So this is actually weird I had a battery replaced coded 850cca showing almost the same on meter, the amps drop on the terminals under the hood to 360-400 but voltage remains the same, car struggles to start when engine is warm, checked without any load on the battery 850cca and on the terminals same 360-400, it needs atleast 600ca or cca to start without any issue, once I connect the battery pack it starts straight away of course with an extra power I am adding
starter replaced
battery replaced
Saw somewhere people installed a device under hood to the terminals to give extra amps

2013 Q7 TDI 3.0
Anyone ?

 

You didn't mention the amp/hours specs/size of battery, etc. The OE battery is super not impressive for cranking amps, but is very impressive on amp/hours at 110 amp/hours, which is how much energy can it store. I'm currently using an H8 AGM battery as couldn't source an H9 at that time...it has 95 amp/hours, whereas the H9 would have given me 105 amp/hours. The cranking amps don't really matter once you get beyond what the car requires to turn over and start...the amount of energy it can store matters a lot on this car.

Known issues: Not resetting the BEM system correctly and verifying it has reset/is charging at full/max voltage (15 volts), etc., when called for based on battery condition, as viewed in the Gateway channel (channel 19, or where you locate same info on yours may possibly differ in Australia market). The door handles go bad internally (prox sensor), and create parasitic battery drains...there will be trouble codes/faults in car related to this when scanned with a VAG-compatible scantool. Resolve this by snipping the power wire at terminal #15 on the harness that comes out of the door (see thread on parasitic drains for exact instructions, pics, etc.)

So, to recap. This car is an energy hog; you want a battery with as much storage capacity as possible; the OE capacity is 110 amp/hours. This car requires you to reset the BEM system when the battery is changed. Failure to recode the car's BEM system will result in premature battery failure. Known parasitic drains occur on all Q7s from bad door handle sensors, which weakens and kills all batteries prematurely, regardless of their capacity...easy to fix this and costs nothing. The more bad handles, the larger the parasitic drain. And of course, you can always have other issues on your car specifically, but these are the known issues that are very simple to resolve.

 

Thanks for the reply champ
it makes sense, yes I have a 2 door handles sensors faulty and causing leakage which I didn’t fix and I reckon these made my new battery weak, I did code the battery and checked I will recheck if I did it right or not, I have 80 Ah on my battery which I think is not good anymore because the battery is weak already, can I ask you how Can I fix that terminal #15 for door sensor issue and where is it located?
you reckon more the Ah is better? What about a lithium batteries they have more Ah capacity

 

https://www.audiworld.com/forums/q7-...3031705/page3/

 

Checking understanding; the battery you have in car is rated for a capacity of 80 amp/hours based on the sticker/label on battery, yes? If that's true, then it's really too small a battery to support this car over the long haul. As mentioned, I've got one size smaller than the OE battery in my own car at only 95 amp/hours, and I certainly wouldn't go any lower than that for the Q7. You don't need to go fancy on the battery type; in fact, the OE battery probably lasts the longest in this car and the price for it isn't terrible, like most Audi parts. The OEM (manufacturer), Varta, makes batteries that are rebranded and sold all over the world via auto-parts stores/vendors...same battery you buy from Audi, but it has a local chain store's brand-name sticker on top of the OEM sticker. I've peeled 'em back at local auto stores and found Varta batteries in two major parts store chains (here in USA), and at reasonable prices too. I bought an AGM type battery, if you are interested in tech upgrade for your Q7. The correct size is the H9 AGM for the Q7, and again, you want to stay as close to the OE battery's amp/hour capacity (110) as possible, regardless of the type of battery (wet cell, AGM, etc.) you install.

You will find in Ross-Tech Wiki or in recent threads on here the BEM code listing for myriad sizes/capacity/technology, to make it easy to program the car if you buy an aftermarket battery that's lacking a BEM code sticker.

 

thanks again guyz
going to snip the wires today let’s see how it goes and will get Back to you guyz

 

https://www.audiworld.com/forums/q7-...ttery-3015231/

Here's an ongoing thread that has BEM info and BEM codes for different sized batteries, etc.

 

sure mate I will definitely ask you about this once new battery is ready to go in

 

so I have snipped the the sensor wires #15 but I didn’t get any fault code saying “Open circuit” got few other fault codes scanned and erased
hopefully Job done
NOW I have to throw a new battery under seat with coding will ask for the help once ready
thanks

 

Take a look in CAN-19 group for the open circuit fault codes.