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Laptop on car charger


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#1 eclipsemullet

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Posted 25 May 2013 - 08:16 PM

I am running Expedition on a MacBook Pro under Bootcamp.

When I power the MacBook with a car charger into the boat's electric panel, it seems to drain the boat's battery rather quickly. It drops from 12.6v to 10.0v in an hour or so.

Is this to be expected or is there something wrong with our batteries?

#2 joe.barry

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Posted 25 May 2013 - 09:36 PM

My batteries (2 x 105s) would drain quickly, so I bought new ones. Problem stopped.



#3 galacticair

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Posted 25 May 2013 - 11:15 PM

10V....! Sounds like your battery is dead.  Read up online on "12V battery state of charge", but in short your 12V battery should be somewhere between 12.2-12.7V (50-100% charged) at rest.  Will be a bit different under load, but it should never read at 12V or below (<50% charged or less is not good for lead-acid batteries), and certainly not 10V especially after such a short load.  Time to replace the batteries iMO...

 

Also, an external laptop battery might be a good add-on if you specifically want power for your MacBook.



#4 allen

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Posted 26 May 2013 - 06:20 AM

Temperature: 67 degrees Fahrenheit

Percent Charge  Unloaded Voltage

100  12.61

75  12.28

50  11.98

25  11.74

0  11.62

 

 

You should not run your battery below 50% charge so not below about 12 volts as has been said.  If you have a fairly standard series 27 batter with about 100 amp hours and if you charger is drawing even 120 amps, which is likely is not, that would be 10 amps and you should get 5 hours down to 12 volts.

 

New battery time, they are dead.

 

Allen



#5 galacticair

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Posted 26 May 2013 - 08:20 PM

Temperature: 67 degrees Fahrenheit

Percent Charge  Unloaded Voltage

100  12.61

75  12.28

50  11.98

25  11.74

0  11.62

 

 

You should not run your battery below 50% charge so not below about 12 volts as has been said.  If you have a fairly standard series 27 batter with about 100 amp hours and if you charger is drawing even 120 ampswatts, which is likely is not, that would be 10 amps and you should get 5 hours down to 12 volts.

 

New battery time, they are dead.

 

Allen

Corrected above. 

 

I think MacBook Pro charger pulls 85W (you should check), so certainly eclipsemuppet should get 5+ hours plus internal battery life if his battery capacity is >100Ah.  Agree with Allen.



#6 allen

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Posted 26 May 2013 - 08:54 PM

Temperature: 67 degrees Fahrenheit

Percent Charge  Unloaded Voltage

100  12.61

75  12.28

50  11.98

25  11.74

0  11.62

 

 

You should not run your battery below 50% charge so not below about 12 volts as has been said.  If you have a fairly standard series 27 batter with about 100 amp hours and if you charger is drawing even 120 ampswatts, which is likely is not, that would be 10 amps and you should get 5 hours down to 12 volts.

 

New battery time, they are dead.

 

Allen

Corrected above. 

 

I think MacBook Pro charger pulls 85W (you should check), so certainly eclipsemuppet should get 5+ hours plus internal battery life if his battery capacity is >100Ah.  Agree with Allen.

Good correction!  






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