Ready to Participate?
Ready to Participate?
Get Started!
Log In

Laptops and batteries question...
My mum is having problems with her laptop which is not charging its battery. Two separate sources have now told her that she should remove the battery from the laptop and only use it when there is no mains power available, that leaving it in constantly damages the battery and that this is a well-known problem.

I've never heard of it. I've checked the literature that came with all four of the laptops I have owned and there is NO mention of this anywhere.

Is she being fobbed off, or is this actually true? If it is true, surely the literature should say something about it?
asked in laptop, battery life

robinsamuels answers:

It's something that my wife always does and the battery on her laptop has lasted a lot longer than mine.

/ reply

siasl74 answers:

No - it's true. Batteries are rated to be charged a certain number of times. As time goes by, the amount of charge that the battery can hold will gradually reduce. Leaving the battery in will have the following effects:
if the battery is not fully charged when the laptop is plugged in, it will charge to 100% of the available capacity. After this, the power supply will stop charging it and run off the mains. In the mean time, the battery will slowly discharge as it will not hold 100% charge indefinitely. Once it has discharged a bit, the power supply will notice and begin charging the battery again. The cycle repeats and the batteries available charge will slowly reduce.

Different batteries will perform differently, but all will slowly lose capacity.

/ reply

xoloriib answers:

Almost anyone who uses rechargeable batteries has heard of the memory effect problem.
For those who have not heard of this problem it is commonly believed that when rechargeable batteries are not fully discharged between charge cycles that they remember the shortened cycle and are thus reduced in capacity (length of use per charge).
This problem was very common with rechargeable batteries up until about 5 years ago. With improvements in batteries and charging technology this 'memory effect' is becoming a thing of the past.

Little known facts:
* 'Memory Effect' is the common term used to replace the more accurate term 'Voltage Depression.'

* Voltage Depression is more a problem with incorrect charging than a battery problem.

* Voltage Depression does not necessarily permanently damage a battery. It can most likely be corrected by fully charging and discharging the battery.

* Voltage Depression ('Memory Effect') is often incorrectly used to explain low battery capacity that should be attributed to other problems, such as inadequate charging, overcharge, or exposure to high temperatures.

* Voltage Depression can be affected by the discharge rate of a battery. Generally speaking, the depth of discharge will be less on discharges at the higher rates. This increases the capacity loss as less of the active material in the battery is cycled.

* Voltage Depression occurs primarily in NiCad batteries. NiMH batteries are almost never affected and Li-Ion batteries are NEVER affected.

So how can you maximize the use of your rechargeable batteries? Here are a few steps to take to get the most use out of your batteries:

1. Invest in a good charger. NiMH batteries should not be charged in a NiCad charger, unless the charger is specifically made for both chemistries. There are cheap chargers and there are expensive chargers. Make sure the charger you get has good reviews and is well made. Chargers with micro-controller chips are usually the best choice.

2. When charging your batteries occasionally discharge them fully before recharging them. This is especially helpful to NiCad batteries. Be careful not to discharge too deeply. (Less than 1v per cell for NiCad and NiMH. E.g., a 3.6v pack to no less than 3v.) Discharging to absolute zero will make your battery useless. It's best if you have a charger with a conditioner that will cycle the battery for you.

3. Be sure to store your batteries properly. Do not leave your batteries in a hot car, or in humid conditions. The best storage conditions are a cool, dry place. The refrigerator is fine if you stick in a packet of silica gel with your batteries in a sealed bag to keep them dry. It is a good idea to charge your NiCad or NiMH batteries fully before use if they have been in storage.

4. Most cordless phones use NiCad batteries. To maximize your cordless phone battery life, make sure to leave your phone off the base every once in a while until it is dead. Then leave it on the base until it is fully charged. You should leave your phone on the base for at least 24 hours to charge it fully.

There is no need to avoid rechargeable batteries. They can save you significant amounts of money over time. Don't be scared off by the 'memory effect'. It is easily manageable if it ever occurs.


Supplement from 11/18/2008 10:56am:

While this article isn't actually about laptop batteries the information given is just as applicable. It certainly is true that you will get better performance if you use the battery power up. The problem could be that there is no indication of when the battery is charging, when it is fully charged or in fact just how much charge it has in it.

/ reply

seacommander answers:

I agree with all that has been said above, however, even if you follow all the excellent guidance given you may still come unstuck. I bought a replacement laptop battery recently and religiously charged it up fully and then only used battery power until the remaining capacity fell to the point where the machine went into hibernate mode. Even so the battery has failed again in a short period. The battery is a lithium polymer battery and the charger is a lithium battery charger as supplied with the machine. My warning is, that despite doing all the correct things with respect to charging and discharging you still need to be prepared that a rubbish battery may have been supplied.

/ reply


No Comments