They're a lot more expensive, but you get what you pay for.

Looking at the BMW battery maintainers that pop up on Google.

https://cdn.bmwblog.com/wp-content/u...15-750x500.jpg

https://images-na.ssl-images-amazon....eL._SX466_.jpg

https://xoutpost.com/attachments/x5-...one-fyi-b1.jpg

https://images-na.ssl-images-amazon....fL._SX425_.jpg

https://i.ebayimg.com/images/g/Gp0AA...XRr/s-l640.jpg

https://images-na.ssl-images-amazon....3L._SX425_.jpg

Have they no shame. Even Porsche are getting in on the rebranding ctek chargers.

I have a ctek branded ctek and it works very well. Even on a Porsche.

http://forums.pelicanparts.com/uploa...1549416259.jpg

I have the exact same one. Had it for at least 5 years. I'm embarrassed to tell you what I spent on it. I have a Schumacher trickle charger for a 1/3 of the price.

Hehe, well they sure look good.

Battery Trickler Question
 

My friend has a 2015 BMW where the battery is the trunk. He needs a battery trickler because the battery keeps going dead. Do they make a trickler that goes through the cigarette lighter? There is no way he can pull the carpet to get to the battery considering he can't put air in his tires.
Thanks.

There are solar chargers that work with the cg-lighter. The only issue, is the cig lighter active with the ignition off? Some are not.

Something like this:

https://smile.amazon.com/Battery-Portable-Waterproof-Maintainer-conversion/dp/B07JLWFPX6/ref=sr_1_5?crid=IKQ6NSUSWRU&keywords=solar+panel+c igarette+lighter&qid=1571239573&sprefix=solar+pane l+cig%2Caps%2C159&sr=8-5

If the cg lighter socket does not work, pretty sure it wont, look for a red cover under the hood and that will be the + connection.

Have your friend plug something into the cig lighter with no key in the ignition , if that item works then the cig lighter is considered " live " . And yes there are plenty of battery chargers/maintainers that come with or have as an option a cig lighter adapter . I use one on my Boxster all the time with a maintainer .

Having said that it is possible your friends car has an excessive current draw and a charger/maintainer may not be able to keep up . A charger/maintainer going through the cig lighter is assuming the battery is close to being " up to snuff " and just needs a topping off or the maintainer to " pulse " so the battery plates don't get coated with corrosion . Remember you are going through fairly thin gauge wires on the charger and even thinner wires from the cig lighter . Hope that helps . :D

The Cig lighter is good for 10A or 15A, depending, so up to 120 Watts or 180 Watts. The solar chargers I put up is 7.5W, which is much less than an amp, but will provide around 21Wh of charging per day, if it is in the sun.

In a garage, this will be useless.

This is an extension which is compatible with a "Battery Tender"

https://smile.amazon.com/SinLoon-Cigarette-Waterproof-Extension-Charging/dp/B073WW13PF/ref=sr_1_6?crid=3EMCI9CCJM4X1&keywords=battery+cha rger+cigarette+lighter&qid=1571241486&sprefix=batt ery+charger+cig%2Caps%2C170&sr=8-6

https://smile.amazon.com/Battery-Tender-021-0123-Junior-Charger/dp/B000CITK8S/ref=sr_1_5?crid=3EMCI9CCJM4X1&keywords=battery+cha rger+cigarette+lighter&qid=1571241540&sprefix=batt ery+charger+cig%2Caps%2C170&sr=8-5

Red do the solar chargers as a general rule have an over charge protection ? Or is over charging/boiling a battery rarely a concern with solar charging ? Not interested for cars but I am considering two solar chargers to charge/maintain my two diesel garden tractor batteries .

He needs to buy a standard trickle charger. All modern BMW's I've seen have charging connections under the hood. BMW engineers already thought of this......

Yes they do if the lighter works with the ignition off.

He has 1 of 2 problems. A) Battery is sulfated and only holding a surface charge. B) Parasitic draw exceeding 50 Ma.

He needs to have someone qualified to find which issue he has, then address it.

I'd just use the terminals under the hood to put the battery on the tender. I do that with the Macan when I'm gone for long trips. Never used the cigarette socket.

The terminals under the hood should be like this for the BMW:
http://forums.pelicanparts.com/uploa...1571264706.jpg

Check this out... https://www.bmwblog.com/2016/01/28/bmws-new-ctek-battery-charger/

They are so low in power/current compared to the battery that you will never get near let alone above 14.4V.

My biggest concern would be whether they installed diodes to prevent overnight losses with the solar panel. None of these would use an actual charge controller, too inexpensive. But a proper diode will prevent battery drain.

He’s trying it now. I sent him the video. It’s all I can do. Thanks everyone.

Battery maintenance, am I doing it right?
 

So my two Mercedes cars and the RV are hibernating for the winter and will be asleep for the next 5 months. I pulled all the batteries, and have them all linked together in Parallel with a battery maintainer on them with the leads on one end and the other lead on the far end battery. The charger shuts off when it gets to set voltage and right now they are all reading 12.62v. I put a 12v heater on them all at once to drain them down a bit and then put the charger back on. How often should I do this, or should I not bother doing it at all?

http://forums.pelicanparts.com/uploa...1573825724.jpg
http://forums.pelicanparts.com/uploa...1573825724.jpg
http://forums.pelicanparts.com/uploa...1573825724.jpg

I think the drain down is overkill with a good maintainer. And I'd rig up a wiring system so you don't have to pull them. If you needed to move one in an emergency for any reason, you don't want to futz with batteries.