# Interesting DIY DEF service lesson.



## Doug Huffman (Apr 25, 2015)

A few weeks ago I intended to top off my passive DEF tank in preparation for road trip south. It only took a liter and that slowly.

We had errands to run after Church today. Later I figured I’d charge the battery to make up for Milady Wife’s use of the bun warmers and so on. While under the hood I tried again to add DEF.

The passive tank took a gallon and a half, and quickly. 

The passive DEF tank is passively heated by the nearby exhaust system and the errands after church took about an hour. It could have been longer but we have weather blowing in, and the windward side of the X5 was a solid sheet of ice before I was able to chivvy Milady Wife home.

And DSL is down.


----------



## n1das (Jul 22, 2013)

How cold was it outside when you tried to add DEF the first time?


Sent from my XP8800 using Tapatalk


----------



## Doug Huffman (Apr 25, 2015)

n1das said:


> How cold was it outside when you tried to add DEF the first time?


Real cold. maybe -20°F.

12°F is pretty nice recently here. ATM it***8217;s -3°F at the airport K2P2 a couple of miles away. That***8217;s 15 degrees below DEF freezing temperature.

In 24 hours we leave for the South for two months. This winter here may turnout to be the new normal but it is exceptional for now. The NWS CPC Climate Prediction Center shows our ***8212; well, I went off to refresh my memory, but the probability is indicated by such a dark shade of blue that I can***8217;t see the average temperature isotherms. I think that our average temperature is about 20°F right now.

Traditionally St. Patricks Day is when the sugar Maple taps will be out, as warm days above freezing and freezing cold nights is what pumps the sap, the expansion of water as it freezes. That ain***8217;t gonna happen this year. But the bar will be full of guys drinking ethanol anti-freeze.

Here is about ten days temperature record at Northport, Wisconsin on the warm water about ten miles away.
http://www.ndbc.noaa.gov/show_plot.php?station=npdw3&meas=atmp&uom=E&time_diff=-6&time_label=CST. NOAA National Data Buoy Center.


----------



## robnitro (Aug 3, 2016)

Wow it must have been very cold! I forget the freezing point of urea, but wow!

You don't need to charge the battery because your wife uses the seat heaters.
It's not draining your battery when the engine is on. The alternator is what powers them and I never have seen a voltage dip putting both front seat heaters on along with the rear defroster. The voltage being at 14.6 v means none of the energy is coming from the battery, plus it is charging the battery the same as if it were 14.6 with no heaters on. The only difference is how much current is coming out of the alternator.


----------



## Doug Huffman (Apr 25, 2015)

I am of the impression from BMW technical descriptions of Intelligent Generator[sic] alternator Control that my X5 charges the battery only on overrun.

newTIS.infobeta
Home / BMW E70 X5 xDrive35d SAV / Repair Manuals and Technical Data / 61 General vehicle electrical system /
00 01 07 (149) Electrical systems E70, E71

https://www.newtis.info/tisv2/a/en/.../61-general-vehicle-electrical-system/2DbnQjI

A full days errands (PO, bank, grocery), usually Friday, don't extend ten miles round trip. Sunday, Church, is about four miles round trip. Recently only the main roads are clear of snow, while side roads are about six inches with significant drifts, so the X5 is under power, not overrun, mostly.

I charge the battery usually Wednesday year around, 5 - 10 AH summer and winter. I attribute the longer charges in winter to more use of electric heat, bun warmers, rear window, and the 1000 Watt 80 Amp PTC heater.


----------



## robnitro (Aug 3, 2016)

The IGR function is not used on our US based e70s as I replied to your thread https://www.bimmerfest.com/forums/showthread.php?t=1318861

Simple test, set up the hidden menu or an obd scanner and watch the voltage... It doesn't follow what IGR does. Anyway, I have a 7 mile city commute and according to the battery charge readings of carly, 90% of the hours are at the highest charge tier.

The only battery user is the starter, preglow and time the car stays on after locking doors (30 mins timeout!).

You don't have to believe me, but verify for yourself and you won't need to worry to charge it due to using options.

I do advocate a top up charge for equalizing the cells and that's a good habit but weekly might be too much for me with street parking, hehe.


