Question about BMW Motorcycles

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I left my motorcycle on and drained my battery my bmw battery charger for my battery is indicating reverse polarity after about two minutes even though it is hooked up to the battery properly

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  • BMW Master
  • 26,833 Answers

Disconnect and remove the battery to charge it. I am guessing the rectifier unit in the bike circuit is causing the problem.

Posted on Jul 02, 2018

Testimonial: "Sorry I did remove the battery"

  • 4 more comments 
  • Leif
    Leif Jul 02, 2018

    The battery was removed prior to charging attempts

  • Andrew Taylor
    Andrew Taylor Jul 02, 2018

    Sometimes a battery can go into reverse polarity. Put a large load on it to deplete it again completely, something like a head light bulb. Then charge it with a non-smart charger.

    Finally, i am sure you checked, but apart from Red and Black markers, also check the embossed Plus + and Minus - in the plastic of the battery.

  • Andrew Taylor
    Andrew Taylor Jul 02, 2018

    If that doesn't work, I wonder if it would fully charge in reverse, plus on minus, minus on plus :>) If not, new battery, they last about 4 to 5 years on a bike.

  • Leif
    Leif Jul 02, 2018

    I wondered about that as well, but was unsure if it would then muck up my bike's wiring once reinstalled. I am going to try a couple things-different charger&different outlets and then just buy a new one if I'm still at this point

  • Leif
    Leif Jul 02, 2018

    Of all things I am ABSOLUTELY 100% certain that the cables I have attached to the battery were done so appropriately each time and did not cause the issue

  • Andrew Taylor
    Andrew Taylor Jul 02, 2018

    Yes, good thought, corrected mains polarity at the outlet was not something i had considered.

    There was a post here about a week ago where someone had connected a car battery the wrong way. Caused a load of damage including taking out the ECM and BCM!



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Posted on Jan 02, 2017


SOURCE: battery charge indicator seems faulty.

Solved own problem. Bad conection between pcb and battery contact pins. Reheat each battery pin on the pcb carefully until solder reflow occurs then remove heat. PDA now repaired

Posted on Aug 17, 2008

jimie jim ja
  • 2 Answers

SOURCE: BMW motorcycle maintenance

to change the oil you need to remove the sump plug, located on the underside of the sump. the plug is a bolt on the botom of the engine. once the bolt is removd, oil will drain out rapidly so have a container ready to catch the oil.once drained put the sump plug back in and refil with new oil.

Posted on Dec 09, 2008

  • 62 Answers

SOURCE: hooked up the battery reversed polarity. Blew the fusible link but replaced it. Now the car will crank but not start.

start checking fuses hopefully its just another blown fuse if your lucky

but if all the fuses are good, you probably fried something like the computer or ignition module and probably the radio

hopefully its something simple and cheep but don't be surprised if you have to shell out some cash to replace the computer

Posted on May 16, 2009

  • 2761 Answers

SOURCE: I have an Icom VHF that was hooked up reverse polarity on 12v.

They likely replaced just about every diode and possibly the main circuit board. The tech should be willing to tell you exactly what work was done, and many return the replaced parts.

Posted on Feb 27, 2010

  • 444 Answers

SOURCE: my 97 bmw 740i has and issue, the battery keeps draining even though i replace the alternator and a brand new car battery. What might be the problem and is their a shortage somewhere in the car electr

misfire is due to a faulty coilpack or bad wire or connection. the drain on your system is another issue. youll have to chase it down with a voltmeter

Posted on Mar 15, 2012

Testimonial: "Well the misfire i took the coil and plug off to check the voltage on it and it measured the same as the rest but when i took the spark plug out their was a crack so i replaced all the spark plugs and the check engine dissapeard thanks"

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Lead acid Car battery was charged with polarity reversed. Can it be re-charged correctly? It blows the charger fuses??

a lead acid will not charge with the polarity reversed
What happens is that in dead shorts and can destroy the battery
it can blow up the battery , blow the charger fuses and destroy the charger
Depending on the damage to the battery cell plates it may be recoverable

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2006 Honda Nighthawk 250 hooked up my battery charger backward

Hi, Roger if your battery out of your bike when it is completely dead and you hook up the battery charger backward your battery will charge fully except the poles will be backward, the Positive pole is now the Negative pole and the Negative pole is now the Positive pole. If you install the battery not knowing the poles have been reversed you will blow the main circuit fuse or circuit breaker on the bike.
If you tried charging the battery while it was still hooked up to the bike it will do the same thing to the fuse or circuit breaker in the battery charger. Most battery chargers have some type of warning light or buzzer alerting you to the fact that the cables are hooked up backward.
If your battery is fully charged backward take it out of the bike hook it to a headlight and let it drain until the voltage reads zero, this may take a couple of days, then recharge it slowly with a trickle charger or a regular battery charger at 1 or 2 amps for 24 hours and you will be good to go.
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Hi Anonymous, drain battery completly buy hooking it up a headlight. It may take a few days but it is the only way, make sure battery has 0.0000 volts before hooking it back up to a trickle or 1 amp charge rate. Good luck

