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series vii 
Member - Posts: 27
Member spacespace
Joined: May 05, 2014
Location: California, United States
Posted: May 05, 2014 at 11:18 AM / IP Logged  
I just purchased a 2014 F150 Platinum and plan to add multiple acc. As I was planning my cable routing, I noticed two sensors, one around the positive and negative cables. I'm guessing these are current sensors (round clamp style, look to be an AC type current doughnuts). Thinking these are to regulate the alternator through the BCM or the ECM? Not sure if these were used on previous years.
My question is, do I need to route all additional cable through these sensors? There is little no space to get more wire in! This could add complexity to the Big 3 install. If there was only one sensor, I would have less concern, however is the control mod comparing both the in and the out of the battery? Would adding an additional battery(s) cause issues?
Considering Ford requires you to the reset the BCM if you change out the battery, anything is possible! Evidently the computer adjust to the batteries age and compensates charging. All we need, more control in our lives . . .
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: May 05, 2014 at 11:56 AM / IP Logged  
I'd normally suggest yes - all current (wires) must pass thru the sensor, but I am unaware of having a sensor in BOTH poles - ie, ve & -ve (except for safety systems - eg, core-balance aka earth leak detectors).
But maybe if the are trying to do what others said they were trying to do, they finally figured out they need a BIG sensor that can monitor startermotor current (ie, the GND sensor) but still use a smaller sensor for more accurate low current measurements (ie, +12V sensor excluding the startermotor).
Not that I am up on such systems, but when I first heard of them, I questioned why...? So far no one has been able to provide me with concrete reasons, nor provide any benefits such as in improved battery or load life, or improved fuel economy etc.
The only benefit I am aware of is greater acceleration by cutting else reducing alternator output, but that doesn't need current measurement - and it's usually at the expense of fuel economy.
The only purpose I see is to sense when a mere float current is charging the battery so that the alternator can reduce output to float levels (eg, 13.4V) to extend battery life - not that I think the extra complexity is worth it...
ELSE to limit the max charge current - ESPECIALLY if AGMs or Lithium batteries are being used.
In my experience the only people that want current monitoring are experimenters and testers, and of course those that think current somehow tells them how healthy their system is.    
If manufacturers have some method of gleaning battery specs and thus altering charge rates or predicting battery failure, then IMO they have come a long way since I dealt with that stuff.
Maybe someone else knows more than me. It's been a couple of years since I last discussed the subject of (OEM) current monitoring.
series vii 
Member - Posts: 27
Member spacespace
Joined: May 05, 2014
Location: California, United States
Posted: May 05, 2014 at 1:26 PM / IP Logged  
Increasing fuel economy was my first thought also. Which is funny designing a 23 foot long 6200lb. truck thinking regulating alternator use would really change the mpg figures! Guess the manufactures are doing everything they can.
I was able to dig into the harness a bit more and found the Positive sensor wraps the Alt cable and not the fuse panel lead. The Negative sensor wraps all the grounds. This would support oldsparks idea about float charging. So the regulator would be adjusting for both voltage and amperage? Would this limit me to only use a wet cell as a primary battery? If this were the case, would it be wise to use a wet cell as a secondary to match the charging characteristics?
'14 F-150 Platinum.
Not giving up my class A/B yet...
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: May 05, 2014 at 6:01 PM / IP Logged  
Ah - now this could get fun... (Well it did on mp3car.com. So much so it resulted in my leaving...)
Again, it depends WHY they are measuring.
As to regulation, they only regulate voltage - ie, if they want to increase or decrease current, the regulator increases or decreases the alternator's output voltage. (V=IR)
Fuel economy - reducing or cutting alternator output so that the battery discharges means and added 30% of inefficiency added to the amount of battery charge used (assuming battery efficiency is ~70%), plus a bit of added inefficiency from the alternator & wiring due to increased recharge current (i2R losses).
Only if the engine fuel efficiency is neutral or gains overall would this be desirable - except where acceleration gain is sought - ie, for performance at expense of fuel.
Being able to reduce alternator output can make sense... IE - do the usual "battery recondition" and fast recovery high recharge voltage (typically max 14.4V long term, or maybe 14.8V for AGM) maybe even with a bit of gassing for wet cells (eg, maybe 15.6V) and then dropping to float voltages once the battery is charged.
That would save typically say (14.4V - 13.4V)i = 1V x i or i Watts where i is the current output by the alternator. IOW a general saving of maybe 20W to 400W if running a 3kW audio system, hence a saving of ~1/25th to half a horsepower of fuel.
I assume the probably typical 0.1 BHP saving is not outdone by the extra power needed to accelerate the added weight of the current sensors and associated circuitry. (I do realise the extra bits and CPU cycles contribute very little mass... f150 electrical -- posted image. )
And of course limiting the max battery recharge current makes sense in theory. That has traditionally not been done and since specs say to limit to 10% or 20% of the battery's C10 or C20 capacity etc - and that can be well exceeded and usually is... But these days I see batteries lasting 6-10 years - a far cry from when I thought 3 years was good.
