Battery diagnosis

[James B]

Hello there,

 

I was wondering if you could help me decide whether I need a new battery for my R1100RT (formerly -P). My bike, because of it's former life with the London Metropolitan Police Service, has two batteries, but I'm talking about the main one under the tank.

 

I was on the way back from a lovely trip up to Scotland in April when the big final drive bearing went. I got towed 100 miles home and procrastinated a long time before learning to shim the new bearing I ordered. I finally got around to shimming it using a dial gauge - a process I learnt from this amazing video: http://www.bmwlt.com/uploads/lt_final_drive_rebuild.wmv and after sticking bits in the freezer and bits in the oven, everything went together swimmingly.

 

However, when I came to start the bike there was just a quick clicking sound from the starter motor, so I jump started the bike, whose name is Adele, by shoving a screwdriver into the positive terminal of the battery - oh it's annoying how inaccessible it is. Anyway, I let it run for half an hour before noticing the engine temperature was getting into the red, so I drove it for a good hour and a half. This morning the bike is just making a clicking noise again.

 

Sorry about the long background story. My questions are as follows: Shouldn't almost 2 hours of engine running be enough to top up a dead battery? - I did have the lights running. Could three months of inactivity have killed the battery completely? Could it be a fault with alternator, and if so, is there a test that doesn't involve any equipment like an ammeter? The bike went like a dream and although I thought the rear wheel might fall off at any moment, it didn't.

 

I am hoping the battery isn't dead because one of the screws in the left hand tuperware is stuck solid, which means when I balanced the throttle bodies I could only synch to the left one and the idle is too high. I think it's the left side fairing that needs to come off to replace the battery. Another question: without damaging the fairing with too much force or too much heat, how could I loosen the fairing screw?

 

Many many thanks. I will be a bit more succinct in future.

James

[biometrics]

Try using PB BLaster or some other thread penetrating oil to get that screw out. You could also "gently" use a hand held impact screwdriver to get it started. One method of applying heat to the screw would be to put the tip of a soldering iron in the hex hole... but try the pentrating oil first.... and watch for smoke or melted plastic... once you get it out, make sure you don't torque the screw back in more than necessary.

 

From the sounds of it, your main battery is probably at the end of its lifespan. Try charging it using a battery charger through the powerlet jack on the left side below the saddle instead of just riding... if that doesn't revive it, replace it.

 

...and don't idle your engine for long periods of time... the heat could melt your tupperware!

[George S.]

Your battery can and did go bad with the 3 month layoff.

 

Your idling the engine for a half hour is a completely wrong thing to do.

You can destroy the engine doing that. And any M/C with a headlight doesn't get enough juice at idle to charge a battery in any significant way.

You'd probably have to ride it to around 3,000RPM to accomplish any charging.

 

I've had some fasteners that were impossible to loosen with a screwdriver, but I just put the Torx bit on the end of a ratchet socket wrench and they loosened.

[James B]

Thanks for all your suggestions. I have ordered a BMW gel battery from Motorworks for half the price the BMW garage quoted. I better buy some thread penetration oil for when it arrives.

 

I knew that the idling wasn't a good idea when something started smoking. I headed for the nearest motorway to cool it down. Such is traffic in London that the engine sometimes gets too hot whilst on the move during the summer.

[Galactic Greyhound]

Hi James,

 

Just clicking on startup can be caused by corroded battery terminal/s creating a high resistance - check that your battery terminals are clean to bright metal and lightly smeared with Vaseline to help prevent corrosion.

 

You can do a rough check without instruments that the alternator is charging your battery by idling the bike with the main beam on and then increase the revs to about 3000 rpm. Observe if the headlight brightens slightly due to the alternator increasing the voltage across the battery to around 14.5 volts. If you have a voltmeter, put it across the battery and look for the voltage rise.

 

You need to get that stuck fairing screw out in order to maintain the bike - The Allen socket on the screw head may have rounded off preventing removal - +1 on George S 's idea on the Torx bit suggestion for removal but don't re-use the screw and get some spare fairing screws from Motorworks. Be careful if it is a tank screw that is stuck - too much force might spin the insert.

 

The original black fairing screws are German DIN specials with a pointed nose to reduce the risk of cross-threading - don't be tempted to use aftermarket stainless versions which don't have the pointed nose. Note the screws for the tank inserts are shorter screws (M5x16) than elsewhere on the fairing (M5x20). A plastic washer goes under each screw. Here are the Motorworks Part Numbers:

 

Screw, Oval, M5x16, BMW Pt No. 46622307956, M/works Pt. No. FAA07956. http://www.motorworks.co.uk/vlive/Shop/Parts.php?T=6&Q=FAA07956&x=13&y=20

 

Screw, Oval, M5x20, BMW Pt No. 46632313439 M/works Pt No. FRA13439.

