Charging System QUICK TEST

[Jon]

Hope its OK to post in this thread? Too late if not - I'm doing it right now. Put a good multimeter on my battery terminals today. about 12.8 to start (before starting engine). First, the voltage reading gradually dropped to about 12.2 regardless of revs, indicating (I would think) not charging. But then with turning the lights on, the readings started to go up. All the way to 16.2 volts at about 3000rpm. Which seems much too high. After turning the engine off and trying it all again, it seemed to read quite normally, ie: just under 13V before starting, up to just under 15V at anything over about 2500rpm.

Something wasn't right the first time. Is it possible for the regulator/rectifier unit, or the stator (or any other component in the charging system) to behave erratically? Or do they either work or not work? Could using the light switch have done something to nudge the system into life?

This was the first time I've ridden the bike properly since buying it a couple of weeks ago, all I know is that the chap I bought it off had fitted a new battery, and that it started dead easily every time, and that when I checked the horn & lights after 10 days, the battery had definitely lost charge. I charged it before starting the engine again, then rode it about 12 miles (including quite fast for a few miles), then did the above test. Hope this gives enough info?

[posplayr]

Hope its OK to post in this thread? Too late if not - I'm doing it right now. Put a good multimeter on my battery terminals today. about 12.8 to start (before starting engine). First, the voltage reading gradually dropped to about 12.2 regardless of revs, indicating (I would think) not charging. But then with turning the lights on, the readings started to go up. All the way to 16.2 volts at about 3000rpm. Which seems much too high. After turning the engine off and trying it all again, it seemed to read quite normally, ie: just under 13V before starting, up to just under 15V at anything over about 2500rpm.

Something wasn't right the first time. Is it possible for the regulator/rectifier unit, or the stator (or any other component in the charging system) to behave erratically? Or do they either work or not work? Could using the light switch have done something to nudge the system into life?

This was the first time I've ridden the bike properly since buying it a couple of weeks ago, all I know is that the chap I bought it off had fitted a new battery, and that it started dead easily every time, and that when I checked the horn & lights after 10 days, the battery had definitely lost charge. I charged it before starting the engine again, then rode it about 12 miles (including quite fast for a few miles), then did the above test. Hope this gives enough info?

First off, you are not making it any easier by not recording the voltages measure as per the Quick test. However, normally it is an absolute; if you are charging at 16V plus the regulator is bad. However, such inconsistency is also not making the diagnosis any easier. I would check the connections between battery and R/R and if they are good and you still see over 16VDC then replace the R/R and retest. You might have a bad stator as well.

[Jon]

These tests were done earlier today, before I even saw the thread about how to do them! Just hoping a replacement reg/rect will sort it. I clicked on your link re. the Solid State Power Box but it just went to another thread.

I'm sure i've seen something, somewhere in the past week or so, to the effect that reg/rec units from most Jap bikes are interchangeable depending on the number of wires. Mine has 5 wires (but it is not the type which has 3 yellow wires - I think each wire is two colours but it'll be a day or so before I can check).

[tom203]

Do some more reading by posplayr and don't just throw and hope new parts will be magic.

http://www.thegsresources.com/_forum/showthread.php?152769-GS-Charging-System-Health&p=1138531#post1138531

his Quick Test offers vital clues, so do it and report all six results- make sure you start with fully charged battery

[posplayr]

These tests were done earlier today, before I even saw the thread about how to do them! Just hoping a replacement reg/rect will sort it. I clicked on your link re. the Solid State Power Box but it just went to another thread.

There are 6 different links in my signature.

[Jon]

Yes. It was the Solid State Power Box link I clicked.

[johnsoma]

When you run these tests, where should the multimeter be connected to the wires on the bike? Like what wire should I touch it to and exactly where?
Also What setting should the multimeter be on?

Thanks!

[posplayr]

When you run these tests, where should the multimeter be connected to the wires on the bike? Like what wire should I touch it to and exactly where?
Also What setting should the multimeter be on?

