Get rid of your battery - if you have a kick starter

[Jordan]

I am impressed if a batteryless Ducati single can happily idle with a usable headlight turned on.
That is, with no surgery required to the stator (apart from not using the red wire).
Can this be reliably achieved without the idle speed needing to be set "rather high" ?
Could it possibly be that Ducati electrics are better than Lucas?

[Eldert]

my 350 scrambler has a 12 volt conversion and idles with the headlite on ( led bulbs )

i used a Boyer powerbox and a Vape electronic ignition sold by Wassell for a brit twin and single

took about half a day milling and turning to make it fit

Eldert

Wassell ignition 002.JPG

[mrkprsn]

The simplest explanation is to wire your bike just like the original (GT, Monza, Mach1) and just replace the battery with a capacitor like the link below. I definitely recommend a spring to hold it. That way you can mount it on top or underneath where the RR goes.

I am most surprised that Jim can start his bike with such a large capacitor. I use both a 10K uF and 15K uF (link below) capacitors and they both work fine at idle and open throttle. I recommend finding a capacitor that is 1.375 " in diameter so that a standard Lucas capacitor spring can be used for mounting.

https://www.ebay.com/itm/392117621176?i ... R5To79uRZA

s-l1600.jpg

https://www.digikey.com/en/products/det ... HV64qF3Wl0

NT 35mm SERIES.jpg

[DesmoDog]

I know just enough to be dangerous, so with a little surfing I came up with a number for the cap size I'd need. It's based on one post from another bike forum and a few assumptions on my part so it may or may not be based in reality.

Using the alternator wattage to guesstimate a cap size

IIRC the alternator on the 250 Monza was rated at 60W. First assumption - rule of thumb is we can use about 80% of that as our wattage demand.
60*0.8=48W

Converted to Amps, Watts/Voltage => 48/6 = 8A

So the capacitor needs to supply around 8 amps between peaks of alternator output. Assuming there are 4 magnets on the rotor (since there are 4 coils) and the engine gets kicked over at 400rpm(?) there would be 4*400 cycles per minute. 1600 cycles/minute => 27 cycles/second

Dividing 8A by 27hz => 0.3 Coulomb (Amps * Second)

A Farad is a Coulomb divided by the voltage

0.3/6 = 0.05 Farads = 50,000µF

Double the voltage rating just to be safe and you end up with 50,000µF 12v
This would seem to be a minimum and higher ratings wouldn't hurt. Change the wattage required to 100% and lower the rpm from kicking to 200 and you get 125,000µF

And again I have no real idea what I'm talking about so won't be offended by opposing views...

Here is a link to the thread I got the info from. With my very basic understanding of electrickery it seemed to make sense.
https://www.dotheton.com/index.php?thre ... ike.27645/

EDIT: I was typing when that last reply was posted...

[Jordan]

That's a brave attempt to arrive at the capacitance analytically, Craig!
However, the first designers of a capacitor type system (Lucas, for an AJS trials bike) reportedly chose 5,000 uF as being adequate.
I use 10,000 uF 25V or better.

[TimP]

This is a really interesting thread. I’m suffering the same overcharging symptoms as the OP; in my case on a mototrans 200 with a solid state RR at 12V

So far 4 batteries and 3x RR tried to solve the problem. Clearly I’m a slow learner and am missing something.

Whilst using a cap’ maybe an option, I’d be really interested in understanding what’s causing the problem in the first place ?

What’s causing the RR to appear to stop regulating to < 14.5v after about 30 min of use and fry the battery ?

The gen is putting out about 20v / 60Hz at idle and 60v 140 Hz and about 4000rpm - this now comes out of the RR at around 12.5v and 16v respectively.

The latest RR is a high quality mosfet unit rated at around 400w / 12v

Thanks for any ideas or advice.

[Jordan]

It is certainly a puzzle.
Maybe it's worth buying a cheap R-R and trying again.
Did I mention the garden tractor type you can get for pocket money?

[themoudie]

May I just add a cautionary word and couple of images?

I understand what you are trying to acheive, but just be aware that if you have an inappropriate Rectifier/Regulator (R/R) connected to your battery, or one that has failed, the images below demonstrate graphically what can happen to your battery!

You have produced either a firebomb, or a boiling acid bath. Be very careful, this was acheived on a 19888 Honda Bros 400 earlier this week on a 92 mile run and the sulphorous fumes were noticeable from 50m behind at 60mph! The bike eventually stopped "Dead", without major mishap and driven home in a "Naughty" van. On testing, the original, 100,000 + miles Honda R/R had failed, the MotoBatt battery failed having been cooked!

Good health, Bill

[mrkprsn]

I believe the modern RR's are not appropriate for our bikes if you are using a battery. My modern battery chargers (6v and 12v) charge at 7v and 14v respectively and when that voltage is achieved they drop to 6.5v and 13v. My modern 6v batteries say to charge to 7.1v and maintain at 6.6v.

I have two modern RR's. The Guzinno one charges at 7.5v and the Electrex on charges at 8.5v. This is way too high. Electrex said that 8.5v is correct and normal. I also had a second Electrex RR with a faulty diode and they would not honor the warranty. I would stay far away from that product and company.

I use a battery in my Sebring which has the original stator and RR. I charges at 7v and I've never had a problem with it. This is my setup.

What stator are you using? What RR's have you used? Do you have you original stator, flywheel and RR. One member here has remagnetized his flywheel and fixed his original stator and can give you tips on doing that. In summary, I like the original system the best.

[DesmoDog]

Well if we're into the aftermath of failed regulators, this is what an 851 can do to a lithium battery even with it's built in "BMS"



It also took out the ECU and a few other bits.