Alternator not battery right...

Alternator not battery right...

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Munter

Original Poster:

31,319 posts

240 months

Sunday 8th January 2017
quotequote all
So this is the alternator failing right? A duff battery wouldn't show this would it. (Don't want to advise someone to change the alternator against their garages advise, if it might just be the battery.)

stevieturbo

17,229 posts

246 months

Sunday 8th January 2017
quotequote all
Your post seems to imply you are changing a battery because it has went flat ? Although you dont say why ?

That combined with evidence the system is far far below where it should be in order to charge a battery properly...


1+1=2

Munter

Original Poster:

31,319 posts

240 months

Sunday 8th January 2017
quotequote all
stevieturbo said:
Your post seems to imply you are changing a battery because it has went flat ? Although you dont say why ?

That combined with evidence the system is far far below where it should be in order to charge a battery properly...


1+1=2
Not changing anything yet.
3 garages baffled as to why the ABS and EPS (steering) lights come on at speed and the steering gets heavy, and eventually the car stops.
1 "trusted garage")Suggested battery, can't be the alternator. Because the battery was flat when the car was recovered, but then it was able to charge it's own battery in their test drive. I suspected the alternator, and then, the owner flattened the battery completely trying to start it.
2)Speed sensor definitely at fault...
3)No idea
Honda over the phone)No idea, next slot in a months time.
Me for a while now)If it was driving then ran out of leccy, it must be the alternator....But I'm not an expert, so just checking.

Penelope Stopit

11,209 posts

108 months

Sunday 8th January 2017
quotequote all
Munter said:
Not changing anything yet.
3 garages baffled as to why the ABS and EPS (steering) lights come on at speed and the steering gets heavy, and eventually the car stops.
1 "trusted garage")Suggested battery, can't be the alternator. Because the battery was flat when the car was recovered, but then it was able to charge it's own battery in their test drive. I suspected the alternator, and then, the owner flattened the battery completely trying to start it.
2)Speed sensor definitely at fault...
3)No idea
Honda over the phone)No idea, next slot in a months time.
Me for a while now)If it was driving then ran out of leccy, it must be the alternator....But I'm not an expert, so just checking.
That diagnostic graph that you posted means nothing unless all the alternator wiring and earths have been checked for volt drops when the fault is on the vehicle
Why use Honda to have a simple circuit tested?
Find a good auto electrician and pay the 1 Hour labour charge for a result

stevieturbo

17,229 posts

246 months

Sunday 8th January 2017
quotequote all
Munter said:
Not changing anything yet.
3 garages baffled as to why the ABS and EPS (steering) lights come on at speed and the steering gets heavy, and eventually the car stops.
1 "trusted garage")Suggested battery, can't be the alternator. Because the battery was flat when the car was recovered, but then it was able to charge it's own battery in their test drive. I suspected the alternator, and then, the owner flattened the battery completely trying to start it.
2)Speed sensor definitely at fault...
3)No idea
Honda over the phone)No idea, next slot in a months time.
Me for a while now)If it was driving then ran out of leccy, it must be the alternator....But I'm not an expert, so just checking.
As said.

Flat battery and evidence of battery not charging correctly....1+1=2.

And if a garage cannot figure out why a car stopped and had a completely flat battery.....seriously, stay far far far far far away from that garage.

Munter

Original Poster:

31,319 posts

240 months

Sunday 8th January 2017
quotequote all
Penelope Stopit said:
Find a good auto electrician and pay the 1 Hour labour charge for a result
The "good auto electrician" is number 2. Speed sensor or "multiplug" affecting the speed sensor reading. Nothing to do with the alternator.
Number 3 charged with changing the speed sensor says "which one? can't find anything wrong anywhere. It's not the alternator".

None of the garages want to drive the car at speed in case the steering fails again.

Munter

Original Poster:

31,319 posts

240 months

Sunday 8th January 2017
quotequote all
stevieturbo said:
As said.

Flat battery and evidence of battery not charging correctly....1+1=2.

And if a garage cannot figure out why a car stopped and had a completely flat battery.....seriously, stay far far far far far away from that garage.
I agree. I just thought I'd check as I'm not an expert on car electrics. And trying to tell garages to do something, they personally don't think needs doing, via a 3rd party...is proving tricky.

FiF

43,963 posts

250 months

Sunday 8th January 2017
quotequote all
Agree with the good auto electrician advice. Update, OK see you have done that option.

Is it one of those systems where the charging is interfered with by a device to eke the last little bit out of the fuel consumption figures?

