Possible Battery drain

Possible Battery drain

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Discussion

Skyedriver

Original Poster:

17,655 posts

281 months

Thursday 19th May 2016
quotequote all
Even fully charged, the battery wil lose power over a two or three day period to the point where the car won't start.
Now it may be coincidence BUT it all started to happen after a certain well known accessory store fitted new all singing all dancing audio unit.
So I could disconnect the battery and see if it still loses charge but how do I determine where it's draining?
Even if I disconnect the battery I suppose it could be the battery itself although when I bought the car I was told it was a new one (year ago)?
I have a multi meter just not sure how to use it!

PositronicRay

26,954 posts

182 months

Thursday 19th May 2016
quotequote all
Can you pull the fuse?

RR-B fixer

16 posts

94 months

Thursday 19th May 2016
quotequote all
Try this... Disconnect the negative cable from the battery. Set your multimeter to Amps. Connect one lead to your battery negative terminal, and the other to the cable you just removed (i.e. re-connecting / completing the circuit). Now read the Amps on your multimeter. That reading is what your car is draining from your battery. Check all your interior lamps are off (common fault / mistake). Generally, it's common for a car to drain 0.05ish Amps. Look for no more than this. If you have more, start pulling out fuses (start with new stereo) and checking multimeter one by one. Remember though... Do not turn ignition on or attempt to start car with battery cable disconnected as you will damage your multimeter! Good luck! Let us know how you get on...

Skyedriver

Original Poster:

17,655 posts

281 months

Friday 20th May 2016
quotequote all
RR-B fixer said:
Try this... Disconnect the negative cable from the battery. Set your multimeter to Amps. Connect one lead to your battery negative terminal, and the other to the cable you just removed (i.e. re-connecting / completing the circuit). Now read the Amps on your multimeter. That reading is what your car is draining from your battery. Check all your interior lamps are off (common fault / mistake). Generally, it's common for a car to drain 0.05ish Amps. Look for no more than this. If you have more, start pulling out fuses (start with new stereo) and checking multimeter one by one. Remember though... Do not turn ignition on or attempt to start car with battery cable disconnected as you will damage your multimeter! Good luck! Let us know how you get on...
Thanks for the clear instructions, will do this over the weekend (after freeing off a rear brake).

AW10

4,421 posts

248 months

Saturday 21st May 2016
quotequote all
You probably won't permanently damage the multimeter by running too much current through it - just blow the fuse within it.

Does the radio work with the ignition off and the key out? If yes it may be wired to a permanent live rather than a switched live.

Boot and glovebox lamps can fail to switch off - one way to find them is to use a smartphone with a video record feature and put it in the boot/gloxebox to ensure the light goes out.

And what sort of car is it? Many new cars "go to sleep" to reduce battery consumption but if something is wired wrong the car won't go into sleep mode and the battery will drain rapidly.

Skyedriver

Original Poster:

17,655 posts

281 months

Saturday 21st May 2016
quotequote all
AW10 said:
You probably won't permanently damage the multimeter by running too much current through it - just blow the fuse within it.

Does the radio work with the ignition off and the key out? If yes it may be wired to a permanent live rather than a switched live.

Boot and glovebox lamps can fail to switch off - one way to find them is to use a smartphone with a video record feature and put it in the boot/gloxebox to ensure the light goes out.

And what sort of car is it? Many new cars "go to sleep" to reduce battery consumption but if something is wired wrong the car won't go into sleep mode and the battery will drain rapidly.
Will look after the MM
Radio off when key out BUT it has a memory for the clock, stations I presume, Bluetooth etc (Screen blank though)
Def not the boot area, will check glovebox.Could be but I think that would drain it quicker. Usually ok overnight, it's when left for a couple of days
Volvo 940 Estate
Thanks

Skyedriver

Original Poster:

17,655 posts

281 months

Monday 23rd May 2016
quotequote all
Well tried the disconnect and multimeter - nothing obvious there, except when I reconnected the battery and came to reset up the audio unit I had a hell of a trouble getting my phone Bluetooth thing to pair but that's probably just me being old and not understanding these modern things.
Last player used cassettes.....

PositronicRay

26,954 posts

182 months

Monday 23rd May 2016
quotequote all
Get the battery checked.

