BMW Optimate

The accessory socket is neither an output or an input, it's a connection to the battery... Electricity, like water, flow from the higher pressure (voltage) to the lower pressure.

If you connect something with a lower pressure (anything that uses electricity) current will flow out of the socket to operate what's plugged in it.

If you connect a charger (to charge a 12v battery, you have to 'push' more than 12v in it) with a higher voltage, current will flow to the battery.

That is somehow oversimplified, a regular charger will not work because the CanBus system 'cuts' the connection between the battery and the socket when the motor is switched off, but, keeps on 'an eye' the socket.

CanBus compatible chargers send a signal for the CanBus to connect the socket to the battery, allowing the charge to reach it's destination.

Thank you for the physics lesson 😂 the short answer was a “yes it will work”

Sorry about my long answer, too many years teaching electronics...

Bonus knowledge... the CanBus circuit also monitor the current used by the socket, if it goes over 5A it shut the socket off, no fuses are used. To reset the socket, turn the key off then back on.

20-100 said:

Sorry about my long answer, too many years teaching electronics...

Bonus knowledge... the CanBus circuit also monitor the current used by the socket, if it goes over 5A it shut the socket off, no fuses are used. To reset the socket, turn the key off then back on.

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if that is correct then you would not be able to use the socket to power heated clothing

I can attest to the 5A load limit. I run a ham radio on my bike and at 55 watts CW or FM the draw is 4.7 amps. If I go to 60 it's 5.1 and the socket trips.

I confirm, the 5A limitation is also mentionned in the user manual.

For Venture Heat vest and gloves (drawing 8.5 A total) I have installed the wire harness directly from the battery (of course, fused at 10A).

20-100 said:

Sorry about my long answer, too many years teaching electronics...

Bonus knowledge... the CanBus circuit also monitor the current used by the socket, if it goes over 5A it shut the socket off, no fuses are used. To reset the socket, turn the key off then back on.

Click to expand...

Can one jump start the bike using that socket, or would that exceed the 5A threshold?

MichaelM said:

Can one jump start the bike using that socket, or would that exceed the 5A threshold?

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NO, jump start is more in the HUNDREDS of amperes... Use jumper cables directly attached to the battery

The dealers around here seem to routinely install a battery charger port on all the bikes they sell (well, at least the new ones) it is the standard 2 prong design (can't remember what it is called). As such, any decent battery charger should work just fine as it doesn't go through the Canbus system, just connects directly to the battery. And, as a bonus, that same plug can be used for heated gear. The connection is fused (Can't recall the fuse rating).

This connection could also be used to jump start the bike I think but I'd tend to use the battery posts directly, especially if you are doing any real cranking.

BC Don said:

The dealers around here seem to routinely install a battery charger port on all the bikes they sell (well, at least the new ones) it is the standard 2 prong design (can't remember what it is called).

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SAE connector is the typical name

Daedalus said:

This Optimate 4 charger will work perfectly if you want to use the accessory 12V DIN socket that is connected to the CanBus on your bike. While my 2021 R1250 GSA has the same 12V DIN socket, my bike was factory fitted with two extra charging cables which are directly connected to the battery. One cable is terminated with a standard 12V SAE connector and is labelled Optimate, the other one with a proprietary CTEK connector. I decided to go with the CTEK charger.

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i wouldn’t of thought they were factory fitted….. if you have had the bike from new, more like the dealer fitted them at PDI

Bumble-Bee said:

i wouldn’t of thought they were factory fitted….. if you have had the bike from new, more like the dealer fitted them at PDI

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You are right, it was installed by the BMW dealer. My bad