Imo they are a pita. On one of mine it only charges when you lift off the gas, until the battery has dropped to a certain level of charge. So if you have a long fast run at night, lights and wipers etc you can get home and despite the decent run the battery is not fully charged. A couple of days of cold weather and only short runs and you can notice a drop in cranking speed especially in a cold morning. The Ctek charger is a godsend on that vehicle.

Edited by FiF on Sunday 8th January 11:25

Munter

Original Poster:

31,319 posts

240 months

Sunday 8th January 2017
quotequote all
FiF said:
Agree with the good auto electrician advice. Update, OK see you have done that option.

Is it one of those systems where the charging is interfered with by a device to eke the last little bit out of the fuel consumption figures?

Imo they are a pita. On one of mine it only charges when you lift off the gas, until the battery has dropped to a certain level of charge. So if you have a long fast run at night, lights and wipers etc you can get home and despite the decent run the battery is not fully charged. A couple of days of cold weather and only short runs and you can notice a drop in cranking speed especially in a cold morning. The Ctek charger is a godsend on that vehicle.

Edited by FiF on Sunday 8th January 11:25
Even with fancy electrics, I'd have thought when the voltage starts to drop it would be designed to kick in the alternator/charging again. My suspicion is that the electrician picked up errors from a time when the systems were trying to run on 9 volts or less and starting to fail. Possibly he cleared them expecting them to return once driven. Because there's no codes my cheap £6 OBD dongle can pick up. But there's also no guarantee the dongle is any good at reading fault codes.

Penelope Stopit

11,209 posts

108 months

Sunday 8th January 2017
quotequote all
Please, a good auto electrician will sort the problem, going by what you have posted, the battery voltage is dropping and electrical circuits are failing
Question. Since when has a good auto electrician diagnosed a speed sensor to be the cause of low voltage at the battery?
Answer. Never
Find a good auto electrician and get it sorted, this is an easy fix

Mignon

1,018 posts

88 months

Sunday 8th January 2017
quotequote all
Oh lord this is a hoot and a holler. Obviously the alternator is faulty, or has an intermittent bad connection somewhere, because it keeps stopping charging. That much should be bleedin obvious. However the battery only has a default voltage of about 12v when it should be 12.6v if it were good and this then drops very quickly due to vehicle load when the alternator cuts out. So it looks like both are toast.

Simple thing to do is put the battery on a bench charger and see if it takes and holds charge back up to 12.6v. If not replace it. Also check the alternator wiring and if nothing is found then change the alternator too.

Munter

Original Poster:

31,319 posts

240 months

Sunday 8th January 2017
quotequote all
Penelope Stopit said:
Find a good auto electrician and get it sorted, this is an easy fix
IF you can find one. Yes I thought that. But at £60 a go... Cash rapidly get's tight testing the local auto electricians worthiness.

You'd think the chap top of the yell recommendations and in business for over 10 years would be a good idea...but...speed sensor.

Penelope Stopit

11,209 posts

108 months

Sunday 8th January 2017
quotequote all
Munter said:
Penelope Stopit said:
Find a good auto electrician and get it sorted, this is an easy fix
IF you can find one. Yes I thought that. But at £60 a go... Cash rapidly get's tight testing the local auto electricians worthiness.

You'd think the chap top of the yell recommendations and in business for over 10 years would be a good idea...but...speed sensor.
You and many others may think that the chap at the top of yell is the man but it doesn't work that way and i understand your frustration, i took a quick glimpse at your profile and gather you are in the Midlands, there are bound to be plenty of gooduns where you are but the problem is finding one of them, if I was you I would phone a few new car dealers and explain your problem before asking them who they use when there workshop staff can't fix one of their new sold cars that has a difficult to find electrical fault, this is a fool-proof way of getting hold of a goodun

stevieturbo

17,229 posts

246 months

Sunday 8th January 2017
quotequote all
Munter said:
IF you can find one. Yes I thought that. But at £60 a go... Cash rapidly get's tight testing the local auto electricians worthiness.

You'd think the chap top of the yell recommendations and in business for over 10 years would be a good idea...but...speed sensor.
It is quite apparent from that graph the vehicle speed sensor is working.

The alternator needs repaired, it is blatantly obvious at times it is not charging. The only other potential issue is perhaps some wiring/connections relating to the alternator.

What vehicle is it ?

Munter

Original Poster:

31,319 posts

240 months

Sunday 8th January 2017
quotequote all
stevieturbo said:
It is quite apparent from that graph the vehicle speed sensor is working.

The alternator needs repaired, it is blatantly obvious at times it is not charging. The only other potential issue is perhaps some wiring/connections relating to the alternator.

What vehicle is it ?
It's a 2004 EP2 Civic.

