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Old 02-07-2016, 06:27 AM   #1
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Rapid battery drain

2004 2.7 boxster draining battery within 2 days. Just fitted new battery, new alternator and new ignition switch but made no difference. All electrics seem to work fine but I have noticed that lower dash lights come on after locked, not immediately but after a few minutes. Presumably this is draining the battery but what would be activating this?

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Old 02-07-2016, 07:29 AM   #2
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Do a search under for finding parasitic battery drains, been covered numerous times.
Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein
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Old 02-07-2016, 01:22 PM   #3
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Thanks for the reply but I have researched forums extensively and can't find a scenario that mirrors mine. Essentially I'm certain it's the the lower dashboard lights that are draining the battery but I'm trying to understand what situation would always cause them to come on when the car has been locked. Is a Faulty alarm or door locking mech likely?
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Old 02-07-2016, 02:41 PM   #4
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Please explain "lower dashboard lights" - which lights are these??
1) Determine which fuse protects these lights.
2) Remove neg side of battery and connect multimeter in series with battery terminal and neg cable.
3) Read mA drain, then remove fuse for "lower dashboard lights" and see if drain reduces.
4) If so, you have a parasitic drain on that circuit.
5) As an aside, do you have one of those tracking devices (Toad ??) fitted so beloved by the English insurance companies? If so, that's the first place I would look.
2001 Boxster S (triple black). Sleeping easier with LN Engineering/Flat 6 IMS upgrade, low temp thermostat & underspeed pulley.
2001 MV Agusta F4.
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Old 02-07-2016, 04:18 PM   #5
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1. New car or had it awhile?
2. Anything non-stock in it?
3. Do all locks, windows, etc seem to work correctly?
4. Does the problem occur when you have locked the car and received no beeps?

disraeli posted this on Porsche Pete's Boxster Board (*)

"The factory technical manual (Section 97-07 page 2) has the following table of total electrical load after the car has been shut off (ModelYear 02):

(electrical current is worst case, i.e. car loaded w/all options...)


0 min 5 min up to approx. 950

6 min 15 min up to approx. 900

16 min 20 min up to approx. 750

21 min 60 min up to approx. 50

61 min until the battery is empty up to approx. 30

1000mA equals, of course, one amp.

If the car had no options whatsoever, the load after 60 min would be 17mA instead of 30mA.

From this table you should be able to insert an amp-meter between the battery and battery cable and tell if the car is within spec before you begin pulling fuses or removing the battery to get it tested."

And once you see the draw is beyond spec, you pull one fuse at a time noting if the current draw drops within spec when the fuse is removed. Find the one that causes the excess draw and you have located the circuit that is causing your problem.

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