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Voltage drain with key off?

  • Thread starter Thread starter RKM50
  • Start date Start date
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RKM50

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I installed a new battery after buying my 1980 gs1100. After sitting for 3 or 4 days the battery is low enough that it won't crank the starter. I disconnected the positive cable and put a meter between it and the battery and see .09 volts with the key off. I'm assuming there is a short somewhere or maybe some other problem? Thanks for your help.
 
You would want to measure current, not voltage.
You want to measure if any current flow (amps) by disconnecting a battery cable and connecting meter between battery and battery cable. So any current would have to go THROUGH the meter. If measure zero amps, then turn on key to light some lights just to see that meter connected properly, instruments light and other lights should come on and meter read a few amps.

If you measure any current with the key off, I would first ask if you have any devices connected on the aux terminals on the fuse block beacuse that is powered even with key off.

Other thing that that is still connected to battery with the key off is the rectifier/requlator ("R/R"). So if you do have a current drain with key off, try disconnecting the R/R as a test to see if that is where you current drain is. Can run biuke with R/R disconnected, will have to charge battery yourself from time to time.

And if the R/R is a current drain, the R/R probably isnt working either and you have a charging problem. Measure voltage ACROSS the battery with enbgine running at about 4000 rpm to see if charging. Leave R/R connected to do this test.

Tell us more what you find.

.
 
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I get zero amps with the key off and the battery disconnected, measuring across the plus terminal and the disconnected plus battery wire.

battery voltage with key off reads 12.1, key on 11.7 (headlight and tail light on), at 4000 rpm 12.1, probably not charging enough? This is after being on the charger for a couple hours. There are no accessories wired in to the fuse block. It does have a dyna ignition "black box" that I assume is not stock. It runs fine except for the battery going dead every few days.

I'll be the first to admit, electrical things or problems are not my strong suit. More of a fabricator/welder/engine builder kind of guy. I have searched here and found posts on checking the r/r and stator, will get to that this weekend.
 
RKM50 said:
I get zero amps with the key off and the battery disconnected, measuring across the plus terminal and the disconnected plus battery wire.

battery voltage with key off reads 12.1, key on 11.7 (headlight and tail light on), at 4000 rpm 12.1, probably not charging enough? .......
Click to expand...

Nope. Not charging much at all.

Big tests will be:
- the stator voltage between each of two of tghe three stator leads disconnected with engine running.
- measure volts between R/R+ and batt+ with bike running and everthing connected. Should be about zero point zero.
- measure volts between R/R- and batt- with bike running and evertthing connected. SHould be about zero point zero.

So seems that problem is that is not charging (as opposed to current drain on battery when parked).

.
 
It sounds at the very least that I might need a new r/r. Any suggestions on where to get one fairly cheap?
 
Do all your testing first, before you jump to buying stuff. You may have one leg of the stator weak or not working at all.
If BassCliff didn't give you a welcome package because he's been too busy, here's his page with all the links to suppliers, troubleshooting and manuals: http://members.dslextreme.com/users/bikecliff/
Have fun, follow the steps, and it should help you out.:)
 
Hi babes. Maybe check your ignition unit... Sometimes it can short out a bit... Try wiggling your key and see if it helps.
Xxx
 
DanTheMan said:
Do all your testing first, before you jump to buying stuff.
Click to expand...

This is probably the best advice I've read on this forum. There are many, many dollars spent on parts chasing problems that turn out te be a loose connection or something out of adjustment. Probably second only to buying inferior quality parts like carb and gasket kits from ebay. Do your testing and prove the part is bad, then buy good quality parts. You'll save money in the end.

http://www.whitehorsegear.com/motorcycle-electrical-systems
This is an excellent book for the beginner motorcyclist that tries to do his own maintenance.
 
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RKM50 said:
It sounds at the very least that I might need a new r/r. Any suggestions on where to get one fairly cheap?
Click to expand...
Do the tests to be sure - ebay has lots of decent used R/R 's

Today's special .... ebay item #251063635957 less than $25 shipped
 
RKM50 said:
It sounds at the very least that I might need a new r/r. Any suggestions on where to get one fairly cheap?
Click to expand...

Are various troubleshooting techniques.
You are suggesting the Credit Card Shotgun technique. Just shoot credit card money all over and hope to hit something.

Your R/R may be good, but just some really bad connection keeping it from being able to work.
Simple tests described in stator papers will narrow down where the problem is.


.
 
I just downloaded the shop manual from Basscliff's site and will print out the appropriate pages for testing. I haven't looked but I assume all the tests and specs for the r/r and stator are in there. I'll look more at his site too.

This bike is 32 years old, I don't mind throwing a little money at it to make it reliable. It's to heavy to push.
 
A lot of little things can end up costing more than the bike is worth. There are always a few items than get bought when it was unnecessary, but big ticket items are to be avoided. Money saved here and there can go into real performance upgrades like shocks, fork springs, and brakes, which will go a long way to giving you a reliable, safe, and fun ride.

That 1100 has enough kick that you want to be in control...
 
Just want to be prepared with some purchase options in case I actually do need one. I prefer new over used, who knows whether the used one will give up the ghost in a month or so. Above all I want the bike to be reliable, it's too heavy to push.
 
Lots of us are using 30 year old Shindengen R/R's with no problems- If you want to go new, look into a Compufire R/R- pricey, but might appeal to you.
 
Took the r/r off the bike and got these readings:
+R to -w/bl 1.19
+R to -w/r 0.0
+R to -Y 1.18
+R to -b/w .37

-B/W to +w/bl 1.16
-B/W to +w/r 1.16
-B/W to +y 1.17

According to shop manual all should be 5-6 ohms except Red to black/white which is supposed to be 35-45.
Also the w/r connector looks like it got hot at some point.

I'm thinking I need a new one.
 
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Ordered an aftermarket r/r and installed it. when revving the engine to 2k or so I get 13.9 v on the battery, seems to be charging. The engine seems to run smoother also, maybe the coils are seeing proper voltage and getting better spark out of the plugs, not sure. After a short ride I let it sit for a few days and it started right up, drained battery issue solved I hope.

The PO had the red wire off the r/r directly to the battery, I didn't see any other place to hook it up so I did the same. The harness has been hacked up some by the PO, I was hoping to get through the summer and redo it this winter.
 
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