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there is a short in the system that is connected to that relay/fuse. Could also be melted wires if you tried to ever jump start it from a car, start position on a charger or jump start box. Jump starting a motorcycle should never be done. The gauge of wires on a motorcycle are much lighter than vehicles.
It is VERY rare but i have seen batteries that are reversed polarity. Check to make sure battery is 12v + when you test it. Not 12v -

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Charging battery

Hi, Anonymous the best way to charge a battery is slowly. I like to use this analogy, would you rather be awakened from a deep sleep with gentle nudging or a violent kick in the rear.
1. Remove battery and check for corroded or damaged terminals clean any dirt, corrosion or electrolyte that is on top of the battery as this will cause premature battery drain, inspect for cracks and swollen/expanded sides which are a sign of overheating and replacement should be seriously considered.
2. Acid plate type batteries should be checked with a hydrometer with recorded readings for each cell to be compared with after charging readings and for sulfation, the cell will appear milky, and incorrect acid level. Fill low levels with distilled water to upper level and remove acid from over filled cells with hydrometer until the level is at upper mark and dispose of acid in the sink mixed with a quart/litre of water.
3. Connect a voltmeter set on the DC scale to the battery and record the reading for comparison after charging.
4. Attach a drain hose that is not pinched, kinked, or plugged to the nipple on acid plate type batteries and let the other end hang into a plastic or styrofoam cup.
5. Connect a 1-2 amp trickle charger that has automatic charge rate reduction if possible and let charge for 24 hours.
6. After charging recheck each cell with a hydrometer a 100% fully charged cell will have a specific gravity reading of 1.270-1.280 and 1.180-1.190 has only a 25% charge battery should be load tested and considered for replacement if necessary. Reconnect your voltmeter and
any readings in the 10-volt range means you have a dead cell and the battery needs to be replaced. Readings between any 2 cells of 50 points or more indicate the battery has failed and needs to be replaced.
7. No maintenance AGM or GEL batteries need to have a voltmeter reading of 12.8-13 volts for a full 100% charge and 12.2 volts is only a 25% charge and should be load tested and replaced if necessary.
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2007 Kawasaki Z 1000 accidentally reversed polarity

Hi, Bm_700 charging a battery can help extend the battery's life and potentially save you money. During the process of charging the battery, you may accidentally mix up the cables and put the wrong one on the incorrect terminal. When this happens, it could damage the battery as well as other associated electrical components.
When charging a battery, it is important to connect the cables to the proper terminals. Connect the red cable to the positive terminal on the battery, and the black cable to the negative terminal. If you connect the red cable to the negative terminal and the black cable to the positive terminal, several problems may result.
If you reverse the polarity of the charger to the battery, the battery may explode. It may also cause the battery to stop holding a charge permanently. When this happens, you will have to buy a replacement battery. When a battery is damaged, you need to dispose of it properly, as it could leak acid.
When you connect the cables directly to the battery, it may damage the charging system in addition to the battery. If you have a battery charger and connect the incorrect cables to the terminal, it could send the incorrect type of polarity into the charger. This could lead to the charger being damaged permanently, then being unable to charge batteries again. Sometimes, it will only partially damage the charger and the charger will charge at a slower rate.
In addition to damaging the battery, connecting the wrong cable can damage the electrical components of anything that the battery is connected to. For example, if you leave an electrical device plugged into the battery while you connect it to the charger, it connection may short out the electrical components of that device. If this happens, wiring and other components may need to be replaced before the device can function again.
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Hi, well the reason this has happened is that these contacts are stored in battery backed up NVRAM, now this RAM is very sensitive to polarity reversal, and also due to the way it works, doesn't have polarity reversal protection, on that circuit. So when you reversed those batteries even though the reverse polarity protection saved the Unit as a whole, the NVRAM would have been destroyed or wiped at best. These is no real way of replacing this NVRAM, I guess you could send it back to the factory though and ask for a "Quote" with view to the repair.

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I charged battery while in camera and left charging for a week and camera won't power up or turn on? it was with a universal charger and may have had higher voltage setting , could this have burned out...

Will your camera power on with a spare battery or through the electrical adapter ? If so then your camera is fine and the problem is your battery!

This is why manufacturers always recommend to use the supplied batteries and recommended chargers only and not some third party junk. This is why you have batteries exploding on people they don't read the warnings.

Yes it is possible to damage your battery - perhaps your battery cannot take a charge - it is NOT normal to charge a battery for a week !

your battery needs a nominal voltage to remain healthy if you allow it to drain below that voltage you have reverse polarity and your battery is good for the garbage bin.

use the recommended charger from now on and get new batteries.

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