YOU CAN REPLACE 18.5V/68W HP WITH 19.5V/90W DELL CHARGER ~ The Young Engineerzz

If you have a laptop that needs a new power supply(Charger). I chatted with a HP consultant and he said I could use one of the new 90W slim smart adaptors for this, that has 19.5V output (whereas the original 65W adaptor was 18.5V). The smart adaptors "Say" they are backwards compatible with all HP business notebooks. How important is it to match up the voltages? Can the laptop compensate for +-1 volt differences?

Solution
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For voltage, + or - 5% -7% is ok, for wattage 90W is much better than 65W.
the 90W 19.5 volt is even charging at faster rate.