Li-ion batteries

[Mo0o]

I heard that when u first get Li-ion batteries you should fully discharge them for the frist couple of uses, then its ok to charge them whenever. Any truth to this calim?

 

[arcenite]

Originally posted by: Mo0o
I heard that when u first get Li-ion batteries you should fully discharge them for the frist couple of uses, then its ok to charge them whenever. Any truth to this calim?

I've never done that, my batteries last forever. Who cares.

 

[mercanucaribe]

You're supposed to drain them completely every time.

Wait, maybe that's NiCd

 

[Dessert Tears]

I don't think you need to fully discharge them the first few times, but I'm not sure.

Originally posted by: mercanucaribe
You're supposed to drain them completely every time.

Wait, maybe that's NiCd

Definitely not LiOn, you can charge them whenever. The NiCd "memory" effect is actually mythical, so the statement doesn't really apply to them either.

 

[PurdueRy]

Originally posted by: mercanucaribe
You're supposed to drain them completely every time.

Wait, maybe that's NiCd

the memory effect happens to NiCd but was fixed with NiMH

 

[imported_KirbsAw]

Most say you shouldn't ever drain your Li ion unless you're having a problem(like it not charging fully)

 

[dighn]

I heard that' amath

 

[PlatinumGold]

Originally posted by: Flatscan
I don't think you need to fully discharge them the first few times, but I'm not sure.

Originally posted by: mercanucaribe
You're supposed to drain them completely every time.

Wait, maybe that's NiCd

Definitely not LiOn, you can charge them whenever. The NiCd "memory" effect is actually mythical, so the statement doesn't really apply to them either.

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

 

[Suspicious-Teach8788]

Memory effect => voltage depression.

The point is you have limited recharges with any battery. You don't just charge whenever you feel like it. Why else do iPod batteries die? Har?

 

[grrl]

Originally posted by: DLeRium
Memory effect => voltage depression.

The point is you have limited recharges with any battery. You don't just charge whenever you feel like it. Why else do iPod batteries die? Har?

So you can buy a whole new iPod?

 

[Dessert Tears]

Originally posted by: PlatinumGold
http://www.batteryuniversity.com/parttwo-33.htm

Good link. IMO, the article falls into the trap of allowing "memory" to mean any loss in overall battery capacity, as opposed to loss in capacity due to not fully discharging the battery. My explanation follows, and I believe it is consistent with your linked article as long as we ignore the distinction in the definition of "memory".

The "memory effect" is so named based on the theory that the battery "remembers" its discharge point as full discharge. Thus, it loses capacity if it is continually discharged to a level above full discharge - this level becomes its effective full discharge.

I don't have any links, but I recall that the original "memory effect" was found in the battery array of an orbital satellite. It had a very regular cycle of charge/discharge as it collected solar energy in sunlight and ran from batteries while in the Earth's shadow. It was designed to have excess capacity, so the batteries were never deep-discharged. Over time, it was observed that the satellite's batteries were losing capacity (from readings sent to Control).

This is the only laboratory proof that the memory effect exists as stated above. The loss in capacity was present, but really not very large.

2 things typically cause loss in capacity for NiCd/NiMH batteries used by consumers - overcharging and cell reversal. Typical cheap chargers either pump a fixed current into the battery or (a little fancier) have a timer, after which it drops the current to a "trickle charge". This overcharging overheats the battery from within, which rapidly reduces capacity and kills the cell. Smart microchip-controlled chargers ($25-50) run much higher currents while the battery can handle it, slow as it reaches capacity, and finally shut off completely. Cell reversal occurs when an individual battery is drained to 0V (full discharge for NiMH is roughly 0.8V) and beyond, i.e. being charged by the other batteries in the device. Cell reversal is a great way to kill batteries.

"Deep discharging" and "exercising" a battery with reduced capacity (not completely dead) does generally improve its capacity, but not to its original state.

When rechargeables first hit the market en masse, marketed as drop-in alkaline replacements, ignorant consumers with crappy chargers killed their batteries and propagated "OMG memory effect NiCds suck." My guess is that "exercise" was publicized as a stopgap, and the opposite of the solution was assumed to be the fault.

 

[Dessert Tears]

Originally posted by: KirbsAw
Most say you shouldn't ever drain your Li ion unless you're having a problem(like it not charging fully)

LiOns really hate overcharging and overdischarging. Luckily, most of their presence in consumer products is in devices that protect them on both sides.

Using unprotected LiOns is playing with fire, literally.

 

[0roo0roo]

li ion has x number of charges.. u just waste those if u try silly discharging tricks