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Messages - LC0112G

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1
Omega General Help / Re: Head gasket?
« on: 28 February 2024, 20:46:07 »
You can buy head gasket test kits from eBay for not very much...
https://www.ebay.co.uk/itm/284004648824

They're easy to use, and will detect any combustion gasses that end up in the water. The coloured dye starts off blue, and will turn yellow if there are combustion gasses present, like this...

https://www.omegaowners.com/forum/index.php?topic=148724.msg1988834#msg1988834

If the dye goes yellow, then you can be pretty certain you've got a head gasket problem.

2
General Discussion Area / Re: New car technology .
« on: 02 February 2024, 09:59:15 »

If you google "Mercedes eco-start-stop-technology-guide-pdf", and click on the link to the glaowners.com, you'll get a pdf describing the system. There is a whole load of guff in there, and I checked it all on my car. The only thing that is out of limits is the battery voltage drop.

What I'm unsure about is if it's the drop on the small auxillary battery, or the main 'big' battery. But I can see on the iCarsoft that the 'battery' voltage dips to between 10 and 11V on my car (from > 12.5V) , and that's enough to disable stop start.

That's not what the document says at all.

Quote
If the voltage dip (U < 11V) at engine start is to great, the engine stop is deactivated for t = 1 minute in order to recharge the Eco start/stop function battery

Its not actually defining what it considers to great and it also is only delaying activation of the stop start for 1 minute. The rest of the doc is referring to 'available electrical power' which is the SoC.

Also, be absolutely assured that your scan tool will not be able to report the mS long volt drop at cranking as its just reading messages at random intevals, you need an oscilloscope on the starter terminal to do that. The volt drop will be down to 9V or less on a cold engine crank (remember, this is my day job on the design side  :y)

The scan tool does show the drop - it plots a nice little graph. AIUI the SAM measures the voltages and stores them in a ring buffer at a high-ish speed. True the scan tool only 'samples' the data at a slow rate (<5 per second), but the SAM reports the minimums/maximums observed in that interval. So you can see the dips and peaks in the voltages.

You can't directly measure SoC either. All you can measure is current draw and terminal voltage - and the Merc system does both. From those two values you can estimate SoC (by integrating the charge/discharge rates) - but these are derived, not measured values.

What I *Think* happens is that during cranking, the car uses the main battery for the starter motor, and a few critical other systems. However, non critical systems are switched over to the Aux Battery during cranking, and it's this battery that is showing the voltage drop. If it drops to < 11 V then Start/Stop is disabled (t = 1 minute in order to recharge the Eco start/stop function battery).  However, if the battery does not recharge to > 13V in that 1 minute period, then...

Quote from: Mercedes
If the open circuit voltage (U > 12.5V) of the ECO start/stop function additional battery is too low, the alternator's output limitation (alternator management) (except model 212.095) is deactivated so that the ECO start/stop function additional battery can be charged.

If the voltage dip (U < 11V) at engine start is too great, the engine stop function is deactivated for t = 1 minute in order to recharge the ECO start/stop function additional battery.

The ECO start/stop function additional battery is only connected if the output limitation of the alternator is not active and the on-board electrical system voltage is high enough (U > 13V). It is disconnected again if the limitation of the alternator is active or if the on-board electrical system is severely overloaded.

So if the Aux battery dips < 11V and then doesn't charge to > 13V, stop/start is disabled. It doesn't say it explicitly, but experiments seem to show that the Aux battery needs to charge to > 13V within 1 minuite, or Stop/Start is disabled for the entirity of that engine start.

3
General Discussion Area / Re: New car technology .
« on: 01 February 2024, 18:54:16 »

They do!

The Merc system monitors the battery voltage drop during cranking. If the voltage drops below (IIRC) 11.5V then it disables Stop/Start. It'll still start all the way down to less than 9V.

It's not really the state of charge that matters, but the batteries internal resistance. The resistance increases as the battery ages, so it can be fully charged (>13.7V) but still drop enough during cranking to disable the Stop Start.

Mine's been like it for over a year. Behaviour confirmed by iCarsoft scanner. New AGM Stop/Start battery would no doubt cure it, but why on earth would I want to do that! £300 to re-enable something I don't want.

