Recommendation for AGM battery for Audi Q7 2007 4.2L FSI

[DeeWS]

Looking to purchase AGM battery for Audi Q7 2007 4.2L FSI. Any recommendations?

[Magnet]

Hello Darwood,

I’ve always used Varta/Bosch - their 4 or 5 year warranty grade. 
Fortunately, we are blessed with a number of on-line battery retailers here in the U.K. Canada-?? 

Just a thought :- 16 year old vehicle needing an AGM battery -? 
Kind regards,

Gareth. 

[DeeWS]

Thanks Gareth.

Always used the regular lead acid battery. Want to switch to AGM as they are supposed to be longer lasting especially considering the difficulty of replacing under the driver seat by myself.

As for availability - Varta with Audi dealer but no local retailer for Bosch. We get Energizer, Exide and Interstate among others. More availability in the US.

Have a good week and best regards.

[Stevey Y]

30 minutes ago, DeeWS said:

Thanks Gareth.

Always used the regular lead acid battery. Want to switch to AGM as they are supposed to be longer lasting especially considering the difficulty of replacing under the driver seat by myself.

As for availability - Varta with Audi dealer but no local retailer for Bosch. We get Energizer, Exide and Interstate among others. More availability in the US.

Have a good week and best regards.

Hi I can't see that buying an AGM battery will be any advantage to you in view of the cars age and assuming it is not equipped with stop start, the charging parameters are lower for the lead acid unit except when the temperature drops, then you have a problem as your existing set up generator may well rise to 15v, that will toast a very expensive AGM battery where as lead acid is far more capable of absorbing overcharge and still being serviceable, AGM will charge up to six times faster than a lead acid unit but won't tolerate overcharge, there lies the problem the charging systems on your car and newer are about the same but the BEM systems are different as the built for AGM system is highly sensitive and won't allow overcharge, I have also seen on this forum where one of the members bought an AGM to replace his old battery and caused himself all sorts of problems with weird faults, this is because you can't code an AGM unit to the older BEM so it can't work out why it can throw the worlds supply of voltage at the battery virtually unrestricted, this is because AGM has a much lower resistance to charge which is why it charges faster, in essence your $ will be much better invested in a top quality lead acid unit.

Steve.

[Magnet]

Hello Darwood,

Varta and Bosch are reputed to be from the same factory and simply branded accordingly. To all intents and purposes, they are one and the same battery. 
Exide are reputed to be good. 
Energiser?? Not seen these as car batteries, but seem to be quite prolific in the cheap domestic bulb market and for domestic dry cell batteries. It could  just be be me, but I associate that make with budget quality. 
Kind regards,

Gareth. 

 

[DeeWS]

Thanks Steve (Stevey Y) for a very informative response. I registered to this forum today as I see while browsing that in the UK and the European continent you people have much more experience with German vehicles than here in North America.

The Audi dealers here try to sell AGM batteries when one goes to them for a battery purchase. They charge nearly twice the other shops do.

Temperatures here are quite low in the winter. When  I look at Measuring Blocks using VCDS (Ross Tech) for Battery Regulation 61, I find that Group 001 Generator (Alternator) Voltage Specified does go to 15 volts. In fact the Output Tests in the module 61 work only for Generator Specified  Voltage of 15 volts and not for the other choices of 13.5 volts and 0 volts. Generator Voltage Specified is also measured in Group 010.  When the Group 001 Generator Voltage is !5 Volts then Group 010 Generator Voltage is also 15 Volts.

However when the Group 001 voltage is lower such as 14.5 volts immediately after starting the car then Group 010 Generator Voltage is 0 volts and the Generator Interface to the module 61 is lost (Not OK). The Generator is OK as shown in Group 010 whether the voltage is 14.5 or higher. When the Generator Interface is not OK I get the DTC 02254.

In time the Group 001 Generator Voltage rises to 15 volts, the Generator Interface becomes OK and Group 010 Generator Voltage also shows 15 volts.

My mechanic says the alternator and battery are both fine. However some time ago he had replaced the Battery Management Module J644 with one for A6 C6 as the Q7 version was not available. I was wondering if an AGM battery with specs 110AH, 950 CCA and 1000 CA would rectify the problem.

Sorry for the long post. 

[Stevey Y]

1 hour ago, DeeWS said:

Thanks Steve (Stevey Y) for a very informative response. I registered to this forum today as I see while browsing that in the UK and the European continent you people have much more experience with German vehicles than here in North America.

The Audi dealers here try to sell AGM batteries when one goes to them for a battery purchase. They charge nearly twice the other shops do.

Temperatures here are quite low in the winter. When  I look at Measuring Blocks using VCDS (Ross Tech) for Battery Regulation 61, I find that Group 001 Generator (Alternator) Voltage Specified does go to 15 volts. In fact the Output Tests in the module 61 work only for Generator Specified  Voltage of 15 volts and not for the other choices of 13.5 volts and 0 volts. Generator Voltage Specified is also measured in Group 010.  When the Group 001 Generator Voltage is !5 Volts then Group 010 Generator Voltage is also 15 Volts.

However when the Group 001 voltage is lower such as 14.5 volts immediately after starting the car then Group 010 Generator Voltage is 0 volts and the Generator Interface to the module 61 is lost (Not OK). The Generator is OK as shown in Group 010 whether the voltage is 14.5 or higher. When the Generator Interface is not OK I get the DTC 02254.

In time the Group 001 Generator Voltage rises to 15 volts, the Generator Interface becomes OK and Group 010 Generator Voltage also shows 15 volts.

