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2022 e-tron GT
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Discussion Starter · #1 · (Edited)
I will preface this post with the statement that I am no engineer, and my understanding of battery technology is amateurish at best. My experience with my GT so far has been great (with the exception of one day where the car briefly illuminated the red Drive system/High-voltage system/Vehicle electrical system; not repeated). Just the same, the posts here and here about the exhaustion of the 12V battery have made me want to have a backup plan. My GT is my DD, but there are times when she will be left unattended for a few weeks. The threads about the terrible delivery experience and the dead GT in the garage contain a couple of recommendations for 12V battery chargers, but none of the posters seem highly confident about their safe application to the GT.

The user manual for the GT is very clear on the specs for a charger to recharge the 12V battery at p. 242-3. The first spec is that charger must have a maximum charging voltage of 14.8 volts. The second spec is that the charger must specifically support LiFepo4 batteries with integrated protective electronics: The third spec is a maximum current of 90 amps. Here’s the excerpt:

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There are a variety of battery maintainers/rechargers that are suitable for the full range of lead-acid batteries, including AGM. Some chargers on Amazon claim LiFepo4 compatibility, but the number that actually seem spec’ed for LiFepo4 seems quite small. And many of those suffer from uneven or occasionally severely critical reviews. I found this one which, despite its almost kit-utilitarian appearance, enjoys good ratings and reviews from people who seem to know what they are doing, and it meets the Audi specs:
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Granted, at 6A of output, it’s not going to get you going in an emergency, but it seems to me it ought to work with zero risk of damage to the OEM 12V battery. There may be others even better suited. The price on this one is right.

Thoughts & recommendations?
 

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I will preface this post with the statement that am no engineer, and my understanding of battery technology is amateurish at best. My experience with my GT so far has been great (with the exception of one day where the car briefly illuminated the red Drive system/High-voltage system/Vehicle electrical system; not repeated). Just the same, the posts here and here about the exhaustion of the 12V battery have made me want to have a backup plan. My GT is my DD, but there are times when she will be left unattended for a few weeks. The threads about the terrible delivery experience and the dead GT in the garage contain a couple of recommendations for 12V battery chargers, but none of the posters seem highly confident about their safe application to the GT.

The user manual for the GT is very clear on the specs for a charger to recharge the 12V battery at p. 242-3. The first spec is that charger must have a maximum charging voltage of 14.8 volts. The second spec is that the charger must specifically support LiFepo4 batteries with integrated protective electronics: The third spec is a maximum current of 90 amps. Here’s the excerpt:

View attachment 3894

There are a variety of battery maintainers/rechargers that are suitable for the full range of lead-acid batteries, including AGM. Some chargers on Amazon claim LiFepo4 compatibility, but the number that actually seem spec’ed for LiFepo4 seems quite small. And many of those suffer from uneven or occasionally severely critical reviews. I found this one which, despite its almost kit-utilitarian appearance, enjoys good ratings and reviews from people who seem to know what they are doing, and it meets the Audi specs:
View attachment 3895

Granted, at 6A of output, it’s not going to get you going in an emergency, but it seems to me it ought to work with zero risk of damage to the OEM 12V battery. There may be others even better suited. The price on this one is right.

Thoughts & recommendations?
Hi Spyder, I chose the Noco Genius 10 because the leads had M10 terminal rings that fit on threaded portion under the GT charging posts and the leads are detachable so I could leave them in place permanently in case frunk would not open and I needed to charge from outside the frunk. The Noco, according to manual, in Lithium mode does 14.6V, 10 amps. Noco Genius 10 at US$100 is also more money than the one you found. I am not an electrical genius so buyer beware :)
 

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I used the waterproof pig tails that came with this charger that meets the required specs.
The pig tails are hidden below the windshield wiper but accessible.
Fortunately haven't needed to use it.
I just installed this same setup. It works pretty well. I store the charger and an extension cord in the trunk, which I can get to by folding down the rear seats. This appears to be a pretty sophisticated charger--i like the BT connection and app so you can tell what is going on with the charger and battery. Hope I never have to use it.
 

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2022 e-tron GT
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Discussion Starter · #7 ·
I just installed this same setup. It works pretty well. I store the charger and an extension cord in the trunk, which I can get to by folding down the rear seats. This appears to be a pretty sophisticated charger--i like the BT connection and app so you can tell what is going on with the charger and battery. Hope I never have to use it.
Thanks for that. If it’s not too inconvenient, do you have a pic of the layout under your hood? And thanks for the reminder about an extension cord in the trunk!
 

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2022 Audi e-tron GT Prestige/Performance/Leather [Mythos Black]
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@Drbarolo, in the event we need to actually use this setup, are there any specific settings we need to tick off in the app to make sure it all goes smoothly?

i just like being prepared ;)
 

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Not sure since I haven't needed to use it. Obviously you need to select LiFeP04 type battery for charging. I read that the maximum charging amps allowed was 90. So this units 15A max charging capacity should be fine.
 

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2022 Audi e-tron GT Prestige/Performance/Leather [Mythos Black]
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Dumb question -- can you open the trunk with a dead 12v?
 

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Hmm, ok so where are you guys leaving the charger in the car in case of an emergency? I guess you can just crawl through the car into the trunk if you fold that middle seat down in the back.
 

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In the trunk. You can open the driver's door manually, then open the rear door from the inside. Fold down the rear seats and access the trunk that way.
 
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