Run a Laptop of Some Old Batteries

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Introduction: Run a Laptop of Some Old Batteries

This Tech. demonstration is to raise awareness that laptop batteries can easily be replaced with any other kind providing it is of correct, or sufficient, voltage. Here I am using two 6V. batteries rigged up to provide twice the voltage to power a Compaq Armada 110.

*Depending on your laptop warranty this may void it!*

Before reading this Instructable, I recommend reading this one first!!

Step 1: Remove the Power

For this you will need to take your old laptop battery apart, The battery I used was very stubborn and I only got it apart with considerable cosmetic damage, For taking it apart try starting by the contacts where the battery connects to the laptop, I have not got any proper pictures of this step as I did it about 1 month ago, and I only just un-earthed the battery casing, Once you have got a little bit of the battery casing prised up things will either be easier or a bit more difficult, the Compaq battery was fused together so I was practically just breaking plastic!

After you have got the battery apart you will find around 9 battery cells depending on the type of laptop battery. You will need to rip all these chunky batteries out, making sure not to rip the wire leads to the batteries off the circuit board (pic. 2)

Step 2: Source and Improvise the Power

To get some batteries to power the laptop I used the two batteries that are in my 5 million candle power torch, which are rating 6V each so to get 12V they were rigged up together for combined power, I don't know how long they would last fully charged but I estimate at the very least 30mins. 100%CPU

If you are using two batteries you will need to connect the positiver (red) of one battery to the negative (black) of the other battery.

Step 3: Connect the Power.

Now after you have got your batteries the next thing to do is to connect them to the leads of the laptop battery circuit board, you will need to connect positive of your new batteries to the positive lead on the circuit board. I recommend using wires of a decent length for ease, and also using red and black coloured wires attached to the corresponding battery connections (i.e. red to red) it will make things easier.

Step 4: Replace Remastered Battery

I had to cut a little hole for the wires to pass out of the battery casing, remember to thing about this and to do it so that the wires come out in a handy place, don't do this if you don't want to spoil your battery casings good looks.

Step 5: Testing the New Power

It has to be said that I had to use the A/C power connector to boot the laptop but after that it worked fine without the A/C power, I don't know whether this was because the laptop is old or it couldn't recognize the batteries to boot the laptop, but it did recognize the batteries with the A/C power plugged in and the laptop off.

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    75 Discussions

    The reason you needed the AC power is because you didn't ad another (=) wire to the 3rd terminal on the power connector. This wire sends a 12vdc signal to the motherboard to let it know its on DC power. If you put a jumper in place you will not need the AC power to turn it on anymore.

    Its pretty dangerous. Shorting them out, or deliberately placing them in a fire or anywhere hot.Did it work for you afterward? I expect it did. My hp laptop battery didn't work before and i didn't repire it.I bough a new one from eachbattery. It is a great source for replacement battery if you can find them.

    It is only dangerous if you don't know what you are doing. Laptop batteries can take A LOT before they actually become dangerous.. Shorting them out, or deliberately placing them in a fire or anywhere hot.

    Anyway, good instructable. I learned quite a bit. I am going to use an old 9.6 volt RC battery pack. I disassembled it and removed the 7 or 8 AA 1.2 volt NiMh batteries.. And rebuilding the old pack for my laptop.

    I even have C batteries from an old cordless drill battery pack, still holds a lot of amperage, enough to melt thin wires.

    The best way of opening old laptop batteries and other plastic casings is to heat up a fruit knife or similar with a gas solerding iron and then cutting it up like butter.
    The "Hot knife" supplied with these types of gas soldering irons usually does not work as well. It should be a thin, flat knife. It is actually less painstaking than using a dremel.

    2 replies

    That sounds extremely dangerous, especially since the batteries "can/might" explode if you are not careful enough. But using your method is still better than spending an hour prying that sucker open. XD

    Contrary to "popular misconception" Li-Ion/ Li-Po batteries are not as volatile as, let's say, nitroglycerine or dynamite. Yes, IF they go off you have a fire that is very difficult to extinguish and they COULD explode, but only if exposed to large amounts of heat ( on a larger surface area ) or charged incorrectly, alternately if they were or their original charging device was incorrectly constructed in the factory.

    If you happen to touch them with a thin hot knife, they are NOT going to explode.
    The cells does not contain free gases such as hydrogen, as some old lead batteries would give off when overcharging. Now - THAT could be really dangerous to light a flame around!

    Listen to xeijix!!! the circuit board, besides charging the battery, has a stored key which the computer needs to access before any power is drawn or charging begins. if you remove power from the board for just an instant that key is erased and the circuit board is no good, will never work again. It is much better to use the EXTERNAL power jack, you know the jack where the ac/dc transformer line goes. it is not an ac power jack it is a dc power jack so just supply it with the proper voltage for your particular flavor of laptop and you all set. much better than ripping apart a internal battery. all you need is a plug to fit the jack and your are set- i have used AA batteries before, two packs of six to make twelve to get the required 18.5v for my presario. even made do with a couple of 9.7v packs from my rc planes, boy did those go for ever!

    13 replies

    This is the best and safest way I built a battery pack that when charged it will power the laptop for a week so this works fine for me .

    sorry man,that is false
    i had just disconnected it and reconnected it and it still boots up from the batt

    But in rare cases,that may be your problem.
    That would also be a really badly engineered because some time in a laptops life the battery will drain to the point that its not enough to keep the key in.

