Power HP laptop with extenal battery source

Thread Starter

dataworx

Joined Nov 27, 2013
12
I have a relatively recent HP laptop, the battery (internally fitted) swelled up and died a couple of years ago so I removed it and have been running the laptop off AC mains, via its dedicated charger/power supply ever since.

We are, however, subject to frequent power blackouts so I want to power the laptop from a LifePO4 battery pack with a regulated 19 volt output. The official replacement battery is a fearsome price and I'd prefer an alternative.

These HP laptops use a jack connector with 3 conductors: +19V, ground, and a central 'sense' pin. If I use only the 19V and ground then the laptop does not power up. I have seen a solution?? whereby the 'sense' pin connected to the 19V with a resistor, which then provides the voltage/current that the laptop requires to start up.

Anyone here familiar with type of setup who is willing to help me get this going?
 

Thread Starter

dataworx

Joined Nov 27, 2013
12
So to round this off, I followed the advice given here, resultant voltage on the sense pin is 17.5 volts, not loaded. Plugged into the external backup and working just fine.
 
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