Battery drain - cause?

[Bellow]

Battery on my recently acquired truck goes flat after a week of sitting and hasn't enough juice to crank the motor into life. I don't know if the battery is good or not as yet but, there's reason to believe it is only a couple of years old and, there's a tickle of spark on connecting at the terminals.

Put a multimeter on it and its reading 0.26A which seems a bit high. It equates (at 12V) to 3Watts.
Pulled the fuses one by one and it never moved. Strangely, it didn't make any difference door open or closed and with the door open, the interior lights didn't come on. I'd disconnected the engine bay lamp. Ignition key was removed during the above so no circuits it switches were enabled.

It's an old (1999) truck with a limited amount of electronics. No alarm/immobiliser - remote central locking is a sophisticated as it gets.

Just wondering where to look next - or is 0.26A static draw OK and my battery is goosed? What's the most likely cause of a static drain?

 

[AMGeed]

A drain of up to 65mA is considered acceptable. You have a drain far higher.
What is the voltage reading at rest with the multimeter?
Your battery is already 50% discharged if its reading 12.0v. Fully charged it should be 12.7v.

I'd try and fully charge the battery (6 Amps for 24hrs) and see if the battery is the cause rather than the drain although a reading of 0.26A is very high.

 

[Bellow]

The battery (on the cars Voltmeter) is low (I can check against another Voltmeter though) but when running shows 14V - so there is some doubt about its health. When I charge it (I have no control over charge rate) the charger shows an initial draw of around 2A. Drops a bit after about 8 hours of that and then spins the engine over easily.

0.26A (3W!) I think is too high and I'm not in the humour to replace the battery to find the drain still causing a problem. On a forum that is for these trucks I've been told to disconnect the +ve lead from the alternator - but not why. Maybe it isolates an alternator fault. The alternator does charge. 14V on start up and no problem driving - only when it has sat a week. (I'll calculate the 0.26A into battery's A/hr rating later to check time scale).
Another guy on the forum has the same with his truck so maybe there is a common problem on them (that is alt related). Getting info from that forum is hampered by the time zone difference as mainly American posters.

 

[mersum1es]

voltage regulator diodes can be faulty and cause the drain - alternator still charging

Because drain is present even all fuses pulled, it must be something not behind fuse, in addition to voltage regulator, breather hose may have heater which is not fused in MB, dunno your truck

 

[markjay]

The battery (on the cars Voltmeter) is low (I can check against another Voltmeter though) but when running shows 14V - so there is some doubt about its health...

If you get a reading of 14V when measuring the voltage with the engine running, that means that your alternator (and voltage regulator) are probably fine.

The condition of the battery is still unknown, but given the execcive current draw then we can safely assume that this is the culprit, rather than the battery.

The only way to deal with this I think is to connect the ammeter and then pull out fuses and relayes one at a time, to see which circuit is causing the execcive current draw, then take it from there.

If nothing can be found and isolated, one way around it would be to fit a battery isolator and disconnect the battery while the car is parked overnight. Not ideal, but I had this fitted on two cars before (a 1998 Toyota and a 1992 Honda, so no fancy electronics) and it does do the job.

 

[grober]

As previously stated you need to look at electrical components with direct connection [unfused]to the battery live- these tend to be very high current devices such as the alternator or starter. Most likely cause would be one or more of the rectifier diodes on the alternator-these are big components and separate from the smaller voltage regulator/brush asssembly which is easily replaced. The best way to test for alternator drain is to disconnect the big live cable from the battery at the alternator [carefully!] and then test for drain hence the advice

 

[Flyinspanner]

Check the date stamped on battery terminals (usually).

More than 5 yrs - ditch it and buy a new one. (They can suffer internal drains if plates fracture/buckle) I had an intermittent battery drain on a 9month old battery.... went through all the following (at some cost) before I went back to square 1 and eliminated the core

Use your phone on video to check things like boot light/glovebox light go off when shut.

Think about systems which may still be available - cigarette lighter/ power outlet/ aftermarket radio install - which may have damaged socket/wire pinched.

Just before this started, had any work been done on a particular area?
Recheck.

To check for drain, it can be better to use a clamp meter. On its lowest milliamperes range, clamp over the battery cable and then don’t move clamp.

You leave the car for 15mins to let all subsystems shut down. Check drain level.
If high, start pulling fuses 1 by 1.

If no joy disconnect alternator. - see if drain goes, if yes the diode pack.

Hope you track it down - annoying as many places where you could get alternator checked are currently shut

 

[Bellow]

Thanks everyone for replies.

Check the date stamped on battery terminals (usually).

More than 5 yrs - ditch it and buy a new one. (They can suffer internal drains if plates fracture/buckle) I had an intermittent battery drain on a 9month old battery.... went through all the following (at some cost) before I went back to square 1 and eliminated the core

I think the battery is only 2 years old. Engine off voltage is 12.0.

