Support Battery - Never heard of it - Have you?

[volvojoe]

I have just had a battery failure on my 2016 XC90. It is the "support battery" that provides power to the electronics, computers, radios, Sensus, etc... for the car when the engine is not running due to the Auto Start/Stop feature has stopped the engine, at a red light for example. It is located under the hood, driver's side, against the firewall, had a red plastic cap on it. Remove the two small bolts and lift the cover and there is what the Service Rep called "a motorcycle battery". I didn't even know of this battery, which is not the "engine start" battery, until a orange/yellow warning came on the dash. The symbol looks like the letter A with the circle with the pointer around it. The symbol came on, and the message Auto S/S system requires service. I Googled that message and found on SwedeSpeed (probably not spelled correctly) Forum where someone else had this issue and what had to be done to repair it.
Upon going to the Volvo dealer, it was determined the battery had failed. The system was checked out and the battery was replaced. As soon as the car was cranked and the Auto S/S system was "activated", the warning came in again. This time it was determined that "a relay device" had failed. My car is out of its' warranty by two months, with only 39k miles on it. The battery was treated as a wear item and no warranty was provided, even if it had been within the 48 months warranty period. Cost for replacing the battery was $180. I requested some "good will' as the car was just two months out and with only 39k miles. Service manager okayed the "good will".
When the system was placed in service and the Auto S/S warning light came on again AND the "relay device" was then determined to have failed, the service rep explained to me that because the "relay device" was a mechanical failure/failure of a part on the car, the Service Manager had contacted Volvo and got permission to fully honor the car warranty, replacing the "relay device" and the battery, my guess the "relay device" prevented the support battery from charging resulting in "failure". Bottom line - I never had heard of this "support battery" until the failure on my car. When driving the car, should the battery/relay device fail, there is no issue with continuing to drive the car - it is safe to do so. The Auto S/S feature will no longer function to shut off the engine. (I thought about not fixing it!.) But, without the support battery, the "main" battery, the one that cranks the engine, powers all the devices on the car, all the time. So - what is wrong with that??? Volvo cars are too complicated and they are dangerous to drive - because of all the touch controls for almost everything except the radio volume knob. I love that one knob.
And by the way - of course the dealer did not have the "relay device" in stock. The service rep I dealt with also let it slip that this battery and "relay device" has been a frequently replaced system in '16 and '17 model cars.
And because the car warranty is covering the problem, the dealer gave me a new 2020 XC90 to drive until my car is fixed. So, before the warranty was honored, Volvo didn't know me - after the Volvo warranty was reinstated, I'm their best customer. Don't ya' just love it!

 

[HectorC]

I have never heard of it till now but I think you should still have a warranty I thought they were for 4 years or 50,000 miles. I have a 2019 and that is what I have.

 

[SRG963]

Had mine replaced around 80k and 2 years, no warranty.

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[elchoche23]

I traded my 2018 Jeep Wrangler JL for a 2020 Volvo XC90; the Jeep's battery you're referring to was replaced before it's first oil change. In your case, it went out after warranty which is way past the Jeep's. Don't get me wrong, I love Jeeps; had two and now down to 1 but my Auto Start battery (does look like a motorcycle battery) went out way before 10,000 miles; so if that's a sign of quality, then your Volvo wins hands down.

 

[charzar]

I just had my support battery replaced on my 2016 T6. I didn't drive the car for an extended period of time and got the "start/stop system needs serviced" message once I did start it; I think the car electronics were slowly draining it over the 2 month period. I put a battery tender on it once I did fire it up but by that time I think the battery could never get back to the charge level needed for the warning to go away.

 

[SwissXC90]

Tip: if your driving habits are such that the vehicle doesn’t get used in just 2 weeks, then set a reminder schedule to put a battery tender on the car once a fortnight or once a month for 24 hours.
This will preserve your battery

During this COVID year my car gets used only once a week for a short shopping trip and that’s pretty much it. I charge the battery once a month to keep it healthy. I also have a CTEK Battery Sense connected so I can view my battery status and see a graphed battery charge over time (going back about a full year) and I have a really good idea as to what is good and what is bad and when my battery needs charging.
This way I never let it drop below 70% charge state,

Here’s a screenshot of my battery over the last month, you can see where I drive (battery charging) and where I do not drive. The discharge rate over time when the vehicle is not being used is clearly visible. Today, my battery was at 89%. Anything above 60% is labelled as “OK”

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