----------



## robnitro (Aug 3, 2016)

I looked into this a year ago when I read that elsewhere and was concerned. 
In testing and later on with coding, I confirmed that it is not enabled in our US models.

Do you have 1CB in your option order?

See here for what the document explains, the engine management does IGR- Intelligent Alternator Control
Option ACEA_CO2 is what allows for it to be ENABLED.
Without 1CB in your options order, you do not have it enabled.
And this is confirmed if you looked at a voltage meter. It does not drop voltage- stop charging the battery as IGR explained above.


----------



## dzlbimmer (Jul 16, 2017)

Doug gets a cookie when his car makes it to 2027 on the original battery. 
Had to.


----------



## FredoinSF (Nov 29, 2009)

dzlbimmer said:


> Doug gets a cookie when his car makes it to 2027 on the original battery.
> Had to.


Nope...

https://www.bimmerfest.com/forums/showthread.php?t=978530


----------



## SPL15 (Feb 3, 2019)

I've monitored the alternator voltage when driving around town & on the highway, in 10F to 40 F temps; it certainly appears that IGR on my 2012 x5d is not enabled, as reported voltage is always 14.4+ Vdc (even at idle w/ a lot of "stuff" turned on, which is not very common unless the alternator is specially tuned to do it)... Unless you're seeing reported system voltages drop down to 12.5 - 13.0 volts or so when the car is at a steady pace for a small period of time (ie not at idle), then you do not have IGR enabled... The 40+ Farads (yes Farads) of capacitive charge on the battery will dissipate rather quickly under any appreciative load on the battery, where true charge state voltage will develop & should quickly reduce down to 12.6 - 12.8 volts on a high quality (low ESR), healthy, & FULLY charged AGM battery w/ minimal loading once the capacitive surface charge depletes, where measured terminal voltage will decrease further below this if there is any appreciable load (due to ESR) & as charge state decreases.

Have designed several "intelligent" lead acid battery charging electronics for both commercial & consumer products; 14.4Vdc is the standard charge voltage for 25C / 77F degree battery temp (13.8 Vdc is standard "Float Charge" @ similar temps), where charge voltage should be increased, according to a linear function, as temperature reduces, in order to actually charge the battery... At temps nearing 0F & below, I'd want to see charge voltage to a 12V lead acid battery more around 15.5 volts or so (depending on exact chemistry / type of the lead acid battery); however, this will not be the case, even in "Intelligently monitored" battery charge systems that are on newer BMW's... Comically enough, my old 1997 Cadillac STS actually did the "Intelligent" charging system right, where alternator voltage increased to 15.5Vdc when monitored battery cathode temps dipped down into the single digits & below... Original factory wet cell lead acid battery located under the rear seat was 8 years old when I purchased the car, & still working perfectly fine at 12 years old when I sold the car...

One would be amazed at the real world service life of a high quality AGM battery when properly charged according to cathode temp w/ minimal depth of discharge. For my home's backup battery system, I'm using retired Enersys telecom batteries that are 15 years old & load test within 5% of brand new AH spec during my annual discharge & recharge cycling. 20+ years of tangible / useful service life (ie 80% capacity) from a quality AGM battery on float charge duty w/ transient high current draw with minimal depth of discharge (ie an automative starting battery) is very realistic if ambient temperatures are moderate within 65F - 85F or so (obviously not the case with automotive applications; however, 10+ years of useful service life is more than possible with a competently designed charging system w/ a battery not located in the engine compartment.

Assuming a healthy battery & factory charging system; the 5-10AH worth of charge being put into your battery via an external charger, is due to normal & predictable undercharge conditions from a charging system that does not properly boost charge voltage in cold weather, and / or a battery that is not being fully replenished due to short drives / frequent starting regardless of ambient temps (in addition to losses due to parasitic resistances, and / or inherent leakage current of the battery)... On a 100AH capacity battery, 5-10AH, equates to 10% or less depth of discharge (hardly appreciable), where it takes an hour or more at a proper full charge voltage to get things fully topped off to 100% once you reach 80% charge state (depending on battery type / chemistry)... As a universal rule for just about ANY rechargeable battery type: The time it takes to reach 100% charge state from an 80% charge state, takes nearly as long as it takes to reach 80% charge state from a 20% charge state (assuming a properly designed charger circuit w/ a constant current bulk charge function w/ adequate current capacity for the battery capacity / chemistry being charged, w/ a finishing "final charge" to 100% that is constant voltage once the battery reaches 80% charge, where internal impedance increases & prevents high current from being forced into the battery without excess / damaging terminal voltage).