Possibly I have two problems - battery and drain. Definitely a drain problem! So, next on the list....

As previously stated you need to look at electrical components with direct connection [unfused]to the battery live- these tend to be very high current devices such as the alternator or starter. Most likely cause would be one or more of the rectifier diodes on the alternator-these are big components and separate from the smaller voltage regulator/brush asssembly which is easily replaced. The best way to test for alternator drain is to disconnect the big live cable from the battery at the alternator [carefully!] and then test for drain hence the advice

.....is the alternator. And if nothing amiss there....

Think about systems which may still be available - cigarette lighter/ power outlet/ aftermarket radio install - which may have damaged socket/wire pinched.

..... then the above.

After checking the alternator I'll probably disconnect the battery and leave it for a week. If it hasn't flattened in a week (like it has twice over already) I'll assume it's fine.

 

[Bellow]

A bit more....
Car has sat with battery disconnected since Saturday and with a Fluke multimeter is showing 12.4V (the plug in one in the ciggy socket shows 11.9V) on its posts.

Disconnecting the only sizeable lead I could find on the alternator makes no difference to the current draw. None whatsoever - so I think that rules out the alternator as a cause.
Current draw is ever present - ie with everything that could be energised by the ignition key not. Next on my mind to check (as suggested) is starter motor cable. What might I expect to find? Conductive dirt permitting a path to earth? There's not much more that isn't switched via the ignition key to check. Three ciggy lighters in the front (maybe another two further back) and the interior lights (working fine). All fused circuits have been checked - fuses pulled one by one. Any further suggestions anyone? At what current does a fire hazard materialise? Is 3 Watts enough to create heat?

 

[Ted]

Has it got a boot/boot light - put a phone in recording a video to see if it is stuck on.
3 watts is enough to create heat if it is over a very small area - think dash (or boot) bulb. Over a bigger area much less so.
I think you are going to need to pull fuses to find out which circuit is causing it.
Here’s a trick - disconnect the battery and put a 5 watt test light in series. If you have a 3 watt drain you will see it glowing around 1/4 of its brightness but still easy enough to see. then go round pulling fuses/disconnecting circuits until it goes out.
beware of interior lights (door open) etc, as with that low current drain just about anything else that draws current will put the lamp on full brightness.

 

[Bellow]

Has it got a boot/boot light - put a phone in recording a video to see if it is stuck on.
3 watts is enough to create heat if it is over a very small area - think dash (or boot) bulb. Over a bigger area much less so.
I think you are going to need to pull fuses to find out which circuit is causing it.
Here’s a trick - disconnect the battery and put a 5 watt test light in series. If you have a 3 watt drain you will see it glowing around 1/4 of its brightness but still easy enough to see. then go round pulling fuses/disconnecting circuits until it goes out.
beware of interior lights (door open) etc, as with that low current drain just about anything else that draws current will put the lamp on full brightness.

Done the fuse thing - nothing changed. It is an estate type body so all interior lights are visible with the doors closed and none are staying on. I don't understand though why the lights don't come on when the MM is wired in series - does the MM limit the current to them?

Bulb analogy is where my thinking was too. Further, if I have a short (or the start of one) and it worsens.....
All I can think of to check is the aux/ciggy lighter sockets and starter cable. Everything else is through the key - AFAIK at least.

While I'm hear with the ear of someone who gets 'sparks'..... Remember the plug into the ciggy lighter voltmeters someone posted a link to on this forum some time ago? How low do they read? Right down to below 1V? Or would I be better looking elsewhere for what I have in mind - if what I have in mind is feasible.
I want to be able to (temporarily) read voltages from the TPS and O2 sensor(s). 0-4.6V for the TPS, 0-1.0V for the O2 sensor and simultaneously. The display (size and brightness) of the plug in voltmeters would be spot on. Can I get the 'heads' of them (without the plug part) elsewhere to wire in parallel with the TPS and O2 sensors - and will that work without skewing outputs read elsewhere. (The car already taps them for the LPG system but (as yet - researching it) I don't know if they are paralleled or switched between LPG and petrol ECUs). Any ideas for two temporary self contained voltmeters and if they will work as proposed?

 

[Ted]

First of all, don’t use a mm - use a testlight. The impedance of your mm will be hugely too high to pass any current when volts are selected - that’s why a dvm is great at measuring volts!
Let me ponder the rest of your post - brb.

edit:
Right. I have a couple of the plug in voltmeters. The first was very accurate as against my Fluke, but the second is 0.3 volts adrift. Too much for me to trust it. Also they flash to alert you if the voltage goes above around 14.5 or below 11.5. I also wouldn’t trust them on lower voltages. Plus don’t forget that there will also be a voltage drop in the overall cabling from the battery if current is being drawn. This doesn’t have to be in just the fag lighter circuit but the main feeds from the battery, which the fag lighter takes its supply from will have a drop. My advice is to use the quality dvm for what you are attempting (not the parasitic drain!)

