Alternator Ripple

[Rebotco]

This concerns my car actually, but it could just as easily be the boat I think.

 

On 3 occasions during the last 2 months, my car's computer has gone a bit haywire, suddenly showing numerous faults on

 

first startup, but apart from the steering and brakes feeling heavy it drives normally.

 

Took it to the garage who tested the electrics with some sophisticated piece of electronic kit, and they reported the only

 

thing wrong was the alternator "ripple too high". They said this probably meant one or more of the internal diodes was

 

knackered, and the only practical cure was to replace the alternator (At £565 for the part alone!)

 

However I found that by simply slackening and retightening the battery terminals, everything returned to normal. Computer

 

reported no faults, steering and brakes same as ever and simply no indication of anything wrong.

 

Question is, am I doing any further damage by continuing to drive? Or can these electrical Gremlins be temporary? What

 

options have I got?

 

Any electrical experts familiar with this and can give advice? Thanks.

 

 

Brian

[Chris Pink]

I guess the question is; which is more useful to manage a boat's systems, a computer or a watchful eye and a spanner.

 

I know which I prefer.

 

And for cars too.

[Rebotco]

I guess the question is; which is more useful to manage a boat's systems, a computer or a watchful eye and a spanner.

 

I know which I prefer.

 

And for cars too.

 

Well thats OK if you know what to do with said spanner!

 

Some of us a little rusty on that, especially nowadays with cars being as electronically complicated as a space shuttle!

 

Brian

[Robbo]

Took it to the garage who tested the electrics with some sophisticated piece of electronic kit, and they reported the only

 

That sophisticated piece of electronic kit can be got for around £20 like this. It will display a code which you then look up to see what's been reported (some devices show full text as well). How that information is acted upon is down to the mechanic (a faulty sensor or a faulty cable to the sensor, etc..)..

[Chris Pink]

A standard that all manufacturers agreed on? Wow.

[Keeping Up]

The alternator ripple they measured may simply have been caused by dirty battery terminals, and nothing to do with the alternator itself which was merely trying to do its job and force some charging current through the dirt into the battery. If the fault seems cured, just carry on. If the fault returns, look into the cost of getting the alternator repaired instead of replaced; your garage probably won't do it but there are plenty of car electrical specialists who will.

[Robbo]

A standard that all manufacturers agreed on? Wow.

 

Had to (EU I believe), the connection also needs to be near the steering wheel.

 

You can also get USB adapters and software so you can plug it into a laptop and see all the running information.

 

Or ipad/iphone: http://itunes.apple.com/us/app/dashcommand-obd-ii-gauge-dashboards/id321293183?mt=8

Edited February 3, 2012 by Robbo

[Guest]

I can't think continuing to drive will be doing any further harm.

 

Not sure of your model vehicle but the heavy steering can be due to the fact the electrically powered power steering, which is quite common now was not functioning at the time - that can obviously related to the fault.

 

When I had a BMW 3 series it once did something very similar and also went into 'limp home' mode.

 

I didn't mess with the terminals but simply turned the ignition off left it a couple of minutes and turned it back on and it was back to normal, and ran for thousands of miles after that with no repeat.

 

Again not sure of make but I'd be surprised if you couldn't get that alternator repaired (if it does turn out to be faulty) for a lot less than you have been quoted...

[Rebotco]

That sophisticated piece of electronic kit can be got for around £20 like this. It will display a code which you then look up to see what's been reported (some devices show full text as well). How that information is acted upon is down to the mechanic (a faulty sensor or a faulty cable to the sensor, etc..)..

 

I think it was a little more than that. He kept it in a locked cabinet because he said it cost over £2000 and none of his mechanics were allowed to use it!

 

Brian

 

I can't think continuing to drive will be doing any further harm.

 

Not sure of your model vehicle but the heavy steering can be due to the fact the electrically powered power steering, which is quite common now was not functioning at the time - that can obviously related to the fault.

 

When I had a BMW 3 series it once did something very similar and also went into 'limp home' mode.

