1983 XS650 Wildly overcharging battery

[zbillz]

Hi,

My son purchased a 1983 XS650. Bike has been converted to cafe style.
Bike is fairly clean and looks like it was built pretty well.
Electric start has been removed. Had a small form factor Lithium battery under the seat, (Anti Gravity 401 Battery)
Battery was very low and would not even turn on the head lights. Bike would kick start/run with jumper pack.
I bought a small sealed lead acid battery, installed and the bike started and ran fine.
Checked the battery after the ride and it was hot to the touch.
Tested voltage at battery terminals while running and its getting 19 volts.
Disconnected battery with the bike running and tested wires, DC voltage through the roof. Increased as RPM's increased.

Guessing the regulator is bad but since nothing is stock, not sure where to start?
Is that ignition unit pictured below a stock piece? There is a little corrosion on the circuit board inside, could this be causing the overcharging?

Any ideas on where to start checking would be appreciated.

Thanks!!

 

[gggGary]

Need to see inside the LH crank cover (what alternator is in there), then we can start making guesses.
If you are still using the TCI pictured it's prolly an original late model alternator.

#1 cheap import regulators tend to fail in full charge mode.
#2 wiring and or regulator is not correct for the type of alternator installed.

 

[gggGary]

The wire from the brush to the regulator being grounded somewhere would be one fairly common issue.

 

[zbillz]

Thanks Gary,
All the wiring seems new and protected in fabric cover. Must be an aftermarket harness?
Could the corrosion inside the TCI be the culprit? Must have got wet at some point.

 

[650Skull]

The TCI is ignition and advance. Not likely to cause charging issues. When the box goes bad the bike cuts out or can stutter.
gggGary pointed out aftermarket SSReg/rect can b problematic causing overcharging problems.

Your is an aftermarket one.

 

[Its been a long time]

The TCI is ignition and advance. Not likely to cause charging issues. When the box goes bad the bike cuts out or can stutter.
gggGary pointed out aftermarket SSReg/rect can b problematic causing overcharging problems.

Your is an aftermarket one.

And may not even be the right type of regulator?

For the benefit of the OP, the XS650 has a field excited alternator. Need to identify the combined reg/rec to make sure it is actually the right type of rectifier/regulator for a >1980 charging system.

Sounds to me like there's unregulated 12v on the rotor. Alternator output will not be regulated.

 

[Wagner73]

And may not even be the right type of regulator?

For the benefit of the OP, the XS650 has a field excited alternator. Need to identify the combined reg/rec to make sure it is actually the right type of rectifier/regulator for a >1980 charging system.

Sounds to me like there's unregulated 12v on the rotor. Alternator output will not be regulated.

Yes! As the bike has a TCI, it would take a Type 'A' regulator. Throughout many threads on this forum, the typically available combined reg/rec units are often the culprits of a charging system that is not working or is off the rails. In other words, not a great solution.

Check out this thread for a great solution that many on here have used.

https://www.xs650.com/threads/diy-reg-rec-5twins-and-jim.55842/

 

[zbillz]

Thanks Wagner, will check that out.

It looks like the wiring harness is a kit. All the connections to the handlebars, turn signals, head lights and regulator are in the same type of loom.
If unregulated power is going directly to the battery terminals, would that mean unregulated power is getting to the head lights and turn signals? (All LED)
I didn't notice the head light getting brighter as RPM's increased when I was running the bike without the battery.
Will have to test voltage at headlights later.
Will check for part number on regulator also.

 

[Wagner73]

Thanks Wagner, will check that out.

It looks like the wiring harness is a kit. All the connections to the handlebars, turn signals, head lights and regulator are in the same type of loom.
If unregulated power is going directly to the battery terminals, would that mean unregulated power is getting to the head lights and turn signals? (All LED)
I didn't notice the head light getting brighter as RPM's increased when I was running the bike without the battery.
Will have to test voltage at headlights later.
Will check for part number on regulator also.