Thanks!

Sorry I added this to the first post.

EDIT 8/10/2016: Make the measurements by stabbing the center posts of your battery. These are direct battery measurements. Avoid any connections.

[RobP]

Hi
my 1986 GS750ES with 24,000km died and the batter was flat last week when I stopped during a ride. This is a new to me bike. Believe it has upgraded RR as it has blade type connections. Since buying it I've driven 1500 km with no issues at all. Just prior to dying, I was driving down a very bumpy road. I also recently switched to a different H4 bulb, but volt tests show no difference in draw on th battery between the old bulb and new one.

Here are my voltages as per test above.

off 14.52
key on 13.12
idle 12.93
2500 rpm 13.05
5000 rpm 13.2
key off 13.15

It is a gel battery. I've checked and cleaned all connections.

I think the volt meter numbers above look ok?

I was thinking id take it out for an hour text ride and see how it looks.

Any thoughts?

thanks,
rob

[posplayr]

Hi
my 1986 GS750ES with 24,000km died and the batter was flat last week when I stopped during a ride. This is a new to me bike. Believe it has upgraded RR as it has blade type connections. Since buying it I've driven 1500 km with no issues at all. Just prior to dying, I was driving down a very bumpy road. I also recently switched to a different H4 bulb, but volt tests show no difference in draw on th battery between the old bulb and new one.

Here are my voltages as per test above.

off 14.52
key on 13.12
idle 12.93
2500 rpm 13.05
5000 rpm 13.2
key off 13.15

It is a gel battery. I've checked and cleaned all connections.

I think the volt meter numbers above look ok?

I was thinking id take it out for an hour text ride and see how it looks.

Any thoughts?

thanks,
rob

You are barely charging (virtually nothing). I would suspect the stator is fried. Run the Phase B tests leg-leg and especially the leg to ground tests in the Stator Pages (ignore the ohm meter tests).
You are obviously providing enough to the electrical system about 10 amps), but nothing excess to charge the battery except[t ever so slowly (think trickle charging).

http://www.thegsresources.com/statorpapers4.php

[RobP]

You are barely charging (virtually nothing). I would suspect the stator is fried. Run the Phase B tests leg-leg and especially the leg to ground tests in the Stator Pages (ignore the ohm meter tests).
You are obviously providing enough to the electrical system about 10 amps), but nothing excess to charge the battery except[t ever so slowly (think trickle charging).

http://www.thegsresources.com/statorpapers4.php

Did the stator (voltage) test first step. Only at 27V for leads 1+2, 1+3. For 2+3 only .5 V.

So so it does look like the stator has given up the ghost.

Rob

[posplayr]

Did the stator (voltage) test first step. Only at 27V for leads 1+2, 1+3. For 2+3 only .5 V.

So so it does look like the stator has given up the ghost.

Rob

You should probably get a Series R/R if you don't already have one. Post a picture if you cant tell. Look up SH-775 and you will see pictures posted of the part number. There are fakes around. It needs to say SH775XXXX (X are various codes)

[RobP]

Finally got around to installing the electrosport stator and r/r.

Did the test and here are the numbers (much better results than the old ones):

off 14.15
key on 13
idle 14.37
2500 - 14.67
5000 - 14.65
off - 14.60

[posplayr]

Finally got around to installing the electrosport stator and r/r.

Did the test and here are the numbers (much better results than the old ones):

off 14.15
key on 13
idle 14.37
2500 - 14.67
5000 - 14.65
off - 14.60

it does appear to be charging now but you still have somewhat of a problem. Either you have a very inaccurate voltage meter or you left the shiny r/r installed or both.

[holli]

hi

I have a gs 750 1977 and I have a charging problem. Ihave change my stator and R/R (not sure is ok). do you have the output volt for the stator ( 3 yellow cable) I have 2.80 AC. I have between 1-2 2-3 3-1 I have 2.8 ac , is the goed method?
many thanks

ps sorry for my english