I agree with the diagnosis, but I didn't want to go storming into a garage going. "Look, it's the alternator, here's a chart to prove it, change it despite what you might think". And then find out actually if a cell dies in a battery it can have the same symptoms for x, y and z reasons that I didn't know about, and I've cost someone a lot of money they don't easily find, doing something they didn't need.

Measure twice, cut once type of thing.

anonymous-user

53 months

Sunday 8th January 2017
quotequote all
"Smart" charging systems use a battery State Of Charge (SoC) model and Coulomb count (current sensor on top of battery terminal) in conjunction with measured electrical system voltage to decide what alternator output to apply. Dealers can reset the SoC model using there dealer scan tool, which may need to be done if a new battery has been fitted. The system broadly speaking tries to charge as little as possible when the driver is on a positive throttle, and as much as possible when the driver has lifted off. Hence, on your graph, the system voltage increases every time the vehicle slows down!


Here's what i would do:

1) Get a wiring diagram, or look at the back of the alternator to establish how it is controlled. Generally 2 options, 1) LIN bus (single wire serial
data link to engine ecu or 2) PWM signal - dumb signal where the duty cycle of that signal represents the required alternator output.

2) Monitor that charge demand signal to establish if the engine ecu (which almost certainly controls the charging) is asking for charge that the alternator is failing to deliver, or if there is a problem in the control of the system and the engine ecu simply isn't asking for charge when it should be (faulty current sensor, voltage measurement, SoC model all screwed up etc.

3) Put a current clamp type meter around the alternator output wire so you can monitor what it is actually putting out, under various driving conditions


However, in most cases, any system voltage below around 10V would be considered critical, and the system should abandon trying to be fuel efficient and just command the alternator to max charge!

I suspect most likely an alternator issue, but it could be wiring fault or something else. Personally, if the car has been running down at 9v i'd probably throw a new battery at it anyway for piece of mind, especially if battery is old (2004 car?), but i wouldn't expect that to fix the issue (it might if the issue is a befuddled SoC model...)

Remember ALL vehicle eletrical power must be supplied by the alternator. The battery is just a temporary store, for starting and when the engines not running etc. So, if the system voltage is falling, then the electrical consumers are pulling more load than the alternator can supply. You can test by turning on large consumers (heated screens, seats, lights etc) and monitoring the alternator output and system voltage.

Edited by anonymous-user on Sunday 8th January 13:47

FiF

43,963 posts

250 months

Sunday 8th January 2017
quotequote all
Accept that the graph shows that roads peed sensor is working, wouldn't a plot versus engine revs be of use now?

Agree with earlier comment that if it's got some fancy control system should be cutting in a lot earlier.

Munter

Original Poster:

31,319 posts

240 months

Sunday 8th January 2017
quotequote all
FiF said:
Accept that the graph shows that roads peed sensor is working, wouldn't a plot versus engine revs be of use now?

Agree with earlier comment that if it's got some fancy control system should be cutting in a lot earlier.

Revs always seems to drop to -64 when at idle. Could be a feature of a cheap OBD device. I can't believe the engine would idle nicely at 800 on the dial if the ECU thought it had a negative value.

Apparently the battery was replaced between 2 and 4 years ago from the owners memory. So not original. But not fresh either.

Edited by Munter on Sunday 8th January 14:32

bearman68

4,642 posts

131 months

Sunday 8th January 2017
quotequote all
There looks to be either an intermittent or logic fault. You can see the voltage is 14v right up until 10:53, and after that, the battery is not being charged. This might well be the alternator, but if it is a smart charge system, I would imagine this is more likely. I would be tempted to energise the smart charge circuit, and do this test again, depending on the wiring diagram. (It might not be smart charge)
Another alternative is to look at the alternator output waveform to check the diodes are working OK - though normally a faulty diode will result is a significant battery drain. - Or just change the alternator as the cheapest likely alternative. (Depends on the cost of the alternator)
I am an auto electrician

paintman

7,669 posts

189 months

Sunday 8th January 2017
quotequote all
Would a faulty diode not illuminate the ignition/charge warning light - even faintly & possibly difficult to see other than in the dark?

Had a recent issue with my RRC - A127 alternator - where the warning light would come on faintly once during a journey & then go out & stay out. Tests with multimeter after a short run & with engine still running & everything off produced 13.8 to 14.0 volts at 2000rpm. Replacing the regulator (cheap & easy on those, about £7 & took me 5 minutes with the alternator in situ) put it back to 14.3/14.4 volts at 2000rpm which I'm told is what I should be seeing & - so far - the light has stayed off. I do wonder if I should do the diode pack as well?


Edited by paintman on Sunday 8th January 19:30