Suzuki GS500 Charging issues

Hi all,

I recently bought a Suzuki GS500 (02 reg) and I've been having problems with the battery. Initially I thought the battery was at fault however I've replaced this and still have issues.

If the bike is not used for a few days the battery has little charge left and when i go out for 20 miles rides it doesn't appear to be charging at all. Actually, the bike frequently cuts out towards the end of these rdies and then I can't get it started again due to dead battery.

I've followed the steps to check the R/R from the John Bates charging circuit test (and a bunch of other guides). Measurements are:

1. (battery) All off = 12.88 / 13.12. Idle (1200RPM) = 13.9. 2500 rev = 14.2. 5000 rev = 14.15 (However, this doesn't always happen, sometimes there is no increase)

2. 14.2

4. 60mv

6. 48mv

8. y1-y2 = 1.5 ohms. Y1-y3 = 1.5 ohms. Y2-y3 = 1.4 ohms

10. OL for all

12. y1-y2 = 65v. y1-y3=66v. y2-y3 = 65V

14. Red – y1 = 498mv. Red-y2 = 510mv. Red-y3 = 513mv

16. OL for all

18. y1 =514mv. Y2 = 512mv. Y3 = 510mv

Stator current (AC) at 5000 RPM between leads:

65v, 66v and 65v

The connection with the Red and b/w connects to the cable coming from the R/R and looks damaged/corroded. The yellow wires that also connect up to those coming from the R/R get fairly hot to the touch. Could the R/R be OK and this connection be the issue?

I'm not mechanically sound particularly but I don't really want to pay a fortune for a mechanic to test things, any help would be greatly appreciated.

Welcome to TMBF mate. ........

Yes.....sounds like you may have a dodgy connection there......The connector shouldn't get hot......

Welcome, can't see your images , its really easy to upload direct to the forum , just go attachments, add files , select from your images , wait for the tick and submit .

Images attached - sorry!

The images aren't the connection that gets hot, that's the three yellow wires that connect from the stator to the R/R. The imags are the other wire that connects to the R and B/w wires coming from the R/R.

Following a bunch of guides, the readings I get from the R/R diode checks would suggest that this is the fault. However, the readings I get are all consistent:

14. Red – y1 = 498mv. Red-y2 = 510mv. Red-y3 = 513mv (positive swing diode, reverse bias check)

16. OL for all (positive swing diode, Froward bias check)

18. y1 =514mv. Y2 = 512mv. Y3 = 510mv (negative swing diode, reverse bias check)

20. OL for all (negative swing diode, forward bias check)

The guides say that I should be getting readings of OL or over 1.5V for 14 and 18 and readings of around 0.5V for 16 and 20.

I've learnt alot about the charging system this weekend but I'm not sure what's going on and don't have a working R/R to test.

Sorry I can't offer any solution, but I did used to have a GS500F which had similar electrical issues (especially in the wet), so I can sympathise. It's a shame, because I loved that bike otherwise, I just couldn't trust it to start in the cold/wet without getting some expensive work done to it

Just a thought, if all this heat is being generated either side of something that is designed to generate and dissipate heat then I can only assume that the reg rec is at fault . Try upgrading to a Honda CB 250 n pattern one .

As above AND - Replace that connector!

And herein lies the clue...."1. (battery) All off = 12.88 / 13.12. Idle (1200RPM) = 13.9. 2500 rev = 14.2. 5000 rev = 14.15 (However, this doesn't always happen, sometimes there is no increase"

The connector in your photo looks well dodgy.......I would suspect a bad/intermittent contact. The presence of heating would tend to reinforce this conclusion.

Try cleaning all of the R/R connectors then pack with dielectric grease. The R/R itself is probably OK as usually they either work or not. Let us know how you get on.

Cheers

S23

Additional,

Heat in wires and connectors come from two sources, either sparking due to loss of connection, in which case something needs cleaning or replacing, or due to being too small to carry the current. For example wires that are too thin often become hot in use.

Heat suggests something is very wrong either clean or swap the connector or piggyback a second wire bypassing the hot section increasing the current flow.

This heating of wiring due to age, low capacity, and insufficient size to carry the current is the cause of most electrical fires.

It needs sorting out.

Dodgy connection due to corrosion more than enough to cause problems described. Needs a good cleaning out.