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Charging Voltage

salty_monk

salty_monk

Forum Guru
Past Site Supporter
TGSR Superstar
on my 83GS750ES.

When I measured it was 15.7v. This was on a battery with decent amount of charge & NO headlight connected. (So 55w less load applied than is normal)

The battery was overfilled by TPO & I can see some evidence of it using it's evac tube...

Is the overfill the problem (i.e. why it's spitting out fluid) or is that voltage too high & it's bubbling out due to overcharging? Maybe the RR is not doing it's job.

Just looking for some idea - whilst the bikes in pieces I might replace RR with one of the Honda jobs.

Cheers,

Dan :)
 
It could also be that the PO topped the battery up with acid rather than water when it ran low. If you've got a hydrometer handy it could be worth testing.
 
I guess once I get it running again I can always throw one of my other batteries in it that are right level & topped off with H20 & see what happens then.

Would the lack of a headlight affect the RR? Obviously not having 55w of load on that system is pretty substantial for a small bike charging system.

Dan :)
 
salty_monk said:
on my 83GS750ES.

When I measured it was 15.7v. This was on a battery with decent amount of charge & NO headlight connected. (So 55w less load applied than is normal)


15.7 volts is WAY too high. That is boiling the battery. Also, reconnect the headlight immediately. The R/R will not survive for long having to dump that much exceses wattage into the R/R heat sink. You ARE going to roast your R/R and shorten the life of your electronic ignition, coils and various light bulbs besides roasting the battery.

You dont want a constant charging voltage over 14.8 and preferably between 14 to 14.5

Earl
Click to expand...
 
Earl - thanks for the feedback - I know it's too high. The bike is in pieces, the measurements were done when I fired it up after some clutch work before I tore it down again.. just wanted to make sure the nasty noises went away!!

I won't be firing it up again until it's fully built so headlight will be installed & operational at that stage & I suspect that the added load will bring the charging voltage down into the 14.5 range.

With these comments reinforcing my own thoughts I think I'll leave it as is till fully built & then take some new measurements at that stage.

Dan :)
 
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salty_monk said:
Earl - thanks for the feedback - I know it's too high. The bike is in pieces, the measurements were done when I fired it up after some clutch work before I tore it down again.. just wanted to make sure the nasty noises went away!!

I won't be firing it up again until it's fully built so headlight will be installed & operational at that stage & I suspect that the added load will bring the charging voltage down into the 14.5 range.

With these comments reinforcing my own thoughts I think I'll leave it as is till fully built & then take some new measurements at that stage.

Dan :)
Click to expand...


Good! High voltage drastically shortens the life of electrical/electronic components.

Earl
 
earlfor said:
Good! High voltage drastically shortens the life of electrical/electronic components.

Earl
Click to expand...
Yep, in technical terms, it increases the pressure of the smoke trapped in those little thingies on all those boards.
Too much pressure and they go BANG. :eek:

:D

.
 
Steve said:
Yep, in technical terms, it increases the pressure of the smoke trapped in those little thingies on all those boards.
Too much pressure and they go BANG. :eek:

:D

.
Click to expand...
I thought releasing the smoke was a good thing. Kinda like a good lay.
 
Voltage does not charge a battery.
Amperage does.
these bikes we all have from the 80's and 70's do not charge their own battery- they are designed to cover the loads only

so you have 15.5 volts WITH OUT the headlight. You have to know the second biggest load on the motorcycle electrical system is the headlight and it is disconnected during your test. so you are creating your own problem here. hence why there is 1 leg of the 3 phase stator shut off when the headlight is shut off on certain gs models. overriding this detail will result in excessive E.M.F. being created when that much electricity is not required . the permanent magnet charging system makes it's total potential (amperage) and what is not needed is gated off to ground. this balance is set from the factory and if you have all 3 legs of the dynamo charging at max rate and the 2nd biggest load disconnected you are messing with the factory set balance.

every wet lead acid battery will vent out the tube, it is natural. over filled or under filled it will always have a certain amount of fluid loss. some bikes a lot some bikes a little.

test the diodes forward and reverse bias in the regulator rectifier
test the total amperage draw and total amperage charge rate to determine the break even rpm speed.

you can just put a switch on 1 leg of the 3 A.C. leads going to the reg/rct when not using the headlight. or use the headlight at all times to keep the system balanced.

to look at wattage consumption is not as good as looking at the amperage draw:
the light uses 4~7 D.C.A.= 2~3 D.C.V. which will have you between 12~13 D.C.V. at the battery if the light is on.
 
trippivot said:
Voltage does not charge a battery.
Amperage does.

.
Click to expand...

Correct, strictly speaking, current is required to charge (current is the flow of charge) , but you can not charge without exceeding the terminal voltage of the battery. So a voltage in excess of 13V is typically required for any meaningful charging.


trippivot said:
these bikes we all have from the 80's and 70's do not charge their own battery- they are designed to cover the loads only
Click to expand...

That is partially true, the charging systems certainly have to provide power to the vehicle system. The fact that they are designed to provide 14-15.5 volts at the battery at 4000 RPM means they will also charge a battery. I presume this was by design and not an accident. This would tend to contradict your unequivocal statement
 
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