tiny Posted January 4, 2007 Report Posted January 4, 2007 Lol. Just noticed yours isnt a Galaxy! Silly me can anyone say wether the battery specifications are the same accross the board?
seatkid Posted January 4, 2007 Report Posted January 4, 2007 First of all, double check those ammeter figures, is it really 0.5A (500mA) dropping to 0.2A (200mA) when pulling the "central electrics" fuse? Is it an autoranging meter? Check the position of that decimal point......what I'm trying to say is that 50.0mA dropping to 20.0mA would be perfectly correct, but 0.5A dropping to 0.2A would imply two (or more) faults which I would say is unlikely. A volt drop test purely tests whether all cells are working, however it may be that the battery is still self discharging. The way to check this 1. fully charge the battery, 2. disconnect the battery from the vehicle, after 20 mins check the voltage, it should be approx 12.8V. 3. come back after 24-48hrs, and the voltage should still be about the same. Believe me, its not unusual to be sold a duff battery, they are rarely stored correctly by sellers.......
seatkid Posted January 4, 2007 Report Posted January 4, 2007 (Mods.....Whats happened to the edit key?) Even if your resting current is 200mA, your battery will discharge in approx 2 weeks not 3 days.
Guest neil_wiles Posted January 4, 2007 Report Posted January 4, 2007 Its all consistent with this However playing withthe edit and delete functions has been restricted for the time being to allow all the bits and bobs to be resolved then normal service may resume.
Guest greenfingers Posted January 4, 2007 Report Posted January 4, 2007 First of all, double check those ammeter figures, is it really 0.5A (500mA) dropping to 0.2A (200mA) when pulling the "central electrics" fuse? Is it an autoranging meter? Check the position of that decimal point......what I'm trying to say is that 50.0mA dropping to 20.0mA would be perfectly correct, but 0.5A dropping to 0.2A would imply two (or more) faults which I would say is unlikely. A volt drop test purely tests whether all cells are working, however it may be that the battery is still self discharging. The way to check this 1. fully charge the battery, 2. disconnect the battery from the vehicle, after 20 mins check the voltage, it should be approx 12.8V. 3. come back after 24-48hrs, and the voltage should still be about the same. Believe me, its not unusual to be sold a duff battery, they are rarely stored correctly by sellers....... You may well be right about the ammeter reading. No, it is not autoranging: one setting is labelled 20, and the other 200. On one setting I get 2.0, and on the other 0.2. Therefore, with all the interior lights on am I reading it right at approx 5 Amps? I will try your disconnected battery test tonight. If the car is draining the battery at too low a rate to discharge it so quickly, then surely there must be some kind of intermittent surge going on? Is this something that VAG.COM will reveal?
Andrew T Posted January 4, 2007 Report Posted January 4, 2007 If a Sharan has the same lights as a Ghia you get 12 come on when a door opens, so at 5 Watts each thats 60W divided by 12 Volts = 5 Amps. Bloody hell, did I remember Ohms law correctly from Physics lessons 25 years ago?
RADIOTWO Posted January 4, 2007 Report Posted January 4, 2007 Radiotwo, which engine is in your Amazon? I would love to run a good sized 4x4 but have never relished the idea of sub 20 miles per gallon. Yet I bet that your Amazon has cost you less to run per mile than my Sharan has. ;) So much for fuel economy! Anyway, I've tried to get it out in the open and out of my system; time now to set about the tasks in hand. I will get to the bottom of this latest challenge, but the distant purr of a Lexus RX is getting closer! Oh, and Merry Christmas everybody! Without being too bitter and twisted, imagine being Santa - no petrol or diesel bills, and no tyres to wear out! ;) Just a quick point, ref the above. The amazon is a 4.2 Lts and if I drive nicely I can get 30mpg Radiotwo
Guest greenfingers Posted January 4, 2007 Report Posted January 4, 2007 Just a quick point, ref the above. The amazon is a 4.2 Lts and if I drive nicely I can get 30mpg Radiotwo When you say 'nicely', surely you must mean at 56mph on cruise control? I've been looking at Merc ML270s, which are listed as 29mpg extra urban, and actually give about 27. A 4.2 Amazon is listed at 25.4mpg extra urban!
