Asking assistance on installing a battery trickle charger on a 2010 328i convertible.

[Pyewacket69]

I have a 2010 E93 328i convertible on which I frequently get the "Increased battery discharge" message displayed on the iDrive screen, much more frequently during the cooler months of the year.

I'm looking for suggestions from anyone that has installed a permanent "plug in/unplug" solution for a battery tender. I wish to avoid the connection "via clamps" each time I connect the tender to the car.

I don't suspect a car problem, but more of a "not driven often enough" fault... For reasons too long to go into here, the simple answer is that I often go 7-10 days in between drives, but when I do use the car, it's driven for a minimum of 15-20 miles or 20-30 minutes at each time. It has never failed to crank, nor even remotely sounded as if the battery wasn't fully charged.

I also have a 2007 Z4 3.0 that I have installed a battery tender pigtail, which I connect to a CTEK 3300 intelligent battery tender.

In that case, it's connected directly to the battery terminals on the battery and has worked well for years. Due to the devices connected directly to the 328i battery, I'm reluctant to go the same route on it as I did my Z4.

My first thought is to engineer a system where I affix the tender pigtails to the positive "jump starting lug" under the hood, and find a suitable grounding location nearby.

Any ideas or suggestions would be greatly appreciated...

Thanks!

[Titanium09]

I connnected a permanent "plug in/unplug" connector on mine. There are two posts on top of the battery that looked to be there for that very purpose. I never had a problem. The dealer even put it back on when they switched the battery as part of the recall.

[Pyewacket69]

I connnected a permanent "plug in/unplug" connector on mine. There are two posts on top of the battery that looked to be there for that very purpose. I never had a problem. The dealer even put it back on when they switched the battery as part of the recall.

Thanks for the response...

If I may ask... What year/model do you have?

[fun2drive]

I have a 2007 E93 335 which has had a battery tender on it since I did ED in March 2007. I am still on my original battery because of that. I use the direct connections under the hood and I leave my tender in there and just plug it in.
I have 54Kmiles on my car but don't drive it that often as the miles would indicate. I have 5 tenders all on various BMWs, jets ski, generators and they have extended my battery life immensely. One other thing I recently learned is to lock your car so the computer will not pulse your car every 4 hours helping to pull the battery down. It will stay asleep that way.
Hope this helps and for the record my M3 has a 2004 battery in it and is holding up just fine. CTEK is also excellent so any of those intelligent battery monitor/maintainers is the way to go...

[Pyewacket69]

I have a 2007 E93 335 which has had a battery tender on it since I did ED in March 2007. I am still on my original battery because of that. I use the direct connections under the hood and I leave my tender in there and just plug it in.
I have 54Kmiles on my car but don't drive it that often as the miles would indicate. I have 5 tenders all on various BMWs, jets ski, generators and they have extended my battery life immensely. One other thing I recently learned is to lock your car so the computer will not pulse your car every 4 hours helping to pull the battery down. It will stay asleep that way.
Hope this helps and for the record my M3 has a 2004 battery in it and is holding up just fine. CTEK is also excellent so any of those intelligent battery monitor/maintainers is the way to go...

Thanks for the info. No question, a tender is the way to go. I have the original battery in my 07 Z4 and it still cranks like a new one. I've used them on my Harley's for years and gotten up to 9 years on 1 bike battery, which I wouldn't believe unless I had seen it myself.

Also, thanks for the locking suggestion. Now that I think about it, it makes sense to keep it locked while its idle, even in my garage.

One question... Did you physically attach the tender charging "leads" to the connections under the hood, or do you just use the alligator clips? If you did permanently secure them, would you please share how you did it?

Thanks!

[rmnelson12]

Also to add on:
Were the direct connections under the hood, directly connected to the battery or the "jump start" connections?

Also in terms of the actual battery tender itself, is a CTEK or "Battery Tender Plus (the green one)" the way to go?

Thanks

[Pyewacket69]

Well, after careful examination of the battery/connections in my Bentley shop manual, it appears that connecting the tender pigtail leads directly to the battery posts securing studs may be the best option.

Looks like it will take a few extra minutes to do it, as a small bracket fits over the positive post and power distribution panel that resides on top of the battery.


Also to add on:
Were the direct connections under the hood, directly connected to the battery or the "jump start" connections?

Also in terms of the actual battery tender itself, is a CTEK or "Battery Tender Plus (the green one)" the way to go?

Thanks

I have used a CTEK "tender" on my 07 Z4 for over 5 years, and had excellent results. CTEK units are also sold by BMW as well as Porsche and private-labeled as BMW/Porsche charger/tenders, although I believe BMW also private-labels other manufacturer's tenders/chargers as well.

As an example...

http://www.amazon.com/Porsche-Dual-Battery-Maintainer-Charger/dp/B001684YCK/ref=sr_1_18?s=automotive&ie=UTF8&qid=1350960692&sr=1-18&keywords=bmw+battery+charger

[fun2drive]

Either approach works. I did direct connections for my M3 in the trunk and just use the clips for the E93.

You have it solved.

I do think once I rotate my E93 to Florida that I will go to a permenate install under the hook and keep the clips for other machines I have...

[Pyewacket69]

Either approach works. I did direct connections for my M3 in the trunk and just use the clips for the E93.

You have it solved.

I do think once I rotate my E93 to Florida that I will go to a permenate install under the hook and keep the clips for other machines I have...

I had considered an under-the-hood "fixed-pigtail" connection, and I actually designed (on a scrap of paper) a method to affix the respective pigtail ends to the jumpstart terminal connection points, but after further analysis (and studying the Bentley manual/pictures in detail) it just seemed to make more sense to affix the pigtail ends directly to each battery terminal clamp "securing studs".

[rmnelson12]

My only problem with attaching the direct connections to the battery terminals is the access. I rather charge/maintain the battery from the hood and not leave the trunk open during the entire process. Leaving the hood open, has no effect on the battery, iDrive, electrical etc..
Or would you still have the trunk closed on the battery tender wire? I am trying to wrap my mind around the "fixed-pigtail" connections and going thru the trunk vice under the hood

[Pyewacket69]

My only problem with attaching the direct connections to the battery terminals is the access. I rather charge/maintain the battery from the hood and not leave the trunk open during the entire process. Leaving the hood open, has no effect on the battery, iDrive, electrical etc..
Or would you still have the trunk closed on the battery tender wire? I am trying to wrap my mind around the "fixed-pigtail" connections and going thru the trunk vice under the hood

Closing the trunk on top of the charging wires is no problem. The wire harness is a dual (and looks to be) 16-18 gauge wire, and the trunk weatherstrip seal easily compresses to allow it. I've had this very same connection set-up on my Z4 for about 5 years. You can try it yourself, by taking a lamp cord and closing the trunk lid on it. Just be aware there are some spots along the trunk mating surfaces that are slightly tighter or looser than others, and find a spot where the gap is sufficiently large enough to route the wire without significantly crimping it. Should take all of a minute to do that task.

Update: completed the connection earlier today.

All works as expected...