1. Dismiss Notice
  2. Hey Facebook people... We've created a group for XS650.com members to connect. Check it out!
    Dismiss Notice

Overcharging issues that just won't quit!

Discussion in 'The Garage' started by Naturalsystem, Sep 11, 2020.

  1. I've been having an issue with my charging system for some time now, I will try to explain as succinctly as possible as there have been a few changes etc along the way.

    I bought this bike relatively stock and only changed out the regulator and rectifier from mechanical ones as I was riding once and the rectifier pins snapped off inside it (unrepairable).

    As I've been building my bike during the pandemic this year, I decided to go with a lithium battery, an 8 cell antigravity, as I wanted to save space when I installed the hardtail on the bike. Admittedly, I was disappointed with it at first as it didn't seem to fix my problems... which actually turned to be my coils (replaced with two bigger green coils and new points).

    To preface, my bike at this stage has:
    • Stock points
    • Stock charging system
    • Reg/rec combo purchased from Geoff's XS in Sydney (which seems to be a mike's xs one or copy)
    • Antigravity Lithium Battery (8 cell)
    • Kick only
    • No starter or safety relays
    • Twin headlights + Tail light
    • No indicators
    • No horn
    • No gauges

    So after completing the build and before paint, I set off for a ride in the evening and about 3km's into the ride, I heard a pop and I could smell a sickly sweet smell. I pulled over and the bike was idling fine, so I thought it was maybe something in the area omitting the smell and continued on. Not 1km after pulling the bike died and I could see smoke pouring out of the battery box. Lithium battery had exploded.

    (fun tip, make sure you clean fire extinguisher powder off bare metal straight away, it's highly corrosive)

    After that gigantic headache, I tried a small 7Ah battery (Generic $30 one from eBay) with roughly the same footprint, rode around for a while and was fine for about a month.... then it exploded too. I figured maybe I had just had some seriously bad luck and because it was a battery I had laying around... I chalked it up to that.

    So, next battery (#3 at this point). Purchased a SSB Lithium Powersport Battery (LFP14H-BS)
    Now this is where I get a little iffy on my battery choice.
    The specs don't exactly match up when comparing the website and the battery itself (battery has 160CCA on it where the website is 290CCA).
    What concerns me is the max charging (15 Amps).
    This lasted all of one ride... yep.
    Same symptoms, pop and sickly sweet smell followed by the lithium smoke....

    Here are the tests I've conducted:
    Tested the rotor, it’s within spec and I’m happy with the results (5.3ohms) and the brushes are within spec too and look nice.
    I cleaned all surfaces too.
    That rules that out being an issue or even collateral damage.

    Next, I’ve tried to measure the brushes in relation to the regulator. I have a 70-79 charging system, so black and green wires. I get continuity between the black and green with everything plugged in. I also checked that on the brushes and they do same.
    I measure 5ohms between the brushes / green and black.

    I measured the white wires from the stator, all measure 0.5ohms against each other, which seems to be within spec.

    At this point, I'm a little lost. I've read so much in the past few months about this charging system that I'm not entirely sure what to believe. So many people say that the stock system is not cut out for a lithium. I've seen PamcoPete say it is if installed with a solid state regulator. Hell I've even seen Reg/rec combo units specifically made for lithium batteries and xs650s.
    I would really appreciate some help and direction as frankly, I cannot afford to blow up another battery hahaha!

    Thanks in advance guys,
    Paul Sutton likes this.
  2. XSLeo

    XSLeo XS650 Guru Top Contributor

    With a battery hooked up have you used a meter to check the charge voltage?
    That's really the only way to know for sure how it's charging. If the reg/rec you have came from Mike's the install directions were probably wrong. They send the directions for the 80 up bikes.
    It's possible the way it's wired is sending unregulated power to your battery.
    I thought I had the proper install instructions to install one of Mike's reg/rec to the early bikes on my computer. I just can't seem to find them.
    I'm sure someone on here has them. Perhaps they will read this thread and post them up.
    The alternator on these bikes when unregulated can reach over 20 volts. That's what's cooking your batteries. For testing purposes you can hook most any 12 volt battery to your bike. A car battery even. If you hook to the one in a car don't have the car running.
    Once you determine what is actually going on then you can figure out just what you need to do to fix it.
    I did find a wiring guide I had written out on paper.
    Mike's reg/rec-----------------------Your bike
    3 yellow wires-----------------------3 white
    Red wire------------------------------red wire
    Green wire---------------------------Black wire
    Orange wire-------------------------Green wire
    Blue wire-----------------------------Brown wire
    Ground the case.
    On your bike the green, brown and black were in a plug te regulator plugged into. The others were found in te plug the rectifier plugged into.
    Paul Sutton likes this.
  3. Hey Leo!
    Thanks for the reply.
    I hooked up a spare 12v motorcycle battery and fired the bike up albeit wasn't it's normal one kick.
    Strangely, the battery initially read 13.5v and then dropped to 12.6v after a few slight revs.
    The bike also was back firing as I revved it, which it never does usually.
    As the bike idled, It stayed around 12.6v, so I decided to increase the revs slowly and no change.
    I shut the bike off and watched the battery drain, with the key out. 12.2....12.19.....12.18 Something is going on here.
    I decided I'd meter the green wire connected to brush with the key on, no voltage. I assumed this was supposed to get 12v with key on? Or is it 12v while running?

