Parasitic draw

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Mr B
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Parasitic draw

Post by Mr B » Tue Jan 26, 2021 9:16 pm

Hi everyone,

Got a nice mystery for this cold and wet Tuesday night

Been having problems recently with batteries going flat overnight, so I just watched a clip on YouTube of how to test for parasitic draw, I followed the instructions and I appear to have a draw of 7.52 volts, so I removed 1 fuse at a time to try and find the effected circuit but no joy so I took all the fuses out and still I have something draining the battery!

How can that be, surely no fuses means no component can work so how come I'm still getting a power drain??

Someone please educate me

Wayne

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Re: Parasitic draw

Post by stevemarl » Tue Jan 26, 2021 10:02 pm

Don`t understand `draw of 7.52v`. How did you get that figure: you would normally put an ammeter in series with battery to show how much current (mA) is leaving the battery. Actual electrical `flow` is measured in amps: volts measure potential difference. An AA battery is 1.5v even if it`s sitting on a shelf if you follow?
There are things which I think are not fused, I don`t remember the ignition circuit for eg. (maybe cos it`s switched by the key???) If someone`s wired something into that (and let`s be honest, there are some atrocious mods out there) , that could be your drain?

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Re: Parasitic draw

Post by Mr B » Tue Jan 26, 2021 10:24 pm

stevemarl wrote: ↑
Tue Jan 26, 2021 10:02 pm
Don`t understand `draw of 7.52v`. How did you get that figure: you would normally put an ammeter in series with battery to show how much current (mA) is leaving the battery. Actual electrical `flow` is measured in amps: volts measure potential difference. An AA battery is 1.5v even if it`s sitting on a shelf if you follow?
There are things which I think are not fused, I don`t remember the ignition circuit for eg. (maybe cos it`s switched by the key???) If someone`s wired something into that (and let`s be honest, there are some atrocious mods out there) , that could be your drain?
Hi Steve, this is what I looked at on YouTube I meant to say amps not volts mate

https://youtu.be/KF1gijj03_0

Wayne

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Re: Parasitic draw

Post by stevemarl » Tue Jan 26, 2021 11:46 pm

So you`ve got 7.5 Amps drain when everything`s off? You`re sure that`s not milliamps (mA)? Wow, thats nearly 100watts, should be about 10mA for the clock - no wonder your battery`s flat! There must be something getting quite hot if it`s dissipating that much: are you sure the coil`s not live. You should be able to feel or smell the heat at that rate. Leave it outside in this weather and see where there`s no ice in the morning? ;)

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Re: Parasitic draw

Post by Mc Tool » Wed Jan 27, 2021 1:30 am

Maybe the alt has chundered . Remove the plug on the alt and see if the draw is still there . If ok check for correct charging .
Im hoping milliamps coz 7.5a is a fair bit , as stevemarl sez something would have to be real getting hot. Do you have a hard wired amp ,a stereo headwork will req stand by current but thats bugger all . Another possibility is that the battery has an internal short . The plates shed lead particles that build up in the bottom of the cell until the stuff is deep enough that the plates sit in the stuff and current flows.....batt flattery . You either tow or jump start the car , drive to work , battery charges , car is fine all day ,drive home , but the cold start next morning ....nah
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Re: Parasitic draw

Post by stevemarl » Wed Jan 27, 2021 10:20 am

Mc Tool wrote: ↑
Wed Jan 27, 2021 1:30 am
Maybe the alt has chundered .
Never thought of that, well worth checking. One of the few things that connect direct to battery.
(Hamish, if it was an internal short in the battery, it wouldn`t show on a meter [in an external circuit]).

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Re: Parasitic draw

Post by Mr B » Wed Jan 27, 2021 11:24 am

Thanks for the replies gents, I really do appreciate it, by giving you guys some history I'm hoping we can solve the issue as it really is a pain in the arse.

Car was fine until last week, its always had that slightly glowing ignition light when braking or signaling with other accessories on.

Alternator output at the battery is 14.4 to 14.5 volts and 13.6 with lots of accessories on.

Recently I've had to start using her for work so lots of stuff on lights, heat blower etc. Noticed the heater blower isn't as fast as it used to be - it's only a year old, the wipers have also started to slow down, in fact the second speed on the wipers is roughly the same as what the first speed would be.

Tried 3 different batteries one of which is brand new, fully charged 12.86 volts, put on the car next morning they read between 7.57 to 10 volts, engine will not even crank.

Back to last night's parasitic draw test - I made a mess of it, I didn't do the test correctly so at this point I cannot actually say I have a power draw or how high that draw might be but as above something is obviously wrong and wiping out the batteries over night.

Apologises for wasting your time, I hope I have explained it better this time.

Wayne

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Re: Parasitic draw

Post by stevemarl » Wed Jan 27, 2021 11:50 am

Mr B wrote: ↑
Wed Jan 27, 2021 11:24 am
Apologises for wasting your time, I hope I have explained it better this time.
No apologies necessary, we`ve all been there.
Mr B wrote: ↑
Wed Jan 27, 2021 11:24 am
Noticed the heater blower isn't as fast as it used to be - it's only a year old, the wipers have also started to slow down
That does suggest the alternator`s not working well. As Hamish suggests, maybe try unplugging the alternator tonight and see if that cuts your drain. Must be fairly large if it`s flattening a new battery overnight, and the alt IS still in circuit even if you remove all the fuses.

