lynall said:
Ah see now trucks were always 24v, apart from the yanks who love 12v for some reason.
Then we have the newer scanias that everyone in the game calls new gen, and they are 24v chassis with the cab being 12v.
Bet you cannot guess who owns scania these days?


Thats right the Vag group!
Click to expand...
So, as I said , known tech.
From what I may have misunderstood, or not, the cars are needing to use more voltage than the battery can supply so it presumably relies on the alternator at those times. Bonkers. Or is it? I am so ignorant of electrickery. :(
 
Having just watched a utube vid on here a few moments ago about a German engineer fixing a transmission leak, it turns out if you change the trans fluid on a disco hse 4 you have to recalibrate summat to let the car you know its fluid is a bit different, i.e. new otherwise the gearchange gets clunky. Utter madness.

Col
 
Colthebrummie said:
Having just watched a utube vid on here a few moments ago about a German engineer fixing a transmission leak, it turns out if you change the trans fluid on a disco hse 4 you have to recalibrate summat to let the car you know its fluid is a bit different, i.e. new otherwise the gearchange gets clunky. Utter madness.

Col
Click to expand...

D3 is the same, basically recalibrates the working of the box so it sorts itself out.

Some trucks you have to tell it that you have replaced the clutch, it will work but might crunch as the box is semi auto and does not have synchros, so the engine and gbox ecu have to match up shaft speeds for a clean change.
 
Stanleysteamer said:
So, as I said , known tech.
From what I may have misunderstood, or not, the cars are needing to use more voltage than the battery can supply so it presumably relies on the alternator at those times. Bonkers. Or is it? I am so ignorant of electrickery. :(
Click to expand...


I think that pretty much sums it up, they are greedy bar stewards.
There was some talk a while back about cars going to 48v systems, think evs stopped that in its tracks.

Fils ev has a separate 12v battery, and if that goes flat the ev will not function!
 
lynall said:
I think that pretty much sums it up, they are greedy bar stewards.
There was some talk a while back about cars going to 48v systems, think evs stopped that in its tracks.

Fils ev has a separate 12v battery, and if that goes flat the ev will not function!
Click to expand...
Still more mad.
And with the expansion of the London ULEZ announced overnight with no warning there must be a shed load of people wondering how the heck they are going to get around. Yet more EVs and modern cars all with their greed for new batts.
Think I must buy some shares in Varta or some other compny!!:(:(
 
Stanleysteamer said:
the cars are needing to use more voltage than the battery can supply so it presumably relies on the alternator at those times.
Click to expand...
FYI all the cars are relying on the alternator/generator once started, the battery is there only for starting, for auxiliary power when the engine is not running and to keep the alarm and other systems "alive" when it's paarked/locked, that's the purpose of the battery ;)
 
sierrafery said:
FYI all the cars are relying on the alternator/generator once started, the battery is there only for starting, for auxiliary power when the engine is not running and to keep the alarm and other systems "alive" when it's paarked/locked, that's the purpose of the battery ;)
Click to expand...
@sierrafery I do love it when you put your teacher's hat on!;):):)
I never thought that the car relied soley on the battery. If it did it wouldn't get far.:rolleyes:
So it relies on the alternator to provide power and the batt to store a load to be used when the alternator isn't running. But as most alternators only supply up to about 14. 5 volts. Yet a previous poster (#18) said that some cars need higher voltage than that, it would seem that at times the battery needs to take up the slack. Or the newer cars need a more powerful alternator. As I can't see how a 12 volt batt normally rated at rest at 12.6 volts, can suddenly whoosh itself up to 15 volts.)
The latter makes more sense to me.
And in coasting through previous posts I read some posts I had missed including at least one from yourself which explained the battery management thing.
So, yes I'm thick, but not completely so!!!
Sometimes I need to poke the anthill with a stick to make the ants run out and explain themselves!!!:D:D:D
 
sierrafery said:
I'll try to make it short cos they overcomplicated a simple thing: The BMS(battery monitoring system) is very complex, it is tracking the battery state of charge and age and stores them in it's volatile memory so any sudden change of parameters will mix it up, not the case when a charger is connected to the known battery. If you don't reset the BMS when you put a new battery it will work on the old stored parameters and will treat the new battery like an old one. This way the charging management will not be optimal for the new battery which can then lead to decreased life of it and other associated oddities so not a catastrophic thing if it's missed but good to be done
Click to expand...
Thanks for this, get it now!
(As far as I get anything to do with new electronix!)
 
lynall said:
I think it is simply that the modern cars electric demands are so high that the old fashioned max voltage of 13.8/14 is simply not enough, so they have that ramped up to just over 15volts, and to stop the battery dying they need smart tech to control it!
Guy I work with knows someone who works at LR and he tells me that the decent techs do all the routine servicing as that is where the money/bonus are at, and they let the newbies do all the diagnostics work, so that is why they are back at the dealership time after time!

