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2005 V70 voltage issue Topic is solved

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IslandV70
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2005 V70 voltage issue

Post by IslandV70 » Wed Apr 10, 2019 5:32 am

My system voltage is variable. Some days it is 14.2, sometimes 13.8, and yesterday was 13.0. ????
Is there a standard fixed regulator on the alternator or is there some kind of "smart" system varying the voltage?



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Re: 2005 V70 voltage issue

Post by RickHaleParker » Wed Apr 10, 2019 6:14 am

All charging systems do that.

The voltage will vary with the battery's State of Charge (SoC). When the SoC is low the voltage goes up to charge the battery. When the SoC is high the voltage drops to keep from boiling the battery.

This is what the word regulated means and it is what the regulator does.


Platform: P80 1998 C70, B5234T3, AW50-42, Bosch Motronic 4.4, Special Edition package, Plant: Uddevalla Sweden.

Platform: X40 (Nedcar) 2003 S40, B4204T3, AW55-50/51SN, Siemens EMS 2000. Plant: Born Netherlands.

Platform P2 2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0, Plant Torslanda Sweden.
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IslandV70
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Re: 2005 V70 voltage issue

Post by IslandV70 » Wed Apr 10, 2019 7:50 am

That actually is not how any alternator worked until recently. Every car I have ever owned until maybe this one has had a fixed set point regulator that tried to maintain one voltage. This is why I was asking, if the car does have a regulation system that tries to keep track of the state of charge that would be one thing and if not entirely another.
* If you look up regulators for the common 10si alternators used on millions of GM cars and adapted to boats, fork lifts, and 100 other things none of them attempt to discern the state of the battery. They are all fixed voltage and you can get various voltages to suite what you want to do.
My old BMW wagon was set to a constant 14.1 or so. The newer ones do as you say and track the state of the battery. When my battery died I just stuck another one in. For a newer BMW you have to use a VIDA like tool to reset the battery tracking system.
If the V70 does NOT track the battery my regulator is acting odd or maybe the battery is.



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Re: 2005 V70 voltage issue

Post by RickHaleParker » Wed Apr 10, 2019 8:21 am

Oh darn .. I guess my education in both electronics and automotive was a complete waste of time. :roll:
I do have one question for you, if you already have the answers, why are you wasting our time?


Platform: P80 1998 C70, B5234T3, AW50-42, Bosch Motronic 4.4, Special Edition package, Plant: Uddevalla Sweden.

Platform: X40 (Nedcar) 2003 S40, B4204T3, AW55-50/51SN, Siemens EMS 2000. Plant: Born Netherlands.

Platform P2 2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0, Plant Torslanda Sweden.
----------------------------------------------------------------
1997 S90, B6304S, AW30-42, Bosch Motronic 4.4 - Sold

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Re: 2005 V70 voltage issue

Post by IslandV70 » Wed Apr 10, 2019 9:09 am

Ah........because I have no idea if the V70 has a fixed set point regulator or a system like newer BMWs that tracks the battery state and thought someone here might know.



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Re: 2005 V70 voltage issue

Post by abscate » Wed Apr 10, 2019 9:57 am

I think the auto world moved to smart regulation about 15 years ago. roughly...so P2s were probably too early for this.

There were CANBUS changes in 2005 so Im guessing thats the earliest for smart reg.


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Re: 2005 V70 voltage issue  Topic is solved

Post by jimmy57 » Wed Apr 10, 2019 9:59 am

Older systems with no external control or temp sensors used internal temp sensor and would lower voltage target when the alternator warmed up. That gave the very repeatable 14.1 +/- that would go down to 13.7 +/- after a few minutes. Batteries by their nature will have variable internal resistance and will have variations in current flow at the same voltage depending on SoC. Batteries that are more deeply discharged will have higher voltage due to the reduced loading of sulphated plates in cells.
A 2005 has external control of voltage regulator due to the single small gauge wire doing double duty as exciter supply for quick charging start when engine reaches a low RPM and the wire carries LIN signalling so the controlling module (CEM on Bosch engine management, ECM if using Denso engine management) can have a send/receive conversation and vary the voltage target on time, computed or measured battery temp and also using ambient temp as a factor. If the system computes higher batt temp then the charge target voltage is lower. On the 2005 and later the voltage will vary and is normal for it to do that. The newer Volvos using the battery monitor sensor with a LIN communication connection do actual measurement of current for accurate computing of SoC and for battery rundown protection. The earlier battery rundown function w/o the BMS is voltage based. With BMS the current at a voltage is used to decide the SoC and state of health. The vehicle with start/stop need much more close battery monitoring as there should never be a risk that the main battery will not be able to operate starter when the system shuts don engine. The more close monitoring on these will inhibit start/stop when the person driving the car senses no issues with the battery.
But to the original question, yes that 2005 can have some randomness to the voltage if you watch it on trips. The initial 6-8 minutes should be over 14 and go down to upper 13s. Ambient temp will slide the voltage lower. Your Denso system can have some acceleration and coast changes too. I have had radar detectors with voltage in the display for many years and drove a lot of different Volvos as company cars. The random ranging V is OK.
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IslandV70
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Re: 2005 V70 voltage issue

Post by IslandV70 » Wed Apr 10, 2019 10:11 am

Thanks! That is exactly what I wanted to know!



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Re: 2005 V70 voltage issue

Post by abscate » Wed Apr 10, 2019 1:38 pm

abscate wrote:
Wed Apr 10, 2019 9:57 am
I think the auto world moved to smart regulation about 15 years ago. roughly...so P2s were probably too early for this.

There were CANBUS changes in 2005 so Im guessing thats the earliest for smart reg.
I so smart on VOLVO stuff, almost 1% as smart as Jimmy....


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