 

[190]

Car has sat with battery disconnected since Saturday and with a Fluke multimeter is showing 12.4V

It depends where the voltage started but a fall to 12.4 volts from fully charged in a few days is bad because it shouldn't have lost even 0.1 volts. From a fully charged and rested 12.7 volts it would represent something like 30% discharge of the batteries capacity. On that basis it would be flat in a week.

For a comparison my 10 year old battery wouldn't lose more than 0.05 volts on the same test.

If it did start fully charged and disconnected then the battery is knackered.

 

[Bellow]

First of all, don’t use a mm - use a testlight. The impedance of your mm will be hugely too high to pass any current when volts are selected - that’s why a dvm is great at measuring volts!
Let me ponder the rest of your post - brb.

You've lost me Ted.
For the drain problem, I have the MM in series and set to read Amps. Why would volts be selected?
What is a dvm? (Google suggests I need a vet - I don't!)

edit:
Right. I have a couple of the plug in voltmeters. The first was very accurate as against my Fluke, but the second is 0.3 volts adrift. Too much for me to trust it. Also they flash to alert you if the voltage goes above around 14.5 or below 11.5. I also wouldn’t trust them on lower voltages. Plus don’t forget that there will also be a voltage drop in the overall cabling from the battery if current is being drawn. This doesn’t have to be in just the fag lighter circuit but the main feeds from the battery, which the fag lighter takes its supply from will have a drop. My advice is to use the quality dvm for what you are attempting (not the parasitic drain!)

The actual value isn't necessarily super critical as 1) I can correlate it to the TPS and O2 sensor outputs as they are read by the LPG ECU when displayed on a lap top, 2) movement more than actual values are what I'm looking for. The lap top will do this but a couple of small gauges stuck to the base of the windscreen would be a lot easier and safer to read. And without having to be switched off to preserve batteries, they can be on as long as the ignition is. Maybe a browse of RS Components' catalogue for something suitable?

Double checked all interior and vanity lights - all switching off as they should - but for the one that isn't working that I mention just in case it can be influencing things. When the lights extinguish, there's the 'click' of a relay that can be heard.

 

[Bellow]

It depends where the voltage started but a fall to 12.4 volts from fully charged in a few days is bad because it shouldn't have lost even 0.1 volts. From a fully charged and rested 12.7 volts it would represent something like 30% discharge of the batteries capacity. On that basis it would be flat in a week.

For a comparison my 10 year old battery wouldn't lose more than 0.05 volts on the same test.

If it did start fully charged and disconnected then the battery is knackered.

You may well be right and if I leave it disconnected until Saturday the answer will be known. It has been draining down over the course of a week when left connected. However, there is the parasitic drain problem that needs sorting so I definitely have one problem - maybe two!

 

[Ted]

Ah - my bad. I thought you might have it set on the volt range as you said the lights don’t come on when wired in series. If current range is selected there should be no resistance to current flow - although there might be a current limiter set if the current exceeds the maximum for the range. Mine blows an internal hrc fuse.
DVM = digital voltmeter. For e of habit, more accurately called a dmm these days.

 

[Bellow]

Ah - my bad. I thought you might have it set on the volt range as you said the lights don’t come on when wired in series. If current range is selected there should be no resistance to current flow - although there might be a current limiter set if the current exceeds the maximum for the range. Mine blows an internal hrc fuse.
DVM = digital voltmeter. For e of habit, more accurately called a dmm these days.

So the interior lights (8 bulbs in total) should have illuminated (with the MM on Amps) - yes?
With the MM set as above, opening and closing the door doesn't show on the MM. Opening the door should energise the lights (even if it doesn't illiterate them) and show a current and closing the door (after a time delay) should de-energise and show as a reduced current on the MM. Why isn't this happening?

 

[Ted]

Yes they should. assume 8 lights = 40 watts = 3.5 amps approx (assuming 5 watt incandescent bulbs)
So assuming you are on the correct range, you should read around that and the lights should be on.
Anything else and I would bechecking the internal fuse in the meter.

 

[Bellow]

Yes they should. assume 8 lights = 40 watts = 3.5 amps approx (assuming 5 watt incandescent bulbs)
So assuming you are on the correct range, you should read around that and the lights should be on.
Anything else and I would bechecking the internal fuse in the meter.

Something strange then that the interior lights show no sign of illuminating - not a flicker - with the MM in series or register on it as a current. When I disconnect the MM and reconnect the terminal and post - the interior lights work as they should (but for one).

 

[Ted]

Then definitely the mm. I would open it up and check if the internal fuse is ok.