If they do then they are fools! (I am confident they don't as we use the same setup!), they wouldn't meet ISO 16750-2 under those conditions

Monitoring the terminal volts under load tells you little about the battery condition as there are to many variables, temperature being the very significant one, as the chemical reaction in the battery is much poorer at low temperatures and so the VBatt drops much lower. There are also variables with connector/cable ageing, engine types and a whole host of other things.

The SoC is the critical measure for start stop, as it is the only means to tell if you have the reserve to complete repeat re-starts, its also the only viable means to determine battery health by checking the batteries ability to absorb energy  :y

If you google "Mercedes eco-start-stop-technology-guide-pdf", and click on the link to the glaowners.com, you'll get a pdf describing the system. There is a whole load of guff in there, and I checked it all on my car. The only thing that is out of limits is the battery voltage drop.

What I'm unsure about is if it's the drop on the small auxillary battery, or the main 'big' battery. But I can see on the iCarsoft that the 'battery' voltage dips to between 10 and 11V on my car (from > 12.5V) , and that's enough to disable stop start.


4
General Discussion Area / Re: New car technology .
« on: 01 February 2024, 14:28:43 »
....
Coded the stupid start stop malarky off mine, Only kicks in if I have it in Eco Plus mode..... Which I never do!

My ML's stop/start has stopped working all by itself  :y I suspect the main battery is a little low, though it never hesitates to start up.

Keep an eye on it, the stop start systems do not look at the cranking ability, only the state of charge, if its stopped working then the battery is probably not recovering to more than 85% SoC which is plenty to crank but, shows the battery is deteriorating and they have a habit of dropping off a cliff after this point.  :y

They do!

The Merc system monitors the battery voltage drop during cranking. If the voltage drops below (IIRC) 11.5V then it disables Stop/Start. It'll still start all the way down to less than 9V.

It's not really the state of charge that matters, but the batteries internal resistance. The resistance increases as the battery ages, so it can be fully charged (>13.7V) but still drop enough during cranking to disable the Stop Start.

Mine's been like it for over a year. Behaviour confirmed by iCarsoft scanner. New AGM Stop/Start battery would no doubt cure it, but why on earth would I want to do that! £300 to re-enable something I don't want.

5
General Discussion Area / Re: New car technology .
« on: 29 January 2024, 10:05:05 »
Worst thing I've had so far was a rental car in the USA. There was something not right with the rear view mirror - it was basically out of focus. Turns out it was a camera/screen, not a real mirror.

Problem is I'm long sighted. That means I need glasses to see things close up (less than 2-3 yards) but can see distant things ok. So in a real mirror, where the objects really are 10-100 yards away, no problem. However, for a camera screen you actually have to focus on the screen, which in the cases of a 'mirror' is less than a yard away - so I need glasses to see the image properly. When your normal 'scan' is ahead, dash, mirrors, repeat, then the time taken to re-focus on the rear view mirror is noticable, and after a while quite a strain on the eyes.

Thankfully at the first stop I managed to find a switch to turn the camera off, and it reverted to a true mirror.

6
General Discussion Area / Re: Alaskan Door escape
« on: 25 January 2024, 10:28:26 »
Did I hear that United was throwing in the towel, and looking at getting a load of 321neo's instead?

Trouble is, the order book is full for all A320/321's stretching out till 2028 so even if ordered now unlikely to be many in service till 2030 ish.

Does look like Boeing have flogged an old horse one too many times instead of biting the bullet a starting a clean sheet design (5-10 years ago).

7
General Discussion Area / Re: Alaskan Door escape
« on: 09 January 2024, 11:06:13 »
Spudulike does due to the density... 737-8200 is a Ryanair only 737-9 aircraft variation. But is fitted with an exit door which is secured differently into the same frame with cam locks and door lock sensors.

And I can't believe that no one would not take advantage of a seat sized hole to fit the interior.

I stand (sit) corrected. Not flown FR since pre pandemic. However, the extra doors on FR are proper emergency exits, with a seat row removed, so hopefully not affected by whatever the 'plug door' issue turn out to be.

8
General Discussion Area / Re: Alaskan Door escape
« on: 09 January 2024, 10:22:26 »
I wonder if Ryanair will charge a premium for non window seats?

Pay £10 priority to guarantee you WON’T get allocated a seat next to an innocent looking window which is actually a “ plug” with loose bolts.

It is like something out of squid games!

Ryanair (and TUi) are buying/leasing Max8. Max8 doesn't have the mid cabin exit.

