[chiefneil]

Originally Posted by SportySpice

With the subzero night time temps we're having here, I've been using a Battery Tender from Costco all week. I don't think it has a desulfation mode like the CTEK maintainers. Does the desulfation mode add considerably more benefit to protecting / extending battery life than a more basic float charger? Which device are you folks using?

TIA. This is a great thread, btw.

Reconditioning isn’t recommended for AGM batteries, and it’s noted in the CTEK doc not to recondition AGM batteries. Interestingly, CTEK’s AGM battery mode is simply the cold-weather mode. I think AGMs have lower internal resistance which makes them look like a really cold regular battery.

[ToniCipriani]

Originally Posted by DrifterX

After reading complaints/feedback from multiple posts in this forum, other articles and that document, a battery tender/charger is a must for BMWs now a days to keep the battery in good shape; especially for cold weather and if you don't drive it everyday like I used to.

Fun when you live in a building and there's no outlet nearby...

Originally Posted by Billfitz

I have a NOCO. The 1.5A is sufficient as a maintainer. I permanently wired the lugs to the charging posts under the hood, adding enough wire to have the connector come through the grille down by the fog light, so I don't need to open the hood to connect it.

I just tried the 1.1A to recharge mine, says 100% but didn't do much, the low battery warning came back after a drive.

[Billfitz]

100% is 100%. One known issue is that the software can be too aggressive at the battery charge where it throws out a warning, especially in cold temperatures. Just to be sure I have one of these:
https://www.amazon.com/INNOVA-3721-B...+voltage+meter

I got it as a 'just in case' item. As it turns out I've never had the need to use it, because my iDrive has never thrown a low battery warning that I'd want to independently confirm. In any event if you get a warning after a drive that pretty much confirms that you should put it on the maintainer.

[ToniCipriani]

Originally Posted by Billfitz

100% is 100%. One known issue is that the software can be too aggressive at the battery charge where it throws out a warning, especially in cold temperatures. Just to be sure I have one of these:
https://www.amazon.com/INNOVA-3721-B...+voltage+meter

I got it as a 'just in case' item. As it turns out I've never had the need to use it, because my iDrive has never thrown a low battery warning that I'd want to independently confirm. In any event if you get a warning after a drive that pretty much confirms that you should put it on the maintainer.

Well it could actually be not full. Charger's manual says for charging it's only rated for 40AH, ours is 90. I really only charged it at a friend for about 8 hours only, manual says full charge needs almost 24-36 hrs for the 1.1A for 80. So it's possible it's still less than half charged.

And considering my battery is now 5 years old, plus an accidental drain, it is a perfect storm.

[Billfitz]

Originally Posted by ToniCipriani

manual says full charge needs almost 24-36 hrs for the 1.1A for 80.

That would be from a more or less dead condition. When that happens you do need at least a 4 amp charger, preferably more. I have a 10 amp charger for those rare occasions. A maintainer isn't intended to do a full Lazarus treatment, it's just supposed to top off a charge that's not all the way there, and just as important to supply the current that the car uses when it's not running so that the battery doesn't have to.

[ToniCipriani]

Originally Posted by Billfitz

That would be from a more or less dead condition. When that happens you do need at least a 4 amp charger, preferably more. I have a 10 amp charger for those rare occasions. A maintainer isn't intended to do a full Lazarus treatment, it's just supposed to top off a charge that's not all the way there, and just as important to supply the current that the car uses when it's not running so that the battery doesn't have to.

Then I guess in that case my battery is indeed dead. I'll get it checked out this week if the message still doesn't go away, it's warmer the next few days.

[Billfitz]

For sure wait until it warms up. Nothing works the same at below freezing temperatures as it does above freezing.

[lkstaack]

Interesting thread. It leads me to believe that BMW's smart charging algorithm is deficient for Bimmers in extreme cold weather. It's common knowledge that smart charger Bimmers must be driven often to keep the battery topped off. It's also known that the management system keeps track of battery condition and ambient temperature. Consequently, a car driven daily should keep the battery charged regardless of ambient temps. The smart charging system is deficient if it can't keep a healthy battery charged under daily driving conditions.

[HighlandPete]

Originally Posted by lkstaack

Interesting thread. It leads me to believe that BMW's smart charging algorithm is deficient for Bimmers in extreme cold weather. It's common knowledge that smart charger Bimmers must be driven often to keep the battery topped off. It's also known that the management system keeps track of battery condition and ambient temperature. Consequently, a car driven daily should keep the battery charged regardless of ambient temps. The smart charging system is deficient if it can't keep a healthy battery charged under daily driving conditions.

BMW state their Intelligent Alternator Control is deactivated and reverts to conventional charging when state of charge is too low and/or ambient temperature is too low. The exact parameters could be the issue.

One question for those with battery condition warnings, does the engine ever fail to start, or is the warning simply that?

[Billfitz]

Originally Posted by HighlandPete

One question for those with battery condition warnings, does the engine ever fail to start, or is the warning simply that?

+1. I've seen dozens of posts saying that they get a warning, but I don't recall any saying the car wouldn't start.

[HighlandPete]

Originally Posted by Billfitz

+1. I've seen dozens of posts saying that they get a warning, but I don't recall any saying the car wouldn't start.

BMW get a bad press on here because they warn of a low battery condition. The amount of actual battery failures would be more reflective of real problems.

