Start/Stop - Low voltage or Battery temp

XC60aches · Post by **XC60aches** » 13 Jan 2020, 17:22

Hey guys, new to the forum... hope to gather and share info here. I always try to be detailed, so everything will be documented and hopefully help someone else.

So I have been battling a start/stop not working due to low voltage or battery temp on the S/S screen. Main battery was initially a little low. Lots of history over the past few weeks:

-- Both batteries checked good.
-- Alternator charging at 14.8
-- Parasitic Amp checked at .04amps
-- Cranks good with no indication of being low

Fully charged batteries. Thought I had it narrowed down to recently keeping the key fob in the slot while sitting in the garage, although this seemed kind of strange. I thought I had it licked, but after a week of being good, today I started it up, no low voltage flag message, but start/stop not working for low voltage or battery temp. The temp in the garage was about 60F.

I went for about 20 mile drive, the battery checked good at 12.7. I manually reset the BMS. For the moment, S/S is working. I will find out tomorrow if it is holding. I have been reading that a bad battery temp sensor can wreak this kind of havoc. I can not seem to locate it on this vehicle (2015.5 XC60, 2.0).... is it built into the BMS module on the negative battery post? Was thinking of cleaning the temp sensor. The BMS module looks decent, no corrosion.

Appreciate any information...

XC60aches · Post by **XC60aches** » 14 Jan 2020, 16:06

Quick update:

This morning the S/S system still not working for “charging” (not necessarily low voltage) or battery temp. But mysteriously on the way home this afternoon it started after about 15 mins of driving it. It was slightly warmer today in texas; about 73F. Maybe that helped. Weird.

I hate the S/S system and normally turn it off as I enter the car. I suppose maybe this is doing exactly what it’s supposed to do as the battery starts incrementally losing life. It’s something that caught my attention and my OCD kicking in in full effect

My guess is it won’t work tomorrow, but I have to plans to stick it on the charger anymore, unless it gets really low.. at this point, just monitor.

Thoughts?

Post by **volvolugnut** » 14 Jan 2020, 16:25

Lots of battery questions here lately. These batteries sound like it should be happy in the warm garage and getting recharged, but APPEAR unhappy. Are these the original batteries? 5 years may be end of life even for best batteries. Any history of getting deep discharged in their life?
volvolugnut

XC60aches · Post by **XC60aches** » 14 Jan 2020, 16:42

This is my second battery. The original lasted just over 3 years. It was probably the same scenario as I’m experiencing now. But that battery actually tested bad. I replaced it with current battery with a high end 94R AGM platinum super start from oreileys about 15 months ago. No history of deep discharge.

Most of my driving is 20 mins or less, so that’s probably not helping.

XC60aches · Post by **XC60aches** » 20 Jan 2020, 15:31

So still not working. In the morning I can open drivers door and open hood and the battery will be at 12.25 - 12.40v. This because everything started to fire up. Usually within about 5 mins it will be between 12.55 - 12.6.

At idle the battery will be 14.82 and 14.75 with heavy load. 20 minutes after driving (engine off everything closed except hood), the battery will be about 12.75. This all seems normal.

At static amp draw 10 minute test. First minute was 3.3 amps because everything fires up when making connection. After that it settled to about .09 amps up until minute 3. From minute 3-10 it was literally .007amps and stayed there. I am confident there is not a parasitic drain. (Just in case, I do have a MOST cable loop on the RDAR). Set this up by removing negative cable, multimeter (mm) on 10amps, mm black taped to negative battery post, mm red on negative battery cable.

I have suspicions of what it could be:

1. The battery ... despite checking good (this is my hunch)
2. So far no low voltage flag upon entering the car. Dunno if Bad BMS (negative battery cable assembly) could cause this?

Appreciate any comments. I will definitely figure it out eventually. I plan on providing periodic updates to help someone in the future..

okidiver · Post by **okidiver** » 20 Jan 2020, 16:59

The A/S/S has a list of criteria for why it might and might not work, but it is still in beta testing and Volvo thanks you for your continued contribution to said testing.

My favorite thing about A/S/S is having it not working all the way home through some nice long lights and then, as I'm edging forward in my garage toward the wall, it decides to work. The system was designed by demons, who are laughing at us all...

XC60aches · Post by **XC60aches** » 20 Jan 2020, 17:22

LOL oki.. I agree it’s a weird finicky system. I am in the habit of always turning it off. I should count my blessings it currently isn’t working. But I kinda wanna know exactly so I know how to make it not work on my terms, not theirs.. lol

Post by **jimmy57** » 20 Jan 2020, 20:26

You my have to get it read with current VIDA as there are many S/S monitored tings with the most effective on for you being last 10 S/S block reasons.

XC60aches · Post by **XC60aches** » 21 Jan 2020, 06:24

Jimmy, I got your message.... tried to reply but it just shows in outbox and wont seem to send. Weird. Anyways, i appreciate any ifo you might provide. Thanks..

Post by **matthew1** » 21 Jan 2020, 07:28

Outbox means it’s in the recipient’s inbox, they just haven’t read it yet. It’s poorly named.

But please, keep knowledge on the forums, in these topics. It does the world no good to hide Volvo information in private messages.