Battery drain - cause?

[Petrol Pete]

I blew the 'big' fuse in one of my Fluke meters a while back, I did not even know it happened or when. I just picked the meter up one day and the fuse had popped. ?? Had to order a replacement fuse from Fluke online.

 

[Bellow]

Can you post a picture showing the meter "connected across the battery terminals" and the meter settings and display?

No! Just no!

 

[Bellow]

I blew the 'big' fuse in one of my Fluke meters a while back, I did not even know it happened or when. I just picked the meter up one day and the fuse had popped. ?? Had to order a replacement fuse from Fluke online.

Kinda the same thing here. Not sure if I've just blown them or they were blown some time ago. Probably on this endeavour as I don't really recall using it as an ammeter before.
It was still working as an ammeter though. And the readings were commensurate with the drain that drags the battery down - providing I observed polarity. Wonder if its sensitivity to that will be eliminated with new fuses. Hope so as otherwise it's easy to get a zero reading with current present.

 

[Petrol Pete]

Kinda the same thing here. Not sure if I've just blown them or they were blown some time ago. Probably on this endeavour as I don't really recall using it as an ammeter before.
It was still working as an ammeter though. And the readings were commensurate with the drain that drags the battery down - providing I observed polarity. Wonder if its sensitivity to that will be eliminated with new fuses. Hope so as otherwise it's easy to get a zero reading with current present.

In my game I normally use an clamp meter when testing for current- or (in a tight spot) the smaller clamp attachment that plugs into a fluke , I don't ever remember testing for current with the leads , so my blown fuse remains a mystery .

 

[Bellow]

Connect the meter in series from the earth. Lock the car and push the door catches over. What measurement do you get after 15 mins?

The measurement I get is 15.2 on the 200mA scale. I take that to be 15.2mA (On the 10A scale I'm seeing 0.02 which I take to be 15.2mA rounded up to 20mA). Am I reading this correctly?

Because, if I am, then there's barely enough current there to flatten a battery. And the battery after a week disconnected will start the engine easily. Even when a few attempts (fuelling issue) are required.

On connecting the battery I still see a tickle of a spark and whiff of smoke. When I first connect the MM on the 200mA scale, first the meter is overloaded for a second, then briefly shows 80, settled to circa 45 for a few seconds then displays 15.2 for as long as it is connected.
The only thing on the car that I know for certain that is energised immediately on connection is a stepper motor (LPG actuator) which assumes its default position then rests. However, to avoid it interfering with the readings I've disconnected it.

The only deviation from the suggested test is that I forgot to lock the driver's door. Re-doing the test now with the door locked via CL.

 

[BlackC55]

The reading should be 0.06A (6mA) or less Anything more is excessive drain. Use the 10A scale. Can you show me what meter you have? When you lock it make sure you touch the positive terminal on with the meter leads connected. Then when its locked take the terminal off.

 

[pmcgsmurf]

The reading should be 0.06A (6mA)..............

Just for clarity as it may be important there is 1000mA in an Amp so 6mA would actually show on a meter as 0.006

 

[BlackC55]

Sorry, Slip of the fingers.

 

[Ted]

That looks like you are reading it correctly.
you are also correct in saying that that level of discharge is imho insignificant. It would take weeks to run the battery down at that rate.
The spark and larger current draw when connecting will be a surge current - despite there being few electronics on your car, there will be a surge as several circuits become live and effectively ‘charge up’. I would expect it on most cars (except a 1965 Morris Minor or similar) and not worry about it.
But that doesn’t help to answer your problem.
The battery holds up well when disconnected.
That suggests that the fault lies elsewhere, but I would still get it load tested just to be 100% sure it’s ok.
15mA isn’t going to flatten the battery in a month let alone a week, so it’s either not 15mA or the is another greater load coming in when you aren’t monitoring. This could be constant (after say an hour) or at regular/intermittent intervals. For that, if you can, leave the meter in circuit and monitor it when you get a chance to see if the current increases.
Basically, a good battery won’t go flat in a week with a 15mA draw.
the corollary applies. A 15mA draw won’t flatten a good battery in a week.
Even with the original measurement of 0.26 amps a quick calc suggests that it would lose 6AH a day - 42AH a week, so half discharge a fully charged 8AH battery in a week.
So my guess is either the battery isn’t performing anywhere near spec, or the current is higher than measured. in the long term.

