In-situ battery charging

I've been using a Ctek charger on some of my older scoots (250's and a
400), without disconnecting the battery cables. A friend with a newish
BMW 1200 (beautiful bike) told me you can't do that on his bike without
risking damage to several of the electronics, so he disconnects the
battery before giving a maintenance charge. Brief searching hasn't yet
given me a clue why this might be so. Can anybody here comment?

 

He's a fuckwit.

 

Considering that the surge from disconnecting/reconnecting the battery is
likely MUCH more of a risk than using a low capacity charger while
everything is still connected...........I second the fuckwit motion. ;-)

 

<High-fives Just Me>

 

What does he think happens to all those expensive components when the
battery is being charged via the alternator?

 

LJ wrote:
....

Sorry, no I didn't, plus I've forgotten a link that mentioned a
BMW-brand charger with adapter that I guessed was meant for an accessory
outlet somewhere on the bike. There was also a comment something to the
effect of turning on the ignition and counting to fifteen and mention of
the BMW charger being the only one could use with glass-mat batteries,
none of which I understood to be what my friend seemed to be going on
about. It does make sense, as several posters here mentioned, that the
battery provides a pretty good sink, especially for a 1.5 or 2 amp
charger. He's away now but when I see him I'm going to look at his
manual and see what it says.


(This came up because I gave him one of my CTEK chargers but couldn't
find the permanent adapter, told him I'd make one for him. But I guess
I could just as well make one that goes into his "accessory port"
instead of to the battery.)

 

Forgot to mention that my own guess as to why they might have such an
adaptor would be for convenience, easier to reach perhaps, nothing
dangling perhaps or perhaps less chance of riding off without
disconnecting the charger!

 

His point being that if the battery was disconnected, it'd be really
hard to get the charge current from the adapter port to the battery
if the battery wires weren't connected.

Make sense ?

 

It makes sense to me just as I think it would to most people I know even
if that may not be true in your circles. Seems to me I answered LJ's
question directly in a different post even though one could take it as
rhetorical. BMW in general does lots of things that will elude the even
the most sensible person, like put hydraulic clutches in their car
cooling fans which cost as much to replace as the drivetrain clutch in a
Honda car.


Regarding the adapter, no matter how unusual the factory BMW charger
might be and admittedly without having a wiring diagram to look at, I
would presume that it is wired directly to the battery without any other
components, neither in series nor in parallel, save perhaps an inline
fuse. If there were other components, they might well be harmed by
charging voltages of 14V or more. So without further information I'd
have to stand by my guess that the adapter is there for convenience.


Thanks to the other posters for their comments. Friend's attitude may
well be f-witted on this topic but that's not true of him in general.
In this case it is a little strange to me since he knows a lot about jet
engines, air frames and avionics - for years his was the final signature
required before the giant passenger planes left the hangar shop.

 

You can stand by anything you want to.
I think I'm now prepared to go with the f*witted assesment.

 

And these relate to motorcycles how????

I've lost count of the number of bikes I've seen buggered up by someone
"who knows all about cars".

Bikes are a law unto themselves, really.

 

LJ wrote:
....

Fine, I thought there were experts here.

 

Actually, the BMW electronics are on a separate power
bus with it's own protective watchdog which will shut
things down if it senses electrical funny business.

The accessory plug and the electronics are about as
isolated from each other as possible.

 

And maybe I was being a bit touchy. I'm not so rabid about buzzwords as
some people I know. It's just that while there have been some chemistry
discoveries in the last 120 years and to boot some subtleties of
electrical fabrication such as the transistor, electrical/electronic
theory remains rather stable compared to politics and social science not
to mention economic theory, while the basics that Ohm, Thevenin, et
cetera came up with remain unchallenged except for corporate word
inventions like the disguised newswitches in the BMW whatchamacallits.
(I certainly wasn't trying to say that the BMW engineers were wrong by
obeying their masters' orders to come up with something that would be
commercially unique and I admire the cleverness of it all even if I
often don't get the practical point). Still I wonder if a few months in
a refrigerator isn't just as life-preserving for an unused battery as
monthly charging in a semi-heated garage. Anyway, thanks for the comment.

 

Well, there experts and then there are EXPERTS.
You will find all kinds here; your mission is to be able pick out the "real"
ones. ;-)

As for the above question, the answer is maybe but probably not.

Cold is good for battery storage, as long as it is above the freezing point
of the electrolyte
BUT
It is much MORE important to keep it fully charged because the real enemy of
lead-acid batteries is SULPHATION. That occurs at a rate that is inversely
proportional to the level of charge.

It is impossible to stop sulphation completely and, as it gets worse, the
self-discharge rate creeps up so that the process is self-accelerating. A
brand new battery, fully charged will (likely) stay near enough to fully
charged that it will survive without any attention over 3-4 months of
storage. A "top off" before starting in the spring is advisable.

An older battery, however, already has some sulphation and thus a greater
tendency to self-discharge during storage. It requires periodic recharging
or a tender.

Regardless of your level of expertise, the best thing to do is attach a
tender because you don't have to figure how old the battery is or remember
to connect that charger every few weeks.

Enough information?
Other questions?

 

I have seen similar warnings for cars with computer systems,
but they seem to refer to the practice of jumping from another
battery,
and using a frame ground instead of conecting direct to the battery.
I suppose there is some possiblity of a damaging surge in that case,
particularly if you get the connection wrong or contact something you
shouldn't..
Oh for the good old days when you could see, fix, & understand the
working
of everything on your bike.!