R1200RT-P Auxiliary battery

NeilH

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Battery Questions


If the auxiliary battery was in poor condition would this drain my main battery?

If I replace the main battery can I leave the auxiliary one disconnected without the bike complaining?

If the auxiliary battery was in good condition would this aid the main battery - is there any sort of connection except the charging circuit?

The auxiliary battery would normally be used to run the official accessories and therefore probably runs on it's own circuit and not via the canbus, am I correct?.

Neil
 
I have two "P" bikes i look after that still have the auxiliary batteries fitted.
The get charged via the bikes alternator but don't assist in starting the bike. They seem to have been used as you suggest, purely for running the police accessories.
One of the bikes has lots of extras running off the aux battery, the other has it disconnected.
 
We have a few RTPs, aux battery will not assist in starting. You can charge both batteries if you connect a conditioner to the rear socket. If its flat it won't impact the bike running, its only used for things like blue lights when the bike is static with engine off. When the bike is running both batteries are charged from the system
 
Have had my ‘08 RTP for six years now. After purchase I reclaimed the glove box by ditching the aux battery with no ill effects

I also removed the plethora of “authority” connectors under the base plate of the radio box and the RHS of the instrument panel. Their wiring was traced and cut back as far as practical. This has removed considerable bulk and potential for dirt to accumulate. When a wire was cut I sealed the end to prevent the ingress of moisture. I should really get round to ditching the oil cooler fan too

As I recall, you are converting the bike to “civvy” condition? IMHO the front crash bars are a godsend in low speed drops and worth retaining

Maybe not for you: but if the pillion seat is not required the radio box base can be opened up to give a good tool storage area underneath while the box itself almost replaces the need for a topbox - especially if civilian panniers are then fitted

Pics below of under box stowage possibilites



If you can locate a pair of the original blue light supports they make excellent mounts for DRLs as they are very visible above usual bonnet height and can be adjusted if required while riding. I wired mine to the LHS parking light
 

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Battery Questions


If the auxiliary battery was in poor condition would this drain my main battery?

If I replace the main battery can I leave the auxiliary one disconnected without the bike complaining?

If the auxiliary battery was in good condition would this aid the main battery - is there any sort of connection except the charging circuit?

The auxiliary battery would normally be used to run the official accessories and therefore probably runs on it's own circuit and not via the canbus, am I correct?.

Neil
As others have said, the secondary battery is not connected with the running of the motorcycle - just the radio & emergency lighting. The whole point is that if extended use is made of these items, & the auxiliary battery goes totally flat, it in no way compromises the riders ability to start the motor & ride-off in the normal manner. In the real world, modern LED lights & radio's are so efficient that the auxiliary will power them for some 18 hours before it goes flat. The only connection to the main battery is that the alternator will always "top-up" the main battery first until it's fully charged, & then & only then divert charge to the auxiliary.
 
Thank you for the feedback.

I think for now I'll leave it where it is, I'll disconnect when it's going to be left standing for a long period.

As for changing it back to a "civvi" - that was my initial thought, but now I'm not sure what I want to do. Crash bars are a "must" as far as I'm concerned so they will stay. I could or course have them powder coated or just leave them as they are.

The wing mirrors have holes cut in the top, if only I could find the standard BMW blue lights but clear (for obvious reasons) I would fit them in the original position. I could choose other shapes etc....I just need to look.

I need time....and it will probably happen in the summer where I can take of the plastics and give it a good look over.

I need to acquire a few tools, like the oil filler cap and perhaps a few others. When the rest of my worldly goods get to the UK including my R1150GS I should be in a good position to get started.

My GS is used as my daily commute and I should really change the rear drive bearings and probably the alternator bearings too, but I can't afford to take it off the road, the commute in a car would destroy my soul. A 20 min bike ride turns into 1.5hrs car drive.

Roll on summer :)
 
As others have said, the secondary battery is not connected with the running of the motorcycle - just the radio & emergency lighting. The whole point is that if extended use is made of these items, & the auxiliary battery goes totally flat, it in no way compromises the riders ability to start the motor & ride-off in the normal manner. In the real world, modern LED lights & radio's are so efficient that the auxiliary will power them for some 18 hours before it goes flat. The only connection to the main battery is that the alternator will always "top-up" the main battery first until it's fully charged, & then & only then divert charge to the auxiliary.