My mechanic says the alternator and battery are both fine. However some time ago he had replaced the Battery Management Module J644 with one for A6 C6 as the Q7 version was not available. I was wondering if an AGM battery with specs 110AH, 950 CCA and 1000 CA would rectify the problem.

Sorry for the long post. 

Hi no apology necessary its refreshing to have somebody do their homework and be committed enough to supply that information, with regard to the management module I can't see replacing the battery would make a difference as the module will only regulate the voltage according to the command protocol from the ECU via a body control module this in turn can confuse the ECU which will go into a default protocol to try and preserve the continuity of charging this means it will undercharge drastically to preserve the system, it does the same thing if the smart charge wiring goes down, it all comes down to the original programming of the ECU thats what runs the whole show it has perameter bands programmed in to deal with just about every sensor on the car, especially engine management for example MAF/MAP sensors which when failing normally throw up implausible signal codes which means that whatever it gets is outside its operating band strategy, thats why on later cars any modifications to the vehicle electronically throw a light unless the item is run through a Canbus system, Absorbent Glass Mat, which sounds like an incontinence aid, has only one real advantage it charges faster and if you look at the dynamics of your current set up even if your energy module is not quite the right one the system as is will accept this as it has a certain flexibility therefore if you start introducing more new variables there is more room for error, can't understand the scarcity of parts where you are but I do realise the North American market is very different, one of my Fords had a diesel fired cabin pre heat and a plug on the engine block with I later found out was for plugging in to a station that stopped it from freezing while you went shopping the antifreeze was a bit special as it was like syrup, apparently it was destined for North America but the build was cancelled so it ended up at a dealers in Hertfordshire then I bought it they never mentioned any of the above, the only way I found out was through a friend at Ford finance who chased its murky past.

Steve.

[DeeWS]

Thanks again Steve. Again very informative. I will make it a point to read your responses on the forum whenever I am free. That should improve my knowledge of these cars. 

Any idea why the status (OK or Not OK) of the Generator Interface between the alternator and the battery management module is dependent on the alternator voltage (Generator Voltage being 15 volts or 14.5 volts respectively)?

Best regards 

[Stevey Y]

11 hours ago, DeeWS said:

Thanks again Steve. Again very informative. I will make it a point to read your responses on the forum whenever I am free. That should improve my knowledge of these cars. 

Any idea why the status (OK or Not OK) of the Generator Interface between the alternator and the battery management module is dependent on the alternator voltage (Generator Voltage being 15 volts or 14.5 volts respectively)?

Best regards 

Hi looking at this its definitely pointing to the Battery Energy Monitor sending the wrong signals to the control module have you acquired the new correct module yet as this would be the sum total of your problems if not, I have found one thing with electrical components to do with engine management the part numbers have to be identical apart from sensors  I.E. Oxygen where if at the end of the number it might have A,E,B,D that is the build year designation or supersession numbers, now we come to electrical sensors which are numbered according to their software operational strategies, to simplify its like a demanding wife and will only accept what it wants, its the way the software is written unfortunately, so it won't have anther version.

Steve.

[DeeWS]

Thanks again Steve. I had put this query on the North American forums without any response.

The new one from Audi is quite expensive. There is an eBay seller located in St. Albans UK who sells refurbished ones with three years warranty and seems to be reliable based on the feedback. Listed on 20 Oct 2022  with the generic part number 4L0 915 181. If in stock, I am asking for faster delivery. Hope he responds today.

[Stevey Y]

16 minutes ago, DeeWS said:

Thanks again Steve. I had put this query on the North American forums without any response.

The new one from Audi is quite expensive. There is an ebay seller located in St. Albans UK who sells refurbished ones with three years warranty and seems to be reliable based on the feedback. Listed on 20 Oct 2022  with the generic part number 4L0 915 181. If in stock, I am asking for faster delivery. Hope he responds today.

Hi I hope you get the part, most of the refurbished stuff I have ever used has been better than the original as these guys find the offending diode/chip and replace it with something better, there is a company in the U.K. called ECU Testing and they have made a science out of refurb on things like dash pods and ABS units I first came across them years ago when my father in laws Volvo dash died, Volvo wanted £1800.00 to supply and fit with a recode at another £90.00, sent it off to ECU and didn't hold out a lot of hope until it came back three days later as a plug in and play repair at £170.00, re fitted and its been fine for the last eight years, in fact it looks like the dash is going to outlast the car, anther one was my friends A4 his ABS went up the wall so at a shade over three grand fitted from Audi the £360.00 repair was a bargain and again no recode, I think Audis view is only people that have loads of money should own their cars which is a farce really as they wear and break down the same as anything else they just take longer to do it, I have studied the American forums and oh boy do they come up with some stunts like bypassing the BEM and then wonder why they fry the modules that communicate with it, if you look at the dynamics of it Audi design a car and programme it electronically to only work with certain parts so there is no reason why once restored to its standard state that it won't run the same for another seventeen years.

Steve.

[DeeWS]

Thanks again Steve. He has asked for VIN to check compatibility. Hope it will materalize.

Best regards

[DeeWS]

On 3/23/2023 at 7:11 PM, DeeWS said:

Thanks again Steve. He has asked for VIN to check compatibility. Hope it will materalize.

Best regards

The part arrived. I will replace on the weekend. Elsaweb says I need to re-encode the module after replacement. Is it necessary? VCDS does not allow coding for the energy management module. It only allows coding of battery.

Thanks and best regards.