    It is the case in Li Po batteries, they are very complex and have such a high energy density. It is very good engineering because my laptop runs for eight hours and the battery weighs one third of what my five year old laptop battery weighs, which lasted all of three hours. BTW the circuit prevents the batteries from discharging below a certain level, this guarantees that power is available as the circuit uses milliamps to work. I pretty sure all modern laptops use Li Po batteries so would think its rare, but if your using surplus or used batteries well maybe it is rare to come across them. I have used all types of batteries in my robots in the past, scrounging/recycling adapting all sorts of things to work. but now that i have discovered li po's It is worth the money to drop the weight and double the power. That changes everything my bots are faster and run longer. I do recycle/repurpose Li po's. I have a universal charger and collect use cell phone batteries to power my micro bots. Sparkfun ha a great website and good prices on Li Po cells and charging circuits, check them out!

    Ok,i don't have enough time to read your full lecture,but its rare to find that problem in a laptop you have the guts to take apart its battery and run it off of another
    No one has the guts to do that with a macbook air,right?
    Also,ALL BATTERIES SELF DISCHARGE
    QUOTE WIKIPEDIA:Self-discharge rate 5% month
    So it self discharges 5 percent a month,so say its 20 percent charged when it not enough to power a laptop.
    Give it a good five moths and your theory will burst in flames,Try it i will bet you 20 bucks if it does not work afterward (the circuit board)
    So if someone at an airport discharged it to 15%,Then did not charge it for another 3 months or so does that mean that they have to buy another battery,no.
    But seriously,batteries WILL discharge to the point that key will be lost

    Hey dude! it was not meant as a lecture, just trying to keep someone from ruining a battery pack, do what ever you want i love the idea of recycling all these old highcapacity batteries and keeping old laptops up and running, hopefully out of the landfills. My only point was to caution peolple about the charging circuit in some batteries. just a heads up about battery packs with the charging circuit built in, we can argue about their true purpose but the fact remains it will prevent the pack from operating if disconnected. People should tear apart all types of battery packs and see what works and what doesn't. Only wanted to warn people that what works for ni cads will not work for all batteries. Please don't take this the wrong way when I ask " have you disassembled a Nickel metal or Li Po computer battery pack?" What did you find? was there a control circuit? Did you disconnect it? if you have please share the details/findings with us. If not Has anyone else on this forum? can they share. Let's learn something together!Self Discharge Characteristics The self discharge rate is a measure of how quickly a cell will lose its energy while sitting on the shelf due to unwanted chemical actions within the cell. The rate depends on the cell chemistry and the temperature. Cell Chemistry The following shows the typical shelf life for some primary cells: Zinc Carbon (Leclanché) 2 to 3 years Alkaline 5 years Lithium 10 years or more Typical self discharge rates for common rechargeable cells are as follows: Lead Acid 4% to 6% per month Nickel Cadmium 15% to 20% per month Nickel Metal Hydride 30% per month Lithium 2% to 3% per month Self Discharge Characteristics The self discharge rate is a measure of how quickly a cell will lose its energy while sitting on the shelf due to unwanted chemical actions within the cell. The rate depends on the cell chemistry and the temperature. Cell Chemistry The following shows the typical shelf life for some primary cells: Zinc Carbon (Leclanché) 2 to 3 years Alkaline 5 years Lithium 10 years or more Typical self discharge rates for common rechargeable cells are as follows: Lead Acid 4% to 6% per month Nickel Cadmium 15% to 20% per month Nickel Metal Hydride 30% per month Lithium 2% to 3% per month

    " have you disassembled a Nickel metal or Li Po computer battery pack?" What did you find? was there a control circuit? Did you disconnect it? if you have please share the details/findings with us.
    Yes
    I found 8 nimh cells
    yes there was a circuit board
    Yes i have disconnected it

    Great! have you tried to reconnect it and use it in the computer? If it does work please let us know what make and model so we can figure out which ones are which. I have a Nimh pack lying around that needs new batteries but I haven't popped the case yet maybe this is the perfect time to see what's in there (ended up getting a new pak from a vender online that repacks them, was about half the cost of a new one).

    Yes i re connected it to a lead acid battery and it booted up from the battery and stayed on for a 8 hours I have a compaq presario 1200 xl106 and compaq presario 1220 203 they both use the same type of battery

    The batteries that have the built in circuit are the lithium polymer! other batteries are usually fine but I've heard of nickel-metal hydrides using the battery level/condition circuit also. that is where all the confusion lies what type of batteries are you using? all batteries charge differently, Ni Cads, Nm-hd, li-po lithium polymer offer such great energy density to weight ratio, greatly exceeding older technology, but it comes at a price. ever hear of exploding laptop batteries! well they are not exploding they are catching on fire, which happens to be a cascading reaction so they are all but impossible to stop. they can ignite in several different ways, one is to overheat them while charging. most Li Po batteries packs have a small smd board made into them that controls temperature by limiting the charge rate. Li Po laptop batteries have a controller that does this plus measures the voltage out and in and relays this info to your computer which translates it into the battery level meter on your screen. It also prevent the li po's from discharging to much as that would damage the batteries. this is not a problem with nicads or nickel metal hydrides, they are "dumb" batteries, all li po's must have a charge discharge circuit to make them safe to use. The model airplane hobbyist use some cells which have minimal circuits, they must charge the batteries in a bucket of sand to allow for the risk. It is this circuit that can not be disconnected or will not allow the battery to reconnect. that is the price we pay for so much energy in such a small volume!

    AHEM,Mine apparently has a circuit board,and it is a NIMH battery.
    I know what i am talking about,because i see it right before my very eyes.
    I will even put a picture up if you want.

    That's not true. If it was, how would you be able to use a newly purchased battery?