The Knowledge - Velocette Owners Club

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L #991 Does any body know the size of the front holding down bolt on the dynamo strap mine is
1/4 o.d but I don’t know what thread.
#992 This bolt at the bottom of the strap is part number SL8 15 which is 1/4inch BSF x 7/16inch bolt.
The bolt at the top of the strap is SL9 22 which is a 1/4inch Whitworth x 13/16inch.
L #1253 Where in the USA to get the proper size 6v battery for my 1948 MAC (I brought home
from England/Beaulieu last year) It has the hard rubber battery box now. I'm not sure if the battery
replaces that or is meant to just go inside.
#1256 I have been told the hot setup is to: I) purchase a dummy battery box, then ii) insert into it a
sealed six volt conventional motorcycle battery. Having previously purchased an original-type
replacement with vented caps, I now also have the unpleasant experience wherein the escaping and
subsequently condensed vapors have corroded my nice, chrome battery strap. The dummy boxes can
be purchased from Groves in the U.K., or here in the States from Ed Gilkison. Others may have them
as well. Sealed 6 volt cells are easily obtained from almost any motorcycle dealer or accessory
provider.
#1258 You can get 6V rubber batteries that cost about $60 in the UK, but I wouldn't waste your time. If
you are running 6v, buy a 5ah sealed battery from www.burlen.co.uk . It's a fit and forget, the lights still
work even after a winter lay up, no need to charge during this period. However, you do have to fit it
inside a dummy case.
#1260 Just one thing to be aware of on this - would also recommend the 6V Burlen - but I have found it
a very tight fit in some of the dummy battery cases on the market. (Needed to cut part of the bottom out
of mine) - externally this doesn’t notice if you are careful. And it may not apply to all dummy cases. The
battery is well worth it though.
L #1759 I have a Miller dynamo transformed to 12V with electronic voltage regulator (don`t know
the maker..). I have a very small 12V battery inside that rubber case what Grove sold. Now the dynamo
popped and is completely dead. It worked well about 100 miles. Question: how big the battery has to
be, how many amperes that it takes all the charge and won`t cause any damage to other parts? I think
mine was too small, I don`t know it`s amperes but I can't risk to use it after dynamo repair if it possibly
breaks it again. There are obviously lots of other reasons why the dynamo breaks but this is my main
problem.
#1762 Sorry to hear about your problem with your dynamo. The size of the battery is not critical, but
bigger is better. In most cases, finding a battery small enough to fit inside the black rubber case will
limit you small lead-acid battery in the range of 3 - 5 amp/hours. This small size is OK. Your dynamo is
probably rated at 60 watts. A watt is a volt amp. When the dynamo was used as a 6 volt generator it
would produce 60 watts or 10 amps @ 6 volts (10x6=60). Now that it is being used with an electronics
converter, it still will only produce about 60 watts but at 12 volts or 60/12 = 5 amps. Batteries are
storage devices, like water tanks. You can not have them too big. A 5 amp, 12 volt battery will become
completely charged with your existing dynamo in 1 hour, if you do not run with the head light on, or use
any electricity. A 5 amp battery will light your headlight and tail light for about 1 1/2 hours with the
engine stopped. Common small lead acid batteries are best for this application, although, there are
some other forms of batteries that may work such as nickel hydride or nickel cadmium. Too small a
battery can be a problem.
What size and type battery did you use?
#1765 I agree, having a small battery shouldn't cause the generator to fail. I'm running on 12v with a 6v
generator and a small battery in a Grove box and have had no problems. The only downside is that you
need more revs before charging starts so if you were to ride in traffic all the time, particularly with lights
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