Disconnect Battery When Using Charger?

So to entertain your brains during the Winter hibernation, please solve this riddle.

Well not really a riddle but a rumour getting around that one should disconnect the battery, at least the negative lead, when hooking up a battery charger (if not removing the battery altogether) as the charger may damage the R/R.

I don't believe it's posible (otherwise why would my CTEK charger come with leads that can be installed on the battery with the battery in the bike that allow you to just hook up the charger without uninstalling anything??).... but would like the hoodoo gurus out there to explain why (it would or wouldn't).

Bust the myth!!

By that logic the battery would also damage the RR when the bike is sitting... unless it takes more voltage to do the damage.  A RR is basically a bridge rectifier composed of diodes that only allow voltage to pass one direction, plus the associated regulatory circuitry.  I say it's rubbish.  Taking the battery out, or disconnecting, for long term storage helps reduce corrosion and parasitic drain of things like the clock.

PS:  I've been known to be wrong about lots of things...  :goofy:

Anecdotal I know but over the last 14 years I've never disconnected either battery and I've always had one bike sat on the Optimate charger.

Can't prove it's tosh but it sounds like it.

Rush has it I think.

Especially if you are using a trickle charger, no worries. Just a rumor.

It might be wise to disconnect the battery if you had to charge it and the only thing available was a 12A car charger.  But I have never intentionally disconnected the battery when charging it.  If you using a 1-2A charger, I wouldn't bother.

Maybe. If the battery has suffered from sulfation after being deeply discharged some battery tenders increase the charging voltage for desulfation. According to the manual that came with my battery tender this voltage can get up to 20V and that may be harmfull to the motorcycle electronics (clock etc, things that use current with the ignition off). That's why in the manual it also says it is essential to remove the battery from the vehicle before charging when the battery was deeply discharged. My battery tender has a LED that shows when it senses a bad battery, when it is lit it is best to remove the battery from the bike.