Your statement " the alternator will always "top-up" the main battery first until it's fully charged, & then & only then divert charge to the auxiliary" is not quite accurate

See below text from the Official BMW RT-P technical literature :

The 720 W alternator on the R 1200 RT-P spins at 1.8:1 crankshaft speed , providing 27A of charging current at idle. This ensures that the main motorcycle battery is always maintained to restart the motorcycle as well as operate the ABS brake system.

Note: No police accessories or radios should ever be connected to the main motorcycle battery. The auxiliary battery should carry the load of all authority equipment .

The charging of the auxiliary battery is controlled by the motorcycle ZFE, which opens and closes a 40A charging relay. As originally designed, the auxiliary battery charging relay closes and begins charging when the motorcycle reaches 1,800 rpm and remains closed until the engine rpm drops below 1,500 rpm, when the relay opens. Under normal operating conditions this provides ample charge to the auxiliary battery. The auxiliary battery does not charge at idle
 
I bought a R1200RT-P a few months back and removed all of the additional wiring other than the secondary battery cabling and relay

I now have a fused distribution panel wired into the secondary battery circuit to power the heated seats and my heated clothing

Here are some pictures of the wiring before and after

And a picture of what the bike looks like after I finished putting it in non-authorities trim - I have since swapped the mirror surrounds out so they no longer have holes cut in them

I have also added normal panniers and a top box

1zoi5wk.jpg


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sdikr6.jpg


n3tfvd.jpg
 
Your statement " the alternator will always "top-up" the main battery first until it's fully charged, & then & only then divert charge to the auxiliary" is not quite accurate
See below text from the Official BMW RT-P technical literature :
The 720 W alternator on the R 1200 RT-P spins at 1.8:1 crankshaft speed , providing 27A of charging current at idle. This ensures that the main motorcycle battery is always maintained to restart the motorcycle as well as operate the ABS brake system.
Note: No police accessories or radios should ever be connected to the main motorcycle battery. The auxiliary battery should carry the load of all authority equipment .
The charging of the auxiliary battery is controlled by the motorcycle ZFE, which opens and closes a 40A charging relay. As originally designed, the auxiliary battery charging relay closes and begins charging when the motorcycle reaches 1,800 rpm and remains closed until the engine rpm drops below 1,500 rpm, when the relay opens. Under normal operating conditions this provides ample charge to the auxiliary battery. The auxiliary battery does not charge at idle
I'm sorry - I was paraphrasing from the official Authorities Workshops notes, in what I hoped was an easily understandable way, but if your small moment of pedantry has made your day, enjoy......
 
I'm sorry - I was paraphrasing from the official Authorities Workshops notes, in what I hoped was an easily understandable way, but if your small moment of pedantry has made your day, enjoy......

Glad you appreciated my attention to detail

If your going to do something do it right

Happy Xmas to all and safe riding
 
I think that looks spot on John, very nice.

I found more on the 2nd battery charging on a Police builtin which reflected everything that nicholsonj2252 mentioned.
 
I have a few conversion bits for sale if/ when you convert yours and need parts. Pillion footrests, pannier hangers, red side panels, red panels for fairing top above the indicators, red front mudguard, left pannier, 28 litre topbox, Light Magnesium colour side panels.
I've done a couple of these and found the grabrails, rear rack and pillion seat very hard to find.
 
I'm lucky, where I am currently they don't have any R1200RT-P models, so the parts don't go at a premium like they do in the UK...I just have to pay for an extra suitcase to bring the parts back to the UK. When I left the UK last I put my front seat in my suitcase and it's being recovered as well as the rear seat I bought here....so it will all match.

I have all the components from the foot rest to the complete tail including the locking mechanisms for the seat....so from the 15th May for about 3 weeks that will be my projects....can't wait. I bought myself a GS-911 too. The only thing I don't have is the top box and I'm undecided if I should look out for the BMW one or go for another brand......but I'm not in a hurry.
 
Hi Guys

An old post I know but hopefully one of you will be able to answer my question. I have a 2012 RTP. I use the aux battery to run all sorts of additional electrical equipmnet. The aux battery has now died.

I see from research that the bike has 2x 19ah batteries. My starting battery is fine. The question is when I replace the aux battery do I need a 19ah. Can i replace with a much cheaper 12ah which would be ok for my accessories as its only amber strobes. Will it cause electrical issues if I have a 19ah on the starter and 12 ah on the aux.
 


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