2011 XC90 - My car eats batteries for lunch...

[JohnCC]

This car is going to drive me to the loony bin! It's currently on its 4th battery in 8 years. It sat for 2 days in zero degree weather, started (reluctantly) on the third day for several reasonably short trips, started fine for each of the trips other than the first, then failed to start on day 4. I jumped it, drove it 10 miles, then put it on the charger. At a charge rate of about 1.25 amps it took 20 hours to top off the battery. I have a volt meter in the console power outlet that shows a system voltage of 14+ volts when running. It's as if the car was designed for the tropics! The only ideas I can come up with right now are, the system voltage is not making it to the battery (can't imagine how...), or the seat heaters come on at night while I'm sleeping... Short of finding a recording ammeter, I'm at a loss as to what to do next.

I've done parasitic draw tests. The draw drops to around 15 mA after 10-15 minutes. The highest I've seen while it's sleeping is about 35-40 mA. I know about the problem with the sat radio, but have been told that if I have Sat 1 and Sat 2 as sources it's already been upgraded.

I'm convinced that something is drawing it down over night, and that in cold weather, several nights is all it can handle, but I'm at a loss as to how to catch the gremlin in the act.

The car was first titled in 2/11. Carfax shows an electrical system check that month, and again in 11/13. When I got the car in 2015 it did not have the original battery. It had the oversize battery, a Duracell/Deka. IIRC, the battery date code showed it was new some time in 2014. I almost replaced it in 2016, but ended up nursing it for another year. I replaced it in 9/17 after charging and testing it on a very fancy, FAA approved battery tester. It tested at roughly 70 minutes reserve capacity at that time. The replacement was an Exide Extreme, also L5/group 49. I exchanged that battery in 10/18. It is possible the first Exide was just partially discharged and didn't need to be replaced; I based my assumption it was fully charged when I tested it on the readings I was getting from the volt meter in the aux socket.

One thing that may be related: the seat memory doesn't work, as far as I can tell. The buttons won't store anything and the seat rarely if ever moves when you unlock the door with either fob. (The fobs used to work, sporadically, but no more.) The passenger's side mirror does seem to have a mind of it's own, though, as I often have to adjust it when I get into the car.

Someone pointed me to the siren. Is there a fuse I can pull for that? It looks like a PITA to get at the actual siren. (Could this be the problem, given it drops to 15 mA after shutdown?)

I have left the battery disconnected for a few days and it seems not to discharge then (I'm not surprised!) but that's not a long term solution as I can't be going out to reconnect it every morning, and I hate having to reset the clock...

BTW, how long should I be able to play the radio without running the engine? I had a Yukon and we could get through the first feature at the drive-in easily. With this car I doubt I'd get half an hour. Makes me think the battery isn't getting charged properly, but it's the same wires that power the starter, as far as I can tell. (I've measured the charging voltage at the battery terminals and it's over 14 volts.)

TIA,

[abscate]

If you use the car for short trips of 10 miles or less, the battery will be in deficit in the cold winter months.

A 1.25Amp charger will take about 180 hours to charge a batter from discharge - you need a bigger charger, like a 10 Amp, to get the battery caught up.

Once the battery sits discharged for a while, it sulfates and dies, so that explains the rash of new batteries needed.

a 50 mA draw on sitting should not take out the battery overnight - that is considered normal.

[JohnCC]

Thanks.

My trips are not all short trips. I've been driving for over 50 years and never had this problem before.

I only noted the charge time to illustrate the state of charge of the battery after the dead/jump/drive for 10 miles/charge cycle. I don't expect to ever have to charge the battery between trips.

Again, it's not the driving, it's the sitting over night for more than a day or two, especially in cold weather, that gets it. If I drive it every day it seems fine, although I don't think the battery is maintaining a full charge, hence the short battery life.

I can charge the battery completely, and come back the next day and it will be noticeably lower, like showing 12.3 volts.

Not trying to be a smart a$$, but this has been very frustrating for me. When I was a working stiff, my specialty was electrical systems. Go figure! It's as if the gremlins are using the seat heaters all night long.