 

[Bellow]

Ted, everything you say is on the button.
I did a recalc and with a 70Ah battery it would take almost half an Amp to drag it down over a week - but as we've covered, disconnected the battery does hold out. Load testing I don't think is an option for now (I don't have the tester and the local garages are closed) but I'd prefer to have that checked.
Not sure if what I did previously with the Fluke has any relevance (blown fuses) so pretty much starting from scratch again I think.
I have found two fuses that when removed affect the current (and have a cumulative effect when removed together). I also saw - or might have - seen the same with some other fuses. But, by then, I was reading from the 10A scale where 15.2mA rounds up to 0.02A and watching it flicker between 0.02 and 0.01 (fuse removal) isn't as convincing as it needs to be to identify a particular circuit.

Going to be more careful today in getting measurements (avoiding 200mA scale) and if the fuses mentioned are actually showing the variance I saw on the 200mA scale then some pointers as to which components to look at. For that, the forum that deals with these trucks is being really helpful. There are more electronic 'modules' than I'm happy with and also the possibility of coinciding problems eg erratic starting on petrol and one of the aforementioned fuses being there to protect the fuel pump relay. It's lucky I'm an obstinate SOB!

 

[Bellow]

The reading should be 0.06A (6mA) or less Anything more is excessive drain. Use the 10A scale. Can you show me what meter you have? When you lock it make sure you touch the positive terminal on with the meter leads connected. Then when its locked take the terminal off.

If I've understood that correctly, that removes the 'spike' that blows fuses on the 200mA scale? So 200mA scale is usable with that precaution - if I can fine a fuse for it....

 

[Bellow]

A little bit done today but as confusing as ever.
First up. a couple (or three) pics of the Fluke showing what it always shows and without its two fuses. Looks like 0.26A to me. Correct?
Worth noting perhaps that with the red lead on the battery terminal and the black on the lead, the reading shows a -ve value. Swap leads and nothing shows.

Next is the cheapo meter.
Here we can see it (I think) showing 0.01A (10mA). Earlier it showed 0.02 but fluctuated between the two. It will also fluctuate between 0.01A and zero - especially when removing two fuses (independently). The Fluke varies by 2mA doing the same. On refitting one of the fuses though, the cheapo will show 3.23A and will hold that value for some 20s or so before defaulting back to 0.01A Not everytime though - sometimes it remains at 0.01A on refitting the fuse. (That fuse, I think is a master fuse for the fuse box).

The only other observation is that early on when I first connected the battery (as per Black C55's instructions) I heard clicking which sounded like a CL solenoid.

What I'm asking in this thread is verification of my readings and comment as to whether the Fluke - given its behaviour and lack of fuses - should be disregarded for now?
TIA.

 

[pmcgsmurf]

Are you trying to use the Fluke without the fuses fitted, haven't you replaced these?

 

[Bellow]

Are you trying to use the Fluke without the fuses fitted, haven't you replaced these?

They are still in China - or somewhere between here and there. Hence the £6 cheapo.
By your comment, I take it that I need to put the Fluke back in its box until the fuses arrive.

 

[pmcgsmurf]

They are still in China - or somewhere between here and there. Hence the £6 cheapo.
By your comment, I take it that I need to put the Fluke back in its box until the fuses arrive.

Yes, won't work without the fuses, I'd have went with RS or Farnell to get them here asap.

 

[Bellow]

OK, Fluke readings are irrelevant and probably were from the get go.
I'v'e also blown a fuse in the cheapo meter - but fortunately that still leaves the unfused 10A scale working - if not particularly sensitively.