 

WASHER, PLASTIC, BLACK [FAIRING SCREWS], BMW Pt No. 46612308593, M/works Pt No. FAA08593

[James B]

Hello,

 

Thanks very much for your advice. It's good to know the headlight tip for testing the alternator. I think I will have to wait for my new battery to arrive tomorrow because I'm without a battery pack or car from which to jump start my bike.

 

I have quite a few spare screws from when I took the police radio box off and replaced it with the tail bit, luggage rack bits and pillion seat. I think the screw selection includes both long and short, tapered and non-tapered. Thanks for taking the time to find the part numbers. Today's task will be to get the left fairing unstuck.

 

Cheers

James

[David R]

IF you have two batteries you should disconnect the other one. It could (and will) draw your new one down if its no good.

 

Get a volt meter.

 

Charge each battery.

 

TEST each one.

 

Static voltage after surface charge has gone off 12.6 volts

Cranking volts No less than 9.6

Charging voltage 14+ but not above 15 volts.

 

Your bike should run fine on one battery. Mine does.

 

David

[James B]

Hi David,

 

It'll also be good to get rid of the battery so I can use the space as a glove box. I'll try and work out where to disconnect the auxillary battery so I don't have surplus wires. Although, my bike already has loads of extra wires under the seat with connection sockets for the police radio, lights etc. I have some bikeviz.com cree day light running lights attached to the axillary battery, so I'll have to rewire them.

 

Thanks

James

[James B]

Just a quick question before I remove the auxiliary battery; I read on the BMWLT forum that the power socket on the dash comes off the auxiliary battery and the one on the left of the bike comes off the main battery. Is that true? Are there any other considerations when removing the auxiliary battery?

 

Many thanks

James

[David R]

I know nothing about how an RTP is wired. Two batteries in a regular bike are too many. You would have to replace both every time.

 

Unhook negative first on both batteries when you take them out.

Hook up negative last when installing. All connections should be cleaned and coated with something. I use a spray. Silicone grease is a good one, plain ol grease or Veenershliden (vasaline) are both good.

 

Good luck

[dirtrider]

I know nothing about how an RTP is wired. Two batteries in a regular bike are too many. You would have to replace both every time.

 

---

 

Evening David

 

I don't understand, why would you have to replace both batteries every time?

 

They don't power the same things, they don't operate in series, they don't charge in series, basically separate systems.

 

[David R]

I know nothing about how an RTP is wired. Two batteries in a regular bike are too many. You would have to replace both every time.

 

---

 

Evening David

 

I don't understand, why would you have to replace both batteries every time?

 

They don't power the same things, they don't operate in series, they don't charge in series, basically separate systems.

 

The biggest clue is the first line. "I know nothing about how an RTP is wired"

 

 

If they charge in parallel one bad one will cause charging voltage to go up which will toast the other one.

 

If one lasts 3 yeas and both were replaced at the same time how long does the other one last?

 

If they are hooked in parallel, one sulfated or internally shorted battery could draw the other one down for a no start even with one good battery.

 

Just my thoughts, you are probably right they would not have to be replaced at the same time.

 

David

 

Heading out on a 1,000 mile 3 day trip on the RT today. Sleeping in a tent. New PC 680 battery last month.

 

The last one was a BMW battery and it lasted 6 years. For the last 3 that I have owned it, I had to pause before starting or the ABS would not set properly. With the new one, it functions flawlessly.

 

Fresh rebuilt motor, new clutch, brakes, tires,.... She runs quiet and sweet!

[dirtrider]

Morning David

 

The charging voltage is controlled by the alternator voltage regulator not either of the batteries.

 

Just because one battery goes bad doesn't necessarily mean the other will too.

 

They aren't hooked in parallel except during charging so one can't run the other one down. They don' supply power to the same loads so they are separate systems with one charging system.

 

 

[Trullion]

My questions are as follows: Shouldn't almost 2 hours of engine running be enough to top up a dead battery? -

 

It is a common myth that a bike or car charging system will fully charge a discharged battery. Modern vehicle charging systems are designed to keep a fully charged battery in that state by balancing the load on the electrical system.

[James B]

Thanks for all your advice. I have installed the new battery. I decided to leave the auxiliary battery in for now because I don't have time to sort out all the wires. I would have to attach the daylight running lights to the main battery and reroute its dimmer switch, which would involve removing the dashboard and soldering. I have a plane to catch in a few hours so that's for another time. I trust that because the batteries are on different systems it won't drain the new battery. The auxiliary battery still powers the daylight running lights well enough. And the bike starts well along with the ABS, which didn't work when I jump started the old battery.

 

Cheers

James