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Please give an opinion as to where to start with this-I recently bought an '87 TW200 with 1100 actual miles, immaculate garage-stored ladie's bike, runs/looks like new--except--the seller told me that there was a starter problem. Looked to me like a bad battery, lights dim, horn barely worked, turn signals stayed on...Kick started fine, then power went up, but not quite fully but significantly more. Last night I quickly checked the battery-to my surprise, it was fully charged 100%!. Now I'm mystified, unless they stuck a 6 volt battery in it--which is possible, I haven't checked that yet--I'm not sure where to start otherwise--any suggestions?
 

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Could be just a cheapo battery. I had a scooter for about a year, but it had a cheapo battery that could barely hold a charge, and never could start it using the starter button, so had to kick start it every time. Of course, lights would brighten up and all, though when I would use the signal or hit the brakes, the headlight would go dim. Kept a tender on it, and would charge to 100%, but still couldn't get the juice out of it that I needed. Replaced it with a new battery, and all was well.



Not sure if that's your issue, but might be a good place to start.



Dan
 

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Load testing a bike battery



  1. Access the motorcycle's battery, by unbolting the seat with a socket wrench.
  2. Leave the ignition switch in the "Off" position and set your multimeter to read a DC (Direct Current) voltage scale, using the setting dial on the voltmeter's face.
  3. Connect the voltmeter's red probe to the battery's positive terminal and black probe on the negative terminal. Take note of the battery's static voltage indicated on the voltmeter. Charge the battery with an automatic battery charger if the voltage is below 12.1 volts DC.
  4. Keep the voltmeter's probes in place on the battery's terminals. Turn the ignition switch to the "On" position and take note of the battery's voltage. Replace the battery if the voltage is less than 10 volts DC while under a load.
 

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How old is the battery? How long did it sit without being charged?



An old battery or a new one that has been sitting for a few months could both be ruined. Pull the battery and hook up jumper cables from your car to the bike's battery cables. All better? Replace the battery motorcycle battery with a new one.



I've seen brand new batteries installed and allowed to sit for 6 weeks without charging or being run ruined from sulfation.





Don't hook up jumper cables from a car to a motorcycle battery. Exploding batteries are no fun.
 

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Why not Qwerty? 12v is 12v, right?


Yeah, but it's the Amps that will get you.



P = I x E. Watts equal Volts times Amps.



The charging system of a car can overpower some smaller or defective motorcycle batteries, causing them to boil & out-gas, creating an explosion hazard.



Now if you leave the car off, or just take the battery out & set it beside the bike then yeah, you can jump safely.



I have a Black & Decker Jump Start that works great.
 

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Discussion Starter #9
In my haste and ignorance(and not having my glasses at the time), I ASSUMED that since the previous owner paid an enormous fee to have his dealer put in a battery, that the dealer would actually check the connections--the battery was put in a week before i bought it, he gave me the receipt-but low and behold, on closer inspection, the negative connection was extremely corroded, they didn't bother to clean it off! A couple swipes of sandpaper, and all is well! I should have known better, although i've never seen a bad connection produce a consistent amount of lesser power before..
 

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The reason you don' t want to charge from an automotive charging system is because the TW, and most other motorcycles, use shunt regulation. The shunt regulator can handle the current from the TW's charging system but not the much higher charging current from a typical automotive system. Shunt regulation doesn't start until about 14.5 volts so you are probably okay below that voltage. But above that voltage the TW's regulator starts trying to disipate the extra power and overheating or just blowing the junction in the regulation transistor.



Limiting the charging current isn't a bad idea but a good TW battery can handle quite a bit. Boiling is usually the result of over-voltage not over-current.
 

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Actually, boiling is a result of overheating. What causes overheating is excessive current flow, either in to or out of the battery. Excessive current flow is caused by large voltage differentials. So, is it current flow or voltage differential? What came first, the chicken or the egg?



The proper trickle-charging rate for a motorcycle battery is one-tenth of the amp/hour rating for as long as 10 hours, depending on how discharged it is. Just guessing, but judging from the size of a TW battery, its amp/hour rating would be about 7.5 or 8. Maximum safe charge rate, then is 0.8 amps. Even the cheapest, lowest quality battery for my minivan, which is on the small, wimpy side of the automotive range, can deliver 500+ amps against a 10 volt voltage differential, which is not unheard of. Even the cheapest 10-gauge battery cables are capable of carrying a 250 amp load for several minutes before melting. So, take a small, cheap auto battery, small, cheap booster cables, and hit your dead motorcycle battery with 300+ times the amount of charging current the motorcycle battery is designed to withstand. Yup, that sounds like a disaster in the making, about the equal of using 9,000psi to seat the bead on a tire.



Charging faster than a trickle causes overheating which can warp and even melt the battery case if ignored. High-rate charging also speeds up internal corrosion, its visible sign is sediment buildup under the plates on the floors of the cells. If the buildup is deep enopugh to reach the plates, the cell shorts out, rendering the battery useless forever.