Degraded / cheap lead acid batteries are much worse in this regard, where they'll more quickly / falsely reach the "80% charge state" terminal voltage in a progressively shorter time frame compared to the "final charge" time needed to actually charge to 100% capacity, as internal impedance increases due to the plate degradation caused by a constant state of partial discharge. The hallmark trait of a worn out lead acid battery is that unloaded terminal voltage measures well within reason, but it cannot produce the necessary current at the necessary voltages to turn over the starter motor; this is due to high internal impedance, where this same high internal impedance causes slightly degraded batteries to need hours of time at 14.4+ volts to actually reach 100% state of charge... In addition, a slightly discharged lead acid battery quickly sulfates & degrades in high temperatures, and is MUCH more susceptible to mechanical damage due to freezing at lower temps, thus compounding the issue that leads to short automative battery life expectancy. Considering the cushy location of the E70 battery w/ the VERY mediocre reported / anecdotal life expectancy of the batteries, one should rationally conclude that our "Intelligent" E70 battery monitoring / charging system, is in reality, not very good at all...


----------



## Doug Huffman (Apr 25, 2015)

Voltage in a parallel connected DC system is the voltage of the highest output voltage component. Observing voltages in an operating system is meaningless, all branch voltages will be the same. Observe component branch currents.


----------



## robnitro (Aug 3, 2016)

Doug Huffman said:


> Voltage in a parallel connected DC system is the voltage of the highest output voltage component. Observing voltages in an operating system is meaningless, all branch voltages will be the same. Observe component branch currents.


I get what you're saying, that the alt can stop charging and voltage will not drop as current comes from the battery... But as spl15 mentioned, the capacitive charge dissipates very quickly.

Also any battery without alternator on would be under minimum 40 amps load, more if you have your wife's seat heaters, ptc and so on. PTC alone maxed would be around 80amps.

Dropping even a 20a test load (heavy duty airfield lighting bulb) on my recent replacement agm battery which was sitting on a 10a charger at around 14.8v eq charging made the voltage drop to 13.5v with a steady decline. This means that even on a 10a load, a 90ah new AGM will drop voltage.

So tell me, if the DC bus voltage is at 14v or more, how could that ever be that the battery is being discharged?

Maybe SPL can help with this.
Oh and SPL, have you noticed an occasional short voltage dip to 13s volts at low rpm when off the throttle? I see it and my friend also gets it on his e60 530xi. He thinks it's a short test to verify the battery can take a load.


----------



## Doug Huffman (Apr 25, 2015)

The battery is load tested at each start as the minimum voltage at highest current is noted.


----------



## SPL15 (Feb 3, 2019)

Doug Huffman said:


> Voltage in a parallel connected DC system is the voltage of the highest output voltage component. Observing voltages in an operating system is meaningless, all branch voltages will be the same. Observe component branch currents.


1st part is true; however, your second statement is a bit shortsighted in the scheme of an automotive charging system, as well as in the real world where super conductors are not common in most consumer, commercial, industrial electrical power distribution systems...

Voltage drop across conductors / series shunts in a branched parallel power scheme is a VERY useful datapoint for determining relative current flow / load, so much so that this phenomena is used in an intentional manner to indirectly measure current flow from & to the battery via the pseudo shunt resistor attached to the IBS module (ie measuring a voltage drop across a parasitic resistance to determine current magnitude & flow direction). A series shunt and / or measuring voltage drop on a conductor is obviously not the same thing as measuring across the entire voltage potential / load; however, the same exact parasitic resistances exist & can be measured the same, albeit with far less accuracy & precision, where the same conclusions on how much & the direction of current can be derived w/ multiple measurements at different points / parallel branches.

