C70 Battery Drain - Any Ideas?

[Tomoose]

Hi all

I have an issue where my battery is fully drained after a week. I've fitted a brand new Yuasa 096 which is the biggest I could find, and still the same problem. I've checked the glovebox, boot and vanity lights, but still a problem.

Before I get the multimeter out and start pulling fuses, any common issues or ideas?

Its a 2004 2.4T manual convertible.

Thanks,
Tom

[Adam1961]

Originally Posted by Tomoose

Hi all

I have an issue where my battery is fully drained after a week. I've fitted a brand new Yuasa 096 which is the biggest I could find, and still the same problem. I've checked the glovebox, boot and vanity lights, but still a problem.

Before I get the multimeter out and start pulling fuses, any common issues or ideas?

Its a 2004 2.4T manual convertible.

Thanks,
Tom

Hiya,

Given the age of the car, it could be literally anything.

However given it's taking a week to go flat, it's likely something small, rather than a main module staying awake which would draw several amps, it's likely a smaller component maybe only drawing 100-200ma or so.

Best thing to start with is a quick standy-by draw test with a multimeter, and see if you've got a Constant Draw, where a single component is simply stuck on, or a Cycling Draw, where you've got something not allowing the car to fully turn off.

You're hoping it's the first one, as doing normal fuse pulls can quite easily find the issue.

If it's a cycling draw, then you'll have to disconnect bits 1 by 1 and wait a few minutes in between to see if the draw goes down to an acceptable level. IIRC aroind 30ma is about right or considered ok.

Hope this helps!

[SteveSarre]

Also check that a door light or boot light is not staying on. Remove the bulbs and see if that changes anything.
Does the remote set and unset the alarm correctly? That might indicate a faulty door lock (and door edge light switch).
Does the alarm siren work?

Multimeter is good.

Steve

PS
But those would probably drain quicker than a week.

[Keith M]

I had a similar problem with my 2003 c70 a few years ago and it turned out to be an internal fault with the radio. Picked up another from a breakers and problem solved.
Diagnosed with a multimeter checking for parasitic drains and pulling fuses to narrow down the cause.
Good luck

[RollingThunder]

I had a problem with my 940 a year or so ago - that turned out to be the alternator... As you can see, there are so many possible causes that your best bet is to do as you originally mentioned - pull fuses and use a multimeter to measure the drop in current. Close all the doors and wait for 5 minutes to allow the various systems to go to sleep before checking the current.

As a general rule for cars of our age, I'd expect a drain of up to 50mA to be normal. That accounts for the radio memory, alarm, electric seat memories, etc.

Happy hunting!

[Rich850R]

Glove box light caused me a world of issues a few years back, another bulb for the list

[Simmy]

iv seen where a child has dropped a coin in the 12v socket/cig lighter

[Keith M]

A top tip I heard a while ago (maybe on here) - put your phone on video, leave in boot, glovebox etc to see if the light actually goes out when closing.
Easiest bit of troubleshooting ever.