This info applies to all models of BMW and
anything else with a battery.
The comment was made that the grease for battery terminals has some
resistance. It is an insulator, so it seems to make sense. That easily hides the
fact that it still should be used between the terminals.
In my work as an inspector of telephone cell site construction, we deal with
large power supplies and batteries. We have current available of a few thousand
amps from the battery bank. That is 10 times that of an electric welder. A tool
that accidentally crosses it can just about vaporize. It is not dangerous
as far as getting shocked, as it is only 24 volts, but the danger is from
The wires that connect them are as thick as your finger. It takes special
procedures and tools to attach the terminals to the wire and then bolt it down. We grease everything. The grease gets pressed out of between the connections and
forms a air tight seal to keep oxygen out. That prevents corrosion and
increasing resistance that will reduce current flow and becoming a diode that
can cause radio interference. As an inspector I require seeing a bead of
grease around the connection to prove that grease was used.
These are properly greased terminals in a cellular telephone (radio station)
site. The key is for size reference. See the bead of light brown grease that has
squeezed out and around the terminals? If you look closely you can also see the
upper part of the terminal where the black cable goes into the terminal. Look
just below the crimp and you can see a "window" or hole in the terminal. You can
see some grease squeezed out through the hole. That is for me, the inspector, to
be able to determined that the cable was fully greased before the terminal was
crimped. All copper wire should be greased before the terminal is crimped.
How do we use this knowledge on our BMW motorcycle batteries?
This is evidence of what the "big boys" do about protecting electrical
connections that carry large amounts of current. Using this practice on all of
your lead acid batteries can only help you. If you don't have the "official"
grease, then use Vasoline. Regular wheel bearing grease isn't ideal, but
far better than nothing at all.
I suspect that we have all seen this under the hood of a car. Grease won't
prevent the leak, but it may prevent the same corrosion from deteriorating the
connections. The molded battery cable terminals are the best ones, but sometimes
we are stuck with using a "universal" cable connector. If it is the crimp type,
then it is best if you solder it rather than crimp it. If soldering isn't an
option, then use grease liberally on the wire before crimping. At that
point it is best if you further protect the terminal by using some shrink tubing
on the connection to help keep any acid or water out.
This photo shows two types of battery terminal connector. The one on the left
is the cheap one that many mechanics use to replace molded connectors after they
are eaten up by acid. If you must
use on of these, coat the wires in the grease first and then mount it. Better
yet, tin the end by soldering it. Still use grease on both mechanical
aspects of this connector.
The one on the right is a quick disconnect type from some government use. They are great. They battery cable must be soldered to the connector. Use grease
on the contact area. Don't ask where to get these, I forgot and am down to
my last pair.
Use a small spot of grease on the connector of any item with a battery, even
a dry cell type. How many times have you opened up a flashlight, multimeter,
radio or other appliance that is battery operated and found a leaky battery. Usually it corrodes the terminal and can even eat it up.
The grease won't prevent a battery from leaking, but it will save the metal
The coil connections really need to have grease under those push-on
connectors too. They cause a lot of trouble. If all of the push-on
connectors had grease under them from the factory, you wouldn't be having
A squirt of WD 40 or other lube in the handlebar switches once a year and you
will reduce that corrosion too. They fail from the water/rain.
Note. On the /5 and later, check under the fuel tank for the throttle cables
being too close to the ignition coils. They tend to move over, wear through the
plastic covering the throttle cables and short out at the coil terminals under
certain conditions. Not fun to troubleshoot.
For charging system diagnosis, go to
http://www.buchanan1.net/charge.shtml and use the well written article by