Yes, ideally current would be measured thru each branch circuit to determine magnitude & direction of flow; however, in a properly functioning automotive electrical system, this is simply not needed to gauge whether a 12 volt lead acid battery has current flowing in, or out, due to inherent, well known, & very predictable properties as an active load.

If voltage across the battery terminals is higher than its fully rested charge voltage (Typically spec'd to be between 12.6 to 12.8Vdc on quality lead acid batteries of any type), then current will be flowing into the battery's negative terminal (Or incorrectly into the positive terminal if you're a conventional kinda guy). If battery terminal voltage is lower than it's fully charged resting voltage, then current will be flowing out of the negative terminal due to internal series impedance of the battery. This obviously does not provide the granularity that an actual current measurement will provide; however, it simply is not needed to determine whether current is being sourced or sunk into the battery, as the difference in battery terminal voltage potential that determines this is so large between the two states that the situation is a binary "Battery is charging, Battery is discharging". A 100AH lead acid battery will sit at 13.8 or so VDC directly after charging for a while if there is no load due to the stored electrostatic / capacitive charge potential across its plates; however, this quickly discharges with any appreciable load, where the terminal voltage will quickly fall to its rested voltage potential, and below as current draw increases and as charge state reduces.

If your battery terminal voltage, which is what I assume is being reported via the IBS from its direct connection to both positive & negative battery terminals, sits at 13.8Vdc & above at all times when the engine is on, then there is absolutely no way that the battery is supplying power to the vehicle, as this voltage potential, that is well above the electrochemical potential that can be provided by a 6 series cell lead acid battery, ABSOLUTELY MUST be coming from a power source that is NOT the battery. As far as I've been able to determine, there exists no device in between the alternator's positive output terminal & the battery's positive terminal that is able to regulate or intermittently shut off & turn on current flow between the two potential power sources of the vehicle (ie they're connected directly at all times); therefore, IF battery terminal voltage is resting at 13.8Vdc or above, then the entire vehicle's electrical power needs are being sourced from the Alternator. In addition, disconnecting the battery from the alternator while the engine is on would be an incredibly stupid design, as the battery helps to act as a low-pass filtering device to smooth out the multi-phase rectified DC pulses from the alternator... If this scheme were to be done, it would be best to shut off current to the alternator's field coils; which means that battery terminal voltage should be fairly representative of the vehicle's system voltage (minus voltage drops from parasitic resistive losses), where one should see voltage drop to around 12.7Vdc & lower as the battery discharges if the vehicle's electrical needs are being supplied by the battery...

If BMW is regulating the alternator output voltage down to 13.8 Vdc when it determines that the battery is fully charged, and / or under certain driving conditions, and proclaiming some marketing BS about this is "Not charging the battery" & saving fuel, I would say this is incredibly dishonest, as it's still charging the battery, even a fully charged battery, just at a reduced rate, in addition to powering all of the vehicle's electronics. If this is actually how the "Intelligent Charging" scheme works, it would help to explain why there is confusion whether it's activated or not, & certainly would be the best possible implementation; however, the marketing material is absolute BS if this is true... I would guess that this is NOT the case though, as it would certainly & significantly extend the battery life of those who do not see prolonged cold temperatures. My own observations show battery voltage that never dips below 14.4 Vdc, & often sits around 14.6 or so, which strongly points to the intelligent charging functioning not being activated on my 2012 X5d...


----------



## SPL15 (Feb 3, 2019)

robnitro said:


> Maybe SPL can help with this.
> Oh and SPL, have you noticed an occasional short voltage dip to 13s volts at low rpm when off the throttle? I see it and my friend also gets it on his e60 530xi. He thinks it's a short test to verify the battery can take a load.


I've seen it plenty with just about all of the other cars I've owned, but so far not my X5d... It's not uncommon at all; my tired E46 does it every time I'm stopped w/ a lot of stuff turned on, and this car has an Odyssey (Hawker / Enersys) PC1500 as its battery (ie arguably one of the absolute best performing / high quality automotive AGM batteries that are available on the consumer market). Battery voltage typically dips down to 12.8-13.0 or so on a really cold night w/ everything on during a really long stop light.