Guest greenfingers Posted January 5, 2007 Report Posted January 5, 2007 Andrew T, you are a genius. I checked the reading again and it is 200mA, but that doesn't help my plight. I have done as Seatkid advised, and disconnected the battery (albeit only overnight), and it showed no drop in voltage, so it's bad news that the battery is not the problem. Worse news, the auto electrician I phoned this morning agreed with Seatkid that 200mA would not drain the battery in a couple of days, so there must be something else happening. Worse news still, he said that VAG.COM or reading the ECU would not reveal a battery drain - he would have to do a Sherlock Holmes job with an ammeter and start pulling out fuses until the fault could be isolated. He is booked up until next week. So now I must beg, do any knowledgeable brains out there if they have any ideas? I am going to try leaving the car unlocked tonight, and perhaps that will show if the alarm/immobiliser has been sporadically causing a drain, but it seems unlikely, because the voltage drop seems so regular.If the discharging happens when the ignition is off, does this reduce the number of circuits which might be faulty? If so, which should I check?I read of a case where a faulty alternator diode was behaving differently when hot than when cold, and this caused a drain. Does anyone know a test I can do on the alternator?
Andrew T Posted January 5, 2007 Report Posted January 5, 2007 Genius? I wish, just hard won experience with the most tempremental car I've ever had. The only reason I noticed the current the interior lights take is because of the impressive sparks that you get when reconnecting the battery lead with the door open! Returning to your problem though, I think you need to explore the Ca or Sb battery angle a bit more. Does anyone know if Sharans are fitted with Sbs from new?(try phoning the service department of your friendly local VW agent?). How long have you had the car? did you put the Sb battery on? If not can you find a production date on it? If a Ca battery has been replaced with Sb prior to your ownership maybe the problems you're experiencing are a result of using an Sb battery instead of a Ca? As I've said before it seems possible that you can have a battery and electrical system that passes all the tests but still fails to perform properly.
seatkid Posted January 5, 2007 Report Posted January 5, 2007 Do you have illuminated vanity mirrors? These often break and don't switch off when closed.......
Guest greenfingers Posted January 5, 2007 Report Posted January 5, 2007 I think you need to explore the Ca or Sb battery angle a bit more. I bought the car last July. It had a lead acid battery on it then, and it was fine. It survived one week at Gatwick airport when we went on holiday. Maybe it was not the original battery, but it looked filthy and old, so when this problem started, I replaced it as the first port of call. I bet if you did a poll of how many Shalhambraxies had lead acid batteries, there would be thousands - otherwise people would have reported problems.I really don't want to go on discussing the battery itself - I need to find out what is draining it.
Guest greenfingers Posted January 5, 2007 Report Posted January 5, 2007 Do you have illuminated vanity mirrors? These often break and don't switch off when closed....... Already checked - yes switching off fine.
Andrew T Posted January 5, 2007 Report Posted January 5, 2007 If you're looking for obscure faults is the battery clean? I once had a problem with a battery self discharging and (believe it or not) it was salt spray off the winter roads that had dried on the battery that was the problem. You could stick an ammeter probe in to the gunge on the surface and see a current that was tracking betwwen the posts. That said the batteries these days are very well protected from the elements that it'smost unlikely to happen. Do you find your problems is related to how the car has been used i.e it's better after long journeys that short?
seatkid Posted January 5, 2007 Report Posted January 5, 2007 Glove box light? Disconnect the alternator - In the dark distant past I have known these to drain batteries Its time to get the TIS wiring diagrams out and plan a sequence of attack starting at the battery and working back. My MK1 has several wires connected to the main battery terminal, maybe I would start by disconnecting these........
Guest greenfingers Posted January 5, 2007 Report Posted January 5, 2007 Regardless of length of journeys, it loses .2Volts overnight.Battery is brand new - no gunge. I have cleaned the leads.Glovebox light is off. Alternator sounds closer. What part could be faulty?I have TIS, so I am going to try and find those wiring diagrams.
Guest neil_wiles Posted January 5, 2007 Report Posted January 5, 2007 In the back of the alternator is a set of diodes that are the primary recification from AC to DC voltages one of these may be leaking back current and there fore it will run your battery flat in a very short period of time but will if measured using a standard analogue meter still be producing about 14.8 volts dc during running, if you switch the meter to ac you may be able to see the ac content of the output of the alternator at the battery when the enigne is running. If the meter show aournd the 4 volts when on AC scale then your alternator is definitley US or if the AC output is detected but relatively small maybe <1.o volts then your Alternator is on its way and should be either rebuilt or replaced.
