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Check if your alternator properly charge the battery. Start the engine and after 5 minutes check the voltage with working engine. Should be above 14V.
after driving it for 15 min yesterday it got up to 12.2, but that was back in the garage with the engine off. I will test it again with engine running.
"Normal" means engine off battery charged. 12,2V in very cold conditions is low but still OK.
Below my battery Voltage, measured in a car parked for 2 days in moderate temperature:
This is just not true. Yes, a brand new battery or one that has been properly maintained will read higher, as is one that was just agitated (e.g. unlocking the car, etc). SOC is a function of temperature, period. Also it is very much a myth that alternators "charge" batteries. Yes, they do add charge, and yes they maintain SOC, but the reality is that most people should actually own a battery tender. I keep mine topped off every few weeks.
Originally Posted by Jdsengineer
after driving it for 15 min yesterday it got up to 12.2, but that was back in the garage with the engine off. I will test it again with engine running.
15 minutes of driving is not enough to 'charge' a battery. Would suggest you get a battery tender.
==
Also keep in mind our cars do *not* have an alternator. It has a belt starter generator which charges the 48V battery which then steps down voltage using the DC DC converter to then charge the 12V battery.
Last edited by angrypengu; 02-17-2023 at 06:43 AM.
This is just not true. Yes, a brand new battery or one that has been properly maintained will read higher, as is one that was just agitated (e.g. unlocking the car, etc). SOC is a function of temperature, period. Also it is very much a myth that alternators "charge" batteries. Yes, they do add charge, and yes they maintain SOC, but the reality is that most people should actually own a battery tender. I keep mine topped off every few weeks.
Maybe it's my English but I think I wrote it clearly. 12.5 -12.8 volts in a charged battery at "room temperature". In addition, modern, maintenance-free batteries are not as sensitive to temperature fluctuations as older generations. This is necessary for the proper power supply of the sensitive car electronics also in the low temperatures.
In normally operated cars, with a functional battery and alternator, there is no need to additionally charge the battery.
Opening the door wakes up the battery but you always have to do this if you want to measure the voltage in the battery installed in the car. Therefore, comparing different battery measurements here is fair.
I top up the battery only when the car is not used for more than 2 weeks and it stems more from prevention than necessity.
This is the knowledge from my experience. Maybe you have a different knowledge, I will not argue with it further. I also think you should be more careful about accusing someone of writing untruth.
Maybe it's my English but I think I wrote it clearly. 12.5 -12.8 volts in a charged battery at "room temperature". In addition, modern, maintenance-free batteries are not as sensitive to temperature fluctuations as older generations. This is necessary for the proper power supply of the sensitive car electronics also in the low temperatures.
In normally operated cars, with a functional battery and alternator, there is no need to additionally charge the battery.
Opening the door wakes up the battery but you always have to do this if you want to measure the voltage in the battery installed in the car. Therefore, comparing different battery measurements here is fair.
I top up the battery only when the car is not used for more than 2 weeks and it stems more from prevention than necessity.
This is the knowledge from my experience. Maybe you have a different knowledge, I will not argue with it further. I also think you should be more careful about accusing someone of writing untruth.
I did not write what you did. All batteries are affected from a SOC perspective based on ambient temperature, whether or not they are lithium ion, LiPO4, lead acid, or whatever. You cannot simply state that "all batteries" are at 12.5-12.8 volts at "room temperature", even, because that's not the case for batteries of other chemistries, or even voltages.
People are entitled to their own opinions, but not their own facts, sorry.
It still seems like there's value in @Jdsengineer talking some additional measurements. I like testing things even if it may not be the perfect test, or necessarily the most relevant thing to test.
I would trickle charge my battery to get it as close to "100%" as is practical, measure it, then drive the car on a short drive, and let it sit over night, and measure it again, take the same drive, and measure again.
If you wanted to go all out, you could monitor the garage temp. Repeat that over a week, and just establish a base line. Then let it stand, an go about your typical use, and measure the battery once a week.
The data could end up being useful. If his alternator dies, and he ends up having the repair, he could do the same measurement process after the repair, and that might end up being useful data.
Also, if the 48 volt battery is something that a user can "easily" access and measure, that might be good to measure as well.
More info on the battery/belt driven generator/voltage converter system in our cars:
I think this video describes the 3 component Vitesco Technologies (formally Continental Powertrain) system in the Q8 cars; the 48v battery, the belt driver generator/starter, and a transformer box:
Interesting fact...
All Q8/SQ8/RSQ8 variants up to MY22 have the following modules in their Gateway installation lists:
Address 61: Battery Regul. (J1120) Labels: 4N0-915-105.clb
Part No SW: 4N0 915 105 B HW: 4N0 915 105 B (Version may vary depending on year) Component: BMS_48V_LiIon H06 0109
Address CC: Starter-Generator (C29) Labels:* None
Part No SW: 4N0 903 028 P HW: 4N0 903 028 P (Version may vary depending on year)
Component: BSG-HP1-65 H18 0527
In a MY23, the starter generator under address CC is no longer present and the battery regulation module at address 61 matches what has been used for the last couple years in the Urus:
Address 61: Battery Regul. (J1120) Labels: None
Part No SW: 4M0 915 169 H HW: 4M0 915 159 H Component: BMS_48V_SCAP H09 0116
is is possible to get a copy of the entire gateway installation list?
Tomorrow morning I will perform a complete autoscan of the ‘23 SQ8 including all adaptation and measuring blocks and will be uploading it to the Ross-Tech forums. I’ll post the link here once I have it.
Yesterday I had to drop something off at the Audi dealer in Indianapolis. That little plastic thing that rental car companies attach to the key ring. They had swapped out my rental from a VW Atlas to a Q5 so they needed the little plastic piece. My SA said he thought they had an SQ5 and was trying to switch me into it. The Q5 I was driving was given to another customer while I was there and the SQ5 turned out to be for sale in the rental companies fleet. Ended up driving one of those Cadillac small SUV's home. While at the dealership my SA said they had received 25 alternators last week and another 20 this past week. He is thinking that mine could be ready in another 2-3 weeks (fingers crossed). So it appears that Audi is getting them out to the dealers all of a sudden.
02-17-2023, 06:00 AM
