Chasing a Current Leak

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Al2O3

Al2O3

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The Landy stood for a week, over Christmas, and when we came to start it the battery was flat. It's a new 105Ah unit. First thought was alternator. Felt it through the week and couldn't detect any warmth. Checked it yesterday with the multimeter and when I disconnected the supply to the alternator the draw on the meter didn't change. The draw is 110-120mA, my meter is flickering around a bit - don't know if that is normal.
Last night it dawned on me that the Landy stood for a week immediately after the Santa Sleigh pull. We had even more lights this year (largely LED) and the usual stereo/amplifier all fed through an inverter connected to my battery. The sleigh pull takes about 5 hours and I suspect the current draw was more than the alternator was putting back! Then the Landy stood with a potentially depleted battery. Thought I'd do a bit of investigation anyway as 110-120mA is still too high. My tracker info says it uses 55mA when it's fully charged and under standard, dormant conditions. I've googled a clock to be about 10mA and a radio possibly 20mA, so approx 85mA to be expected, largely due to the tracker. So, I'm about 25-35mA over expected.
So pulling fuses today, fuse 2 out and it dropped to 49mA and the tracker sent me a text to say it's mains supply had been cut. No other fuse affected the meter :confused: Fuse 7, the radio fuse, did nothing. I've got a Sony radio in, so maybe it doesn't use anything when not actually on. Which fuse is the clock on, perhaps 2 or 3? I'm not sure from the symbols on the cover and it doesn't mention the clock in the fuse section of my handbook o_O
Any of you electrical chaps point me as to where to look next? Big fuses in engine bay? What fuse is the clock on? I've searched LZ, but it's not easy to find anything relevant.
This is a pic of my fuse cover
P1040356.JPG
 
Firstly the “flickering around” is normal because you’re using a digital multi meter, an analogue meter is better for auto electric testing your doing.
While you were pulling the sleigh around the alternator didn’t provided sufficient current, l assume vehicle lighting was on fully the engine was stopped/started a few times hence a flat battery.

25-35mA over what u expect is nothing to a fully charged battery, as for pulling fuses any fuse that are on an ignition controlled circuit will be off when the key is removed, so I expect that leaves only a few circuit alive 24/7 security being one of them.
A leaking alternator is another which will flatten or at lease drop the battery voltage down making starting impossible.
So start with fully charging the battery with a battery charger for 24-48 hours and check the day after.
 
discool said:
Firstly the “flickering around” is normal because you’re using a digital multi meter, an analogue meter is better for auto electric testing your doing.
While you were pulling the sleigh around the alternator didn’t provided sufficient current, l assume vehicle lighting was on fully the engine was stopped/started a few times hence a flat battery.
Click to expand...
Thanks for confirming the multimeter is ok :)
Yeah, the Landy headlights were on too, forgot about those. It wasn't stop/started that often, but didn't do much more than ticking over for most of the time.

discool said:
25-35mA over what u expect is nothing to a fully charged battery, as for pulling fuses any fuse that are on an ignition controlled circuit will be off when the key is removed, so I expect that leaves only a few circuit alive 24/7 security being one of them.
A leaking alternator is another which will flatten or at lease drop the battery voltage down making starting impossible.
So start with fully charging the battery with a battery charger for 24-48 hours and check the day after.
Click to expand...
Yeah, fully charged the battery mid week. According to my handbook fuse 20 is the alarm, but it did not affect the current on the meter.
Made no difference disconnecting the alternator to the current draw, so I reckon the alternator must be ok.
I've identified that the tracker is on fuse 2. No idea where the other current is being used from or what is drawing it?
 
It would be interesting to see if the current draw matches the spec supplied with your tracker.
Your radio has a switched live but also a permanent live to retain its memory some mobile phone kits are the same. There isn’t much that isn’t on a switched circuit ignition or otherwise, radio/security/mobile phone kit are the only items that have an additional permanent live on my disco.
 
discool said:
It would be interesting to see if the current draw matches the spec supplied with your tracker.
Your radio has a switched live but also a permanent live to retain its memory some mobile phone kits are the same. There isn’t much that isn’t on a switched circuit ignition or otherwise, radio/security/mobile phone kit are the only items that have an additional permanent live on my disco.
Click to expand...
When I pulled fuse 2 the leak dropped to 49ish mA, so about 60mA vanished when the tracker was disconnected, that's sounds about right.
Do you have any idea, from the symbols on my fuse cover, which circuit the clock is on?
So, I have a mysterious 50mA going somewhere. It's not the end of the world as my battery should last 36 days with a 120mA draw on it, if my calculations are correct! It would be good to know where it is going though. :)
 
discool said:
Sorry no idea at all, it wouldn’t be the one for lighting or heater but the fuel gauge or the radio looks interesting, pull each one until the clock stops I believe that’s the way to find out. :)
Click to expand...
Yeah, I know, but I couldn't be bothered to wait last weekend :rolleyes::oops: If no one knows I'll have to do that this weekend. :):)