    The reg/rec is actually not colour coded like the mike's one.
    It's the same as my bike: green, brown, black, triple white and red.
    I assumed those would just correlate with the same ones on my bike....
  4. XSLeo

    XSLeo XS650 Guru Top Contributor

    On the stock system when you turn on the key power flows to the regulator on the brown wire. The reg reads the voltage on the brown wire, If below the preset voltage of about 14.2 volts the reg sends full battery voltage to the brush on the green wire. This voltage flows through the rotor and out on the other brush. This brush has the black wire. It grounds to the stator housing through the mounting screws. The black wire runs up to the harness ground.
    Once the bike starts the voltage will still be low. As you slowly increase engine rpms the battery voltage will increase. At about 1800 to 2000 rpms the voltage will reach the preset voltage. Once it reaches the preset voltage the reg shuts off the power flow on the green wire. This stops the charging till it drops below the preset then sends power on the green wire. It repeats this cycle hundreds of time per minute to hold the battery voltage at the preset voltage.
    As you further increase rpms the voltage should never go over the preset of 14.2 volts.
    The solid state regulators work the same way but cycle at a much faster rate. Perhaps thousands of time per minute. I don't know for sure but much faster than the old mechanical unit did.
    This provides a smoother voltage. On the stock battery this isn't an issue. On the Lithium batteries They require more specific charge voltages. To much and they blow up. I had one do it. I went back to a AGM battery in the stock size.
    At idle getting around 12.5 or so is ok. It's what happens at the high voltages that matters.
    Your spare battery, was it fully charged when you hooked it up to your bike? If not that can cause issues on charging.
    I might suggest you contact Geoffe's and see what he has for advice.
    Paul Sutton likes this.
  5. Hey Leo,

    I understand how the rectifier and regulator work, it's actually a pretty cool system for something on an old bike!
    Spare battery was sitting around 11.8v before I hooked it up (have it on tender now)

    What I'm still not sure about is the continuity between the brushes...
    I get continuity between both brushes and continuity to ground, no matter which way I measure them.... That's with all the harness unplugged.

    With Key Off I had:
    0.02v drain on the green wire (which is subsequently being grounded somehow)
    0.02v between battery negative and ground

    I feel like I'm over thinking the brush thing, but the parasitic drain has me scratching my head.
    Last edited: Sep 11, 2020
  6. I couldn't help myself... that continuity thing was bugging me but I think I made sense of that in my head.
    The Rotor is a coil and each copper ring are the ends of the coil... duh haha

    Here are some further tests:
    • Key Off 12.22V at battery
    • Drops to 12V with key on
    • Brown ignition wire with key on measures at 10.55v and starts to drop
    With ignition on I have very dim headlights, but accessories on, headlights are nice and bright, which makes sense as the ignition system isn't being utilised.
    I feel like this is another piece to the puzzle.

    This makes me wonder, is it possible that I have such a big drain / load on the ignition system somewhere that it's in turn asking too much from the charging system and overcharging the batteries? That seems like a stretch but I'm just thinking 'out loud' here.


    Didn't want to make another post - I metered the brown wire (at the ignition switch) for voltage drop between the coils connected to the regulator and without.
    Without them connected, there is no drop and the regulator / ignition switch matches the battery voltage.
    With them connected, huge drop....
    Last edited: Sep 11, 2020
  7. Just for posterity I've included the wiring diagram I am using.
    I've continued testing today, still getting interesting results.
    I've now decided to use a known, good working car battery for testing purposes.

    If Stator plug and Points are unplugged, I get no voltage drop with Key On. If either or both are connected, my battery starts draining quite quickly.
    I anticipate some drain, but it feels a little too quick.

    When Key On and the stator and points are plugged in, I measure 1V on all my grounds.
    When I the points I get 0.6V on ground and then 0V on ground when stator is unplugged in as well.

