8Y RS3 is a Battery Hog

[fzr100098]

I keep an Optimate 6 (best automatic trickle charger I've ever used by far) hooked up in the trunk at all times and charge whenever it is parked, but with all the computers, electric motors, light show, etc etc this thing burns the juice like a mini EV. It will charge at 5 amps for several hours after a single drive (!)

Just a warning - I wouldn't be surprised if the battery is shot after a couple of years without an automatic charger

[theverge]

I keep an Optimate 6 (best automatic trickle charger I've ever used by far) hooked up in the trunk at all times and charge whenever it is parked, but with all the computers, electric motors, light show, etc etc this thing burns the juice like a mini EV. It will charge at 5 amps for several hours after a single drive (!)

Just a warning - I wouldn't be surprised if the battery is shot after a couple of years without an automatic charger

sounds like my stupid Subaru. I have left mine sitting for weeks though and it started fine.

[Def_Jukie]

I keep an Optimate 6 (best automatic trickle charger I've ever used by far) hooked up in the trunk at all times and charge whenever it is parked, but with all the computers, electric motors, light show, etc etc this thing burns the juice like a mini EV. It will charge at 5 amps for several hours after a single drive (!)

Just a warning - I wouldn't be surprised if the battery is shot after a couple of years without an automatic charger

Out of curiosity are you locking it when it's in the garage?

[Rod Paine]

We have a 2019 RS 3 kept in a garage and its original battery is still holding a charge
after our usual 3 days a week 10am to 2pm country back roads run, as weather
permits. Only changes we've made to the RS 3 were the tires using 245/40/18
Michelin AS3+ on Neuspeed 18x8.5 alloy wheels. It is ALWAYS locked in the
garage and while in our driveway!

[Alex D]

I keep an Optimate 6 (best automatic trickle charger I've ever used by far) hooked up in the trunk at all times and charge whenever it is parked, but with all the computers, electric motors, light show, etc etc this thing burns the juice like a mini EV. It will charge at 5 amps for several hours after a single drive (!)

Just a warning - I wouldn't be surprised if the battery is shot after a couple of years without an automatic charger

I've left mine sitting for about 3 weeks so far without driving and it started right up.

[Yes2m3cs]

I left mine for 4 months in storage and started right up - thank god lol!

[fzr100098]

Short trips are definitely harder on battery life

Typically not locked when in the garage

[Def_Jukie]

Short trips are definitely harder on battery life

Typically not locked when in the garage

If the key is somewhat close by it could be trying to communicate when it's left unlocked causing the slight drain.

[Spike Spiegel]

If the key is somewhat close by it could be trying to communicate when it's left unlocked causing the slight drain.

I experienced this with my AA Wireless module. I had my car unlocked and was talking to my neighbor while standing next to it. The module is powered via the USB port, and the USB ports in the car would power cycle every 5 to 10 minutes or so. My phone would notify me that "Android Auto has been started" and then turn off after some time. It kept happening for a while.

[Jetdriver]

sounds like my stupid Subaru. I have left mine sitting for weeks though and it started fine.

Subarus do have a known battery charging issue. I replaced my battery charging fuse with an aftermarket one that fixed this problem. There is much more consistent charge from the alternator now.

[tegxsi]

Subarus do have a known battery charging issue. I replaced my battery charging fuse with an aftermarket one that fixed this problem. There is much more consistent charge from the alternator now.

That's been corrected for a while on Subaru's if you have the latest fix in your tune.

Most modern cars have a lot electronics sucking on the battery...even the fuel pump primes when you open the door. lol

[A418t81]

Mine sits for weeks all the time with zero problem.

[kevin#34]

I left my TT unused for 2 months, and it started perfectly.
when the car is not used, all modules shut-off, so battery draining is really minimal

[fzr100098]

Whether the car starts is not the point and basically irrelevant to my OP

My point is all the computers, motors, lights, etc suck down the juice and you need to keep a good trickle charger on the car at all times for the sake of battery health, not so your car starts. If you don't have a good battery charger/tester, you don't know - it has to be nearly dead for the starter not to work

[RMode]

Whether the car starts is not the point and basically irrelevant to my OP

My point is all the computers, motors, lights, etc suck down the juice and you need to keep a good trickle charger on the car at all times for the sake of battery health, not so your car starts. If you don't have a good battery charger/tester, you don't know - it has to be nearly dead for the starter not to work

Anything shy of around 11.5 volts and the car will not start on it's own. I doubt the starter even turns.

Yes, it will charge at 5 amps after a drive - for a period of time. Depends how long of a driver you were on, but I could easily see it charging for 2-3 hours at 5 amps after even an hour drive. I can't think of a car of mine that won't do the same, ranging from a 2000 all the way up to our 18 and 19 Audi's (all Audi family here!). It's a 75ah battery, and the alternator is 180 amp. I believe the 8Y RS3 uses it's own alternator that isn't shared with other cars.

Nothing is operating when the car is off beyond the clock and immobilizer. Everything else goes to sleep. You can verify this with any number of tools. That is, unless the key is in proximity to the car. Once that occurs, the two will constantly talk, regardless if the car is locked or not. Moreso a problem for the tiny key fob battery than the car.

