Philes’ Forum – Winter 2020


By Vic Lucariello, Sr

Hello Bimmerphiles! This time out I have a great tech tip from bimmerphile Carl Francolini and some thoughts on battery maintainers.

Inveterate Philes’ reader and correspondent Carl recently bought a 2008 [E60] 528i and he experienced some problems with the iDrive controller knob. Carl reported that knob would intermittently not allow the downward push input that is a menu -selection input. Other than that, all the other iDrive functions seemed to be normal.

Now I am neither a fan of nor expert with iDrive, but it is an efficient means of providing multiple functions to the driver and passenger with a minimum of old-fashioned pushbuttons, which consume a lot of valuable and expensive instrument-panel space. A great advantage of iDrive is that it is operable with a gloved hand. Not so for the plethora of pushbuttons and selector switches that would be required to duplicate all the functions of iDrive. While to some inveterate, hard-core bimmerphiles iDrive may seem to be a new-fangled feature, BMW has been using it for two decades!

Photo #1 – iDrive, circa 2008

Anyway, other than suggesting to Carl that a common cause of iDrive problems is spilled beverage that invades the controller via the iDrive-knob shaft, I couldn’t be of much help to him. I had heard of iDrive problems where the system did not respond to downward movement of the control knob, but never where the knob refused to move down.

A few days later, Carl reported that he had solved the problem! It seems that he was using a USB cable plugged into the port in the console, and that occasionally the cable would slip under the iDrive knob and impede its downward motion. Carl said that he was embarrassed to report this simple fix, but I don’t think any embarrassment is warranted. Given the proliferation of USB- connected devices and USB ports in vehicles nowadays, I’ll bet Carl is not the first to experience the problem.

Much thanks to Carl for sharing his experience with Philes’ readers.

Anyone who has read Philes’ for any length of time knows that for decades I have been a fan of and user of battery maintainers. During a quick jaunt around the shop, storage container and enclosed trailer, I stopped counting battery maintainers after around 15! No, I am not Jay Leno and I am not making this up!

The maintainers vary from the more expensive CTEK and BMW [Battery Tender] units to the less expensive Harbor Freight and Morange models. Heck, I even have a few from J. C. Whitney and one from Walmart! Some of the maintainers, such as the CTEK and VDC Electronics models, purport to recondition batteries by removing or reducing sulfation. My testing suggests that there might even be some merit to these claims. Of all the maintainers I have used over the years, only one, a Black and Decker, failed to operate properly. Whether this a generic flaw or a fault of my particular unit I don’t know. The B&D did have a nice AC cord and battery leads, though, which I snipped off and kept prior to disposing of the unit.

My sojourn through the realm of battery maintainers began in the early 1970s when I stopped driving my hotrod as frequently as I wanted to. When I did find the time to take the old girl out, many times I would find the battery dead or severely discharged.

[You probably know that one of the best ways of significantly decreasing the life of a lead-acid battery is to let it sit in a discharged state. You probably also know that “jump-starting” a car and driving it around will not fully recharge the battery. BUT it may cook your alternator.]

This was before battery maintainers became popular. Indeed, if they existed I was unaware of it. So, I tried connecting a “trickle charger” [very low amperage charger] to the hotrod battery. This served to overcharge the battery after a couple weeks and boil away the electrolyte. This is another good way to ruin a battery, probably even more efficacious than letting it sit while discharged.

My next approach was to connect the trickle charger to a timer such that the charger only charged the battery for an hour or so every day. This achieved a modicum of success, but one had to be careful with the charger on-time so as not to overcharge the battery. What was needed was a trickle charger that was smart enough to sense the battery state of charge and shut off at full charge; resuming charging when the battery needed it. Enter the battery maintainer.

If you have a modern vehicle that sits for more than a few days at a time, my experience suggests that using a battery maintainer can significantly extend the life of the battery. Here are some factors to consider when selecting a battery maintainer:

  • The length and quality of the AC cord [if equipped] and the battery leads. A maintainer with a metal housing should have a 3-prong AC plug.
  • The quality of the clips that connect to the battery terminals.
  • Whether the maintainer has multiple options and leads for connecting to the vehicle.
  • If the maintainer has a fuse in its positive battery lead.
  • If the maintainer has reverse-polarity protection. My J.C. Whitney maintainers do NOT have this protection. See below.
  • The charging capacity of the maintainer. Some maintainers will recharge a discharged battery [albeit over a couple days] while others should not be used on a discharged battery.
  • Whether the maintainer has indication[s] of what it is doing. The CTEK is probably the best in this regard, while the JCW maintainers have no indication, except they let you know of reverse polarity by letting their smoke out!
  • Whether the maintainer draws battery current and discharges the battery if the maintainer’s AC power is interrupted.
  • Whether the maintainer’s leads spark when being connected to the battery.
  • Whether the maintainer is suitable for use with an AGM- type battery.
  • Warranty.

That should be enough to get you thinking about battery maintainers. If you would like more detail, email me, and I will write a follow-up column where I describe the features of the various maintainers in service here at NJ Chapter West/ Rocky Mountain Chapter South. Anyone wishing to contribute to Philes’ Forum can contact me at I’m interested in comments, tech tips, repair /maintenance questions, repair horror stories, emissionsinspection sagas, product evaluations, etc.

© 2020; V.M. Lucariello, P.E.

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