BMW R1200RT/R1250RT Forum

DaygloDavid wrote: Based on the above, the Optimate automatically disconnects & reconnects itself to the battery as required.

Yup, same with the CTEK I have and other smart chargers. I though they all did that whether bus models or direct battery connection. That's why they can be left on indefinitely ensuring the charge state is always optimal, neither under or over charged.

I'd be surprised if the BMW bus model doesn't do this, it is meant to be a smart charger I believe. Surely it doesn't just switch off permanently with no further monitoring of the battery once charged. Does it? :eek:

BMW one doesn't disconnect but I don't think it continually feeds power to the battery. It shows a slowly flashing stand by light but the unit is stone cold suggesting no power to me.

CTEK/Optimate etc. don't constantly charge once fully charged, they monitor and test to decide when further charge is needed.
With your BMW bus model, if you leave it connected and don't use the bike for a time so that the battery starts to run down, will it do this? It must surely. I'd be flabbergasted if it doesn't!

Sure it would but I never leave it on for more than 24 hrs. Just not necessary.

gaggle wrote:That's why they can be left on indefinitely ensuring the charge state is always optimal, neither under or over charged.
I'd be surprised if the BMW bus model doesn't do this, it is meant to be a smart charger I believe.
Surely it doesn't just switch off permanently with no further monitoring of the battery once charged. Does it?

Looks like the BMW Charger goes into a Maintenance mode when Charging is complete.

The latest model doesn't show this.  Shortly after showing 100% charged the display switches off and you get a slow flashing power light that indicates Power Saving. 

gaggle wrote:With the BMW bus model, if you leave it connected and don't use the bike for a time so that the battery starts to run down, will it do this? It must surely. I'd be flabbergasted if it doesn't!

From RealOEM, http://www.realoem.com/bmw/enUS/showpar ... Id=77_0018,
this is the latest BMW Motorrad Battery Charger for a 2016 RT LC.

BMW MOTORRAD BATTERY CHARGER Product Code: 77028551898, http://shop.ridersmotorcycles.com/bmw-m ... y-charger/

"Fully automatic, by application of the charge characteristics stored in the microprocessor's memory.
The device can remain connected to the vehicle or to the battery for a lengthy period of time.
Charging cycles are run, the battery is monitored and recharged as necessary."

Yes thanks RTMan and David, that's what I expected. It would not be worth having if it didn't monitor. The BMW bus charger does exactly the same as other brands, bus or direct, and can be left on indefinitely in the same way. No surprises there really so there's probably nothing to choose between them on technical grounds.

There was just a bit of confusion (as I saw it) in the messages which suggested that the BM charger switched off at full charge and the others didn't. In fact as I thought, both do the same thing. Their circuitry, appearance and pretty lights may differ in some respects but the end result is the same. Charge then monitor, test and recommence charge as required, with no time limit.

I'm sure your right they all monitor .  BMW do say they can be left on for lengthy periods. Not quite the same as indefinitely.  I'm into my 21st year of having bike batteries in the shed and have yet had the need to replace one. So for me my method seems to work, ie once a month for a whole day if the bike is not being used.  If it's being used, never.

Good that it works that way.
In my case I have on occasion left the charger constantly on a vehicle unused for months and the battery remained in perfect nick with no ill effects that I could judge. So I have no fears about this.

I know of some Folks who change their Bikes every 2 years & are therefore always covered by the BMW New Bike Warranty.

In this example, they would never have to buy a new Battery.

DaygloDavid wrote: I know of some Folks who change their Bikes every 2 years & are therefore always covered by the BMW New Bike Warranty.

In this example, they would never have to buy a new Battery.

That is what the smart chargers are designed for, but you will always find someone who thinks it will damage their battery if left connected. As stated in a previous thread, I have done this for over 15 years and never had any issues.

Never found the need to charge the battery on the two 1600's I have had, and the one I have at the moment hasn't moved since September. My FJR and little SV gets a full day's charge every three to four weeks when not being used. A couple of years ago I left the FJR hooked up over the winter and when it was time to take it out again it started straight away ran great, came home parked it up, went to go out on it two day's later, battery dead, new battery required. From then on I never put a charger near a bike battery unless it's showing signs of low charge. I.E.  Sluggish starting.

I'm with Jim.  Modern chargers might be designed not to damage batteries if left on but there is absolutely no need on a bike like an RT to do it. Think of all the penny's I save on my electric bill.

Jim +1

Service manager at my BMW dealership and a.n. other on here who also, if I understand correctly, works/worked at a BMW dealership both advise against overuse of battery chargers. I would imagine that between them they have seen quite a few bikes and come to their respective opinions through experience.

I'll stick with my once a month overnight through the winter and not at all in summer and my battery buying experience will hopefully remain inadequate.
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