2002 Porsche Boxter battery draw

Alfredo Mechanic California Posted   Latest   Edited  
Unsolved
Electrical
2002 Porsche Boxster S 3.2L 5-spd
Battery Draw

Customer brought this Boxster to us to install a battery saver because the vehicle only gets driven about once a month and needs to jump start it sometimes. I check for a battery drain and found after a few minutes is down to about 115 ma drain, witch is high but after two hours everything goes to sleep. My question is, if it goes to sleep after two hours should I not worry about it, or is two hours to long for this vehicle? By the way battery and charging system is all working good.

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Sevan Owner
California
Sevan Default
 

Are you checking that 115 mA drain with the vehicle locked or unlocked? If unlocked, measure drain with the vehicle locked and the front bonnet latch manually tripped. Take note of an audible beep when locking the car.

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Alfredo Mechanic
California
Alfredo Default
   

Vehicle is lock and hood shut closed, thank you

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Sevan Owner
California
Sevan Default
 

In that case, yes, 2 hours at 115 mA draw is too much. When all is normal they typically draw about 35 mA depending on how the car is optioned. Is this vehicle totally stock, and no LoJack? Are you measuring draw in series, or inductively at the battery cable? What is the Ah capacity of the battery that is currently installed in the car? Is the battery lead acid, or AGM?

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Robert Owner/Technician
California
Robert Default
 

Also make sure you had now water entry into cabin, especially under drivers seat where the alarm module sits. If module is shows sign of corrosion, clean water drains in comportment next to battery, it has drains on either side of it and they get filled with leaves and mud.

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Alfredo Mechanic
California
Alfredo Default
   

I did check module under the seat, and there is no evidence of water or corrosion, thank you.

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Obie Technician
Washington
Obie Default
 

Ditto to what Sevan posted. You should also verify the battery is the correct size and rating for the car. It is also worth noting the battery is not a deep cycle type battery. Constant deep discharge damages batteries. It may pass a basic check but not have the capacity of new and the self discharge may be much faster than new. A maintenance charger may simply finish off the battery. Garage…

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Alfredo Mechanic
California
Alfredo Default
 

We are sure the battery is the correct one, we installed it two months ago but will double check on that, thank you.

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Irek Mobile Technician
New York
Irek Default
 

If you have scan tool like piwis scan the car . Also check both windows make sure there up position. With both hood close make sure all light off​.​check alarm system

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Stephen Technician
Tennessee
Stephen Default
 

If it is going below 50ma after 2 hours and is it staying that way, asleep,? Then the 115ma for 2 hours is of no consequence. It’s not enough to be a problem. I more wonder what the scenario is when it is started? Is the battery brought back to full charge? I’m thinking that it’s not and that it is put back partially discharged. A couple months of that is enough to cause a no start.

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