Battery Tender

[Boothbkk]

I’ve been charging my X5M F85 for each day for the last 4 days now on Ctek 7.0. Every time set the mode to AGM the charger shows bulk charging, takes >6 hours to get full charge but toggle back to AGM mode it’s starts over. I noticed the recharge icon comes up on the iDrive under coasting or breaking; it never did before. So, hard to find what battery (two batteries in rear) is the problem one. Stop / start rarely worked, no other issues I.e. car starts fine. Thought high temp (close to 50c) here caused the stop / start issues but it’s working now after two days of charging. No expert but believe one of these batteries needs replacing as I can’t hold a charge because of continual charging? Or do I keep charging until the Ctek charger stabilises with a full charge?

[yewlock]

Do a diagnosis with your ctek on each of the battery to narrow it down.

[White Dragon]

I have this BMW branded charger that I got with my E46 M3 that plugs into the cigarette outlet. Any thoughts on if this would work on an F85 if plugged into the cigarette outlet by the front cup holders?

[Btt335]

Go for the BMW battery tender and connect directly to the battery , is more easy open and close the trunk than the hood

[White Dragon]

Originally Posted by Btt335

Go for the BMW battery tender and connect directly to the battery , is more easy open and close the trunk than the hood

Are you talking about this one?

[baliano]

+1 for the Deltran. I've used them on multiple cars for years with no issues and great results. Both M's are sippin' on a charge for the winter.

[HPIA4v2]

Using the engine bay terminal, the trickle charge only seems to charge the big battery the secondary batt needs to be directly hook up to charger in the trunk.

I haven't tracked down what the secondary batt is for so maybe that's ok

[cncmastr]

Originally Posted by White Dragon

I have this BMW branded charger that I got with my E46 M3 that plugs into the cigarette outlet. Any thoughts on if this would work on an F85 if plugged into the cigarette outlet by the front cup holders?

The newest cars have a battery intelligence system, you need to charge through the positive and negative terminal in engine bay. It will keep track of voltage.

Cigarette lighter charge is not recommended.

[Btt335]

Originally Posted by White Dragon

Are you talking about this one?

Yes, I use in my cars and works perfect for a good price

[Qsilver7]

Originally Posted by White Dragon

I have this BMW branded charger that I got with my E46 M3 that plugs into the cigarette outlet. Any thoughts on if this would work on an F85 if plugged into the cigarette outlet by the front cup holders?

Originally Posted by cncmastr

The newest cars have a battery intelligence system, you need to charge through the positive and negative terminal in engine bay. It will keep track of voltage.

Cigarette lighter charge is not recommended.

Ditto cncmastr...the old BMW battery tender you have doesn't play well with the new generation BMWs with AGM batteries that are also monitored by an IBS (intelligent battery sensor). Plus the 12 volt sockets inside the car shut down after approx 15-16 minutes...thus will not be able to maintain the vehicle's battery (batteries).

Also, you may want to check the manual/paperwork because that charger may not work well with AGM & Lithium batteries...it may only work with regular wet cell lead acid batteries.

[White Dragon]

Thanks for the info - that definitely helps!