Batteries are the number one cause of breakdown callouts during the winter here in the UK.

Auto Express and RAC Recovery don't mention BMW as having a particular problem, simply applies across the marques. At least we get a warning.

Incidentally, Auto Express and the RAC recommend charging our batteries in the winter months, particularly if motorists make short journeys and due to the high electrical loads and energy sapping technology in our vehicles these days.

[ToniCipriani]

Originally Posted by Billfitz

For sure wait until it warms up. Nothing works the same at below freezing temperatures as it does above freezing.

And just like that everything is back to normal. Still below freezing but more like -2C rather than -25C.

I'll still bring it to my indie to get the battery checked, just in case. Same temperatures last year didn't throw the codes.

Originally Posted by Billfitz

+1. I've seen dozens of posts saying that they get a warning, but I don't recall any saying the car wouldn't start.

The warning also shuts off accessory power though.

[Kailec]

Originally Posted by ToniCipriani

And just like that everything is back to normal. Still below freezing but more like -2C rather than -25C.

I'll still bring it to my indie to get the battery checked, just in case. Same temperatures last year didn't throw the codes.

QUOTE=Billfitz;22619817]+1. I've seen dozens of posts saying that they get a warning, but I don't recall any saying the car wouldn't start.

The warning also shuts off accessory power though.[/QUOTE]

Yeah I was about to pull the trigger on the CTEK Polar charger but now not so sure..

[HighlandPete]

Originally Posted by ToniCipriani

The warning also shuts off accessory power though.

Power management can be doing that even without a visible warning. Some consumers get reduction in output to keep energy consumption within battery and alternator capacity.

[lo_xyooj]

I bought NOCO genius 3.5amp from Amazon and charged my car pretty much all weekend. Thank you BMW for the easy access charging points!! I will be using it often when the temps dip below freezing thats for sure.

[Ralph335]

Originally Posted by ToniCipriani

Fun when you live in a building and there's no outlet nearby...

Yep. Same situation for me.
I did find an outlet in an elevator lobby in my parking garage on the top floor. Thinking I could sneak the car there and charge it up on weekends.
Another option could be using a solar charger and parking the car in the sun for a while but I'm not sure how viable these are.

I still haven't pulled the trigger on a charger. Drove the car for a few days last week in EcoPro mode and focused on making sure I was engine braking frequently to optimize recharge time and haven't gotten the warning since.
Probably will just order the 1.1A Noco charger just to be safe. It's a good thing to have.

[Billfitz]

Originally Posted by Kailec

I was about to pull the trigger on the CTEK Polar charger but now not so sure..

An ounce of prevention...
I plug my car in every night that the temperature goes below freezing, often don't drive it for 5 or 6 days, never had a warning, not even over the last few weeks when lows went to -15F and highs were around 0. Coincidence? I don't think so.

[anotheran]

Got the discharged battery message to go away with the weekend's relatively warmer weather and did a bunch of coasting. Think it was mostly the warmer weather

[jeffc83]

Originally Posted by Ralph335

Drove the car for a few days last week in EcoPro mode and focused on making sure I was engine braking frequently to optimize recharge time and haven't gotten the warning since.
Probably will just order the 1.1A Noco charger just to be safe. It's a good thing to have.

I decided to do the same over the past few weeks since my commute is always full of joy (needed a new game anyway) I'm not saying that what we did worked but knock on wood, no message here at all and the car is only driven 4-5 days week max.. I've been very impressed with Zee German engineering, especially coming from Caddies.

[ToniCipriani]

Originally Posted by Ralph335

Yep. Same situation for me.
I did find an outlet in an elevator lobby in my parking garage on the top floor. Thinking I could sneak the car there and charge it up on weekends.
Another option could be using a solar charger and parking the car in the sun for a while but I'm not sure how viable these are.

I still haven't pulled the trigger on a charger. Drove the car for a few days last week in EcoPro mode and focused on making sure I was engine braking frequently to optimize recharge time and haven't gotten the warning since.
Probably will just order the 1.1A Noco charger just to be safe. It's a good thing to have.

The only outlet I found was in the underground car wash, for people to use their vacuum cleaners. There's a security camera there so I don't think security wants me to stay there for hours.

[ToniCipriani]

Originally Posted by anotheran

Got the discharged battery message to go away with the weekend's relatively warmer weather and did a bunch of coasting. Think it was mostly the warmer weather

Same here. Everything perfectly normal again since yesterday when temperatures become above -10C.

[Ralph335]

Originally Posted by jeffc83

I decided to do the same over the past few weeks since my commute is always full of joy (needed a new game anyway) I'm not saying that what we did worked but knock on wood, no message here at all and the car is only driven 4-5 days week max.. I've been very impressed with Zee German engineering, especially coming from Caddies.

Yea seems to work well. Just a shame the car is so boring in Eco mode. But it seemed to resolve the issue.

Originally Posted by ToniCipriani

The only outlet I found was in the underground car wash, for people to use their vacuum cleaners. There's a security camera there so I don't think security wants me to stay there for hours.

You have an underground car wash? So jealous! I can't find any place with that so I tend to go to the self service car washes or do a Optimum No Rinse wash on the roof of the garage when the car isn't too dirty.
Do you think the camera is really monitored? Park nearby and just run an extension cord over to the outlet. That way you aren't blocking the car wash bay.