Lifetime of Rechargable Battries

Laptops these days use LI-PO batteries, which have no memory effect from being discharged/charged whereas NI-CD and NI-MH do. Never completely discharge a LI-PO battery because this WILL kill it, I should know, I have done that with 2 laptop batteries. With regards to whether to keep it plugged in or not, it is a decision because if you were to have a power cut the battery would come into play, but also having the battery in all the time can shorten it's life, not substantially but enough. What I reccomend is to have the battery plugged in, to protect against power cuts/surges -It acts as a surge protection for the machine. With this though, try to almost fully discharge every month or so. This can be achived by turning the mains power off and then leaving the lappy turned on and just leave it. This will not fully discharge it because laptops have battery protection where they shut down when the battery gets to about 10%, which can be changed.

How do you mean "Industrial purpose"?

Hai, Thankyou for suggestion, I'll try. Industrial... means some 220V/24V DCDBs having the batteries under float charging. I am asking to utilize those batteries for some time also or not?..

With out testing these batteries on a regular basis how would you know if these batteries are even ready to do the work they where installed for. Leaving them attached to a maintaince charger is OK but they should be tested periodically in a simulated emergency condition. That way if they fail or run low during a test a repair can be made before they are really needed.

Batteries are strange animals and can fail for seemingly no reason at any time!

Hey Bondy, my old Toshiba had a lousy battery charging circuit. I pulled the battery pack and made a charging holder from wood and some screws positioned to contact the battery pack in the right place. I connected a variable power supply with both voltage and current meters on the front panel. that allowed me to adjust the output to match what the battery needed. It looked crude but it worked. It also allowed me to measure exactly what went into the battery and to check case temperature during charging.

elnav,

Good answer.

The battery manufacturer data sheet is the best source for battery charging voltages. Most charging circuits tend toward a diode and not much else. The customer then has to put up with reduced battery life.

Thanks for the GA. I agree that it is time for new batteries if they only last 5 minutes.

In laptops, if you connect it to power line ,it will operate on line power only -even if the battery is full. If the battery is on low charge, the line power will do both functions -charging the battery as well as providing power to the laptop.

When you are not connected to external power, it will operate on battery till the battery get discharged to a safe minimum level . When it reaches such level you get low battery indication , then it shuts down the system automatically.

Batteries in laptop and mobile phones can be charged and discharged any time , whereas cordless phone batteries have to be charged fully and then recharging shoud be done only when it is almost fully discharged .This is due to memory. Otherwise charge retention will get reduced substancially. Therefore it is advisable to put the phone back on station only when it indicates battery low.

The optimum way to cycle a rechargeable battery is dependent on the cell chemistry. Some batteries are best run down to full discharge and then recharged, others only to a partial discharge. An excellent site that contains this information is batteryuniversity.com.

jhammond

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www.patent-innovations.com

I agree with answer "1". It is almost exactly what I do. About once a month I will use the battery down to less than 1/2 charge but more than 1/4, This seems to let the battery achieve its best life compared to my friends that discharge and charge a battery almost fully twice a week or more. My batttery will last almost twice as long. They will buy four or five batteries in 4.5 years and I might buy one. I change up computers every 4 years.

The link in answer #6 is the best source I have seen for some time. There is now so many different battery technologies available it becomes very difficult to answer the original post without reference as to what type of battery is used. Some tolerate a continual trickle charge others do not. Some lap top charging circuits are sophisticated others not so much. The fact is, battery life over many cycles is not a priority concern with most laptop manufacturers. Run time per charge is a concern because it is one of the things consumers look for when comparison shopping. However, depth of discharge is always detrimental to longevity except for Ni Ca batteries and those are pretty much no longer used for laptops. That means a laptop manufacturers could be tempted to run the battery deeper into discharge than what is considered good practice. Besides if the battery lasts two years or so its just more profit if the customer has to buy a new replacement battery. As a general rule excessive trickle charging creates heat. Heat is destructive to long battery life regardless of chemistry and technology used for the battery. The argument out forth by Bondy regarding what about if the mains cut out is better addressed with an external UPS designed for the purpose than baking the internal laptop battery with continual trickle charging. Best performance and longevity is obtained by following the battery manufacturer's recommendations. Not the laptop manufacturer.

GA Elnav!

right.

the fact that laptop manufacturers do not make their own batteries provides another angle to this situation. I'd suppose laptop manufacturing engineers would not design their machines without taking into account existing batteries' specifications and ratings, unless they are developing some new machine with entirely new power specifications in coordination with battery vendor.

in short, laptop manufacturers won't bother about batteries' lives, but will only be concerned about batteries' ability to power the machine.

therefore, queries about a certain battery's characteristics are better answered by the battery manufacturer themselves.

How old is it and how did you treat it?

Is there any indication what type of chemistry is used in the laptop batteries. I had an old Toshiba with Lead AGM type batteries. My newer Dell had Li Ions and friends has one with Li-Mh. But I notice the cordless phones still use lead acid.

Almost all new laptop batteries are LI-ION

Not really sure as to the age, I guess between 2 and 3 years; - I bought the machine second hand. As far as I know, the battery was always plugged in. The power lead goes into the machine not the battery if that makes any difference. It's a Packard Bell R4622

You had a good life with your battery, many do not last so long.

But with proper battery maintenance, you could easily achieve 5-7 years!!

Depending on technology some batteries can be revived. The link to Battery University hints at these revival techniques. Lead- acid types are the best candidates. Some ni-Cad can also be rejuvenated. Although the website does mention desulfation, the recommended techniques does not even mention the most effective equipment which is patented. A google search for "desulfation" brings up a lot of hits. I have not bothered to research other battery chemistries in depth simply because my work involves lead acid and mostly in much larger battery sizes than what you use in laptops and portable equipment. I know some model airplane and R/C car enthusiasts who claim to be successful in rejuvenating Ni-Cad batteries that have been left sitting on the shelf too long. It works better on the lead acid. The common feature of their rejuvenating attempts is to deeply discharge the battery. Then immediately recharge at maximum allowable current. This is repeated several times for best effect. CAUTION!! This is something requiring constant attention. You cannot leave the setup unattended for even an hour. If the battery requires constant current you either adjust voltage to maintain the constant current or you need an automatic charger designed for this. You must also monitor the battery temp and shut down as soon as the temp limit is reached. Its not for the faint of heart, but it can be done.

I have read all the responses to this battery issue , and the answers given are perfect . There is one small idea and it will make sense if one when utillizing your Laptop , rather use mains instead if you are near mains . When in the field try and have at least a backup battery . Use that battery in the field till its flat and rather recharge when you are back at mains again .

to a certain degree , all new tech batteries are worth the price and dont have a scare when using them .

I have three ( not bragging ) Lap tops and have two batterys to each laptop but when im at mains i remove the battery and work from mains , its not whether i'm scared or anything but Prevention is better than cure . Meaning that as in any high tech appliance , It can fail , so the meaning of battery is using it when you do not have mains .

Simply clever/correct.....

I agree with most of the answer but my personal opinion is different: To me it is more important to have my cell phone, notebook, pda, pocket radio or whatsoever is accu driven operable. Usually do I charge e.g. my cell phone nearly each night, not because of a weak accu, but to have it fully charged the next morning. I have never put myself in the situation of not being able to receive or make phone call due to discharged accu. The same applies for the notebook computer. I charge it overnight - if possible at all - to simply have it fully charged the next day. I'm aware of how proper accu treatment should be but I prefer to shell-out the money for a new accu over being left with useless tools, that's it.