Motorcycle Forum banner

1 - 5 of 5 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter #1
I've been troubleshooting my 1975 Suzuki TS185 charging system for a while now and am a bit of a dead end. While riding the bike the battery will not charge and if I ride for about 40 miles the battery will be completely discharged. At that point pretty much none of my lights work... blinkers, brake and rear light but the Headlight will continue to work. I've checked the Rectifier (using directions in the Clymer repair guide) and according to the troubleshooting info the rectifier is good. The batter is approx six months old, water level is good and i routinely keep in charged on a 6v 2a motorcycle charger. I've done some voltage testing and these are the outputs after the battery charged to 100% on a motorcycle battery charger:
Bike off: 6.3v
Bike idling, lights off: 6.55v
Bike revved, lights off: 6.8v
Bike idling, lights on: 6.35v
Bike revved, lights on: 6.15v (weird that it drops when revved)
Bike idling, lights on and brake light on: 5.84v
Bike revved, lights on and brake light on: 5.8v.

From what I can gather it seems that is should be charging when I have the lights off. I typically run the lights on during the day while riding to create more visibility for other drivers. It's interesting that when the lights are on that when the bike is revved it actually puts out less volts. I'm not sure why this would be the case.

Hopefully that is enough information to get some good advice/next steps on this forum. I think I'll try riding the bike for a good 40 miles without the lights on and see if the battery get's drained that way. At this point my best guess is that the lighting/charging coil is under performing and cannot handle charging with the lights on but should be able to without them on. I'm thinking I need a new coil.

Any help is much appreciated.

Thanks.

James
 

·
Super Moderator
Joined
·
13,035 Posts
Bike idling, lights on: 6.35v
Bike revved, lights on: 6.15v (weird that it drops when revved)
Any time that the measured voltage while running is more than the voltage while off, then the battery is charging......or at least not DIS-charging.

It is not necessarily "wierd" that the voltage drops off some at higher rev's, that's just the regulator working.
In this case, however, it looks like it drops too much.

You need to repeat those tests with the battery nearly dead to get a better picture.

The automatic guess is a bad regulator. On a bike of that vintage, the rectifier and regulator are probably seperate pieces.
Alas, the regulator is hard to test individually.......and a known good one might be hard to find.

Sometimes just a bad ground at the regulator can cause problems.

P.S. If your battery charger is NOT an automatic, tender type, leaving it on the battery ALL the time is actually a bad idea.
If you remove the charger for 24 hours or so, what does the battery voltage do (without running the bike).

These situations are tough because the initial design assumed that the headlight would be OFF most of the time......but now it is required to be ON all the time.
 

·
Registered
Joined
·
3 Posts
Discussion Starter #3
Thanks for the tips Easy Rider. I'll try out all the voltage tests when the battery is nearly dead and will check voltage on the battery tomorrow without running it for 24 hours.

Quick follow up... I just rode thirty miles with the lights off and the battery tests out at 6.3v (which is the same as before) after the ride. Also, the charger I use is a Speed/Charge SC-600A Automatic 6v/12v charger. I charge it at 6v 2a. I'm not sure if this is technically a "tender" type charger but it does say "automatic."

Thanks.
 

·
Super Moderator
Joined
·
13,035 Posts
I'm not sure if this is technically a "tender" type charger but it does say "automatic."
I don't think I'd trust it for long term use. Are there lights on the front? If so, what are they labeled?

I'm having a hard time finding a Voltage Regulator on the bike.
It may not have one.
(Edit: It doesn't. Magneto systems usually don't. There is a set of contacts on the light switch that cuts in a different winding on the mag. when the light is ON. Those contacts could be bad. Then unless the mag itself is bad, I'm afraid your stuck.)

A really low capacity charging system can use the battery to "sink" any extra current that is produced.
But that assumes that there EVER IS any extra current.......and when the voltage goes DOWN at higher engine speeds, that might not be a good sign. Then we might be back to: The bike wasn't designed to be run with the light on all the time.......maybe.

Only suggestion I can make at this point is to check all the ground connections REAL good.....as they are important and tend to corrode over time.
 
1 - 5 of 5 Posts
Top