OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines electric start victa

hello all.
i was wondering about the victas with a key starting system.
i know they use a rechargeable battery.
but i dont know if the mower itself charges the battery whilst running.
my victa manual has nothing about key start models.
just curious is all.cheers bazz

bazz, I'm told the ignition system works as an alternator and charges the battery. See this thread:
https://www.outdoorking-forum.com.au/forum/u...Words=keystart&Search=true#Post50729

If you want more information, hopefully Joe Carroll and others will be able to help.

wow thats cool. would really like to see the insides of one of these magnetos. to see how and or if it may have another coil etc . my brothers outboard has 2 coils one is the engines run coil the other is a separate one just for powering the boat lights. if indeed they charge the 12 volt battery then it could also be used as an emergency car charger??

Well guys, you learn something everyday...I would like to see a schematic of how that works....

Deejay and ODK members,
I'm sure you'll find this useful, although apologies in advance for the format. It was a pdf which was password protected so i had to snip the pages and save them in order to attach them.






Enjoy

Thanks for that info Bigted, I have now learnt something else about Victa's, didn't know they charged the battery. I also often wondered about the second magnet on the flywheel of some normal Victa's.
Cool.
With just one diode only, I can tell you this is the simplest form of ac to dc rectification.

Hi bigted and mark electric,
Thankyou for that info, a very simple system, but obviously works very well.
This info will also help members diagnose a failed diode.
All good stuff!

well if thats the case then converting it to a full bridge rectifier should double its output.in theory anyway.would also decrease the diode load and probably stop them burning out as seems to be a problem.
however the 200 milliamps would take quite a while to charge a full size car battery. but if you weren't in a hurry it would at least boost it to cranking voltage again.eventually.
i kinda wonder why they didnt just put full bridge rectification. seems a minor expense to me?

Gizmo, yes, a bridge rectifier would nearly double the DC output - by doubling the load on the Victa ignition module. Bear in mind it was probably only designed to carry ignition current, and even the half wave rectifier might be making conditions stressful for it.

It may not matter in this application, but the bridge rectifier always has two diodes in the current path instead of one with the half wave. This reduces the output voltage by about 0.7 Volts. That is why it only "nearly" doubles the current.

The load from the car battery would damage the charging circuit very quickly, I think they have a 1 amp fuse at best, any of my batteries accepts a minimum 5 amps at charging voltage any time of the day. For an emergency charger, I used to have an old 3hp briggs engine with a small alternator belt driven on a frame, that worked eally well if the batteries were only slightly discharged, start it up, go and have a bourbon (or coffee if your like that) and generally there was enough to start most things we owned on the farm.

A decent modern car alternator should be rated at 60 to 80 Amps, which at 14 Volts is 840 to 1120 Watts (1.1 to 1.5 hp). Including the losses in the belt drive, they are not a lot better than 60 percent efficient, so you need an engine that can deliver 1.8 to 2.5 hp continuously. A 3.5 hp Briggs can't do that - it is rated based on gross power, not nett power - but a 5 hp Briggs, Honda or chonda can do it. Of course an alternator with built-in voltage regulator is best, then the only wiring you need is two heavy wires: one from battery positive to alternator output and a second from battery negative to alternator ground, plus a very light wire with a switch in it from battery positive to the alternator's field terminal. I doubt a car alternator would object to running for the few hours a battery charger operates with its rotor vertical, so you can use either a vertical or horizontal crankshaft engine - whichever falls to hand. The whole charging device should be carryable with one hand for short distances. In practice of course you would only use that large an alternator on a full sized car or truck battery, or you'd overheat the battery and ruin it.

I think i'm being haunted. My physics lessons from high school and uni are all flooding back to me.

I used a stock 35amp corolla alternator, hopeless for most other purposes, I just went from 35 amp to 80 amp in the ute and my lights are now white at night time rather than yellowed out c*ap.

Sorry about that issue bigted, I dont have that issue, school wasnt interesting and sure wasnt earning me any money, so I quit and began scrapping at 15

yeah car alternators need high torque engine to spin the necessary speed. could replace the windings with permanent magnets.
But if i built an axial flux alternator similar to a wind generator, a mower motor would have no trouble spinning it up.
put that on top of a mower to charge the battery.
better still ,put a fischer and paykel washing machine motor on it and re wire to 12 volts output through a 3 phase bridge rectifier and regulator. a fischer and paykel washing machine motor has no trouble creating 1000 volts and good amps even at reasonable speeds. there are also ways to reduce the cogging effects of the magnet drag.
sorry guys this has gone way over board from my original question. but i do like to ponder. he he

well i decided to dig out my old key start mower and have a good look at it. now i am full of new information i decided it was time to have a play around with this one.i kept it on the back burner cos i didn't have a battery for it and didn't want the expense of buying one as yet.
Then it dawned on me???
i have some super capacitors, 6 x of them at 2.7 volts each.
i sticky taped them up in series to 12 volts.
then i quickly charged them up to 12 volts.
attached this contraption to my mower and presto she starts easy as anything.
i checked the voltage output of the magneto and it slowly began charging the caps but it only puts out 3 volts max.
so i hooked up my mini solar panel to them and what do you know about 15 minutes and back to full charge.
it ran and charged as i cut my lawn.
now these capacitors are tiny buggers and they easily start my mower.
in fact they have enough grunt to start my car.
if you dont know anything about super capacitors i suggest you look these babies up. they are awesome.
so now i will build a bracket for the solar panel and capacitors and have myself a solar start mower.

magic !!!!

G'day Gizmo,
Can I ask how many farrads your capacitors are.
I have been looking at them and am wondering about the capacity of them.
Thanks from Mark

hello Mark. yes the only ones i have are 90 farad. they have more than enough grunt for the little mower starter.
i have ordered some 30 farad 2.7 volt ones which should also be more than ample for this project as i want the 90 farads for my ride on mower starter.
the 30 farads should charge alot quicker too. these are about the size of a AA battery, so tiny. when i try them out, i will keep getting smaller ones until i get the lowest ones that will start the mower.
the 90 farads would kick over a small car engine.
if you have seen them coupled to a car battery then you know their potential. just awesome things they are.

well i got the 30 farads.not quite as strong as i 1st thought they would be. they do kick over the mower ,but only about 4 turns. which for a victa isnt enough really. they go flat too quickly for any real usefulness.
its still amazing that they event turn the engine over.
so i will stick to the 90 farads which work much better.
the wiring is important however as they are pumping a lot of amps in a short burst so dont be skimpy.
my newest thoughts on the whole capacitor only start system has changed after playing with the 30 farads.
we all know that sometimes victas can be a real bugger to start at times even when they are in good shape. if your capacitors go flat,well you will have to resort to pull starting which kinda defeats the purpose.
i see now why they are most beneficial used alongside a 12 volt battery instead. the starting crankup is what destroys batteries over time. but combining them with capacitor startup is supposed to improve battery life by as much as 70%.
i think this is how i will eventually go with this project.
it just means i wont have to purchase the rated cranking amp battery that is recommended .i can go for a much smaller capacity battery.and combine it with the caps. cheers bazz

Thanks Bazz, for sharing your experience with these capacitors.