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PostPosted: Wed Jan 31, 2018 9:35 am 
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Black Belt
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Location: USA
HI. I got Dell laptop with 19.5v charging power and trying to modify power supply for it from similar dell power adapter but with lower voltage output (doesntworth to buy a new one).. I'll text model number after job. Any chances I got? Thanks.


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PostPosted: Wed Jan 31, 2018 12:04 pm 
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Black Belt 2nd Degree
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I think you're trying to do something that may end up not being safe.

If I understand correctly, you have a laptop that accepts a power supply provided at 19.5v. You have a power supply which supplies power at a lower voltage than 19.5 (let's presume 12v)...and want to get it to 19.5v so as to match the input for the laptop?

In the simplest terms, you can do it. The output is simply DC, which you can create a step-up (or boost) converter for it. however, that'll reduce your power (amps) and charge at a slower rate as a trade-off. my concern is that the components within the existing lower-voltage power supply would not be designed specifically for a higher voltage...and could be (or do) damage. damage to things with electricity always raises a risk of heat, and therefore fire.

-R

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PostPosted: Wed Jan 31, 2018 2:38 pm 
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Black Belt
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Yes, that's what I was going to do. But if it isn't safe then have no choice. Thanks a lot.


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PostPosted: Fri Feb 02, 2018 10:23 am 
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Mobo-fu Master
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Any power supply from another unit should work with no problem, as long as the plug type and polarity match.
the same voltage ratings are preferred, not lower or higher. Current could be a few mils higher, but still safe.
Trying to "adapt" another type to higher voltage needs circuit and component redesign.. mainly a differnt IC chip.

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PostPosted: Fri Feb 02, 2018 12:30 pm 
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Black Belt 2nd Degree
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I've used multiple power supplies which provided different amperage, but always had matched voltage outputs. higher amps provide more power, so charge a battery faster. there's risk in doing so that the battery components are not rated or designed to handle increased power loads, and could cause damage to circuits or even the cells themselves.

any kind of mismatch is "potential" for incompatibility and therefore some level of risk, and subsequently a chance for danger (while I consider it to be pretty small).

if you have the appropriate equipment and components it's feasible, and you may not have any problems. however, if I were to do it I would be sure to have plenty of testing to verify the before/after output of the modified supply is matching my expectations without much variation.

-R

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PostPosted: Sat Feb 03, 2018 2:10 am 
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Enlightened Master
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You can use the same voltage with laptop chargers ie if the laptop requires 18.5v, then any 18.5v charger will work providing the tip is compatible. However the driving force is the AMPs. The AMPs required must be equal or higher to the rating of what the laptop requires. If the AMPs are too low, the voltage may spike higher and this usually damages onboard components, but usually there is not enough power to start things up (laptop will show 'charger plugged in, but not charging' and the battery will drain. If the Voltage is too low and you lets say, plug a 12v charger into a 19v laptop, the AMPs will increase to make up for the voltage shortfall and you will usually see smoke and a cratered power control IC. You may get away with a higher voltage and lower to equal amps that the laptop requires, but the charger tends to get a tad hot.. From lots of experience, if an external power source is required (laptops/routers/switches/drive caddies etc etc...) use one with the same voltage and equal or higher amps.

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PostPosted: Wed Feb 21, 2018 4:09 am 
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Mobo-fu Master
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Quote:
use one with the same voltage and equal or higher amps.
and always check for matching AC or DC output. Most equipment is protected but still...

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