluvus]

Consumer NiCd batteries will never realistically demonstrate an actual memory effect. Neither will other consume batteries.

Additionally, what you have heard about fully discharging NiCd is wrong.

In both cases, partial recharges cause less stress than complete (or near complete) recharges. And in both cases, all recharges will cause some degredation.

Hardcore RC folks do completely discharge batteries between uses (even going so far as to separately discharge individual cells) in order to maximize the amount of charge stored. But this is not beneficial to the lifespan of the batteries.

 

[imported_Dekard]

lead acid and li-on have no memory effect as well. NiCad and NiMH has a memory, NiMH's is pretty small though. In high charge or discharge applications memory effect isn't noticeable.

 

[pm]

I agree with all of Aluvus's points. Fully discharging all battery types will lead to reduced longevity - they wear out faster. While NiCd batteries - and to a lesser extent NiMH batteries - can show something like the memory effect, it is not as common as many seem to think... particularly with the modern chemistries used in these batteries. The Prius operates it's NiMH cells in a very restricted range - like 40% full to 60% full - to keep them running longer.

And I agree with Aluvus that hardcore RC'ers do do full drain-charge cycles - and many of the higher end RC chargers have built-in functions to automate this - it is not a good idea if you want your batteries to last a long time.

Lithium and lead-acid batteries do not like to be fully discharged and discharging both frequently will wear them out quickly. The key to a long life with lithium-based batteries is to keep them cool and try not to drain them down too far, too often. The cooler, the better.

 

[Special K]

Originally posted by: Aluvus
Consumer NiCd batteries will never realistically demonstrate an actual memory effect. Neither will other consume batteries.

Additionally, what you have heard about fully discharging NiCd is wrong.

In both cases, partial recharges cause less stress than complete (or near complete) recharges. And in both cases, all recharges will cause some degredation.

Hardcore RC folks do completely discharge batteries between uses (even going so far as to separately discharge individual cells) in order to maximize the amount of charge stored. But this is not beneficial to the lifespan of the batteries.

So basically, for consumer electronics devices like cell phones, laptops, cameras, and electric toothbrushes, I should always recharge them at the end of the day rather than waiting until they are fully drained?

 

[pm]

Originally posted by: Special K
So basically, for consumer electronics devices like cell phones, laptops, cameras, and electric toothbrushes, I should always recharge them at the end of the day rather than waiting until they are fully drained?

Yes. Although if it's an older electronic item which uses NiCd, periodic reconditioning can help increase the lifespan of the battery.

http://www.batteryuniversity.com/parttwo-33.htm

 

[Special K]

Originally posted by: pm

Originally posted by: Special K
So basically, for consumer electronics devices like cell phones, laptops, cameras, and electric toothbrushes, I should always recharge them at the end of the day rather than waiting until they are fully drained?

Yes. Although if it's an older electronic item which uses NiCd, periodic reconditioning can help increase the lifespan of the battery.

http://www.batteryuniversity.com/parttwo-33.htm

If the device is used very infrequently, is it better to leave it fully charged or completely empty?

 

[Aluvus]

Originally posted by: Special K
If the device is used very infrequently, is it better to leave it fully charged or completely empty?

The standard advice for Lithium Ion is to shoot for 60% or so (always store lithium ion and lead acid batteries with at least a bit of charge). This seems reasonable for most rechargeables.

If it is only being used very infrequently, rechargeables of any kind may not be an optimal choice. Alkalines will have lower self-discharge than any rechargeable, and zinc-carbon will have even lower still (though zinc-carbon batteries have other drawbacks, notably that they can't handle high-drain devices and will not deliver as much total charge as alkalines).

 

[patentman]

Check out Sanyo's eneloop batteries on amazon. They are supposed to retain 95% of their charge after 1 year with little to no memory effect.

 

[Special K]

I just got a new cell phone and it says to give the Lion several complete charge/recharge cycles to ensure maximum battery lifetime.

 

[NeoPTLD]

Originally posted by: Special K

Originally posted by: Aluvus
Consumer NiCd batteries will never realistically demonstrate an actual memory effect. Neither will other consume batteries.

Additionally, what you have heard about fully discharging NiCd is wrong.

In both cases, partial recharges cause less stress than complete (or near complete) recharges. And in both cases, all recharges will cause some degredation.

Hardcore RC folks do completely discharge batteries between uses (even going so far as to separately discharge individual cells) in order to maximize the amount of charge stored. But this is not beneficial to the lifespan of the batteries.

So basically, for consumer electronics devices like cell phones, laptops, cameras, and electric toothbrushes, I should always recharge them at the end of the day rather than waiting until they are fully drained?

It's ok to recharge before fully discharged, but letting the device live in the charger whenever it's not in use isn't good for the battery.

 

[Special K]

Originally posted by: NeoPTLD

Originally posted by: Special K

Originally posted by: Aluvus
Consumer NiCd batteries will never realistically demonstrate an actual memory effect. Neither will other consume batteries.

Additionally, what you have heard about fully discharging NiCd is wrong.

In both cases, partial recharges cause less stress than complete (or near complete) recharges. And in both cases, all recharges will cause some degredation.

Hardcore RC folks do completely discharge batteries between uses (even going so far as to separately discharge individual cells) in order to maximize the amount of charge stored. But this is not beneficial to the lifespan of the batteries.

So basically, for consumer electronics devices like cell phones, laptops, cameras, and electric toothbrushes, I should always recharge them at the end of the day rather than waiting until they are fully drained?

It's ok to recharge before fully discharged, but letting the device live in the charger whenever it's not in use isn't good for the battery.

Don't the chargers automatically shut off after the battery is charged?

 

[NeoPTLD]

Originally posted by: Special K

Originally posted by: NeoPTLD

Originally posted by: Special K

Originally posted by: Aluvus
Consumer NiCd batteries will never realistically demonstrate an actual memory effect. Neither will other consume batteries.

Additionally, what you have heard about fully discharging NiCd is wrong.

In both cases, partial recharges cause less stress than complete (or near complete) recharges. And in both cases, all recharges will cause some degredation.

Hardcore RC folks do completely discharge batteries between uses (even going so far as to separately discharge individual cells) in order to maximize the amount of charge stored. But this is not beneficial to the lifespan of the batteries.

So basically, for consumer electronics devices like cell phones, laptops, cameras, and electric toothbrushes, I should always recharge them at the end of the day rather than waiting until they are fully drained?

It's ok to recharge before fully discharged, but letting the device live in the charger whenever it's not in use isn't good for the battery.

Don't the chargers automatically shut off after the battery is charged?

No. The charger on things like toothbrush and electric shavers are passive, so it continues applying a small current.

 

[Aluvus]

Originally posted by: NeoPTLD
No. The charger on things like toothbrush and electric shavers are passive, so it continues applying a small current.

You would be hard-pressed to find a battery charger for sale in the US that does not at some stage have a system for actively controlling the charging process. In electric toothbrushes and electric shavers, the electronics are typically inside the device itself.

Some chargers are indeed fairly dumb, and will recharge too often (or not often enough) when a device is left attached; many laptops used to have this problem. But this wasn't because they were incapable of halting the charging process. It was because they would reinitiate charging too frequently.