I forget exact numbers, & the numbers differ by manufacturer, but a typical 80 amp factory alternator w/ factory pulleys & factory idle speed, typically only can put out around 20 amps or so, if that, when the engine is at 600RPM, where it dips significantly & rapidly with anything lower than this...

The voltage drop you've noticed is inherent to most "regular duty" factory alternators, as they simply cannot provide the necessary current at low RPM's to keep voltage up when a lot of "stuff" is turned on. A partially discharged battery, which is nearly always the case in northern climates (especially your common short trip driver), will significantly increase this effect, where a degraded / leaky battery will drastically increase this as well. A significantly degraded battery / significantly undercharged battery is not noticed by the average consumer, as the car will only not start once the damage / degradation / discharge is absolutely ridiculous & horrendous, not just "significant". One of the very 1st symptoms of a battery that is just starting to degrade "significantly", or is significantly undercharged (which will lead to significant & permanent degradation) is an idle alternator voltage sitting around 13.5-13.8 or so with a fairly moderate load, such as only headlights on. This gradual degradation / chronic undercharge can go on, completely unnoticed, progressing for well over a year or more until the battery is finally damaged enough to cause tangible issues with starting the engine (usually occurring when the temperatures drops below freezing).

A typical alternator's current output rating is only achieved with engine speeds usually around 2K RPM or higher (assuming factory pulley sizes). There's a reason why many manufacturer's "Tow Packages" / "Off-Road Packages" include a seemingly stupid high-output upgraded alternator, and why every commercial aligned / pro-sumer truck / van has an upgraded alternator that is rated for seemingly well above what could ever really be needed by anything besides an ambulance... These upgraded alternators produce much higher current at engine idle speeds as a simple function of increased high RPM output = increased low RPM output, but are also sometimes specifically tuned to produce a much more flat current output vs RPM curve. Legit commercial use vehicles tend to need the highest electrical power delivery at idle engine speeds for a variety of accessories that are only used when you're parked, where it may take a rated 180 - 250 Amp, or higher alternator to actually produce the much more realistic 50-100 amps needed at idle engine speeds.

The 80 Amp alternator spec is fortunately slowly fading in more modern cars that have a lot of accessories that need to be powered, with 120 - 140 Amp spec'd units seemingly becoming much more common, where this used to be considered a "High Output" rating not too long ago. Unfortunately, with this increase in output, reliability & durability issues seem to be a bit more common of a topic than was previous with the lower current units, with sometimes fairly elaborate cooling setups to cope...

When I was younger & a bit more paranoid about law-enforcement, I always knew a cop was behind me simply because of how unusually bright & unwaveringly consistent their headlights were due to the massive upgraded alternator in their car. Not the case anymore, as incandescent / halogen headlights are not the case in modern police cars, where HID & LED lighting simply does not show differences in electrical system voltage / consistency.


----------



## robnitro (Aug 3, 2016)

Thanks for the technical details. So basically if the battery wasn't being charged, or being used it would have to dip the voltage to transfer load off the alternator. The only other way it can be done without that would be crazy- using transistors to buck/boost. Again, it would be voltage that determines whether the battery was being discharged or charged.
On AC circuits it's a whole other story. Voltage is important but phase angle moreso. It's pretty wild when our substations at work can have circulating current flow on the reactor bus that essentially shows up as zero watts due to it being purely inductive.

My dip is totally unrelated to load. ( I have the 220A alt btw comes with 4 zone climate package)

It's not dipping at idle, besides the first instant you turn on a big load like the rear defroster.

It happens like this: cruising at 1700 rpm, 14.6v.
Lift off, still doing around 1700 rpm (tc locked), slight dip to 13.5 or so quickly going back to 14.6. It's almost not perceptible with my obd scanner (torque with bt adapter used)
No change in load and it's inconsistent... Random sampling it seems.
It can happen under very low loads, like in spring or fall.
It didn't happen this cold morning commute despite having defroster, seat heater, wheel heater, and blower on high.

It's the same observed by a friend, and he's technical too: thinks it's a quick check of either the battery state (amps and volt drop can give you internal resistance) or just verifying that the battery is "there".


----------



## n1das (Jul 22, 2013)

I'm not sure what all of the discussion about the car's electrical system has to do with the original thread topic about a DIY DEF fill.