[abscate]

I guess I would hook up a logging ammeter and monitor it. 50 mA draw won't kill a good battery, even in the frigids.

Once it is dead to the point of a no-start, though, you need a good 10 Amp charger to bring it back = driving won't do it.

The car fax does seem to indicate this isnt the first time this unit has experienced this problem though, doesn't it?

[JohnCC]

I guess I would hook up a logging ammeter and monitor it.

Yeah, I wish I had one. Of course, it would have to run all night on its own batteries...

50 mA draw won't kill a good battery, even in the frigids.

Yeah, I know. That's what's so puzzling; it would have to be a pretty significant draw to get it to the point where it won't start in a couple of days.

Once it is dead to the point of a no-start, though, you need a good 10 Amp charger to bring it back = driving won't do it.

Well, maybe if I drove cross country...

The car fax does seem to indicate this isnt the first time this unit has experienced this problem though, doesn't it?

Yeah, I'm wondering if it hasn't been this way since day one. If you drive it every day it's not a problem, at least for a year or two, although you can't sit with the engine off and listen to the radio for very long. Being only partially charged, though, shortens the battery life, or at least that's my theory.

[SuperHerman]

You have something wrong. First a similar story - my brother had a brand new Chrysler Pacifica a dozen or so years ago that kept draining the battery. It left him stranded a few times. Under lease, he brought it to the dealer and they kept changing the battery and telling him it is good to go. Nothing changed, finally the big tech guns were brought in, and they said all is well. Come pick up the Pacifica. This happened on a Thursday, over a long weekend where Monday was off. My brother called me and asked what to do - I told him to say, you cannot pick it up until Tuesday. Come Tuesday, I had him call the dealer and have them pull the car out and get it ready for his noon pickup. They called back and said the battery is dead. That was our plan - we knew it would happen - and it did. They took the car back and made things right. The point of the story is there are gremlins that sometimes cannot be found.

In your case, I would see if you can find a computer program based OBDII reader that will track and log the voltage drain the entire night. You have something that is pulling power at random times. From there you can start doing the various circuits and logging those, one at a time, until you find the culprit.

For the siren module, I have read that one can access it through the passenger headlight, if it is removed. You should be able to snake your arm in there and disconnect the harness at least. Should take ten minutes top as the headlight is super easy to take out.

[JohnCC]

I have VIDA/DICE, or whatever it's called. although I'm not very proficient at using it. Don't know how I can keep it running all night, though, in a locked car, and won't having something on the OBD port all night keep everything from sleeping?

I think what I really need is a network sniffer...

[regent]

Like abscate suggested:

Assuming your charging system is flawless, I would leave a clamp-on recording ammeter on the batt. negative overnight - it should tell if there was any significant draw.

(VIDA DiCE pulls about 1.5 A from the car if no 12 V external power is present, I would not leave it connected and unattended)

[JohnCC]

I do not have access to a recording ammeter. I guess I figure it will only (at best) tell me what I already know; something is waking up in the middle of the night and draining the battery.

One thing I've though of that might help is if I could pull one or more fuses of "usual suspects" to see if it continues or not. Problem there is I don't know enough about the overall system to know if pulling a fuse may actually affect more than one system. I wouldn't expect killing one system to make another draw more current, but can't say for sure.

I should probably note that the only thing I've ever seen out of the ordinary is the ventilation fan running, and I know that is in fact normal.

Can anyone confirm that, if I have Sat1 and Sat 2 inputs, the sat. radio has had the update? Is there a fuse I can pull that will disable it? (I thought it was fuse. #9. On the fuse box cover it said "Infotainment/RTI". I don't have definitive data, but I pulled it a couple of weeks ago and my feeling the next day was than battery was more discharged than the night before.

[oragex]

Haven't read, but remember of an infotainment issue with the XC90.. Maybe pull the fuse after driving, then read the voltage (allow 10 min so the computers shut down and the voltage stabilizes) and measure the battery, then next morning before driving connect the multimeter again - allow again a 10 min after opening the car and compare the readings. www.youtube.com/watch?v=VsrmpXpZGVs