[nazali]

Well, I'm now using my car as I intended (not necessary as BMW intended - according to them at least)

Since my battery replacement, short stop starts, and also doing 10km to work one way.

I've been using the BA9 to monitor it, I also put a voltage checker device/gauge (cheap old thing) it's actually pretty accurate, although the voltage change seems a little sluggish.

So To confirm what a lot of people have been saying (I've now been seeing wiv me own eyes)

When I unlock the car from sleep, it's around 12.3volts, start the car up and get going, (in the 13's, 13.3 ? from memory) have been using the electrics as per normal

BUT I have noticed, when I floor the car, voltage does not rise, neither does keeping it on a nice speed.

BUT when I coast or come of the gas, BOOM the volt's shoot up to 14.7

SO indeedily the alternator looks like it is only charging the battery on coasting ! and only maintaining the electrical equipment at all other times.

My SOH's and SOC are all ok, mid 90th percentiles

[MarcoZandrini]

You really should take the car on a 30+ mile trip at highway+ speeds on a weekly basis. This gets all of the fluids up to temperature and it boils off any condensation in the crankcase. It will also charge the battery up.

[nazali]

That's actually a great idea, and one I was trying to do.
Although that's not going to put a charge in the battery
(not unless I coast a lot of the way )

Originally Posted by MarcoZandrini

You really should take the car on a 30+ mile trip at highway+ speeds on a weekly basis. This gets all of the fluids up to temperature and it boils off any condensation in the crankcase. It will also charge the battery up.

[jzeiler4]

If you are getting ANY voltage reading higher than the 12.7 at any time, then it IS charging the battery. The reason it goes to 14.5 when coasting means they are using the alternator to use maximum energy from the engine coasting while fuel flow is zero. In other words the engine is NOT making power (fuel cutoff) and coasting kinetic energy is powering the alternator.

[TrboMike]

I might be wrong, but I thought our car had a clutched alternator so it doesnt charge during accel, only during cruise or decel. Like an a/c compressor thats only clutched while your A/C is on.

[freakystyly]

It's more computer controlled than simply on only when coasting/braking.

P# 61219117877 is the IBS that reports the battery voltage to the DME. It will be telling the computer when there's low voltage and to start shutting things down to save power.

I think they started using these around the 2000 era.. maybe before in Rolls Royces.

If you google "e92n55 ibs" it has a ridiculously detailed pdf explaining how the system works on the previous generation E chassis cars. I can only imagine the F chassis is the same with some minor changes.

[Shovelman]

Ok, I read thru the training module at that link. Our cars have very complex power management. Some communications are even via fiber optics. When I started driving, the voltage regulator was a 'black box' that could not be repaired with my skills. The rest of the electrical system was accessible. Now the 'black box' is from bumper to bumper, with the exception of lamps and battery. Mechanics are not paid enough.

[aerobod]

Originally Posted by Shovelman

Ok, I read thru the training module at that link. Our cars have very complex power management. Some communications are even via fiber optics. When I started driving, the voltage regulator was a 'black box' that could not be repaired with my skills. The rest of the electrical system was accessible. Now the 'black box' is from bumper to bumper, with the exception of lamps and battery. Mechanics are not paid enough.

With the right tools it is often easier to diagnose issues with cars than it ever was due to the ability to home in on problems when specific modules, sensors or components are failing. It just means that an automotive technician ("Mechanic" is perhaps a dying bread that don't have the right skills anymore) has to become comfortable with software based cars, as opposed purely mechanical ones.

[nazali]

don't you mean "computer analyst" ?

Originally Posted by aerobod

With the right tools it is often easier to diagnose issues with cars than it ever was due to the ability to home in on problems when specific modules, sensors or components are failing. It just means that an automotive technician ("Mechanic" is perhaps a dying bread that don't have the right skills anymore) has to become comfortable with software based cars, as opposed purely mechanical ones.

[nazali]

"Hello Maam, I'm John calling from Microsoft BMW support , we are wishing to let you know, that your current BMW model has a virus, I can fix it for $400 , do you have a walmart near you, good, please go and buy $400 in itunes cards, and I can resolve.
Oh no, please don't drive your car it is very unsafe to do so, it might get burned"