Is this common prioblem with charging systems..

[gs11ezrydr]

Been working on a 85 GS 1150 It charges 14.6-.8 at idle then when revving the engine to approx 4500 r.p.m's it drops to about 13.8 or so. Over a volt loss....I've cleaned all connections, grounds etc.Could just high resistance in these old wires cause the problem.I searched the site some..Thanks..

[Brendan W]

You could measure the voltage drops on the pos and neg lines between the R/R output and the battery.
There will be some resistance and as the charging current increases the voltage drop will increase.
Ideally a tenth of a Volt at 5000 rpm between the R/R positive and the battery positive and between the R/R ground wire and the battery neg.

[gs11ezrydr]

You could measure the voltage drops on the pos and neg lines between the R/R output and the battery.
There will be some resistance and as the charging current increases the voltage drop will increase.
Ideally a tenth of a Volt at 5000 rpm between the R/R positive and the battery positive and between the R/R ground wire and the battery neg.

A tenth...Thanks for the info..I will start some voltage drop test between components..I grounded the R/R directly to the battery..and frame..Thanks again

[phydeauxmutt]

13.8 at idle is not bad at all. It's not a volt "loss", it just hasn't been generated. Our crude permanent-magnet alternators simply generate as much as they can, all the time. At lower engine speeds, it simply does not generate full voltage, but 13.8 volts is still charging the battery, so don't worry about it.

[gs11ezrydr]

13.8 at idle is not bad at all. It's not a volt "loss", it just hasn't been generated. Our crude permanent-magnet alternators simply generate as much as they can, all the time. At lower engine speeds, it simply does not generate full voltage, but 13.8 volts is still charging the battery, so don't worry about it.

Thanks for the input..At idle it charges at about approx.14.6 -.8 then when revved up it drops to about 13.6 -.8 ..Still charging but about a volt loss between idle and revved up..That is what I was concerned about..Thanks again

[salty_monk]

That sounds like symptoms of a bad RR to me. It may just be a bad ground. Try running one direct from the RR to the battery & see if it changes anything. If not fit a Mosfet one. The SH775 series type is best as it protects the stator but the FH020 Shunt type are cheaper. I probably have one of those you can buy if you want it.

[gs11ezrydr]

That sounds like symptoms of a bad RR to me. It may just be a bad ground. Try running one direct from the RR to the battery & see if it changes anything. If not fit a Mosfet one. The SH775 series type is best as it protects the stator but the FH020 Shunt type are cheaper. I probably have one of those you can buy if you want it.

Ran all new grounds...Even straight to the battery..Thanks ..I suspect the R/R also..Still need to do resistance checks and voltage drops between components..Old wires...Replace as needed....Then I need a SH775...LOL...thanks again..

[bitzz]

Check the AC output of the stator
If the AC voltage doesn't drop with revs: You have a regulator problem
If the AC voltage does drop with revs: You have a stator problem

[gs11ezrydr]

Check the AC output of the stator
If the AC voltage doesn't drop with revs: You have a regulator problem
If the AC voltage does drop with revs: You have a stator problem

Wow never thought of that in a while..100% Thanks ...I think I'm getting a little old anymore..lol..Forgetting the basics..ty again...