Conditiong Laptop Replacement Battery ?

[3v0]

Just put a new battery in my old laptop. Lithium Ion.

(1st charge) The battery instructions said to charge overnight (I charged for 27hr).

(1st discharge) The instructions said to fully discharge it. I ran it down to 1%.

(2nd charge) After several hours of charging it did not go above 96%. I charged it with the laptop turned on so I could monitor the % charge.

(2nd discharge) It is currently on it 2nd discharge.

On the first discharge should I have run the unit till it failed due to lack of power? It shut down at some % maybe 4 (do not recall). Started it back up and ran it till it showed 1%.

Should I be worried that it did not reaching 100% on the second recharge?

 

[Boncuk]

Hi 3v0,

NiMH batteries require a few charge- and discharge cycles before they develop full capacity.

Discharging to 0% means already heavy damage to the battery.

Why not discharge to a safe point which is reached when the Laptop switches off automatically? Before switching off the software will power down the OS. So from that side there shouldn't arise any problem.

No battery will put up with being discharged to 0% capacity. Retaliation will be the early death of the battery.

Hans

 

[MacFeegle]

I've seen a few articles that recomend not discharging a Li ion battery below 3 volts, was the battery at about that voltage when the laptop shut itsefl off?

 

[3v0]

This is the first time I purchased a Li ion battery. I had some doubts about the instructions and what the battery should do. Thus the questions.

Hans
This is not a NiMH Battery.

Why not discharge to a safe point which is reached when the Laptop switches off automatically?

Because the instruction sheet that came with it said to "fully charge then fully discharge the battery up to 4 times".

MacFeegle
I tried measuring the voltage but the multimeter probes are too wide to go into the slots the computer contacts slide into. I could mess with sticking wires into the slots but do not want to. Since I should not try to run it to 100% discharged I will stop when the laptop shuts down due to low battery.

If I can not get XP to tell me the voltage I am sure there is a program out there to do so.

 

[audioguru]

How many Lithium-Ion cells are in the battery?
If a cell is discharged to below 3V then it is ruined.
Surely the laptop has a circuit that monitors the voltage and reports complete discharge when each cell discharges as low as 3.0V and shuts off the laptop to prevent damage.

The laptop's battery reporting program knows its origibal battery but does not know or needs to learn about your new battery so I think its report of 96% after only a few hours of charging is pretty good.

 

[3v0]

How many Lithium-Ion cells are in the battery?
If a cell is discharged to below 3V then it is ruined.
Surely the laptop has a circuit that monitors the voltage and reports complete discharge when each cell discharges as low as 3.0V and shuts off the laptop to prevent damage.

The laptop's battery reporting program knows its origibal battery but does not know or needs to learn about your new battery so I think its report of 96% after only a few hours of charging is pretty good.

I do not know how many cells are in the battery. It is rated at 4400 or 4800mAH. I do not know what voltage the battery is I can not know how many cells total there are.

Got it, let the computer manage the discharge.

My intent was to do right by this battery and get the most mAH out of it. Following the instruction to the letter (fully discharge) would ruin it.

Thanks.

 

[Mikebits]

I have had the worst luck with computer batteries. My camera batteries never give me trouble. WTH? I just do not think I will ever understand those darn things.

 

[3v0]

I have had the worst luck with computer batteries. My camera batteries never give me trouble. WTH? I just do not think I will ever understand those darn things.

I do not use laptops much as I prefer multiple monitors. I almost junked this one. It is only 650 MHz but I replaced the HD earlier this year and it is the only laptop I have.

My collection of NiMH AA and AAA's is getting sizable. I need to remember to rotate them to keep the unused ones from going bad. Some time I need to build a better charger that holds more cells.

The one I have charges too fast (cells get too hot for my taste). But that is another (often rehashed thread).

 

[Gayan Soyza]

I also one time had a similar problem.The amount of NiMH cells getting update.The commercially available charger won't except to charge higher amount of cells.They are some advanced chargers which can charge more than 8 cells at a time but they are really expensive.

I use LM317T to charge my NIMH cells.& I have great results with it.If I need to charge higher amount of cells like 8 cells I just configure it to the requirements.

 

[3v0]

One more question regarding laptops with LI IO batteries. What is the best care and feeding if not heavily used?

 

[Sceadwian]

LiIon/Poly batteries don't need special care and feeding really. They last almost as long when being used as when not being used as the ultimate age of the chemistry involved determines it's shelf life more than anything else asuming it's charged and discharged sanely. The big ones are never over charge (thermal runaway (fire)), never charge faster than 1C (bad for chemistry), never discharge any one cell in a pack bellow 3.1 volts (fatal to chemistry). Discharging a LiIon/Poly to 1% is WAY too close as far as I'm concerned, one cell may actually be bellow the fatal limit while another is still holding the voltage up so the whole pack seems to be above 3 volts per cell. Basically the more cells you have in a pack the higher you should place your max discharge limit, ideally you want to monitor each individual cell separately. Most laptop batteries are in the 14 volt range? So that's 3-4 cells? Just a ballpark I haven't sampled many laptop batteries. With that many cells I'd put the discharge limit at 3.1 volts per cell, you really need the saftey margin if you have mismatched cells. For safe discharge I honestly would put it at 10% Lipoly/ion do not suffer from memory effects so you should basically keep it as close to fully charged as you can at all times. I've never heard of conditioning a lithium pack though a few charge/discharge cycles on a brand new pack might not hurt. If you're going to use it frequently store it fully charged in a spot where a fire isn't going to burn down your house or kill someone. Mainly store in a cool dry place, if it is heated too much charged it can enter thermal runaway all by itself if the package gets damaged especially.

 

[Diver300]

Laptop batteries are often 4 LI-ion cells in series.

They always measure the voltage on each cell, and they will shut off before getting to 3V on the lowest cell. 0%, where the laptop shuts off, should happen before damaging the cells. There doesn't seem to be much point in the laptop makers having a mechanism for shutting off just after the cells have been damaged, when it is just as easy to have it shut off before damage happens.

I think that laptop batteries have balancing on each cell so that the voltages can be kept the same on each cell.

Some laptops can be told to charge to higher levels to give maximum duration, or lower levels to give longer battery life.

 

[Sceadwian]

They do not always measure the voltage on each cell. You're assuming way too much. Balancing doesn't work well on lipoly cells because they don't tolerate over current as much as other chemistries, so you have to individually peak charge each cell and even then they have to be well matched or you can easily over discharge individual cells. 0% charge status does not always mean anything depends too much on the battery management system which is usually almost an afterthought on a laptop. Cells in series are usually taken off of the line in series so they don't generally even check for cell ballance. Discharge to volts per cell on a pack basis are at best a guess. S'why 3.1 volts is a safer margin. Peak charge on a lipoly is what 4.3 volts or so? Yer not losing much capacity at a .1 volts overhead on the low end of the power band.