If the charging system is running essentially unregulated, then yes, the over voltage condition will travel all thru the bike to everything.

Strongly suggest you either replace the combined reg/rec with a known good unit (?), or take a look at the referenced thread and convert. It may look a little daunting, but it's really not, it's easy to follow, and it works.

 

[Its been a long time]

If the charging system is running essentially unregulated, then yes, the over voltage condition will travel all thru the bike to everything.

Strongly suggest you either replace the combined reg/rec with a known good unit (?), or take a look at the referenced thread and convert. It may look a little daunting, but it's really not, it's easy to follow, and it works.

Agreed ^^^^^^.

 

[zbillz]

Before I attempt the conversion, I woukd like to try replacing this. No part numbers on the unit, any ideas where to find the replacement? I see a bunch on Mike's but not sure which one?
Seems like this just started happening after i installed the small SLA battery. When the lithium battery was in, i had metered battery while running and it was at 14 volts.

 

[5twins]

That's your combined aftermarket reg/rec, and as we told you, they're junk. Don't buy another. You're better off with a used original or get the automotive reg from the link provided.

 

[Raymond]

Well, I run a Fiat solid state regulator like this





It was cheap and has given no problems in six years. And the bike is still running the solid state rectifier the PO fitted.

Some of the cheap Chinesium ones will fail but then again they're cheap to replace again.

 

[Its been a long time]

Yes, the Chinesium rectifier I'm using was £4 (~$6). So far it's working fine.

 

[gggGary]

If you can find a mosfet reg/rec for a ground side control excited field alternator and KNOW the harness wiring is correct that'd work but good one's are in the $100 dollar neighborhood. Can't figure out charging for lack of a bit of patience is one of the prime drivers of ran when parked XS bargain bikes.
Then again just needs a battery is one of the most common seller's lies ...

 

[Its been a long time]

If you can find a mosfet reg/rec for a ground side control excited field alternator and KNOW the harness wiring is correct that'd work but good one's are in the $100 dollar neighborhood. Can't figure out charging for lack of a bit of patience is one of the prime drivers of ran when parked XS bargain bikes.
Then again just needs a battery is one of the most common seller's lies ...

They exist?

 

[gggGary]

They exist?

I think so but I'm to cheap to buy one...... The aftermarket combined reg rec in madness has been on duty for decades, now taking care of a lithium battery and going strong. But it was aboard when I got her....

 

[Its been a long time]

I think so but I'm to cheap to buy one...... The aftermarket combined reg rec in madness has been on duty for decades, now taking care of a lithium battery and going strong. But it was aboard when I got her....

I thought (maybe incorrectly) that real (as opposed to fake) MOSFET reg/recs were only to be found on PMA systems. The market for such devices on field excited charging systems must be tiny. Old Guzzis and BMWs mostly? I might be wrong, I don't know.

As always, it's best to read the excellent threads in the technical section to build a cheap and reliable rectifier and regulator system.
(The system I put together on my 650D was about $25 to build).

 

[gggGary]

The wiring mess on madness. Don't knock it too much, it's been on duty a long time


A 79 spII I'm rehabbing. Remove the wires from the 6 pin connector block on the main harness, clip the terminals on the rectifier a bit to fit the harness spades and Bob's your uncle. Back left terminal has been clipped.

 

[Wagner73]

I thought (maybe incorrectly) that real (as opposed to fake) MOSFET reg/recs were only to be found on PMA systems. The market for such devices on field excited charging systems must be tiny. Old Guzzis and BMWs mostly? I might be wrong, I don't know.

As always, it's best to read the excellent threads in the technical section to build a cheap and reliable rectifier and regulator system.
(The system I put together on my 650D was about $25 to build).

High quality MOS/FET shunt and series R/R's (Shindengen) are easily available for PMAs albeit a bit pricey. I've never seen a comparable version for excited field but that would be great it they existed. Even one of the biggest proponents of high quality R/R's (Jack Fleming - Roadstercycle) shows an automotive 2-component solution like the "XS650.com standard" on his website.