Connecting voltage source instead of of a battery on a laptop

[zvucnabasta]

My toshiba laptop(c870-17g) doesnt charge a battery anymore nor it works on a charger due to reversed polarity, not repairable they said. It works only on battery which I charge outside the laptop with external charger.
Original charger is rated at 19v and 3.95A and
Battery is li-ion pack, model no: PA5024U-1BRS and rated at DC10.8V/10.8V , 48Wh/4200mAh
Question:
Can I connect a voltage source supply(for instance 10.8v de-walt cordless charger or ac dc step down concverter or anything else I could buy or make myself ) with sufficient current output directly to laptop instead of a battery?

I opened laptop and I could see two pins: battery plus and minus

 

[BradtheRad]

Theoretically yes, although you'll need to make the effort to construct your power supply so it is as safe and reliable as the battery pack.

You need to build in safeguards as to voltage regulation, isolation from mains AC, etc.

Measure battery voltage, both after it is charged, and while it runs the laptop. Your power supply should always stay within this range. Otherwise the laptop may refuse to operate.

To convert mains AC, a step down via transformer is safest because it provides isolation.

A buck converter does not provide complete isolation. As a result it may provide a path for high voltage, through cables to equipment that you have connected to the laptop. Or a path for high voltage through you if you touch the wrong things.

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You should also try to make sure that all power drawn from the supply, is used only by normal computer operation. It contains a ruined AC power adapter which may admit undesired current, with bad results.

Have you seen any trouble occurring on battery power yet? If not, then it is likely a homebrew power supply will be all right too.

 

[PatrickPribyl]

I agree this should work, although you don't have to go to any great lengths to make a charger.

The Li-ion batteries put out about 13.6 V when fully charged, down to about 10.8 V when they are close to discharged. They typically prevent discharging below this voltage to help prolong the life of the battery.

So a 12V "AC to DC Adapter Power Supply" (search on ebay, ~$9) is right in the middle of the voltage range that the battery is supplying. I would assume 4 Amps is sufficient since the battery only provided 48 Watt-hours (i.e. sucking 4A out of the battery would have discharged it in an hour or so), but would look for 6 amps or more so as to not run the cheap supply at its limit.

 

[FvM]

The Li-ion batteries put out about 13.6 V when fully charged, down to about 10.8 V when they are close to discharged. They typically prevent discharging below this voltage to help prolong the life of the battery.

The said "10.8 V" Akku uses 3 Li-Ion cells in series (actually 2x3), "13.6 V" means 4 in series. In so far, it may be unsafe to apply a voltage above 11.5 or 12 V to the battery terminals. Or the notebook computer could be prepared to work with 3 or 4 cell batteries alternatively.

Need to check the specification.

 

[zvucnabasta]

Theoretically yes, although you'll need to make the effort to construct your power supply so it is as safe and reliable as the battery pack.

You need to build in safeguards as to voltage regulation, isolation from mains AC, etc.

Measure battery voltage, both after it is charged, and while it runs the laptop. Your power supply should always stay within this range. Otherwise the laptop may refuse to operate.

To convert mains AC, a step down via transformer is safest because it provides isolation.

A buck converter does not provide complete isolation. As a result it may provide a path for high voltage, through cables to equipment that you have connected to the laptop. Or a path for high voltage through you if you touch the wrong things.

- - - Updated - - -

You should also try to make sure that all power drawn from the supply, is used only by normal computer operation. It contains a ruined AC power adapter which may admit undesired current, with bad results.

Have you seen any trouble occurring on battery power yet? If not, then it is likely a homebrew power supply will be all right too.

Thank you very much for the answer, but I had not ment the battery charging. What I ment was replacing battery with other non-battery voltage source.
Now the only way for me to use laptop is with battery which i have to plug out every time it is empty and charge it with this external charger since laptop circutry doesnt charge it due to twice reversed polarity with second hand charger.

 

[zvucnabasta]

The said "10.8 V" Akku uses 3 Li-Ion cells in series (actually 2x3), "13.6 V" means 4 in series. In so far, it may be unsafe to apply a voltage above 11.5 or 12 V to the battery terminals. Or the notebook computer could be prepared to work with 3 or 4 cell batteries alternatively.

Need to check the specification.

This is my laptop.. It says six cell battery pack, if that was information you were looking for.
Just to clear things up: did you mean to battery itself or just as you said battery terminals. In my scenario I do not include battery. So, I am considering to connect charger directly to battery terminals on laptop - without battery?

 

[zvucnabasta]

I agree this should work, although you don't have to go to any great lengths to make a charger.

The Li-ion batteries put out about 13.6 V when fully charged, down to about 10.8 V when they are close to discharged. They typically prevent discharging below this voltage to help prolong the life of the battery.

So a 12V "AC to DC Adapter Power Supply" (search on ebay, ~$9) is right in the middle of the voltage range that the battery is supplying. I would assume 4 Amps is sufficient since the battery only provided 48 Watt-hours (i.e. sucking 4A out of the battery would have discharged it in an hour or so), but would look for 6 amps or more so as to not run the cheap supply at its limit.

Do you think I could use AC220V to DC12V adapter for LED lightning systems since I was told it provides straight signal to avoid LED blinking or should I even consider this property of a voltage source for this purpose?

 

[ads-ee]

This is my laptop..

Wow terrible user ratings for that laptop :-(

LEDs are usually driven by PWM schemes as they would use a lot more power conducting constantly without a significant improvement in lux output.