Hiya If you hold the -ve wire, and the +ve wire on the meter when on Volts, the reading will jump around with similar readings due to the electrical field from mains circuits, high voltage wires etc in the area. Bear in mind the length of wire in a car, this will even pick up radio waves etc. Think of it as the transformer effect. (And look up 'Crystal Radio' on the web - you can make a radio which does not need batteries using the same principle - Maplins do a kit for £6)
The meter may not be calibrated to read exactly zero either - a tolerance of 0.1% is considered good for a home meter. As Jim says - this is normal, and likely to be a red herring. Best regards James T On 24 May, 22:47, "Susan and Martin Scott" <[email protected]> wrote: > No radio, and the alarm fuses are removed - are there capacitors elsewhere > (maybe the suppresor on the alternator) which could cause this effect? > Martin > > > > ----- Original Message ----- > From: Jim Hearne > To: [email protected] > Sent: Monday, May 24, 2010 10:35 PM > Subject: Re: [Quantum Owners] Battery drain > > The voltage you are seeing is tiny. > It will be coming from the capacitors in the radio and alarm that were > charged when the battery was connected. > voltage from those will be leaking back through the circuitry and seen by > the meter. > Because the route through the various components is high resistance it > drops as the meter loads it up then recovers from the capacitors when you > remove the load. > Don't worry about it, it's normal. > > Jim > > On 24/05/2010 22:32, Susan and Martin Scott wrote: > I'll try putting the ammeter in circuit tomorrow. What i can't understand > is why there is a voltage without the battery connected? > Martin > ----- Original Message ----- > From: Jim Hearne > To: [email protected] > Sent: Monday, May 24, 2010 10:23 PM > Subject: Re: [Quantum Owners] Battery drain > > At the others have said, you need to measure the current drain from the > battery by removing one battery lead and connecting the meter between that > and the removed wire. > Do not even turn on the ignition. > A typical current drain with a car radio and alarm will be below 20ma > (0.02a), anything over 50ma indicates a problem and will flatten the battery. > Isolate the problem circuit by removing fuses until the current drain > disappears. > > Jim > > On 24/05/2010 21:53, Susan and Martin Scott wrote: > Sorry I forgot to say both were new batteries. The first battery was > new last year, when the car was finished. The battery was flat after being > left 2 weeks, and I thought it was a faulty battery. It was replaced, and I > kept the battery on charge in the garage on a smart charger over Winter. > The car drove to Stoneleigh and home no problem (left overnight with > alarm on as well during weekend). The week after (having been used off and on > I started and moved it on the Friday, on the Sunday I went to open the boot > and the battery was dead flat. It was replaced again (a good supplier!), but > I can't expect to rely on their generosity again, and I need to be able to > have confidence that all will be ok. > ----- Original Message ----- > From: Derek Clews > To: [email protected] > Sent: Monday, May 24, 2010 9:03 PM > Subject: Re: [Quantum Owners] Battery drain > > Hi. If you have a possible problem with the battery, try > disconnecting the battery (and remove from the car if convenient) just charge > via a mains charger and then check the voltage after a good charge and over a > period of time after. If it goes down to below 12V sitting over a day or two > it is shot. You cannot get a real view of the battery while connected it may > be a drain from the car. This has worked for me with cars and the canal > boat. (four batteries in two banks!) > > Alternatively, try and see what AMPs are flowing out of the battery > when everything is switched off. You may need to read the manual with your > meter to see how to connect this or even if your meter is suitable. But > would be in line between one terminal and the lead, not across the two > battery terminals. There may be legitimate drains on the battery. e.g. a > car alarm or an interior light on. I have had a failed light switch before > so the boot light was on all the time. I traced it that way. > > If you are checking the battery the first way is really the > business. That way you can really confirm it's OK. Alternatively your can > take it to a specialist who will test it under load and see if it is weak. > The second way is more for car fault finding. > > Derek > > On 24 May 2010, at 20:39, Susan and Martin Scott wrote: > > I've now had a second battery replacement, and have therefore > come to the conclusion that it may not be a fault with the battery. The last > time it drained to nothing in 2 days (and it was absolutely nothing, not even > enough to light an LED!). I immediately detached the terminals and found > there was no resistance - indicating nothing in circuit? > Although I'm confident with simple circuits, I'm the first to > admit that electronics is beyond my brain power................. I set about > some detective work today > Findings 1. With meter set on ohms, I get no reading across the > battery terminals when disconnected from the battery and nothing in circuit. > 2. With the battery terminals connected and the engine > running the voltage across the terminals is 13.7V > 3. Without the engine running the voltage across the battery > is 12.6V > 4. With the battery terminals disconnected and the meter set > to 2V, I found there was a voltage of 0.048V when the meter was connected, > which reduced to level out at 0.015V. It didn't seem to matter when the meter > was connected ie If I measured across the terminals 3 Sec after disconnecting > from the battery it was the same as if I waited 2 minutes, and also the drop > once the meter was put across was delayed if interrupted eg . 