battery drain? having problem

[mk3 vinny]

I have seen an old post showing my problem http://www.pngclub.com/forum/showthread.php?184384-Battery-drain&highlight=draining+battery

I have followed Mowgli advice also have a new battey there is 12.67v in the battery and 12.67v showing on the volt meter between the +ve termanal and the termanal conector, I went through all the fuses and was still the same so i am at a loss, the earth on the battery is fine and iv fitted an earth between the gearbox and the shell.

when i fitted the earth to the box it did make a difference to the car cranking it seemed to crank faster so that is that one sorted. voltage still the same tho.

any common problems or helpfull advice would be greatly apreasiated

thanks vinny

[paul james]

Does the car have an alarm system or big audio set up?

[mowgli]

make sure your ignition key is out.

if it has one, disconnect the wires to the dim dip relay and re do the fusebox test.
if that doesn't show up a fault, disconnect the wires to the alternator, then do the fusebox test again.

[mk3 vinny]

Paul no the car dosnt have eather

Mowgli today i was fiddling again and disconected the starter and alternator still with no change and then did the fuse box again voltage droped when i hit fuse 16, ( radio, clock, luggage compartment light, interior light, hazzard switch)

so i put the fuse back in i disconected the clock and hazzard switch, the car has no radio or wiring, no compartment light, and doors closed. Still got the voltage drop so got no idea

pulled the fuse back out and reconected the alternator and voltage returned with the fuse out.

i will try and pull the dim dip relay tomoz and see if that dose anything.

any ideas

[mowgli]

fuse 16 is definitely where the trouble is. there will be a short there.

the interior light circuit also has connections to the boot & engine bay for different markets (scandinavia etc). i'll look into it

[mk3 vinny]

thanks Mowgli i will look in to it

[marc69]

I had a problem like this, fuse 16 kept on setting the alarm off. It turned out that some twit (me) had damaged one of the wires for the boot light and that was shorting against the body work under the palstic trim at the passenger door sill.

Try leaving the car with the fuse out to see if the battery still drains? If it doesn't then you will have to check everything that runs from this fuse.

[mk3 vinny]

i still cant find the drain on the battery if i pulled the fuse with the alternater wire off, and tested the curcuit with the multi meter and may have done it wrong i connected the multi meter to the +ve terminal off the batery then tested the ends of the terminals i can find and no continus curcuit so im stuck again in the haynes it says for sweeden they have a mixture heater not sure if it on that curcuit tho.

Mowgli did you find anything out or do you know anything that it could be?

Anyone elce know its doing my head in?

or how can i find the short or live

[meritlover]

how big is the voltage drop and how much current is cct 16 pulling if you measure across the fuse contacts (with the fuse removed obviously)
if you.are getting a voltge drop there with a 300A+ battery there is a seriois short that you can probably find with your nose or with your friends IR camera.

[mowgli]

Mowgli did you find anything out or do you know anything that it could be?

i still think my extra interior light wiring idea might be where the fault lies.

as you have said, all the big items, like the hazard switch look ok, then it must be a wiring fault

[mk3 vinny]

merit lover the voltage drop is whats in the battery so 12v+ and i will check across the fuse terminals tomorrow.

mowgli the hazard switch is brand new and everything elce looks ok, however i have been back through the the wiring diagrams tonight and found on the circuit there is

heater control illumination,
clock illumination
clock
connector ( auxiliary )
radio
interior lamp
trailer socket
LH front door switch
RH front door switch
Interior lamp switch
luggage boot lamp switch
hazard warning switch ( then through this leads to ) Fuse 7

Direction indicator switch
hazard warning lamp
flasher unit
direction indicator warning lamp
RHF direction indicator lamp
RHR direction indicator lamp
LHF direction indicator lamp
LHR direction indicator lamp
fog lamp switch
clutch switch
stop lamp switch
RH stop lamp
LH stop lamp

so i have a few more things to check hope the weather stays fine

[mowgli]

that's the trouble.. you seem to have a fault on a very busy bit of wiring

[mk3 vinny]

right I have found the problem it was the kiekert central locking system I disconected the box and off the drain went and its not even suposed to be on that fuse and i dont even have the key fob to work it so its getting left off. Just as well I started disconecting everything and when I started reconecting stuff it was fine till I got to the clock and it jumped back up to 12.87 draining so I have left it off for now.

