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Topic: The Autobox, Cat and battery! (Read 1006 times) |
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harry.m1byt
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The Autobox, Cat and battery!
« on: Jun 20th, 2009, 9:25pm » |
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For the past 12 or so months, at gentle throttle, often when climbing a gentle slope and at about 20 to 30mph with the windows open - I have heard an horrible gratting noise, which I always assumed was from the auto gearbox. The noise perfectly synchronised itself with the behaviour of the gearbox.
Recently it became much louder and then I found I could reproduce it even when not moving, by just revving the engine and traced the noise to the front Cat box. I even got under neath to check it wasn't the heat shield attached to the Cat loose and rattling.
This morning I arranged for a new CAT to be fitted, then found the battery completely flat, needing to be charged to get it to start. I had used it on a good run, just the day before.
Once at the exhaust fitter, he said the Cat was fine it was just the heat shield rattling, which he sorted out. Then I asked if he could track down a large capacity (the recommended 71Ah 680 cca) battery as my present one has given me a few problems in the time I have had the car.
He managed to get a Bosch one delivered as I waited, then they decided it would not fit in the space and it had posts instead of flat terminals. About to drive off, I changed my mind and decided to measure it myself and worked out it would just fit and took it, collecting some post to flat adaptors on route home, from Halfords.
The battery was a perfect fit for the space, I think their fitter must have been fooled by the side clamp, which can be moved to a second tapped hole further inboard.
The new Halfords clamps (cast brass) both snapped in fitting them, so I had to go out and buy a different type make from pressed brass. The positive was a perfect fit, but the negative turned out to be too large to properly grip the post. I had to pack that with a short bit of 15mm copper pipe split length ways so it would tighten onto the post.
Once that was all sorted I put a multimeter in series with one of the battery leads, to check the discharge, these are the figure I got:-
With no interior, boot or glove box etc. lights on and the car having just been left unlocked - 300mA
Some 30 minutes later that fell back to 20mA. Locking the car and double locking - again it dropped to about 20mA.
I checked out the battery saver relay, which is working fine. I also checked the charging system and that is also doing what it should.
I use the car irregularly, sometimes not using it for several weeks, so I customerily have it on a maintenance charger in the garage to keep the battery topped up - especially so in winter. The car has been in use more regularly than usual recently, so I've not bothered to use the charger for some weeks. Yesterday it got a long run, yet this morning it was completely flat.
I have been faced with a flat battery a few times before, so something is not quite right. The old (60aH) battery seems to be taking a good charge, so it was probably fine and the new battery unecessary.
I'm stuck at the moment to find the cause of this very irregular loss of battery power.
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harry.m1byt
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Re: The Autobox, Cat and battery!
« Reply #1 on: Jun 21st, 2009, 1:32pm » |
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The old 60aH battery was fine - just over 13v after standing fully charged and idle over night, so it is down to something very occaisionally discharging the battery.
The problem in trying to track it down is that if you put a mA meter in series with a battery lead, you need to be measuring values of sub 100mA, yet the cables are intended to supply upto 100amp on the none starter cable so it really cannot be left in circuit. Putting the meter in and out of circuit is no quick task, everytime you need to use the car - so I'm looking at alternative methods...
I'm presently checking out the possibility of connecting a millivolt meter in parallel with the cable that runs from the battery, to the fuse box adjacent to it, so it measures the volts drop along that short length of cable.
On the 200mV range, I'm seeing values of 30.6mV with headlights on, 3.6mV with just the interior lights on and this drops down to 0.2mV once these have gone off. Less than this it just cannot detect, so I cannot even prove it is going into sleep mode by this means. It really needs a microvolt range to be able to make sense of the voltage dropped over the short bit of 100amp cable.
There is also the possibility that the source of the occaisional battery drain whilst parked is on the none battery side fuse box.
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Tompion
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1997 2.3 Ultima estate.
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Re: The Autobox, Cat and battery!
« Reply #2 on: Jun 21st, 2009, 3:20pm » |
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Harry
It’s a tricky one, pulling fuses may show where a problem lies, but it’s just as likely to be a leaking loom or fuse box problem so could send you down the wrong path. You could try cleaning the big multiplugs on the wing (found a bit of silver foil in mine – fortunately hadn’t shorted anything).
I think others have had trouble with the wires pinched under the auxiliary fuse box.
Don’t be put off by the lack of response – trouble is we know you know your way round electrics.