Sent from my XP8800 using Tapatalk


----------



## n1das (Jul 22, 2013)

Doug Huffman said:


> A few weeks ago I intended to top off my passive DEF tank in preparation for road trip south. It only took a liter and that slowly.
> 
> We had errands to run after Church today. Later I figured I'd charge the battery to make up for Milady Wife's use of the bun warmers and so on. While under the hood I tried again to add DEF.
> 
> ...


At -20F that you mentioned earlier, it could have been frozen or slushy DEF blocking part of the system. Heat from the exhaust system warmed things up after driving for a while and then you could do a more complete DEF fill. Interesting.

I never add DEF to my cars until they call for it and the 999 mile countdown to no-start begins. I only fill the passive tank in my E70 X5 35d as you recommended to know that the transfer pump between tanks is working.

Thanks for the heads up about warming everything up when it's really cold out before adding DEF.

Sent from my XP8800 using Tapatalk


----------



## robnitro (Aug 3, 2016)

n1das said:


> I'm not sure what all of the discussion about the car's electrical system has to do with the original thread topic about a DIY DEF fill.
> 
> Sent from my XP8800 using Tapatalk


"
We had errands to run after Church today. Later I figured I'd charge the battery to make up for Milady Wife's use of the bun warmers and so on"

We were addressing this as to the reason as he did not respond to the other topic about his claims of the battery not charging. I'm all for figuring out a reason why or why not to do something and here is the place where it was addressed.


----------



## Doug Huffman (Apr 25, 2015)

Threads get forked and drift, the nature of the beast.

I am quite satisfied with my understanding of the E70 IAC / IGR IBS electrical system and have not had any experience suggesting my misunderstanding.

For me a sign of credibility is a clear, concise and correct explanation while avoiding the narrative fallacy; the human propensity to simplify data through a predilection for narratives over complex data.


----------



## robnitro (Aug 3, 2016)

Doug, you didn't address any of the data here.
1) It's not coded for US models- gas or diesel (proved in screenshot)
2) It would show a voltage dip to 13.8v or lower as SPL15 explained well in detail. His technical explanation matches everything I have seen with what DC I work with- UPS and switchgear "house power" systems.
None of us have noticed that. My Torque OBD scanner is always on and I can turn logging on if you don't believe me.
-2a) only way you could drain the battery if voltage was stable at 14.5 for example would need transistors which could do buck/boost voltage. Meaning you up the output of the battery to this 14.5v, while the battery itself dips well below 13.8 and so on. I understand your point on DC current flow, but never a battery can be at 14+v and still be putting out voltage. That's impossible. Go CTEK your battery for days, come back to it - put a simple load of a few amps on it (a headlight bulb or what not) and remove the charger. See how the voltage dips quickly to below 13.5 v or so. No way a battery will be discharging while under load with a voltage of 14+! 

Can you log your voltage/ etc and prove us wrong? Because all you are doing is stonewalling and not giving constructive criticism. We have questions, data, and doubts. 
You are allowed to have doubts too, but just dismissing all of that is pretty unscientific.


----------



## SPL15 (Feb 3, 2019)

Doug Huffman said:


> Threads get forked and drift, the nature of the beast.
> 
> I am quite satisfied with my understanding of the E70 IAC / IGR IBS electrical system and have not had any experience suggesting my misunderstanding.
> 
> For me a sign of credibility is a clear, concise and correct explanation while avoiding the narrative fallacy; the human propensity to simplify data through a predilection for narratives over complex data.


Lol! I appreciate your politeness in basically stating that you believe me to be "full of it"... 

I'll admit I can be a bit "over the top" in my explanations, & often rely upon a relatable story to drive points home (after nearly 10 years in consumer products as an R&D engineer, dealing w/ marketers & sales folks who make the decisions & demand physics defying results, will do this to a man...).

Maybe when the weather warms up, I'll do some testing to get actual numbers for when the system is 'enabled' vs 'disabled' (assuming it can be "coded"). I'm interested in this for my own curiosity; depending on the specifics of how it actually operates, it could actually be beneficial in the warmer months.

Anyways, sorry for dithering your thread


----------

