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Can a power surge reduce the battery capacity?

Hello there.

A couple of days ago, a lightning caught me by surprise and landed in the electrical grid near my home. I had my macbook pro connected via the thunderbolt display at the time.

Both screens flickered for a second like 1 second before i heard the thunder, and i heard a electrical noise coming from the lower middle-left side of the Thunderbolt Display. Like a discharge.

I immediately disconnected the system from the wall.

The display seems running fine, despite a strange low frequency noise in the same spot i heard the electrical noise at the time of the lightning. Is like something is charging and after few seconds it releases. It's not always there the noise. It comes and goes.

Im not sure if the noise was already there or it was due to the surge.

About my laptop i did every freaking test i can conceive of (from apple hardware test, to any benchmark available, passing by any RAM test ) and everything looks normal...

Everything except my battery...

It went from 99% current capacity to 93%. I've already calibrated it, but it remains on 93%.

Could it be possible that this drop was due to some damaged inflicted by the power surge? Or is just coincidence?

If it was due to the power surge, should i be worried that the rest of the battery may die? Or damage the rest of the components?

And lastly, i'm guessing that the Display took the extra power like a champ and "protected" the system, so, is it safe to connect the laptop to the power cord of the display? Could it be damaged and damage my laptop?

Thank you in advance.

P.S. - i have a belkin surgemaster thingy...


Oh and another thing... The power surge burned the building main power switch of the public areas... We are still without lights in the stairs and garages and all that stuff... :/

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Was both the MBP charger & the external display plugged into the Belkin surge suppressor (assuming that is what you had)? Also, you'll need to get a new suppressor as these units loose there effectiveness after one good hit (which clearly you got here).


The Macbook was powered through the Thunderbolt display, and the display was plugged to the belkin thingy.

So far no more changing's in the capacity of the battery... It looks like it's stuck at 93% (7884 mAh).

But to be honest i'm a bit afraid to connect it to the display again.


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OK, so you did have it daisy-chained via the TB connection, thats good, so the displays transformer isolated out your system and the display. Was the surface your system and display on non-metalic? If so there's no path to ground via the display or the MBP via their cases. Then you should be fine (other than the surge suppressor). At this point I would give your stand-alone charger a try to see if it improved things. I'm not sure how a surge would have passed through the surge suppressor could effect the systems battery without leaving other kinds of problems. For now see what happens. I would review the Belkin warranty and check your renters/home owners insurance to see what recourse you have to get the battery replaced. Good Luck

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