What is the reason that now more and more cars come with digital odometers?
What was the wrong with analog ones?
If battery is disconnected, what happens to the digital odo reading?
I assume cars manufacturers are wise enough [?] to probably supply a backup energy source. But what if that alternative power dies? Will it reset to 0 miles then?
Mine is analog though.
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Makes complete sense to have a digital odometer - less to go wrong, easy to read, and accurate. No little gears whizzing around to worry about.
The overall mileage is stored in non-volatile memory (in several different computers in the car) so can easily tolerate a power loss, although the trip counter may reset to zero.
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I think the reason digital versions became popular was a theory that they would be easier to clock. As it turns out, they're easier if anything.
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Obviously the theory was they'd be harder to clock. I really must re-read before clicking that post button...
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My VW Bora's speedometer retains the mileage if the battery is disconnected but, as David Horn suggests, the trip reading is lost; this is of little importance normally although a record could be taken beforehand.
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What\'s for you won\'t pass you by
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and accurate
Not in itself a factual statement any more than a digital ammeter is necessarily any more accurate than the archaic, fabulous, and beautifully engineered analogue devices I used at college.
Any display device is as good as the transducers or sensors that feed it, and if these are cheap and cheerful, so probably will be the resultant values shown.
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Main advantage for the manufacturers is the ability to switch from miles to KMs with the same unit and integrate with the trip functions.
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> Main advantage for the manufacturers is the ability to switch from miles to KMs
Certainly a distinct advantage but digital are also cheaper than analogue - guess which the manufacturers found most attractive?
Kevin...
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> Main advantage for the manufacturers is the ability to switch from miles to KMs Certainly a distinct advantage but digital are also cheaper than analogue - guess which the manufacturers found most attractive?
It's the same point, economies of scale.
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I rarely heard of the little geary whirring type digital readouts (which by definition they must be as opposed to the LED/LCD version) breaking but pages on websites are peppered with knackered electronic displays of both types.
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I rarely heard of the little geary whirring type digital readouts (which by definition they must be as opposed to the LED/LCD version) breaking
thats funny, all my dads cars seemed to break the mechanical odometer as soon as he got them.......
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TourVanMan TM < Ex RF >
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I would have thought vastly cheaper. Just replacing the spinning cable with a bit of wire must save them plenty, never mind the gubbins.
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It's not even economy of scale, they are significantly cheaper to manufacture in their own right. A 6-digit counter/display costs peanuts. Think how much a basic calculator costs nowadays then get rid of the case, the keys, the battery and half of the internal components.
A digital odometer probably costs less than the cable that used to drive their mechanical/electro-mechanical counterparts.
Kevin...
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Accuracy: seems more likely to me that a system that simply relies on a single pulsing signal to measure a speed is going to be more accurate than one that relies on a cable spinning from somewhere which must then go through a set of complicated reduction gears.
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Except that we owned a Pug 307 that used to do an additional 1 or 2 miles when lock in the garage overnight.
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The accuracy of speed, and hence distance measurement on cars is so poor that it doesn't really matter whether you count distance electronically or mechanically. You can have up to 100% slip at the wheel - complete inaccuracy!!
To talk of accuracy with these systems is to miss the point. As Kevin says, it is cost.
Once you have the electrical pulse, from the legally required ABS system perhaps, the electronics to count and display the distance travelled is a tiny cost. Displaying speed is also quite straightforward, frequency to voltage convertor chips are available, and the speedo becomes simply a voltmeter.
For the mechanical system, you must provide some gear pair to drive the cable. You must then route the cable to the back of the dash - the cable is a significant NVH path. Then you have to provide the gearing and mechanical display. There's no way you can provide this system for anywhere near as low a cost as the electronic system.
Number_Cruncher
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Further to NC's point about gearing and my previous points about the ability to switch from miles to KMs and the economies of scale this offers, of course gearing is not a factor with elec units so the same unit can be fitted in many different vehicles with simple firmware changes.
Anyone who has a bike computer than can be calibrated to different wheel sizes will know how easy it is.
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Last time I went on a 200+ miles trip I compared the ODO reading with the GPS reading for total distance travelled. ODO was about 10% higher than GPS reading. I know GPS 'shortens' distanaces on hills as it cannot take account of the slope, but would it make this much difference?
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I think it is probably a long time since mechanical odometers were driven by 'spinning cables'. I seem to remember my Rover SD1s had senders from the gearboxes. Dodgy too, IIRC.
As with most things, reliability of a system comes down to the engineering integrity of the manufacturer to whom you choose to hand your money.
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>>I think it is probably a long time....
No, not really.
>>Dodgy too, IIRC
Yes!, but what in the SD1 wasn't a bit flaky?
Number_Cruncher
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What on earth is an analogue odometer? All cars I have ever owned, even my 1947 Triumph, had a row of digits. I have never seen a car with an analogue meter like a speedometer or a clock dial, and cannot think it would be very helpful.
Or do you mean mechanical/electronic/LED ?
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Confusingly my BMW motorcycle has the mechanical display but no actual drive is visible.
Presumably some kind of motor turns the number reels?
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I wasna fu but just had plenty.
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Confusingly my BMW motorcycle has the mechanical display but no actual drive is visible. Presumably some kind of motor turns the number reels?
Yes. Both speedo (analogue) and odo (digital) on my Volvo work like that. Electronic signal from a sensor (in the rear axle), converted by a motor to a mechanical display using a needle and a row of little wheels..
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I first became aware of electronic speedos with my Dads K-reg Rover 820Si. A dodgy sensor meant that you could intermittently accelerate from an indicated 0-100 in 0.5 secs.
Other times you could be driving in traffic and the needle would drop to zero for a few seconds or sometimes until the end of the journey. You had to memorise your speeds in different gears at different engine revs to avoid getting 'done'.
He had a V-reg Alfa 166 that had a similar problem also.
;o)
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