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Re: Parasitic draw

Post by Mc Tool » Wed Jan 27, 2021 5:21 pm

Stevemarl , I guess I meant to say "partial short "πŸ€”. The battery will go flat just like you left the lights on ,except that the current draw is inside the battery , and unless you measure the internal resistance of the battery there is nothing to see . If the drain is really 7.5a theres your problem , if its 7.5ma it may be the battery . If I was to put my money on the table Id say the alt is crook ( one or two crook diodes ,and they can be a bit intermittent in early stages of failure ) , but its hard to say .
Wayne , its 6am and Im already checking out what you guys have been up to overnight ,far from waisting anyone's time , certainly not mine , I like it here πŸ˜€.
Id rather have a bottle in front of me :beer: than a frontal lobotomy 🀯

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Re: Parasitic draw

Post by Mr B » Wed Jan 27, 2021 11:17 pm

Hamish, Steve,

Thanks so much guys, I haven't been able to do anymore today as I'm not feeling to good - I sense a Covid test in my near future..

Quick question, as the alternator is still connected to the battery regardless of whether the fuses are in or not does the same apply to the starter motor?

Wayne

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Re: Parasitic draw

Post by stevemarl » Wed Jan 27, 2021 11:49 pm

Mr B wrote: ↑
Wed Jan 27, 2021 11:17 pm
I sense a Covid test in my near future..
Wayne, hope you`re OK!
Mr B wrote: ↑
Wed Jan 27, 2021 11:17 pm
does the same apply to the starter motor?
The starter is and isn`t connected though: the heavy red lead only connects to the solenoid (which is like a big relay, sits on the back ): the solenoid itself is obviously disconnected when the key is out. Starter is only connected to the battery when you operate the solenoid (it uses power): the alternator can be connected all the time as it produces power. I.e. power only goes OUT of the alternator. Or that`s how it should be, as Hamish says, you can have faults in the alternator, intermittent diode packs, who knows which could allow current to leak back?
If you do suspect the solenoid, for eg, IS drawing current - does it get warm? A couple of amps will warm it up quite a lot, quite quickly.

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Re: Parasitic draw

Post by Andrew 2.8i » Thu Jan 28, 2021 11:45 am

Here's my own parasitic draw.... :D

Image

I hope you're feeling better Wayne.

Andrew.
Image

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Re: Parasitic draw

Post by Bug » Thu Jan 28, 2021 1:28 pm

Andrew 2.8i wrote: ↑
Thu Jan 28, 2021 11:45 am
Here's my own parasitic draw.... :D

Image
That gets a tick from me ;)

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Re: Parasitic draw

Post by Major_Tom » Thu Jan 28, 2021 2:40 pm

Bug wrote: ↑
Thu Jan 28, 2021 1:28 pm
Andrew 2.8i wrote: ↑
Thu Jan 28, 2021 11:45 am
Here's my own parasitic draw.... :D

Image
That gets a tick from me ;)
:applaud: :applaud: :applaud:
I'm the one that leaves all those shoes in the carriageway.

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Re: Parasitic draw

Post by Mr B » Thu Jan 28, 2021 11:29 pm

Andrew 2.8i wrote: ↑
Thu Jan 28, 2021 11:45 am
Here's my own parasitic draw.... :D

Image

I hope you're feeling better Wayne.

Andrew.

Thanks Andrew :D

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Re: Parasitic draw

Post by Mr B » Mon Feb 15, 2021 7:58 pm

Hi all,

I thought I'd update this thread as the issue is apparently now sorted, it turns out that Hamish was correct, the alternator was causing the problem, new 65amp alternator on the car and all is well in Wayne's world.

Thanks for all the advice gents it's very much appreciated.

P.S does anyone have a picture of a cracked rear light cluster when the fixing bolts/screws have been done up to tight?

Wayne

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Re: Parasitic draw

Post by Mc Tool » Tue Feb 16, 2021 3:37 am

No but if you were to take a x head screwdriver and a camera to the rear of your car .......Im sure you can see where this is going πŸ˜†
Id rather have a bottle in front of me :beer: than a frontal lobotomy 🀯

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Re: Parasitic draw

Post by Mr B » Tue Feb 16, 2021 10:41 am

Mc Tool wrote: ↑
Tue Feb 16, 2021 3:37 am
No but if you were to take a x head screwdriver and a camera to the rear of your car .......Im sure you can see where this is going πŸ˜†
I think I'll pass on that mate :D

However just by saying take a x head screwdriver to it you have given me a clue, someone has replaced those screws with bolts which makes me think there is a very good chance they have been done up to tight, I have fixed a lot of the botch up"s on the car since I bought it and I expect this to be another thing to add to the list.

Thanks for your help MC

Wayne

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Re: Parasitic draw

Post by Mc Tool » Tue Feb 16, 2021 7:42 pm

Im pretty sure there should be a screw with a o ring /rubber washer under the head . O-ring is probly both sealing water out and providing a bit of "spring " so as not to crush/split taillight lens. One of the 1st things I did upon recieving my crapi was to find a spare set of lenses ( cant for the life of me remember where I got them ) , I then chucked a lump of firewood at one cracking it , and dear old Mavis Cleaver rear ended me at the supermarket totalling the other ( and my bumper ) .......but I fixed her , as I drove forward , none to cautiously my tow ball tore the whole front apron off new suzuki swift .....heh heh heh
Id rather have a bottle in front of me :beer: than a frontal lobotomy 🀯

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Re: Parasitic draw

Post by Bug » Wed Feb 17, 2021 8:19 am

Hold up!
Think there's a misunderstanding occurring here?
Yes, the lenses are held on with small screws and seals which I always thought were to keep the moisture out? Doing them up too tight may indeed crack the lenses.
However, I think the question may be more to do with the two big fat screws that hold the light assembly in place, from inside the boot? If you do these up too tight, it cracks the back plate. As this carries the common earth for all the lights, back through the mounting screws to the bodywork, then a crack can cause all sorts of odd lighting issues. I've even seen it cause a problem with front sidelights! That one took a a while to trace.

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