Guest greenfingers Posted January 5, 2007 Report Posted January 5, 2007 In the back of the alternator is a set of diodes that are the primary recification from AC to DC voltages one of these may be leaking back current and there fore it will run your battery flat in a very short period of time but will if measured using a standard analogue meter still be producing about 14.8 volts dc during running, if you switch the meter to ac you may be able to see the ac content of the output of the alternator at the battery when the enigne is running. If the meter show aournd the 4 volts when on AC scale then your alternator is definitley US or if the AC output is detected but relatively small maybe <1.o volts then your Alternator is on its way and should be either rebuilt or replaced. WOW! I just measured 13.8Volts DC at tickover, and when I set the meter to AC, it came up with a massive 28.5Volts. With the engine off, I still get a reading of 27Volts AC.What on earth does that mean?
big_kev Posted January 5, 2007 Report Posted January 5, 2007 WOW! I just measured 13.8Volts DC at tickover, and when I set the meter to AC, it came up with a massive 28.5Volts. With the engine off, I still get a reading of 27Volts AC.What on earth does that mean? The DC voltage looks about right for tickover.......ignore the AC voltage...it doesn't mean anything other than your rectification circuit is not perfect ( which is normal for a vehicle alternator ). If you have any non-original equipment in your car thsi is the most likely source of the battery drain.ie do you have any sta-nav..mobile phone..non-original lights or anything else on the car that it didn't have when it came out of the factory ?
Guest neil_wiles Posted January 5, 2007 Report Posted January 5, 2007 Trust me if you have 28.8 VAC going in to a battery its gonna cook, your alternator is US get it either replaced or repaired. AC voltage kills batteries and will heat it up till it boils. The rectifier is US.
seatkid Posted January 5, 2007 Report Posted January 5, 2007 Nah....red herring...27VAC with the engine off? I think not....you've either got a dicky meter or you're reading millivolts!
Guest greenfingers Posted January 5, 2007 Report Posted January 5, 2007 Trust me if you have 28.8 VAC going in to a battery its gonna cook, your alternator is US get it either replaced or repaired. AC voltage kills batteries and will heat it up till it boils. The rectifier is US. Now, just to be sure, I was measuring the voltage across the two battery terminals - is that right? So with engine running I get 28.5, and with engine off I get 27. Does that not mean that with the alternator running it is putting in 1.5Volts AC?I will be delighted if you have cracked it.I am going to disconnect the alternator now, and check the battery DC voltage now and then again in the morning. If it is the same, I owe you a drink! However, I still don't understand why it seems to charge normally, and why the current drain does not show on an ammeter. :wacko:
RADIOTWO Posted January 5, 2007 Report Posted January 5, 2007 Trust me if you have 28.8 VAC going in to a battery its gonna cook, your alternator is US get it either replaced or repaired. AC voltage kills batteries and will heat it up till it boils. The rectifier is US. Thats a load of rubbish, Greenfingers says it is reading 13.8V DC and on his AC scale (alternating current) its 28.8AC which is right. So NO PROBLEM WITH ALTERNATOR A little knowledge dangerous !!! Radiotwo
RADIOTWO Posted January 5, 2007 Report Posted January 5, 2007 Trust me if you have 28.8 VAC going in to a battery its gonna cook, your alternator is US get it either replaced or repaired. AC voltage kills batteries and will heat it up till it boils. The rectifier is US. Now, just to be sure, I was measuring the voltage across the two battery terminals - is that right? So with engine running I get 28.5, and with engine off I get 27. Does that not mean that with the alternator running it is putting in 1.5Volts AC?I will be delighted if you have cracked it.I am going to disconnect the alternator now, and check the battery DC voltage now and then again in the morning. If it is the same, I owe you a drink! However, I still don't understand why it seems to charge normally, and why the current drain does not show on an ammeter. :wacko: As I have said in my other post, "a little knowledge is dangerous" Dont put the meter on AC, when reading DC If you are reading 13.8V DC thats great, Your problem is down to something draining the battery. As some one has said it could be the Alternator but unlikley, go back to the Ammeter and get your reading (what ever you said "200mA") and then start taking the fuses out, and when you get a 0A, that is the circuit thay is causing the problem. Make sure you try all fuses ! Its a shame you don't want a ride up to Derbyshire, and I would check it out for you !! Just to change the tact, you mention about the fuel consumption, Yes if I do abou 60mph I can get a avarage of 30mpg, which is not bad for a 2600kg 4x4 4.2lt lump. Radiotwo
big_kev Posted January 5, 2007 Report Posted January 5, 2007 Ok guys a bit basic eletrical knowledge to clear the confusion. A standard cheapo multimeter can only actually measure a dc voltage. It manages to read an AC voltage by rectifying it using a bridge diode ( or similar ) which then feeds the resultant DC voltage to the meter....this will appear as a DC voltage of around half the AC voltage..a little bit of simple computation in the meter ( it knows to do this because it is switched on to its AC range ) then shows the calculated AC result. Therefore if you put 13.8vDC into the meter whilst it is on AC this goes straight through the bridge rectifier and the meter sees the DC votage does its simple computation and returns an AC voltage of 27vAC...which is approximately double the DC voltage....( should actually be well more than double but there will be some loss through the bridge rectifiers and other AC circuitry ). Two options..either use a better meter...or..... Dont use AC when measuring an obvious DC device. Hope this helps
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