 

I didn't mess with the terminals but simply turned the ignition off left it a couple of minutes and turned it back on and it was back to normal, and ran for thousands of miles after that with no repeat.

 

Again not sure of make but I'd be surprised if you couldn't get that alternator repaired (if it does turn out to be faulty) for a lot less than you have been quoted...

 

 

Thats interesting. Its a BMW 530D se. So maybe its something "inherited" from the German genes!

 

Brian

[Albion]

Manufacturers are only obliged by EU law to reveal certain information to generic diagnostic code readers. It is usually stuff that concerns emissions so I would be surprised if his scan tool kit could reveal a non-emissions related problem. Having said that, an old fashioned diagnostic tuner could reveal abnormal ripple on the alternator charging which could be down to a diode in the rectification having gone down.

There, are however, lots of other fault codes stored in a different part of the ECUs memory that cannot be accessed except by the manufacturer's own code reading equipment. This is the info that they are not required by law to divulge and that's why it is only accessible to their own technicians using their own equipment. The position of the diagnostic socket (which has a number designation which I have forgotten now) is also covered by the EU and has to be within a tightly defined position and to allow a certain standard sized plug to be attached to it and is close to the steering column.

Roger

ex On Board Diagnostics (OBD) Euro legislation engineer for Jaguar Cars.

[Guest]

 

Thats interesting. Its a BMW 530D se. So maybe its something "inherited" from the German genes!

 

Brian

 

Hi Brian,

 

When that happened to my 3 series I described the symptoms to my brother in law (he works in the trade) and he said whilst it certainly not a common thing it was not unknown for such glitches to occur with BM's and then never happen ever again and not to worry about unless of course it permanently incapacitated the car or left any warning lights on....it never did.

 

I see now why the alternator is priced so highly but am sure as I say it could be tested an repaired as Allan says for a lot less.

 

BMW's parts pricing always seemed to me to be all over the place with some things like locking wheel nut sets being ridiculously cheap through to needing a second mortgage for stuff....

 

ex On Board Diagnostics (OBD) Euro legislation engineer for Jaguar Cars.

 

 

I bet you were a busy man....

[Chalky]

Thats interesting. Its a BMW 530D se. So maybe its something "inherited" from the German genes!

 

Which 530D Se? Pulling the power will cause the ECUs to clear their memory which will cause them to reset the fault codes. The problem may still exist. The BMWs are designed to work down to very low temperatures (not as low as Land Rover ) so it's unlikely to be thermal although the cold weather may give a clue. Sometimes the algorithms can be a bit too clever and sensitive so you might be ok. My thoughts are (in no particular order)

 

blown diode

loose fan belt

flat battery

damaged battery

dirty /loose connections

nothing wrong at all, just too enthusiastic to log a fault (DTC)

 

It's possible that the battery is old, the belt slipping and the engine is using the glow plugs at the same time as the heater, seat heaters, heated rear window, mirror heaters, headlamps on, audio on, wipers going etc. That would produce ripple! Also the BMW battery is in the boot which is great for weight distribution but doesn't help with volt drops etc.

 

The bit of diagnostic kit could be a modic and they are Very expensive.

Edited February 3, 2012 by Chalky

[Albion]

I bet you were a busy man....

 

Unfortunately for you, the common perception that used to be so true admittedly , was inaccurate while I was there as Jaguar actually toppled Lexus from the top spot of the American J D Power reliability index on one occasion and ran Lexus a close second on a few other occasions.

However, old reputations do take a lot of living down.

Roger

[Chalky]

Unfortunately for you, the common perception that used to be so true admittedly , was inaccurate while I was there as Jaguar actually toppled Lexus from the top spot of the American J D Power reliability index on one occasion and ran Lexus a close second on a few other occasions.

However, old reputations do take a lot of living down.

Roger

 

Very true. I've known a company that built 2 models of the same car on the same production line using the same people and same parts. 1 was badged as a UK manufacturer, 1 Japanese. In the quality surveys 1 came at the top of the list and one at the bottom. Perception is everything.