Too high a charging rate can also result in a battery that does not hold a charge because too-rapid transformation of the lead sulfate may actually trap sulfate under a surface coating of rejuvenated lead, producing a battery that can test okay but fails quickly. Thankfully, this last effect can be reversed with a very slow charge of no more than 1/20 (yes, that's one-twentieth) of rated capacity (that's 0.4 amp) for 25 to 30 hours. When was the last time you saw a 0.4 amp capacity battery charger?



Usually the first indication you've really messed up is the faint sound of boiling, then the whistle of air pressure trying to escape through the vent, then the sizzle of hot sulfuric acid eating paint and metal. If you are lucky. If you are having a really bad day the steam from boiling electrolyte (including a dose of highly flammable elemental hydrogen gas, think Hindenburg disaster) cannot escape fast enough and pressure builds up inside the battery until the case pops like an over-inflated balloon. Then instead of spilling down, acid is splattered any whichaway. Not good. Oh, that is a best-case scenario for a battery explosion. Should a spark occur, say, from a jumper cable falling off in the pop, the hydrogen goes off like a bomb. Fun, fun. Nothing like digging acid-coated shrapnel out of your face with a pair of pliars.



So, if you want to jump a motorcycle with a dead battery from a car, the secret to doing so safely is not to use automotive jumper cables. Instead, cut 2 pieces of plain old 12-gauge primary wire about 15 feet long, solder an alligator clip on each end of each wire. I've found the 10amp fully insulated heavy duty alligator clips from Radio Shack entirely adequate. Yup, you've pretty much just built a long set of heavy duty test leads. The internal resistance from the long (length is important from a safety standpoint, don't scrimp), small diameter wires will limit current flow to the motorcycle battery, enough to prevent the bike from starting off the car battery, and enough to prevent overheating the battery.



Do not start the car. The car battery is so overkill for starting a small bike it isn't necessary. Hook up the positive jumper to both batteries. Hook up the negative jumper to a cooling fin on the engine. Finally, hook up the negative jumper to a ground on the car engine. Allow the car battery to charge the bike battery a minute or two. Monitor the charge rate by touching the case of the bike battery. If warming is felt, then start the bike immediately. If not, allow a few minutes for the bike battery to charge, then start the bike. Disconnect the negative lead from the car as soon as the bike starts.



Your 12-gauge jumpers will also work from bike-to-bike. If you have a bigger bike, you'll want to use 10-gauge wire and more substantial clamps. Keep in mind that the big clamps on automotive jumpers are easily shorted in the confines of most motorcycle battery compartments. 10-gauge wire requires heavier clamps, about 30 amp capacity will do, such as these: http://www.unicornelex.com/detail.php?itemno=15-7250& Note that they are almost completely covered with insulation--always a good idea with boosters no matter the capacity. Extra insulation is a decided safety advantage when compared to these: http://www.autozone.com/autozone/accessories/Motormite-30-Amps-Red-and-Black-Insulated-Clamps/_/N-25ta?itemIdentifier=297432&_requestid=1862941
 

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More "Electrical Mysteries" ... Battery is dead. I know why, don't ask.



However, when I kickstart it, at idle all the lights are bright like they should be. But the second I give it any throttle, lights go dim but stay constant.



Thoughts or ideas ?
 

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More "Electrical Mysteries" ... Battery is dead. I know why, don't ask.



However, when I kickstart it, at idle all the lights are bright like they should be. But the second I give it any throttle, lights go dim but stay constant.



Thoughts or ideas ?
Mine acted like this once it turned out to be a fuse.
 

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I replaced the big fuse on the throttle side rear cover. That was only fuse I found. (This includes a section of wire from the harness as it was really worn and frayed).
 

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I replaced the cylindrical fuse under the right side cover and a good portion of the wire where it branches out from the harness as it was really frayed and worn... (2 strands actually went into the fuse connector). I'm thinking about replacing the relay like This Post suggests, but not sure if I can find it locally or if I need to order it from RMATV....
 

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I replaced the cylindrical fuse under the right side cover and a good portion of the wire where it branches out from the harness as it was really frayed and worn... (2 strands actually went into the fuse connector). I'm thinking about replacing the relay like This Post suggests, but not sure if I can find it locally or if I need to order it from RMATV....
You don't indicate why you are thinking of replacing that relay. Is your headlight problem persisting or what? I doubt that the relay has anything to do with the headlights dimming.
 

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I have the mystery electrical problem. Faulty relay ?



I'm grasping at straws here, But even though the battery is dead, shouldn't I have brighter lights as I throttle up instead of the opposite ??
 

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I have the mystery electrical problem. Faulty relay ?



I'm grasping at straws here, But even though the battery is dead, shouldn't I have brighter lights as I throttle up instead of the opposite ??
When trouble shooting always check the condition of your battery first. If it is low than charge it or replace it. A low battery could cause all sorts of strange problems.
 

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I had electrical problems on my '87. It was faulty corroded plug connections under the ignition switch. Unplug them and look at them and see how they are. Another member had similar problems and it was corroded contacts inside the switch. Good luck.
 
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