Dave
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joe-satch
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Re: The Autobox, Cat and battery!
« Reply #3 on: Jun 21st, 2009, 6:58pm » |
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hi all.someone has asked me to have a look at his 2.3 ultima tomorrow afternoon....because he states that over a period of about 2 weeks the battery goes flat..although whe uses the car on a daily basis,im not looking forward to this fault find mission,but he needs help...so i have put myself in the firing line..between now and tomorrow afternoon (monday 22nd june)..would anyone have any tips for me please.?..of where to look,im going to do a few tests that i know of...thank you all.. ..regards den...ps..i dont mean to hijack this post so sorry to be a pain.
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Tompion
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Re: The Autobox, Cat and battery!
« Reply #4 on: Jun 22nd, 2009, 1:03am » |
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Make sure the glovebox light goes out.
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joe-satch
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Re: The Autobox, Cat and battery!
« Reply #5 on: Jun 22nd, 2009, 7:34am » |
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thank you tompion...thats on my list for sure .
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joe-satch
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Re: The Autobox, Cat and battery!
« Reply #6 on: Jun 22nd, 2009, 5:10pm » |
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well in this case it turned out to be the alt.  .
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harry.m1byt
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Re: The Autobox, Cat and battery!
« Reply #7 on: Jun 22nd, 2009, 6:09pm » |
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on Jun 22nd, 2009, 1:03am, Tompion wrote:| Make sure the glovebox light goes out. |
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The glove box light, interior lights and boot light being left on should not make any difference - they are all powered through the battery saver relay. Leave one on and it should go out if the car is left undisturbed for 20 to 40 minutes, at which point the relay drops out and shuts the all the lights off. Test it by deliberately leaving a door open.
My alternator was producing a voltage of 13.8v irrespective of load, if the engine was run at a little more than a tick over. Others suggest that is the bottom end for voltage so yesterday evening I checked the alternator's main connection. It wasn't what I would call loose, but nor was it as tight as I would have made it. I pulled that apart, cleaned up the terminal, refitted and retightened it. The voltage has now risen to 14.02v under exactly the same circumstances.
Nice when you find a problem, but I don't think I have found The problem.
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Tompion
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Re: The Autobox, Cat and battery!
« Reply #8 on: Jun 22nd, 2009, 6:38pm » |
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Yes I know what is supposed to happen. 
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joe-satch
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Re: The Autobox, Cat and battery!
« Reply #9 on: Jun 23rd, 2009, 7:29am » |
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good point...and is fixe your alt output...on the ultima..its a diesel..and the batt light is glowing,if i put my meter across the batt..(engine off)...the voltage drops while watching the meter..when the engine is running input voltage is around 12.5 volts,i am sure that the batt voltage is leaking to earth through the alt.as everything else is working as it should..so in with a new alt in a few days. .
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harry.m1byt
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Re: The Autobox, Cat and battery!
« Reply #10 on: Jun 23rd, 2009, 7:00pm » |
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Bloody Glove box light 
I (in theory) might have worked out what might be happening and why it is discharging....
The battery saver relay cuts the supply to the interior light, glove box and boot lights etc after 20 minutes if there is no change in the status of these things.
The glove box switch has a known design problem in that it can fail to turn off if there is a lot of weight in the glove box. Fully on or fully turned off, the battery saver relay will cut the supply and save the battery, but if the glove box switch is just on the point of switching, the battery saver relay would be constantly retriggered. That might explain why sometimes it goes flat quickly and the rest of the time there is no problem. I had reckoned with the battery saver relay being infallible under ALL circumstances.
When I got the car, the glove box lamp was burnt out. I replaced it, then found it was hot when I opened the glove box so I assumed it was staying on. I fixed it (I thought) at the time by bluetacking a 1p coin on the lid where it strikes the switch plunger.
I turned the interior light on via the interior light switch, sat very still and quietly in the car until the battery saver relay timed out, then nudged the glove box lid - back on came the interior light. Seems like i shall have to invest in a second 1p coin to bluetack on top of the other one 
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Tompion
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Re: The Autobox, Cat and battery!
« Reply #11 on: Jun 23rd, 2009, 7:47pm » |
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Glad you got it sorted
I tapped a couple of holes in some 3mm brass strip & covered it in black insulation tape so it didn't show. I took the panel of the glovebox and screwed it on from behind where it strikes the switch.
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