Ducati 450 Scrambler Voltage regulator question

[450jupiter]

Hi, I have a '69 450 Ducati Scrambler (Jupiter) that I have owned since I was 15 (1975). Finally completed a full restoration of this bike and was out riding today (steady rpm over 5000 for 20 minutes) and when I got home (fortunately!) the bike died. I noticed a bunch of battery acid leaking out. Upon removal of the battery, I noticed two of the cells had lost some acid probably from getting hot (over charging)? I suspect the voltage regulator is faulty. After trying to charge the battery (it does not hold charge well once key turned on), I started it and noticed that with a volt meter on battery, I could get battery voltage up to over 8 volts. I am thinking that this might be too high? Are these regulators tough to rebuild/find parts for?
Thanks for any input. Erik W.

[450jupiter]

Here's a few pictures of the bike. I also am including a picture of the bike as I got it in '75 missing correct headlight, fenders, correct taillight, correct exhaust, stock rear shocks, amongst other things.
Erik

[DewCatTea-Bob]

[quote= 450jupiter ...
" was out riding today (steady rpm over 5000
and when I got home
I noticed a bunch of battery acid leaking out. "

____ That's a fairly common-problem due-to vibration !
Ya really need to secure-mount the battery by some improved means to better isolate it from it's frame-mounting.
What-all do you currently have for mounting your battery in place ?



" I noticed two of the cells had lost some acid probably from getting hot (over charging)? "

____ The stock-type of battery with breather-caps, allow the battery-fluid to get expelled-out through the breather-holes in the caps !! _ And that's due-to not-only engine-vibration, but also rough road-surface handling.
__ Anyhow,, even if the rect/reg.unit performed straight/full rectification with no regulation, the stock charging-system isn't powerful enough to be capable of overheating the (stock sized) battery in such a short time (under 2-hours), (unless possibly, perhaps if the installed battery is merely a very-small 6v.model).
Even if overcharging could possibly lead-to overheating of the battery, it would take at-least 4-hours for a (relatively)- very-hot battery to vaporize & expel sufficient battery-fluid to lower it's fluid-level enough to be obviously noticeable.
So you can be-sure, that 'leakage' is the sure cause of your lost "acid" issue, (and not evaporation).



" I suspect the voltage regulator is faulty. "

____ The w-c.type r/r.units do go-bad fairly easily,, BUT when they malfunction, they either provide much reduced charging-power or don't allow any charging at-all !



" I started it and noticed that with a volt meter on battery, I could get battery voltage up to over 8 volts. "

____ That indicates that your r/r.unit is still working.



" I am thinking that this might be too high?
After trying to charge the battery (it does not hold charge well once key turned on) "

____ A half-volt too high perhaps, but not significantly so.
__ Maybe your battery is no-longer absorbing as much power-juice as it's supposed-to. _ Have you checked it's s.gravity according-to spec ?



" Are these regulators tough to rebuild/find parts for? "

____ It's rectifiers can be replaced, but yours don't seem to be bad.
It's particular regulator-component/circuitry however, is surely something ya wouldn't be able to order !
__ But not to be too concerned with though, as there's another simple & cheaper (and more reliable) method to regulate system-power !
But since this is not a real concern for YOU now, I'll elaborate on this later.


Hopeful-Cheers,
-Bob

[450jupiter]

Hi Bob
Thanks for the reply. I had initially speculated that the battery housing cracked due to vibration or perhaps I had it tightened down too hard. I have the rubber battery carrier on the bottom and original style strap that hold the battery down. It is the thin, wide band that hooks in front and is tightened with a wingnut from down below. I have never had this problem before with batteries and you are right this beast vibrates like mad.
I suspect that something happened internally to the battery if the voltage regulator is not to blame as it does not hold charge now. The battery was a new Bikemaster B38-6A. It has push in plugs at the top and a vent that comes out of the side. They were all secure after removing the battery. I am wondering if the thing short circuited somehow. I am getting a new one and hopefully this does not happen again. Thanks again for the comments, they were very helpful. Erik

[ducwiz]

Erik,

under http://i.minus.com/ibepAKwCOCJ4eh.jpg you can download an instruction as well as a circuit scheme how to test the regulator.