Skyedriver

Original Poster:

17,655 posts

281 months

Monday 23rd May 2016
quotequote all
PositronicRay said:
Get the battery checked.
It has 12.5V across the terminals but that's not to say it isn't eating itself inside. It's a Varta and when I bought the car 10 months ago it was apparently new, but I cannot see a date on it.
Still think it's strange that this only started after the new radio was fitted - coincidence maybe

RR-B fixer

16 posts

94 months

Monday 23rd May 2016
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What was the battery draining (how many Amps) when you checked with the multimeter?

Penelope Stopit

11,209 posts

108 months

Tuesday 24th May 2016
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As RR-B fixer has already asked, what reading did you get when you wired up the meter, there is always a drain of some sort to be found when first connecting the meter in series with battery negative post and negative lead, if you didnt get a reading you were doing something wrong
Please post back with the current drain reading

Skyedriver

Original Poster:

17,655 posts

281 months

Tuesday 24th May 2016
quotequote all
Think maybe I was doing it wrong if there's got to be a reading of sorts as I was getting 0 or 1 depending on setting.
I'm a well practiced idiot, been at it for 63 years...

Garybee

452 posts

165 months

Wednesday 25th May 2016
quotequote all
We will need a 'unit of measurement', 0 or 1 what?

I would ignore this method of testing though as you have a decent guess as to where the problem is. Find the fuse for the radio and measure the voltage across it. Leave everything connected and the fuse in place. If you are not sure how to do this post a picture of your multimeter and I will guide you.

Skyedriver

Original Poster:

17,655 posts

281 months

Thursday 2nd June 2016
quotequote all
Haven't gone away, or rather I did, holiday in the Volvo.
long journeys charge the battery and the car spins over fast but after a couple of days of shorter journeys and the laddie leaving a door open ocassionally and the car refused to start.
TBH I'm beginning to think it's either the battery or the alternator putting the light out but not charging very much.
Further tests to come now I'm back home.

AW10

4,421 posts

248 months

Friday 3rd June 2016
quotequote all
Engine running at 2000 rpm you should see 13.5 volts or just a bit more when measured at the battery with little to no drop when you switch on the lights and the heater blower. Anything below 12.5 volts or so suggests the alternator is suspect. Otherwise it's likely to be the battery that can't hold a charge. All this assumes the battery cables are clean and tight etc.

SebringMan

1,773 posts

185 months

Tuesday 7th June 2016
quotequote all
Does your HU turn off with the ignition or not?

What car is it and what HU?

I'd check the drain on the car myself if it is going flat in a few days, it will have to be a hefty drain to flatten the battery that much.

Skyedriver

Original Poster:

17,655 posts

281 months

Wednesday 15th June 2016
quotequote all
Well it's not the alternator, or I've got two dodgy ones.
One problem I seem to have is the belt (new) keeps working slack.
But car fully charged with a charger, two 6 mile trips per day plus a couple of 10 milers over the weekend and it was dead this morning. Jump start from pack, 6 miles to work, bump on a slope this evening and it spun over quickly when I got home. Now on a charger though.
Beginning to think its just a knackered battery.

Skyedriver

Original Poster:

17,655 posts

281 months

Wednesday 15th June 2016
quotequote all
SebringMan said:
Does your HU turn off with the ignition or not?

What car is it and what HU?

I'd check the drain on the car myself if it is going flat in a few days, it will have to be a hefty drain to flatten the battery that much.
HU - head unit?
Yes but I'm also switching it off.
Must have a permanent live though as it has a memory for the stations

Garybee

452 posts

165 months

Thursday 16th June 2016
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You're changing components you haven't tested and ignoring people who are giving you the information you need to find the problem in minutes. I'd suggest that you just call an auto electrician at this point. It'll cost you less than your current approach.

Skyedriver

Original Poster:

17,655 posts

281 months

Thursday 16th June 2016
quotequote all
Garybee said:
You're changing components you haven't tested and ignoring people who are giving you the information you need to find the problem in minutes. I'd suggest that you just call an auto electrician at this point. It'll cost you less than your current approach.
Not cost me anything so far as the alternator was sitting in my garage.
Car now fully charged, will try and leave it a few days with the battery disconnected and see where I stand. It's just a right pain resetting the radio unit again from scratch.

And yes will recheck the battery drop while I'm on.