PWM signals are quite interesting, have a google and a read, even the heater fan in the D3 is PWM controlled!
You can buy PWM controller on pcb for a few quid to play with some old fan motor etc
Click to expand...
WOW!!!!
I actually remember reading about this donkey's years ago as a way of saving on your electricity bill if you had to heat up things like night storage heaters, or as the articles in places like Wiki indicate, running fans etc.
If reliable I get the feeling they should be, or maybe already are, in a a lot of electrical stuff.
I love this forum, I learn so much, even though some comes with pain!:):):)
 
Colthebrummie said:
Having just watched a utube vid on here a few moments ago about a German engineer fixing a transmission leak, it turns out if you change the trans fluid on a disco hse 4 you have to recalibrate summat to let the car you know its fluid is a bit different, i.e. new otherwise the gearchange gets clunky. Utter madness.

Col
Click to expand...
Was that the one where he made a bit out of aluminium and glued it in place with JB Weld?
Yep!
Bonkers!:rolleyes:
 
Stanleysteamer said:
But as most alternators only supply up to about 14. 5 volts.
Click to expand...
most alternators would output around 20V(or more) which drops to around 14 on the battery's internal resistance as long as there's no electronics to boost that up. If you spin up an alternator without anything connected to it you'll see
 
sierrafery said:
most alternators would output around 20V which drops to around 14 on the battery's internal resistance as long as there's no electronics to boost that up.
Click to expand...
Aha!
Thanks for filling in yet another gap in my knowledge.
This must be why they say never to run an engine with the battery not connected but the alternator still turning
Or am I wrong again?
Still got my skool cap on!!;)
 
Stanleysteamer said:
Was that the one where he made a bit out of aluminium and glued it in place with JB Weld?
Yep!
Bonkers!:rolleyes:
Click to expand...
It was that car but an earlier vid of him buying the car from a dealer. The test drive showed clunky gear change which was caused by dealer changing trans fluid but not recalibrating to tell the gearbox it had new fluid.

Col
 
Colthebrummie said:
I think if car manufactures are now making their cars to need reprogramming after simple routine tasks like changing a battery or certain fluids, they should include a relevant code reader and reprogramming tool with the vehicle.

Col
Click to expand...
I think I said this as well years ago, it stands to reason that the diagnostic should either be built in, after all, they manage it with the sat nav, or a small dedicated reader should be provided with the tool kit. After all, the manufacturer thinks the driver is capable of changing a tyre don't they? Or do they?
But no, they just want to tell the driver that he has a problem but to keep the problem a secret, that they can then make him/her pay to have discovered.
Logically if not, then why give a driver a dipstick or allow him/her to top up tyre pressures?
Stinks.:mad:
 
Stanleysteamer said:
I think I said this as well years ago, it stands to reason that the diagnostic should either be built in, after all, they manage it with the sat nav, or a small dedicated reader should be provided with the tool kit. After all, the manufacturer thinks the driver is capable of changing a tyre don't they? Or do they?
But no, they just want to tell the driver that he has a problem but to keep the problem a secret, that they can then make him/her pay to have discovered.
Logically if not, then why give a driver a dipstick or allow him/her to top up tyre pressures?
Stinks.:mad:
Click to expand...

spot on there mate , so nice where we always go out our way to help each other , well apart from the ones who can’t be bothered to say plse or thk u , lol

Plus what a massive benefit it is these days where diagnostics have come down dramatically in price allowing us to work on our own motors and saving us a fortune from garage fees
 
Stanleysteamer said:
I think I said this as well years ago, it stands to reason that the diagnostic should either be built in, after all, they manage it with the sat nav, or a small dedicated reader should be provided with the tool kit. After all, the manufacturer thinks the driver is capable of changing a tyre don't they? Or do they?
But no, they just want to tell the driver that he has a problem but to keep the problem a secret, that they can then make him/her pay to have discovered.
Logically if not, then why give a driver a dipstick or allow him/her to top up tyre pressures?
Stinks.:mad:
Click to expand...

Nice to see some else on my soapbox, or one of them!! :)

Sons BM doesn't have a dipstick - the 'puter tells you how much oil is in the engine - but not the gearbox, which is "sealed for life" :rolleyes: :mad::mad:
 
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