Battery tender , stupid question .. or is it ?

[Gordyzero]

This is my first S4 with start stop.. and I will just go ahead and guess it has an auxiliary battery. I want to put a battery tender on my 19 S4.. but. Do i charge from the trunk battery like I always did on my B8 and B8.5 ? Or perhaps the jump start terminal ? Or do i charge them independently ?

[TheDon89]

I hook mine up to the jump terminals in the engine bay. Worked last winter and so far this winter with no issue.

[will13k7]

there's just one battery. it is located in the trunk. the manual says use the hookups under the hood.

[Gordyzero]

Super. That's a relief only having one battery ! I'm new to the B9 and I have much better luck asking questions here than the dealer. Thanks for the quick help fellas !!. And this is much easier. I can put my spare tire back in now. One more question.. where the hell did the rear fog light go >? I've never owned an Audi without one.

[crhh95]

there's just one battery. it is located in the trunk. the manual says use the hookups under the hood.

Well this is news to me I didn’t even know that was there...

[ywang98]

I am not driving as much because of the pandemic, so I've also been using a battery tender. Occasionally, I get a "auxiliary battery" fault scanning with OBD11, but the fault seems to go away by itself. Because of this, I was like... there is another battery? Anyway, I know there is only one.

[Bobby Kinstle]

Ha, my dealer called me to say it had been a year since my last service, the first time I've ever hit the time limit before the mileage. I think I've driven around 3000 miles during the pandemic. But thankfully I haven't had to worry about the battery going dead. I also have a VW/Audi solar panel that plugs into the cigarette lighter that I've had sine about 2002 ish. Now I wonder if it'll work in my S4 since it turns off the cigarette lighter when the car is off.

[nerdag]

I use a Ctek on all of my cars, S4 included.

I hooked up the Ctek quick connect eyelets to the charging points under the bonnet, and its quick and easy.

[Kondax]

I've just had a ctek charger delivered today so going to give that a go.

[RickNY]

where the hell did the rear fog light go >? I've never owned an Audi without one.

They removed the rear fogs midway through the 2018 production run

[YoYo]

Is the CTEK (56-353) MULTI US 7002 good enough for coding/ECU flashing? Some have suggested min 20 amp to be safe. That would require the CTEK (56-674) Multi US 25000. I'm thinking the 7002 would be ok if I checked the battery/charged it first then used the supply mode. Kondax, what model did you get?

[Diokhan]

I used that model in supply mode without issue. Shut off circulation, headlights/running lights, dome lights, and anything else you don't need when the ignition is turned to the "on" position.

[will13k7]

there's a slight chance the battery suddenly dies, the ctek 7002's supply mode provides 7A, which is supposed to prevent your settings from getting wiped out, is that enough for ECU/TCU flashing? 034 recommends 15-20A. I charged the battery overnight and just left the ctek on normal mode, the battery is 3 years old, so I wasn't too worried and just took the risk.

[YoYo]

Thanks for the info guys. I'll probably just go with the 7002 and charge it before any flashing. I'm on my original battery so I'm getting a little worried about it.

[ebarberena]

I would like to recomend an alternative to Ctek: Solar Pro-Logix PL2320: (https://www.amazon.com/Clore-Automot.../dp/B007ESQW08).

I’v had the CTEK 56-959 MUS 4.3 for 4 years and the Solar for 7 years.

I like the Pro-Logix much better. it has the same battery maintenance and conditioning features as my Ctek but much more powerfully charging capacity (2A/10A/20A). It is also much more intuitive to use.

The fixed Ctek plug is a very convenient feature though, if you are planing to use the charger frequently. That’s why I bought mine, to charge my RZR which needed to be charge through the week to work reliably on the weekends.

[YoYo]

Thanks.. I will check that out.

I would like to recomend an alternative to Ctek: Solar Pro-Logix PL2320: (https://www.amazon.com/Clore-Automot.../dp/B007ESQW08).

I’v had the CTEK 56-959 MUS 4.3 for 4 years and the Solar for 7 years.

I like the Pro-Logix much better. it has the same battery maintenance and conditioning features as my Ctek but much more powerfully charging capacity (2A/10A/20A). It is also much more intuitive to use.

The fixed Ctek plug is a very convenient feature though, if you are planing to use the charger frequently. That’s why I bought mine, to charge my RZR which needed to be charge through the week to work reliably on the weekends.