987.1 battery drain

[832ark]

Bit of a strange one this I’m struggling with. I’ve a 2005 3.2 987.1 Boxster. Battery was flat around a month ago and as it was reasonably old I replaced it. The issue is I keep getting a flat battery. I can drive it, park it and then within 48hrs there’s insufficient juice to start it.

I’ve tested parasitic draw, stood and watched the meter with a locked car and it hovers around 45-55mA. This seems about right and would take some time to deplete a fully charged battery.

Next up is the charging system - when I first start the car I’m seeing around 14.3v across the battery. As the car warms up this gradually drops to around 13.5v which seems low to me?

Any ideas? I’m starting to get a bit cheesed off!

TIA!

[gsewell]

Background current draw should be below 10mA. This is with doors closed, frunk light disabled (assuming frunk is open to access the battery) and car shutdown for at least 30mins so that a lot of the standby circuitry goes to sleeps.
Typical drain is from tracking devices, especially is the subscription has lapsed.

[832ark]

gsewell said:

Background current draw should be below 10mA. This is with doors closed, frunk light disabled (assuming frunk is open to access the battery) and car shutdown for at least 30mins so that a lot of the standby circuitry goes to sleeps.
Typical drain is from tracking devices, especially is the subscription has lapsed.

Thanks for that, it has got an active tracker so I’m expecting that. I’m not really concerned about the level of the parasitic draw, it would need to be significantly higher to drain the battery in 24hrs, something like 2A. I understand in some modern cars the normal range can be up to 80mA!

[gsewell]

A 24ah battery may not drain completely before it can no longer crank an engine over.

[832ark]

gsewell said:

A 24ah battery may not drain completely before it can no longer crank an engine over.

It’s an 85Ah battery.

[LunarOne]

Could it be that your new battery is faulty? It's not unheard of!

[832ark]

LunarOne said:

Could it be that your new battery is faulty? It's not unheard of!

It’s possible, although I’ve had it tested and it passed. I think the next test is to charge it then isolate it for 8hrs or so and see if there’s any voltage drop, if it’s in the car for 8hrs there is a recordable drop in voltage.

[Heaveho]

832ark said:

gsewell said:

Background current draw should be below 10mA. This is with doors closed, frunk light disabled (assuming frunk is open to access the battery) and car shutdown for at least 30mins so that a lot of the standby circuitry goes to sleeps.
Typical drain is from tracking devices, especially is the subscription has lapsed.

Thanks for that, it has got an active tracker so I’m expecting that. I’m not really concerned about the level of the parasitic draw, it would need to be significantly higher to drain the battery in 24hrs, something like 2A. I understand in some modern cars the normal range can be up to 80mA!

This is what happened to mine. About the same level of drain. I bought the car and unbeknown to me, it had a tracker. No probs until the battery was disconnected to upgrade the head unit. Had a few false starts looking for none existent faults until it transpired that reconnecting the battery had woken up the previously dormant tracker, which I assume was faulty given the drain from it.