Another thing for anyone reading this. If I disconnect the battery, or I think it was on fuse 2, I could hear what sounded like a motor whirring from behind the fuse box area. It only whirrs for a few moments then stops. Put the fuse back in or reconnect the battery and it whirrs for a few moments again, as though it's going back in to it's correct position. Does anyone know what this is? Can't remember anything motorised in there from doing the rebuild. (1996 300Tdi 90)
 
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I've just been away for a week and the Landy wouldn't start this morning. This was following be used as a daily drive to work. Parked up on the drive last Friday, so 8 days later there was just enough current left to very slowly turn the engine over.
First off, am I doing something wrong with my calculations?
Current draw 120mA
105Ah battery
105÷0.12 = 875 (hours)
875÷24 = 36.4 days but mine is not lasting 8 days.

I wonder if I'm reading the meter correctly! ie not reading the digital display appropriately to the setting :rolleyes:
EDIT
I've just been out and checked it again and the settings on the meter. On the 10A setting I'm getting 0.12, on average. It flickers between 0.1 and 0.13, but more often 0.12 is showing. So, I reckon my using 120mA is correct.

I wonder if my alternator is carped? Only charging a small amount, just enough to keep it going when it's being used on a daily basis?
 
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Assuming a current draw of 0.13 amp (using your higher figure) then over 8 days that would equate to about 25 amphr.

Whilst the capacity of the battery maybe 105 amphr as the battery is discharged the voltage on the battery will decrease.
A fully charged 12v vehicle battery will have a voltage of about 12.6-12.7 volts
At 50% discharge the battery voltage will be down to 12.0-12.1 volts and will start to struggle with starting a diesel engine.

Now if the battery was only 75% charged when you parked it up that would explain things. With a 100% charged healthy battery I would expect about 16 days parked up with that current draw before battery started to struggle to start your engine.

HTH


Brendan
 
Might be worth checking the resting voltage of the battery which should be about 12.6-12.7 volts. Then measure it with engine running voltage from alternator should be about 14.6 volts.


Brendan
 
leeds said:
Might be worth checking the resting voltage of the battery which should be about 12.6-12.7 volts. Then measure it with engine running voltage from alternator should be about 14.6 volts.


Brendan
Click to expand...
Cheers, Brendan. That's interesting and might explain things. I presume you think my alternator is up the creek. It would be fair enough I reckon as I suspect it's the original one and it's a 1996 vehicle :eek:
I'll check the charging voltage at the battery tomorrow.
Cheers.
 
If it is the original alternator then it has done well. We have a 1996 110 and we upgraded the alternator to a 120 amp(?) alternator about 05 in readiness for some big trips. In 2017 it failed and the replacement one last 6 months before we had to change it in Denmark! Not a happy bunny about that.


Brendan
 
leeds said:
If it is the original alternator then it has done well. We have a 1996 110 and we upgraded the alternator to a 120 amp(?) alternator about 05 in readiness for some big trips. In 2017 it failed and the replacement one last 6 months before we had to change it in Denmark! Not a happy bunny about that.


Brendan
Click to expand...
I've just been looking on Paddocks and ebay in preparation for replacing it. What make would you recommend?
 
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Gmacz said:
Did you put multimeter on battery for voltage and then start it up and see if it goes much higher.
Click to expand...
Just done that as I got in from work.
Engine off = 12.98v
Tick over = 13.97v
Engine revving = 13.88v

Does that mean I've got a carped alternator?
 
With those figures of be looking at a voltage drop between your alternator and the battery terminal. Have you checked all connections are clean and tight? Might be staying the obvious but make sure nobody had used silicone grease on the battery terminals, as that doesn't conduct
 
That's what I would do too, clean everything, I would also suspect the battery but not before I cleaned all the terminals , earths and live connections.
 
Try starting it with the meter attached to the battery, you can then see what the battery is doing under a starting load.
 
I would have expected a charging voltage of over 14 volts. Officially the old Lucas 17ACR alternators were deemed ok if they produced 13.8 - 14.5 volts when all loads were switched on.

(Leastways thats what my memory says from when I briefly worked as an Auto-electrician 35 years ago. )
 
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