Thinking about the battery (in the absence of a meaningful load test) it maintained charge for three weeks and flattened after multiple engine starts without the alternator (belt off) and probably some drain when I explored (as you do with a new motor) all the switches and what they do. That doesn't IMO condemn a battery.
The next flattening after one week - could I have inadvertently left something switched on? Subsequently I have been disconnecting it and it fires the motor up after a week without any difficulty.

Plan now is going to look for drain with cheapo meter on 10A scale (factoring in the inevitable surge current on connection) and if nothing concrete there, next week I will leave the battery connected for the week and see what gives. The 10-20mA it displayed (as per Black C55's test) for hours on end isn't surely a battery killer (and can possibly be eliminated - see below).

There is though I think a problem with the fuel pump circuitery as starting on petrol is erratic and the fuse for that is the one that shifts the current reading with the cheapo MM (NB I'm completely disregarding all previous Fluke readings). There is weirdish arrangement where if the fuel pump relay is defective it will start by energising the fuel pump via the oil pressure sender (Yanks do things differently it seems). Obviously, that takes a bit more cranking (my symptom) and if I change back to petrol from LPG on the hoof (with plenty oil pressure) it runs faultlessly. When I do the same when it is idling, the motor sometimes stumbles and quits - the delay between not being fuelled by the pump relay and defaulting to oil pressure signal? It will restart quite easily in that situation though.

 

[Ted]

I would tend to agree with what you have said.
the Fluke results aren’t trustworthy right now.
the battery seems to have a reasonable amount of capacity - it certainly doesn’t sound like it’s completely buggered.
10-20mA isn’t going to flatten it in a week.
Time to monitor any discharge over a period of a few days.

 

[Bellow]

I would tend to agree with what you have said.
the Fluke results aren’t trustworthy right now.
the battery seems to have a reasonable amount of capacity - it certainly doesn’t sound like it’s completely buggered.
10-20mA isn’t going to flatten it in a week.
Time to monitor any discharge over a period of a few days.

Thanks Ted - and apologies for late reply - missed your post yesterday.
It sat for hours yesterday at 10-20mA so next week I will leave the battery connected and see what happens. Very possibly I ran it down the second time without noticing.
I feel so stupid for getting led astray by false readings from the Fluke but at least you have straightened me out on that - cheers! Ditto the surge current - now I see it drop away to 10-20mA. We live, we learn.

 

[Bellow]

I would tend to agree with what you have said.
the Fluke results aren’t trustworthy right now.
the battery seems to have a reasonable amount of capacity - it certainly doesn’t sound like it’s completely buggered.
10-20mA isn’t going to flatten it in a week.
Time to monitor any discharge over a period of a few days.

If I'd only known all of that a week or so back!
Yep, no drain problem but a problem reading (and believing) erroneous readings from a meter with blown fuses.
Two tips then to anyone with a battery drain problem that I have learned during this.
1) Disregard the initial current spike on connection. It is as Ted says, circuits waking up and will very quickly stabilise.
2) Use a cheap MM. Because they are easily damaged and don't give erroneous readings when the fuse protecting the 200mA scale blows and the unfused 10A scale is safe and reliable.

Fired up the motor this morning effortlessly after being sat since Saturday with the battery connected to the truck continually during that period. Problem what problem?
Thanks to everyone's help here - particularly the advice re MMs. Hopefully, the above can prevent anyone else from making the same mistakes as I did and wasting a pile of time.

 

[Ted]

Glad it sounds like it’s sorted.
I also keep a cheap voltmeter that plugs into the fag lighter socket permanently plugged in to both of my vehicles. One is very accurate as measured against my Fluke, the other is about 0.1-0.2V low but good enough.
They tell me if/how much the battery has discharged when left for a long time, a good indication of charge voltage, and when the smart charging is kicking in - a useful indication of battery state of charge/state of health. Asa bonus, you get a couple of usb charge points where the display changes tocurrent draw if used.
They are around a tenner, often less on Ebay, but make sure that you check them against a known good voltmeter first so that you know how ‘off’ they are.