Random no start / Electrical Guidance?

[dk31285]

I've got an '04

Here's the deal...

Monday morning the bike fired up as usual, rode fine for about an hour, came home and parked it.  Nothing out of the ordinary.  Monday night through Tuesday night was rain and cold, so the bike sat covered in the parking lot (apartment complex).  I went out to fire it up this morning (Wednesday) and the bike didn't want to start at all.  Choke, no choke, tried petcock on prime to hopefully rule out fuel issue.  The cranking eventually became slower, the sound of a dying battery from so many unsuccessful attempts at starting.  I have a jump box which I hooked up and tried to start again, but that didn't change anything.

Took a break for a few hours to run some errands, then came back to tinker a bit more.  I took my multimeter to the battery and read 11.94 volts with the ignition "OFF".  When I switch the ignition to "ON" the voltage immediately begins to drop, slowly but consistently.  Each time I tried to start it without success I would check the battery to find the voltage lower and lower.  When I stopped trying to start the bike and turned the ignition back to "OFF", the voltage immediately begins to climb again.  Give it enough time and it returns all the way to 11.94 volts.

I'm assuming some sort of electrical issue or short must be to blame.  I know where the rectifier is, as well as the relay for the starter motor.  Not so familiar with what else I might want to check.

Is there a resource anywhere that would tell me what type of current I should see from these parts with ignition on/off so I can begin to hunt down the issue?

Any ideas aside from this plan are greatly appreciated.

Thanks!

[bmf]

A good battery should be at around 12.5 v . seems your battery is bad. How old is it? Tried charging it?

You can check the charging circuit specs, the manuals explain that better than I can.

Bmf

[dk31285]

A good battery should be at around 12.5 v . seems your battery is bad. How old is it? Tried charging it?

You can check the charging circuit specs, the manuals explain that better than I can.

Bmf

Battery is one year old.  I removed it from the bike for winter storage and kept it inside, though I did not charge it at all during that time (about 4 months).

I was hopeful that if it was just the battery, the jump starter would help get it running and then it could charge back up, but that didn't happen.

[Janx101]

What sort of battery is it? Lead acid or gel AGM?

[dk31285]

What sort of battery is it? Lead acid or gel AGM?

Pretty sure it's a lead acid.  I'll link the exact one I have..

http://www.interstatebatteries.com/b/motorcycles/2004/suzuki-motorcycles/gs500/N-12ZzihwqaZ1ybaq84Z1z0tr4yZzihwsq?dsNav=A~Part+Number&1=1

[dk31285]

So it appears that the issue is indeed the battery itself.  I left the jump box sitting on the battery for about 15min and then tried starting it.  It resisted, but eventually fired up.  I warmed it with the choke, then let it idle for about 20 minutes, revving it occasionally. 

While idling, the battery read about 12.20 - 12.30 volts.  When I would blip the throttle I would see a spike to about 13.30 - 13.40, and then it would drop back to about 12.20 volts.

After idling for about 20 minutes I shut off the bike and read the battery.  It showed only 11.64 volts.  With the key in the ignition and turned to "ON" but not running, the voltage steadily dropped as it was doing before I was able to get it started.  It went down as far as 10.90, at which point I packed up and turned in for the night.

Thanks for the input.  I know what I'll be shopping for in the morning...

[Janx101]

Righto ... When you replace the battery.. Ask for an AGM one from the battery place... Costs a little more but so much more worth it!!

My bike has been sitting virtually silent for nearly 2 years... The AGM battery I put in it STILL fires the bike up.... And it's not on a tender and hasn't been charged at all apart from a few mins running the motor every 3 or 4 months...

You really do get what you pay for!!