0.048 then > watch it drop to 0.030, remove meter for 5 seconds, reconnect meter and the > reading was 0.030, then dropped further. > 5. Having removed all the fuses, the same occurs. > The alarm fuses have been disconnected as well, but I don't > think it has a battery in it. > > 6. Connecting the meter between the engine block and the > positive battery terminal measures a lower voltage 0.028V, which drops to the > same 0.015V > > Is it maybe electrolytic reaction within the block? As I say I'm > not into electronics. > Why is there no measured resistance, but the battery drains? > Any ideas gratefully received. > Martin > > -- > You received this message because you are subscribed to the > Google Groups "Quantum Owners Group" group. > To post to this group, send email to > [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group > athttp://groups.google.com/group/quantumowners?hl=en > > IMPORTANT NOTE: All information presented herewith is provided on > an "As Is" basis, without warranty or the implication thereof. Neither the > Quantum Owners Club nor the individuals associated with the Quantum Owners > Club or in the preparation of the above information shall have any liability > to any person or entity with respect to liability, loss, or damage caused or > alleged to be caused directly or indirectly by the instructions contained > within this or related message(s). > > -- > You received this message because you are subscribed to the Google > Groups "Quantum Owners Group" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group > athttp://groups.google.com/group/quantumowners?hl=en > > IMPORTANT NOTE: All information presented herewith is provided on > an "As Is" basis, without warranty or the implication thereof. Neither the > Quantum Owners Club nor the individuals associated with the Quantum Owners > Club or in the preparation of the above information shall have any liability > to any person or entity with respect to liability, loss, or damage caused or > alleged to be caused directly or indirectly by the instructions contained > within this or related message(s). > ---------------------------------------------------------------------- > > No virus found in this incoming message. > Checked by AVG -www.avg.com > Version: 8.5.437 / Virus Database: 271.1.1/2893 - Release Date: > 05/24/10 06:26:00 > > -- > You received this message because you are subscribed to the Google > Groups "Quantum Owners Group" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group > athttp://groups.google.com/group/quantumowners?hl=en > > IMPORTANT NOTE: All information presented herewith is provided on an > "As Is" basis, without warranty or the implication thereof. Neither the > Quantum Owners Club nor the individuals associated with the Quantum Owners > Club or in the preparation of the above information shall have any liability > to any person or entity with respect to liability, loss, or damage caused or > alleged to be caused directly or indirectly by the instructions contained > within this or related message(s). > -- > You received this message because you are subscribed to the Google > Groups "Quantum Owners Group" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group > athttp://groups.google.com/group/quantumowners?hl=en > > IMPORTANT NOTE: All information presented herewith is provided on an > "As Is" basis, without warranty or the implication thereof. Neither the > Quantum Owners Club nor the individuals associated with the Quantum Owners > Club or in the preparation of the above information shall have any liability > to any person or entity with respect to liability, loss, or damage caused or > alleged to be caused directly or indirectly by the > > ... > > read more » -- You received this message because you are subscribed to the Google Groups "Quantum Owners Group" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/quantumowners?hl=en IMPORTANT NOTE: All information presented herewith is provided on an "As Is" basis, without warranty or the implication thereof. Neither the Quantum Owners Club nor the individuals associated with the Quantum Owners Club or in the preparation of the above information shall have any liability to any person or entity with respect to liability, loss, or damage caused or alleged to be caused directly or indirectly by the instructions contained within this or related message(s).
