electrical short circuit

[Red Baron]

After returning home from a 4k tour I have had an experience with some sort of a "short" circuit somewhere in the works. While on tour I had to replace the battery and thought nothing of it as the batt was ten years old. After getting home I parked the scoot and about two weeks later went to ride it and the battery was totally dead. New battery ? Yep ! I took the battery to the vendor and got a new one. Installed it and did a base charge and all was well. Next morning I checked the voltage with my digital volt meter and the battery was down to 12.4 volts. Oh oh, something is not "right". I disconnected the battery, charged it back to full charge and then started hooking it back up. When I hooked up the cables I noticed a tiny spark. What the H...? The key is in the off position and nothing should be drawing current. What could it be ? Any one have any ideas ? The bike is a 1990 Venture. It has a new battery, a new R/R and the stator was replaced about 5000 miles ago. I tried to trace the offending circuit by removing fuses and testing but to no avail. I am now thinking this is what caused me to have to buy a new battery while on tour. Does anyone have any ideas what could be drawing current when the key is in the "off" position ? Thanks for the help.

 

Red Baron

[Peder_y2k]

The clock is a parasitic drain. When I store my bikes for more than a few days, I disconnect the main fuse connector.

-Pete, in Tacoma WA USA

'83,88

[frankd]

Baron,

 

What I'd do would be to disconnect the negative battery lead. Then I'd take my digital meter and move the leads to the 10A. position. Then turn the selector switch to the 10A position also. Connect one test lead to the NEGATIVE terminal of the battery and the other to the NEGATIVE battery cable. This way, your meter will indicate the actual discharge current. A couple of cautions here......Make sure you connect the meter exactly as I have written, and when you are finished with this test, make sure you move the meter leads back to their normal position. The meter is usually protected with a fuse, but..... Also do NOT turn the key on. The draw with the key on will be way over 10A.

 

If it's draining the battery to 12.4 overnight, you'll probably see .5A or so drain. Normal battery drain for the clock, radio and CB memories would be so small that you probably wouldn't be able to measure them on the 10A range. They draw so little they would read almost zero on the 10A range. Check and make sure the light in the travel trunk is switching off. Have you added anything to your bike (lights or a lighter)? Start disconnect things one at a time and remember any added fuses and the aux. fuse box in front and to the left of the normal fusebox. Your voltage regulator is another possibility. If it's the original type, unplug the connector that has the red and black wires in it. If it's not, you will have to disconnect the red wire to make sure that it's not your culprit. If you are drawing .5A or so, you may be able to feel the regulator getting warm while the bike hasn't been started for a while if it's the cause of your drain. Let me know what you find, and we can go from here.....

 

 

Peder......the power that the clock and radio memories use is miniscule. With a good battery, a First Gen. can sit unused for a long time and still have plenty of battery to start. Now that doesn't mean that you should let your battery sit for months without being charged, but I'm just saying that the clock and radio memories will not discharge your battery unless something is defective.

 

Frank D.

[Red Baron]

Thanks for the response to my dilema.

 

I have already disconnected the R/R, and all other items that are connected to the battery. I reconnected the negative terminal and then used my meter to check voltage between the positive terminal and the wire that connects to the main fuse located on the positive side of the battery. I get 12.8 volts. I have been disconnecting circuit plugs one by one and then checking voltage in this manner. So far, I get 12.8 everytime I check. I am starting to suspect the diode in the starter relay circuit but have not tested to confirm yet. As time is short I will do additional testing during the next few days and let you know what I find.

Thanks for the help.

 

Red Baron

[Red Baron]

OK ... FrankD ... thanks for the suggestions.

 

I just checked for amp drain as you suggested and I get .01 reading and it is intermittent. It looks almost like the drain from a ticking clock but the timing is wrong for a clock. What do you suggest I do next ? I suspect this will be a bearcat to find as it seems to be intermittent.

 

Thanks again for the help.

 

Red Baron

[frankd]

.01 amp is nothing to worry about. The reason it comes and goes is that it's really less then .01 amp, and the meter is averaging the reading. Don't worry about this.

 

Leave the meter leads connected and reading the draw and start plugging everything back in. Hopefully something will make it indicate more. If it's intermittent then we'll have to get serious.

 

Let me know what it reads with everything connected. Open and close your travel trunk and make sure the light goes out every time. You will see a higher drain when it's on.

 

I'll take a look at the print for other possibilities.

[Guest tx2sturgis]

When I hooked up the cables I noticed a tiny spark. What the H...? The key is in the off position and nothing should be drawing current.

 

The radio memory circuit and clock, and possibly other electronic items, can draw tiny amounts of current on standby, and the tiny spark you saw may be from one of those components recharging a filter capacitor. Filter caps will draw some current briefly when reconnected to the power source, and can cause a tiny spark.

 

What matters is the parasitic current draw measured with a digital meter as you have done, and the reading of .01 amp, (10 milliamps) is not abnormal.

 

I suspect you may have some corrosion somewhere in the ignition switch, a connector, or some other location, causing the intermittent passing of current. Or possibly your stator and or regulator has a failing diode or two.

 

You may have a failing stator that is not supplying enough current to keep the battery fully charged during operation, but IS working just well enough to keep the bike starting and running.

 

Let us know how your tests go.

 

 

 

 

[Red Baron]

After testing and reassembling I can get no reading greater than the .01 amp. This is my worst fear, an intermittent problem that won't manifest itself in a manner I can identify. I guess this comes under "Oh well". I have started the bike and all works as normal. All I can think to do now is wait for this to happen again. I sincerely thank all of you that responded to my question. IF I ever locate what the cause is I'll share here with you.

 

Thanks again,

Red Baron

[Guest tx2sturgis]

A year later....how is that new battery doing?

 

Or did you ever find the problem?

 

 

 

[Venturous Randy]

A year later....how is that new battery doing?

 

Or did you ever find the problem?

 

 

 

 

Here I have been sitting here on pins and needles waiting for a followup. Brian, thank you for asking about this.

RandyA

[Guest tx2sturgis]

Here I have been sitting here on pins and needles waiting for a followup. Brian, thank you for asking about this.

RandyA

 

Like a DJ at the radio station...sometimes I have to dust off the moldy-oldies and play 'em...