[Ducati] batteries

[Allen B. Judy]

Robert asked..
challenged and unable to find a listing for batteries suited to a Vintage 
Single, who can tell me how to select a battery?  My bike has an updated 
12-volt system using traditional points (stock was 6V).

Stuart replied:
Depending on how original you want to keep the bike, I would be tempted to 
keep it simple and do without the battery.  The horn will be a problem 
though.  If you do want to run a battery, capacity is not important as the 
bike is kick start and has no computer.  So the only real consideration is 
the physical size.  Look for one that fits the space on the bike and has the 
right kind of terminals in the right places.
As far as the type goes, I'm old fashioned and would stick to the 
traditional flooded sort.  Having said that, I must admit I run AGM 
batteries in my truck and boat with good results.  My only adventure on my 
bike was an AGM on my Elefant that lasted less than a year.  I'm sticking to 
Yuasa flooded for now.

Then Rich said:
Robert...best suggestion is to find the 12 volt battery with the greatest
amount of amperage-hour rating available...that fits in the tray.   Having
changed to 12 volt  has not actually increased the output of the system
as it is basically limited to what the charging system can provide to
recharge the battery.  The lights are the biggest draw on the battery and
therefore the greater amp-hour rating you can find means the greater reserve
you have in the battery itself before the marginal ( IE low output in
watts/amps) charging system has to begin working itself to death.
The standard battery in 6 volt was a B38-6a and came with 18AH rating...
they were 4 1/2" long  3 1/2" wide and 6 1/2" tall.     I do not think there
is a standard 12 volt that match that exact dimension..so you'll be faced
with some bit of retrofit.    You then have the choice of newer sealed high
density types which will perform well but have a modern look.
I'd just do a web search for batteries and choose a place near where you may
live...you'll probably find something cheap at a Wal mart type store...  to
something insanely expensive for the modern compact types.

And now I chime in with:

Robert:
I agree with both Stuart and Rich.  Depends on how "stock" you want to keep 
the bike and what you want to use it for.  If you have already changed the 
bike from a 6V to 12V system it is already non-stock.
One question I have is what 12V alternator/magneto did you use to replace 
the 6V system?  Have thought about doing the same on my 450 scrambler but 
have not found a way to do it.
For street riding I would keep the battery.  Keeps the headlights bright and 
keeps the bike from stalling out at stop lights.  I am also of the school of 
the "bigger the better" when it comes to batteries.  I replaced the original 
in my 450 with the largest one (with the highest amp/hr rating) that would 
fit in the tray with good results.  If it is any help, here is a link to a 
chart from Interstate batteries that lists both 6V and 12V motorcycle 
batteries that they sell with their part numbers, physical dimensions and 
amp/hr ratings.
http://www.ibsa.com/www_2001/content/products/product_motor_con.asp
I think that their part numbers are pretty industry standard, but if not, 
I'm sure that they can be cross referenced.
Have you thought that maybe your brake light stalling problem my not be your 
battery but maybe a short somewhere?  Easy to find out with an Ohm meter.
Good luck and let us know how it turns out.

Al Judy