 

Back to the alternator have a google at the owners forums. As Albion would probably agree not all diagnostic messages are "accurate" and it's not unknown for a fault to be logged that actually refers to something else and is totally misleading. Manufacturers and their dealers do a lot of work to correct these issues, after market testers may not. Also if it's an after market tester it will have been developed using vehicle manufacturer supplied data. The chances are that it was coded in another part of the world and the descriptions of faults and their meanings could have gained something in the translations, especially if it went from German to English to (name a far eastern / Asian language.)

Edited February 3, 2012 by Chalky

[Guest]

Very true. I've known a company that built 2 models of the same car on the same production line using the same people and same parts. 1 was badged as a UK manufacturer, 1 Japanese. In the quality surveys 1 came at the top of the list and one at the bottom. Perception is everything.

 

Indeed - Skoda still have an 'image' problem despite the reliability and satisfaction surveys saying something else..

 

Isn't it the Ayago (Toyota), 106 (Peugeot) and the C1 (Citroen) that are all made on the same line?? or is that a myth?

[Chalky]

The Mitsubishi Miev, Peugeot iON and the Citroen C-Zero are a common platform.

[Albion]

Very true. I've known a company that built 2 models of the same car on the same production line using the same people and same parts. 1 was badged as a UK manufacturer, 1 Japanese. In the quality surveys 1 came at the top of the list and one at the bottom. Perception is everything.

 

Back to the alternator have a google at the owners forums. As Albion would probably agree not all diagnostic messages are "accurate" and it's not unknown for a fault to be logged that actually refers to something else and is totally misleading. Manufacturers and their dealers do a lot of work to correct these issues, after market testers may not. Also if it's an after market tester it will have been developed using vehicle manufacturer supplied data. The chances are that it was coded in another part of the world and the descriptions of faults and their meanings could have gained something in the translations, especially if it went from German to English to (name a far eastern / Asian language.)

 

My background was as an independent garage businessman and Bosch Service Agent so I had a lot of experience/training in the high tech aspects of vehicles and diagnostics (but as an independent) before I left my employees to continue running the business for me while I went off and worked for Rover Cars, Lister-Petter Diesels and Jaguar Cars. When I worked for Jags (then owned by Ford) I realised just how avidly the manufacturers (both Jags and Ford) guarded their diagnostic information, viewed from my previous standpoint as an independent. They wouldn't reveal anything to anyone (including the generic code reader manufacturers) that they weren't forced to reveal by legislation and that why all non-emissions-critical info was hidden in another memory within the ECM only accessible by manufacturer's equipment (Mode 4 IIRC but I could be wrong). So, it is no wonder that the generic readers are OK but less than perfect in some cases. In theory each DTC (Diagnostic Trouble Code) should mean the same the whole world over but there can be slight differences or interpretations depending on the case in point. Also, due to the massive expansion of diagnostics the sheer number of required codes were starting to become a difficulty as diagnostics had moved from the early few flashing codes that you could read out with an LED to the vast number of codes required to cover the number of complex faults descriptions. This sometimes meant that the same code had to stand for two slightly differing faults depending on the individual manufacturer's engine management system.

My role, before I moved on to running a small team doing the OBD for all Jags using the 2.7 V6 turbo diesels, was keeping up with and advising Jags (and liaising with Ford) on all Euro legislation that affected OBD. It also involved getting VCA (Vehicle Certification Authority) approval for OBD systems fitted before the new release of cars could legally be sold (So I got certified the X Type 2.0 litre diesel and the S Type 2.7 V6 diesel for example). That was a few year ago now though (I left in 2005) so, as with all things, I'm starting to feel a little rusty on some of the detailed info.

Roger

 

Indeed - Skoda still have an 'image' problem despite the reliability and satisfaction surveys saying something else..

 

Isn't it the Ayago (Toyota), 106 (Peugeot) and the C1 (Citroen) that are all made on the same line?? or is that a myth?

