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Tuesday, January 25, 2011

In some cases, especially for us employees, tests on the laptop AC adapters usually lead to some undesirable results on ourselves. Several days ago, we have performed some examination on hp pavilion dv4000 adapter by adjusting the output voltage to about 17V which is absolutely higher than the nominal value set by the manufacturer.



With such a level, I have charged the laptop batteries seriously for some minutes to activate it. However, after reinstall into the notebook computer, I figure out by accident that the indicating LED comes to crush out so that it cannot get any other power energy any more. Such a consequence has reminded me a lot about the internal circuit in its functions and influence.



To learn clearly about the root causes, my colleagues and I decide to unpack the AC adapter hp charger 402018 001 to check on each component inside the internal circuit board. It should be divided into several parts in the leaders by external and internal situations.



According to the former experience, lithium-ion laptop batteries won’t be hurt directly by higher output voltage. It is also certainly that such a level of voltage has already caused overcharging while it occurs at the first time of charging is another accident to us.



Under this circumstance of output voltage, the structure of lithium niobate crystal has been destroyed seriously due to overloading. That is to say, protection circuit has taken actions unless it is out of work before. Normally, FET MOS will shut once overcharging exists here to prevent it from explosion and fire.



After that, we begin to recharge the battery by compaq presario 3000 ac adapter with output voltage of about 10V to 11V. Normally, as to temporary accident, protection circuit will escape the charger from working to avoid further accidents. Thus experiment has already renovated both motherland receiving and battery providing system effectively. It means that we don’t need to worry about HP pavilion dv4000 adapter too much.

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