    I've re checked all my wiring, I've even rewired some connections with solder that were originally crimped.

    I am now starting to pull my hair out haha

    Attached Files:

  8. According to the pictures on Geoff's XS site, you have the regulator for an 80-84 bike.

    The 70-79 regulator has the wire colors Leo called out:


    gggGary and Paul Sutton like this.
  9. My regulator has a totally different body than that and the wires that correspond with the original harness.
    It also came with two plugs like the 70-79 pictured, just not with those coloured wires.

    Mine looks identical to this one here.

    Just as an aside... I think it's strange that Mike's XS (as well as "Geoff's XS" where I purchased the reg/rec from) use a 1981 "wiring diagram" for the 1970-79 Reg/Rec unit.
    Last edited: Sep 13, 2020
    gggGary likes this.
  10. I hate it when businesses don't keep their websites up to date. Carry on..
    gggGary likes this.
  11. Without derailing my investigation into this issue haha, I don't think it's a matter of keeping their websites up to date as they've probably never been correct in the beginning; aligns with their narrative.
    I think it's laziness and poor attention to detail. I daresay that those instructions were put there so they could say "there are instructions online".
    Imagine how many emails they might receive due to that discrepancy.

    Gotta keep testing
  12. Some further results from this morning's testing:
    • Slap test is fine - can hold a screwdriver or spanner to it and it pulls it in quickly.
    • Stator resistance wires against housing are infinite.
    • Double checked stator wires against each other, still 0.5ohms.
    • With everything plugged in and measuring the voltage, the voltage drops quickly. I also don't get the full battery voltage at the positive brush terminal on the stator (about 10.5v compared to 12v at the battery). Interestingly enough, I also get 0.4v on ground.
    • If I unplug the stator, no voltage drop. No voltage present on ground.
    • If I remove the stator housing but keep the stator plugged in, no voltage drop. no voltage on ground. I get full battery voltage at the positive brush terminal.
    At this point, I can't tell if the reg/rec combo has killed these batteries or there is something I'm missing in the charging system.
    After pouring over threads on this site, I've found one that is similar in nature to mine but it didn't seem to have a resolution.
    It can be found here.

    Any direction or ideas at this point would be greatly appreciated!
  13. 5twins

    5twins XS650 Guru Top Contributor

    Honestly, I don't have much faith in those aftermarket combined reg/rec units. There's thread after thread on the site here about problems with them. Price is very high and it seems the quality is very low. I'd go with the proven low cost upgrade, an automotive regulator and a rectifier from the electronics world.
    Jan_P and Naturalsystem like this.
  14. 5twins, I appreciate the reply, but I don't really want to throw more money at anything before I understand what's wrong!
    I'm happy to build the regulator and rectifier setup, but it's the principle. I also wonder if the "DIY" reg/rec is applicable to lithium batteries...
  15. *Mac must have deleted his question*
    The headlights are switched and are a pair of 21W bulbs. They are always off when starting.
    I've decided I'm going to replace the regulator and rectifier as I don't think my issue comes from stator or rotor.

    The "DIY" setup that is mentioned all through the forum is actually pretty expensive to do in Australia... Those VR794 (VR170 apparently on eBay) and VR115 regulators are about $80AUD including shipping, not to mention the rectifier being approximately $25AUD.
    So at that point, I'm at $100AUD and probably a month's wait time to receive a regulator from the US... was really hoping to find a local solution.

    At this point, I'm also considering the reg/rec offered from TC Bros. and the one from Rick's Motorsport Electrics.
    The good thing about the Rick's one is that it has a lower voltage set point, apparently ideal for lithium batteries... which I would like to run due to the size restriction in my battery box.

    One final question, can someone confirm that, when their regulator is unplugged, they have continuity between their brown and green wires on their reg?
    When I checked earlier, I did.
  16. 650Skull

    650Skull SSSSSSSSSlither Top Contributor

    Naturalsystem likes this.
  17. Alright you've twisted my arm!
    I've attached the Wiring Diagram to reflect the addition of the Bosch RE55 just for those playing at home.
    I'm also going to order this rectifier. Hopefully have it back on the road by the end of the week providing all the parts come together.

    And just to clarify, this setup being for a Type B, I don't need nylon screws or to rewire the brushes?

    Thank you skull!

    Attached Files:

  18. 650Skull

    650Skull SSSSSSSSSlither Top Contributor

    RE55 is for a points model, B type.............no nylon screws...........
    Rasputin likes this.
  19. Just as I thought!
    Excited to get to the bottom of this haha
    Will report back with info as soon as I get the parts in.
  20. 650Skull

    650Skull SSSSSSSSSlither Top Contributor

Share This Page