 

The Skoda is, I've heard, getting so good/has got so good that it is starting to challenge its parent company Volkswagen for build quality etc.

Yes the Aygo, 106 and C1 are all built on the same line and this badge engineering is very common now due to the costs of development and production.

Roger

[Rebotco]

Well, thanks to everyone for loads of good advice and inside info. That has been massively helpful.

 

One small point tho - exactly what is ripple and what harm does it do?

 

Thanks again

 

Brian

[Albion]

Well, thanks to everyone for loads of good advice and inside info. That has been massively helpful.

 

One small point tho - exactly what is ripple and what harm does it do?

 

Thanks again

 

Brian

 

Right, difficult to put succinctly into words but I'll try. Alternators are three phase machines and so there are three sinusoidal waveforms output from the stator per rev. So, as it is sinusoidal you have three positive waveform peaks and three negative ones. When these are rectified you then have 6 positive peaks all over-lapping each other. When you look at the overlapping waveforms on a diagnostic oscilloscope you see the tops of the waveform peaks only which gives a sort of series of shallow lumps pointing upwards and is is the mean (RMS)of the slight lumps that gives the output steady state voltage. The actual waveform though is still slightly 'lumpy/peaked' and it is this that is termed the ripple. If you get a diode failure you can get a situation where, say, one phase goes down and, on an oscilloscope, you would see two peaks and a miss, two peaks and a miss (and so on). This gives an even bigger voltage ripple and the RMS (Root Mean Square) of the voltage is now altered due to the fact that you haven't got the smoother ripple waveform that you had when there was no fault. So, in this scenario, the ripple waveform is much more exaggerated by the missing phase.

Roger

[Chalky]

The alternator produces 3 voltage sine waves (known as phases) that don't over lap. (120deg or 2/3 pi radians out of phase). These sine waves are connected to a set of diodes that convert the voltage (rectify) into a voltage with a series of lumps in it. These lumps are the ripple. These are then smoothed out using a filter network to produce a smooth DC voltage. In a power supply the filter is made up of capacitors in a car it's the battery.

 

Thus the comments earlier about the possible causes of the ripple. The algorithms to detect the ripple can be really simple e.g. the voltage is below a threshold for nnn seconds etc or really complex (e.g. alternator has been commanded to produce nnn A @ nnn V and isn't). I don't know the one used on this system.

 

The effects can vary. On a simple car you may see nothing or perhaps some flicker on the lights. You may hear a buzz on the radio (depending on the level of ripple and the quality of the audio system design). On a more sophisticated car it could do interesting things to the electronics since it can upset the power supplies in the control units as well as upset some of the communications between them. All of the control units have their own power supplies and these are designed to manage a level of ripple without a problem. The ripple can also be described as a transient and common automotive specs exist that define safe working levels. Typically the vehicle will be expected to work at 10V ish but be able to survive a short transient to 5v ish for a cold climate crank. The comms busses and the communication protocols etc are designed to be fault tolerant.

 

Overall it's very difficult to say what the effect would be since it depends on what the ripple is (and does it actually exist) and how the system has been designed.

[Guest]

 

Yes the Aygo, 106 and C1 are all built on the same line and this badge engineering is very common now due to the costs of development and production.

Roger

 

A quick correction before the pedants spot it - I meant the 107 not the 106...

[Keeping Up]

Trying to put it more simply, imagine if your battery voltage went slowly up to 15 and then back to 12 again, that's probably not a problem. Now imagine it doing the same thing but more quickly, up to 15 and back to 12 again as quickly as you can say "15, 12, 15, 12" over and over again; it's probably still not a problem. Now imagine it doing that a couple of hundred times every second. That's called ripple. You couldn't keep up, if you tried to say it that fast you'd just get tongue-tied; well the car's electronics, especially the computer, can't keep up either, and it gets tongue-tied as well.

 

It can happen if the alternator has a fault, especially a dead diode - but it can happen just because the battery terminals are dirty.