Charging circuit and batteries. Help me understand.

[Guest]

Hi!

I have read a lot of posts on this forum and others to try and understand the charging system.

My bike is an 81 GS1100E.

I have read then SHUNT_vs_SERIES_RR_Compare_Tutorial and I am having a hard time figuring it out. I dont even know if it's relevant to my question.
What are the amps values for 1, 1.5, 2 and 3k RPM's?
I ask is because I have read that a low RPM's the charging system is incapable of charging the battery and the default equipment.
I do a lot of city riding and have noticed a drop in my battery voltage. It comes back if I do a bit of highway.
If I know the max output I will be in a better position to find a solution. Example substitute the low beam with super bright LED's as daytime running lights.

I have read that running a GS without a battery would burn the RR. I think this is not true.
What I understand is that the RR is always working. Once the battery is full you still need to feed the lights and other gizmos right?
And even if it's the battery feeding the demand you will still need to charge it up.

Thank you in advance for your help.

[Killer2600]

To not get into too much detail without a battery to store power in or pull power from the charging system will over-voltage the electrical system causing the regulator to work extra hard in a futile fashion to bring it down to acceptable voltage levels. On the other end of the spectrum when the charging system doesn't put out enough to run everything (at low rpm) the bike just dies without a battery to make up for the missing power. The risk of over-voltage frying all kinds of electrical and electronic goodies is a good enough reason for most to leave the battery in without even considering how the RR will fair.

[JTGS850GL]

Actually you need to think of the battery as a huge capacitor. It filters out much of the transients that are generated by the stator and other interference sources. By removing the battery from the system you introduce a ton of noise onto the system. It's the noise that will damage sensitive electronics like the ignition module and regulator.

Unless you've added a LOT of additional electrical draws, if you're bike isn't keeping up with the charging needs while riding around town then you have issues that need to be addressed with your charging system.

Go here: Quick Test to identify what the problem is.

[posplayr]

Hi!

I have read a lot of posts on this forum and others to try and understand the charging system.

My bike is an 81 GS1100E.

I have read then SHUNT_vs_SERIES_RR_Compare_Tutorial and I am having a hard time figuring it out. I dont even know if it's relevant to my question.
What are the amps values for 1, 1.5, 2 and 3k RPM's?

The alternator (charging system) generates current that varies with RPM. At low RPM it is the least and it maxes out around 3500-4000K RPM as show in the figure.

At slow idle the bike probably is discharging slightly, like -1 amp ; this might be at like 1000 RPM. By the time you get to 1100 RPM it might be right at the pint where you are reading the quiescent battery voltage (e.g. 12.8V) and the battery is neither giving up or receiving any current. By the time you get to 1200 you might be charging the battery with 1 amp. This is purely an example based on recollection of prior measurements.

To tell how your bike operates, put a voltmeter directly onto the battery with the key off. Note the battery voltage (say 12.82V). Now start your bike up and adjust the RPM till you read the same voltage (approximately). That tells you at what RPM you bike will discharge at. Of course this will change if you have brakes on signal and other loads above normal.

As far as running a bike with the R/R connected but no battery, you will destroy light bulbs and sensitive electronic components especially as you rev the bike up. At idle it will not be as bad but higher RPM will start to destroy stuff.

This is not unusual or any mystery. Any power supply that switches relies on energy storing devices to "smooth" the voltage output. By having a battery connected the R/R are designed as very simple devices with essentially no energy storage because there is a (relatively) huge battery connected. You take that away and you are violating all design assumptions.

You can pull the R/R out and run in depletion mode without the R/R but not the other way around.