I'll address dual batteries etc later. Of course if they are matching their alternator output to the battery, I'd like to know what battery specs they have preprogrammed and how they are updated for new or different batteries, or of these days they have the ability of determining all that without knowing battery data (ie, manufacturer's specs).
And finally I'd like to see the results of all this - ie, the effect on battery life AND resulting fuel economy or CO2 output etc.
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: May 06, 2014 at 12:10 AM / IP Logged  
Ok, batteries...
If the +ve current sensing loop is around the one & only battery +12V cable EXCEPT for the startermotor +12V, then (I'd assume) it is for battery monitoring.
Based on your wiring description where the alternator output splits to the battery and to everything else (ie, fuse box and onwards), the battery supplies all loads aka everything-else (except startermotor) via the alternator.
If so, if you take a feed straight off battery +12V you will stuff up whatever they are trying to do with their battery current monitoring.
IMO they would therefore have warnings or notes NOT to tap from the battery direct. But if you did it probably means the EMS or BCM etc does not reduce the alternator to float voltage and hence wastes a MASSIVE 1/10th horsepower or whatever.
And I guess battery life will be compromised... they won't last more than the normal 6-10 years that ordinary wet cells get with non-current limited fulltime charging at 14.4V or 14.2V or alternators that drop to lower voltages (eg, 13.8V) depending on temperature else after a delay.
With dual batteries, the usual rule is that they do not have to be matched unless permanently paralleled.
Certainly parallel charging 2 or more mismatched batteries will not matter (**) and keeping them paralleled whilst supplying a load depends on preferences - eg, max capacity or minimal battery strain for winching or big audio versus the desire for an independent cranking reserve/battery.
My (**) above is to note an assumed caveat - namely that neither battery suffers any cell collapse. (And that alternators have reasonable output capability.)
But collapsed batteries should NEVER be charged and that is irrespective of parallel battery(s) - though a collapsed AGM paralleled with any battery can be a recipe for disaster.
There are those that insist that paralleled batteries must be matched. That is true for permanently paralleled batteries but my (UIBI or) battery isolator and other multi-battery discussions are not about prime movers etc with such permanent series &/or parallel battery configurations.
One avid such claimant is unable to explain how one battery can discharge into another while both are being charged (ie, >13V) off the same alternator despite that being the basis of her or his "matched" argument. Furthermore they support single battery isolators (including diode types!) yet have never explained that they must be in EACH pole and that the batteries must be co-located and symmetrically connected (ie, +12V or +24V taken from one and GND from the other (string). IOW it merely prevents parasitic loading and collapsed cell issues but can NOT be used for those wanti8ng independent batteries as most of us want - eg, to run fridges, PCs, audio, etc.
Alternatively they have not explained at what point batteries become mismatched, nor how to determine that. It's as if you buy 2 matched batteries you'll be fine - it doesn't matter if one is in the engine bay and one in the trunk; how they are connected or isolated, or if one is used for loads whilst isolated. I presume they magically continue to be matched (LOL!!). [Ah yes, these young(?) KIAs have a right to arrogance and flaming.]
If BCMs & EMSs do vary charging with battery type & age, then you have problems.
If you substitute an AGM for the wet cell cranker I wonder if the alternator will increase its output to 14.8V or whatever is recommended for the AGM (generally higher than for wet cells).
Or if it was an AGM, was it charged at 14.6V or 14.8V and will it reduce to 14.4V for a wet cell or just corrode its plates to an early grave?
And if you substitute a 7AH or 15AH cranker will it lower its max charging current?
I suspect no to all the above.
Smart chargers can (allegedly) do all the above. So are vehicle manufacturers now adding the cost of smart charging so we get extra life out of our batteries? f150 electrical -- posted image.
So I get back to what I hinted at earlier - wth are they doing with their current sensing? (Or ytf are they doing it?)   
The only stories I have read or heard IMO do not stack up. Some are (IMO) obviously self contradictory. Others MAY have merit, but either battery understanding and technology has recently leaped else they have tightly defined parameters for battery replacement do not allow added loads direct off battery terminals.
And whether there is any practical or profitable point in doing the above for lead acid batteries... Lithium batteries yes, but then you wouldn't be bothering with lead acids; their behaviour is simply too different.
series vii 
Member - Posts: 27
Member spacespace
Joined: May 05, 2014
Location: California, United States
Posted: May 07, 2014 at 2:43 PM / IP Logged  
Thanks, old spark!
your insights are always appreciated!
I am going to proceed with caution and find a 220A police package alternator and keep the stock battery for now. Being a Ford spec'ed Alt. does give me more leverage with possible warranty claims.
Going to turn to some aftermarket Upfitters and see what they have encountered.
'14 F-150 Platinum.
Not giving up my class A/B yet...

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