9
General Discussion Area / Re: Alaskan Door escape
« on: 09 January 2024, 10:21:07 »
The fact they seem to be finding the same/similar fault on some United Airlines planes suggests to me that it's not an Alaskan Airlines servicing issue.

The B737 fuselages are actually built by Spirit Aviation (in Witchita Kansas), and then moved by rail from Spirit to Boeings final assembly in Seattle. This is correct - they was a rail accident a few years ago where several fuselages were wrecked. One rumour going round is that in order to prevent dirt and grime getting into the airframe whilst in transit, Spirit fit the the main doors and door plugs. Once in Seattle the main doors and overwings are removed by Boeing for proper emergency exit fitting, but the plug doors are not. If Spirit only put the doors in 'loosly for transit' and don't fit them properly expecting Boeing to do that during assembly, then we have the required holes in the cheese. 

10
General Discussion Area / Re: Capacitors
« on: 08 January 2024, 21:06:51 »
Capacitors - particularly Electrolytics - are funny beggars. There are lots of other parameters other than capacitance and voltage that matter - things like ESR and AC cycle current. If at all possible, try to look up the exact specs for the brand of capacitor you are replacing, and use one that matches those specs as closely as possible - ideally the same brand.

Not all 680uF 6V3 caps are equal, and going for the cheapest you can find is rarely a good idea.

11
General Discussion Area / Re: Back to school today!
« on: 08 January 2024, 20:58:32 »
Surprises me how many People never bother to learn the lingo of the country they're in.   :-X

Wales instantly springs to mind!  ;D

I think it's something like 85% of people living in Wales can't speak Welsh.  :-\

A nephews girlfriend is a Taff. She says that welsh students now do have to study Welsh at secondary school (O levels or whatever it's now called). Also if you continue in further education to do A levels you have to continue taking Welsh. She moved to an English college to do her A levels.

12
General Discussion Area / Re: Alaskan Door escape
« on: 07 January 2024, 18:44:00 »
It's an additional emergency exit that can be fitted to what is called 'high density' layouts - basically where the whole cabin is packed with as many seats will fit in the sardine can. Alaska Airlines don't do that - they have first class and buisness class, so the max number pf PAX on their B737-9's is only 170 odd. For that number of seats (up to 200 IIRC) the rules only require 8 emergency exits - which on a 737 are two front, two rear and 4 over-wing.

In their wisdom Boeing have fitted all Max-9s with provision for 10 exits - the additional ones are in the middle of the rear cabin each side - and if fitted and useable the aircraft can legally carry (IIRC) 239 PAX. However, in low density seating, this extra exit is sealed and blanked off, with all the hinges, handles and emergency slide stuff removed to save weight. Inside the cabin the passengers can't tell that the 'porthole' window they're looking through is any different from any other window, and there is no way for them to use this extra exit in an emergency.

So the question becomes how/why does a supposedly sealed emergency exit 'blow out'. Duff Boeing Design, Duff Boeing Manufacturing or Duff Alaska Airlines servicing would appear to be the obvious candidates.   

13
General Discussion Area / Re: Capacitors
« on: 07 January 2024, 18:30:51 »
If you're not in a super hurry, PM me the RS or Farnell Part numbers and I can order them through our work account. If they're ordered tomorrow (Monday) they should arrive Tuesday and you might get them by Wednesday/Thursday.

14
General Discussion Area / Re: Haneda incident.
« on: 05 January 2024, 20:13:55 »
Also, my mind keeps returning to an incident in the Middleish East involving a widebody aircraft that had an emergency landing due to a fumes event in an AC pack and they taxied off the runway and stopped. Everyone on board was asphyxiated but had they shutdown and evacuated as soon as they stopped everyone would have survived :-\

Damned if I can remember the specifics though...

Point being, as soon as it becomes more dangerous to stay, you need to be out the door.

Saudia 163. https://en.wikipedia.org/wiki/Saudia_Flight_163

15
General Discussion Area / Re: Water, Water, Everywhere.
« on: 05 January 2024, 20:11:11 »
The Somerset levels have been flooded since the end of November. The river and fields in/around Ilchester are as high as I've seen them for 20 years. Much of the airfield at RNAS Yeovilton is underwater. The A37 north of Yeovil has contraflow traffic lights due to flooding.

But you don't hear us complain. Because we're nowhere near a city and no-one gives a fvck till Surry gets a bit damp.

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