A trickle charger is always a good idea if the car will see extended periods of time, over and over, without being used. But even a couple months at a clip won't be any issue. If it is and the car fails to start, there is a draw somewhere, which is a mechanical issue, and not the nature of the car.

[fzr100098]

Anything shy of around 11.5 volts and the car will not start on it's own. I doubt the starter even turns.

Yes, it will charge at 5 amps after a drive - for a period of time. Depends how long of a driver you were on, but I could easily see it charging for 2-3 hours at 5 amps after even an hour drive. I can't think of a car of mine that won't do the same

That's my point - I've owned many cars, none of them drain power so quickly. My (older) V6 Accord for example...after multiple short trips it's fully charged ("green") within about 30 minutes. With the RS3 is can be 5+ hours charging at 5 amps

A trickle charger is always a good idea if the car will see extended periods of time, over and over, without being used.

I keep mine in the trunk and connected whenever the car is parked. I've had good luck getting at least 5 years of life out of a battery

[RMode]

That's my point - I've owned many cars, none of them drain power so quickly. My (older) V6 Accord for example...after multiple short trips it's fully charged ("green") within about 30 minutes. With the RS3 is can be 5+ hours charging at 5 amps



I keep mine in the trunk and connected whenever the car is parked. I've had good luck getting at least 5 years of life out of a battery

How long it will sustain a 5 amp charge is a simple function of the ah rating of the battery to begin with, and it's reserve capacity. It's not related to the onboard systems because they are all powered off when the car is off, and there is very minimal current draw for the memory of the ccm modules. The battery doesn't power them when the car is running, the alternator does. But yes for sure, with all the onboard systems, when the car is on, I'd bet it's relatively current hungry. Which is why it has such an alternator despite the small car.

Yep, any good battery nowadays should last at least that long, or around 65k or so. While the car largely sits (haven't driven it since September last year, and aybe I did 300 miles total all of 2022, 0 in 2023), my B7 S4 only just received it's second battery in it's life last August. The original served me well, so I did another Audi one. Inexpensive too all things considered. I will likely have to do the one in the B9 S4 this year, if I ever get back to that house. It too, just sits, with only ~3700 miles since I took it home December of 18. Neither has a trickle charger on them, as I am never really there, and don't want my tenants dealing with the cars, but the batteries are left disconnected.

I do have a Noco10 where we live year round, but I've yet to take it out of the box lol.

[XMetal]

That's my point - I've owned many cars, none of them drain power so quickly. My (older) V6 Accord for example...after multiple short trips it's fully charged ("green") within about 30 minutes. With the RS3 is can be 5+ hours charging at 5 amps

This is not a fair comparison because your RS3 and Accord charges the car differently during operation (different charging strategies). The accord will constantly charge the battery and maintain a constant 14.4V while the engine is running. Your RS3 on the other hand, will only charge the battery while off throttle (while coasting). If you don't believe me, connect up a cigarette lighter voltmeter and see when it will jump to 14.4V - 14.7V! Most of the time, it will remains at 12.0V - 12.8V, which means the car isn't charging the battery - the alternator is outputting enough just for operation. Also, one of the fuel economy gauges will also shows you the charging info (you'll see a green section at the battery end of the bar when the alternator is charging the battery). Most of the time (when throttle is maintained), like when you're on the highway, the alternator on the Audi isn't charging the battery! This is the reason why you're still seeing the battery accepting a long charge even right after a drive, especially if you don't often "coast" in your drive.

How do you know your RS3 is charging 5+ hours at 5 amps? Just because you have a 5-amp charger doesn't mean that it charges at 5 amps the entire time you have it hooked up. Most trickle charger don't remain at their max charging amperage during the entire charge time. It will ramp down the amperage as it gets closer to topping off the battery. It may only be at 5 amps the first 10-20 minutes or so.

[WtA4WtQ5]

Normal. If the 8Y RS3 is battery managed anything like my B9 SQ5 the battery never gets fully charged (as legacy older vehicles did) in normal driving. The vehicle is always "leaving room" to charge the battery by going downhill or decelerating with your foot fully off the gas pedal.
If the RS3 has the fuel economy gauge like SQ5 that is the green zone in the gauge. Alternator only really works hard when decelerating and going downhill. All for corporate fuel economy.

[fzr100098]

How do you know your RS3 is charging 5+ hours at 5 amps? Just because you have a 5-amp charger doesn't mean that it charges at 5 amps the entire time you have it hooked up.

Optimate shows charging amps - superior to Battery Tender or CTEK (in my experience) in every way, especially service life

Most trickle charger don't remain at their max charging amperage during the entire charge time. It will ramp down the amperage as it gets closer to topping off the battery. It may only be at 5 amps the first 10-20 minutes or so.

Not on this car!

[RMode]

Optimate shows charging amps - superior to Battery Tender or CTEK (in my experience) in every way, especially service life



Not on this car!

So it will depend on which charger specifically you're using. Only one of their units offers variable amp charging that I can see. The rest are fixed, so their output does not change. All that does is determine how fast it can put a full capacity charge into the battery in the first place (for a battery of a given ah).