.. Hans

[DewCatTea-Bob]

[quote= 450jupiter ...
" I have the rubber battery carrier on the bottom and original style strap that hold the battery down. It is the thin, wide band that hooks in front and is tightened with a wingnut from down below. "

____ Later w-c.models came updated with a rubber-strap rather than that metal-band, but that update didn't much help the shook-battery problem. _ The main-issue with the metal-strap, is rust-corrosion mostly due-to close proximity to battery-leakage. _ I've seen many,many strap-threads so corroded that the band would rather twist & bust instead if it's retainer-nut coming loose. _ So if you wish to save yours, then better clean it well with baking-soda or the like.



" I have never had this problem before with batteries "

____ It's not such a common occurrence with batteries which have smaller/lighter plates, but still it's unfortunate that a great number of the stock-size batteries aren't up-to holding-up & sooner or later give-in to vibration-damage.
Such is indeed a common-problem though,, so while this may be your first encounter with such, it likely won't be your last.



" and you are right this beast vibrates like mad. "

____ The shaken-battery syndrome is only a problem on 250-models which have loose motor-mounts, and-so that contributing force could make your 450 an even greater battery-destroyer ! _ So if your motor-mounts aren't as tight as they ought be, then that's quite likely the main-cause for your battery to have shook-apart.
So check your motor-mount bolts to be sure they are all good-&-tight.



" I suspect that something happened internally to the battery if the voltage regulator is not to blame as it does not hold charge now. The battery was a new Bikemaster B38-6A.
I am wondering if the thing short circuited somehow. "

____ The B38-6A size 6v.battery is the type that if it's not robustly constructed by it's manufacturer, will commonly get shaken-apart internally. _ And that damage leads to internal short-circuits and/or open-circuits.



" It has push in plugs at the top and a vent that comes out of the side. "

____ That's a nice updated feature which helps keep the leaked acid from getting all-over things (above the vent/spout-outlet), but of-course the battery-fluid can still get expelled-out (along-with gasses, due-to the shaking combined with internal-pressure [due-to normal charging-process] ).



" I am getting a new one and hopefully this does not happen again. "

____ If you change nothing else and you get your replacement-battery from the same manufacturer, then you can pretty-much expect a fairly identical repeat of the very-same experience.
__ I'd suggest trying a smaller battery (with internal-plates that are less venerable to being hard-shaken),, and more extensive rubber mounting, or anything else which may help isolate your battery from the destructive vibration.
The rather large stock-size battery has advantages, such as maintaining system-voltage for more extended low-RPM riding with head-light left on,, but if your ratio of low-RPM to higher-RPM riding is-not an issue (and is rather over 4000-RPM average), then a smaller battery would be fairly suitable for you (to help get isolated from vibration).


Hopeful-Cheers,
-Bob

[450jupiter]

Hi Bob
What battery do you recommend on the 450 single? I used to use a YUASA one long ago. They seem to be getting harder to find. Erik

[DewCatTea-Bob]

[quote= 450jupiter ...
" What battery do you recommend on the 450 single? "

____ I've been out-of-the-loop too long to have any idea as to what's best these-days.
If you were looking for a 12v.battery, then I'd suggest the std.battery made for early '70s Yamaha 250/350-twins.
I guess I'd suggest looking on eBay* for a modern sealed-type battery of some suitable size which could either easily fit onto the battery-tray or could possibly be hung/suspended above the tray (so as to be more isolated from vibrations). _ (* http://www.ebay.com/sch/i.html?_trksid= ... &_from=R40 .)
__ I'm sure we must have someone here amongst us who can steer you better, towards a battery which doesn't suffer from the same-old battery-problems we've always had to deal-with in decades past.
Here's what Jim-himself has posted on this-topic most recently... viewtopic.php?f=3&t=1566#p11455
__ Let us know what bat.models you may consider, before actually purchasing your next battery.


Hopeful-Cheers,
-Bob

[graeme]

Hello Erik,
I use Yuasa sealed lead acid batteries in 3 different 450's and haven't had any problems.
I make a battery tray from high density foam. The type that is used on race bike seats.
Then tie them down with cable ties but not too tight. Works for me.
You could ask you local battery seller for advice.

Graeme

[ducwiz]

Greame,

I agree with you. I used a Yuasa 12N5.5A-3B (12V, 5.5Ah) on my 350 Desmo, after installing a self-made 12V conversion circuit into the R-R.
It features roughly the same base area as the original 6V battery, but is smaller in height, hence needing a shortened mounting strap. To isolate it from the engine's severe vibrations, a cushioning base plate or tray is essential.

cheers Hans