Thanks for the help lads

[meritlover]

iam glad you found happiness in your solution

[mowgli]

the clock will hardly draw any current at all, so it shouldn't flatten anything

[mk3 vinny]

well the clock wasn't ticking and it was drawing 12v+ as well so left it off for now as its probs broken anyway.

[meritlover]

\

A new battery might help, but it'll be worth you checking for any voltage drain. Remove the +ve battery lead, and put a volt meter between it & the +ve terminal & see if there is any reading.

I think you mean current drain? i have seen several confusing references to this in this post "voltage drain/drop"

the impedance of a volt meter is so high that you will never pull enough current through it to find any fault or have any meaningful readings, only that you have enough continuity to show a 12v potential between each end of your circuit. this does not help you in your quest for your 'drain'

Your meter should be on 'Amps' if you are doing this. You measure current in series. if you were looking for voltage drop you would have to measure across the battery posts with the leads connected as normal. but looking for a voltage drop on a 300+Amp battery you will struggle or you will have lots of smoke and fire where your short is (although this will make it easy to find)

take your battery to a garage and have them test it.

[meritlover]

in fact, if you can measure the current which is being pulled, you will be able to calculate how long the battery will last if you find out the Ahrs of the battery.

for example, a common petrol Nova 063 battery has a CCA of 420Amps (which is the amount of current it can deliver in one 'burst' of the starter. Not helpful in this case, but if you had a significant short you would have enough energy to cause a nice fire (approx 5KW of fire!) This figure doesnt tell us how long it can it can deliver that 5KW so its pretty much useless in this case. But this is why we get scared and run away when we short our jump leads together.

What is interesting is the fact Ah or Amp hours of the battery. which is a measure of how long it takes to discharge on a fixed load. this tells us the capacity.

The 063 has a 45 Ah.

this would mean the battery would be flat in one hour if it had a 45A drain on it or conversely, 45 hours at a one amp drain. This will not take into account the internal resistance of the battery its self, so the figures are only approximate but it should be an indication on whether the load your pulling is enough to flatten your battery in the time you mention, or whether it is the batter that is beyond its life.

enjoy your Thursday.

[mowgli]

ML, i stand corrected and i thank you.

i used the term because most people trying to work out car electrics from a beginners standpoint don't need the added confusion of current drain, ampage & ohms. i refered to 'voltage' because using a volt-meter to look for volts is IMO the easiest way to find a short or failed circuit, as it give a roughish guide to the current drawn. ie 6v shown means there is a slight 'leak' with a high resistance, whereas 12.8v would mean there is a short, and asking people to check for a voltage is a quick way of determining a fault. on our equipment, we regularly start off with a test lamp before even resorting to a multi-meter

and just imagine the fun you can have trying to get people to understand a drop test....lol (you put a discharge tester across it)

[meritlover]

i know, but telling a beginner to measure voltage in series will cause more confusion. and result in pointless and meaningless readings

my point is, that looking for a voltage drop on a 400Amp battery would be looking for too small a change to notice anything of any relevance.

Battery voltage only drops about 1-3v even when cranking! let alone a small resistive load on a 0.75mm wire somewhere.

current is the only way to go. Then you go across the points on the circuit to earth until you find where the fault is. you would have to work out whether you have a failed component (clock for example) that's pulling too much current, or a fault to earth (which would normally just pop fuses)

a 'drop/load test' measures the voltage drop ACROSS the high resistive load of the tester to measure the cranking capacity of battery.

[mk3 vinny]

thanks meritlover i will keep your info for the future as the stuff i done has sorted the problem for now

thanks again vinny