hillbillyracer
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| posted on 4/9/10 at 12:04 PM |
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Using 240v to start an engine?
Not something you'd normally want having to need access to the mains just to start your engine is it?! I have a generator that supplies 3ph
power for my workshop, it's the power unit from a large fridge trailer with a 4cyl Kubota diesel engine & at the moment it lives in the
workshop & is the biggest single thing preventing me getting my car in to make progress with the build.
As it can stand for a few weeks at a time without starting it's a pain in the erse having to keep sorting/charging a battery for it & as
it's never really going to move once sited outside it'd be really handy to be able to just hit a button in the workshop to fire it up.
Now your average 240v motor is'nt built to do this short burst of high load sort of thing that a 12v starter is so I'm tiring to work out
what it would take & if it's even practical.
Gettin it to drive the engine is something I could engineer if a suitable motor were available.
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mangogrooveworkshop
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| posted on 4/9/10 at 12:11 PM |
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Schiples
get a trickle charger to keep the battery topped up and that's you answer
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hillbillyracer
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| posted on 4/9/10 at 12:19 PM |
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Yep, that's the original plan & a likely course but I'm just looking into the alternative.
It would ironicly mean I could'nt start the genny in a power cut but it aint for mains back up anyway, I've got a 5kva single phase for
that.
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dan8400
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| posted on 4/9/10 at 12:26 PM |
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quote:
Originally posted by mangogrooveworkshop
Schiples
Pissed Meerkat?  
Dan
Hey - That's Journey!!!
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SteveWalker
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| posted on 4/9/10 at 01:17 PM |
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240V ac motor to spin up a flywheel and a clutch to start the genny off it?
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hillbillyracer
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| posted on 4/9/10 at 01:48 PM |
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quote:
Originally posted by SteveWalker
240V ac motor to spin up a flywheel and a clutch to start the genny off it?
Yeah that's a possibilty, with a shaft direct onto the front of the crankshaft which I could make easy enough.
Most 240v motors are 1400rpm so I'd need a reduction of between 10-1 & 14-1 to get a sensible cranking speed. An old FWD car geabox would do
that & it's ready made for the clutch & flywheel if I had a scrap block/engine backplate to mount the motor on.
It'd be a case of engage the gear needed, disengage the clutch, spin the motor up & release the clutch, once started disengage the clutch
& put the box back in neutral. It'd mean the gearbox would be spinning in neutral on the output side but what harm would that do?
It'd also really need an over-run clutch on the shaft to the front of the crank so as the engine fired & picked up speed it could'nt
drive the gearbox & motor.
So there it is a somewhat Heath-Robinson set-up but do-able on a locost basis. Mabye more trouble than it's worth & it'd be sensible
to follow Mango's advice but if we were all "sensible" then there would'nt be a forum about building sportscars from scratch
when you can buy a perfectly good & much more practical hatchback from the main dealer!
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blue2cv
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| posted on 4/9/10 at 02:11 PM |
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blimey its got to be easier to plug a batt charger in
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Werner Van Loock
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| posted on 4/9/10 at 03:05 PM |
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forget about it, AC motors can't supply the torque a DC motor can from standstill
AC motors can only deliver torque at speed, DC motors have max torque at standstill, that's why starter motors are still DC and not AC as they
did with alternators, in the past they used DC generators instead of alternators. (alternator is a AC gen with a rectifier added to it)
http://www.clubstylus.be
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RazMan
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| posted on 4/9/10 at 03:45 PM |
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quote:
Originally posted by blue2cv
blimey its got to be easier to plug a batt charger in
Are you related to a Mr H.Robinson by any chance??
All this talk about gearboxes, clutches etc - Trickle charge the little blighter - even if the power goes off it will still start because the battery
is fully charged! 
[Edited on 4-9-10 by RazMan]
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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MakeEverything
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| posted on 4/9/10 at 04:44 PM |
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Bloody hell, you need to occupy your mind a bit more!
Kindest Regards,
Richard.
...You can make it foolProof, but youll never make it Idiot Proof!...
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hillbillyracer
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| posted on 4/9/10 at 05:47 PM |
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Do I get the feeling some of you fellas dont like the idea....
I know AC motors in general aint designed for this which is the reason for the post in the first place! I was looking to see if someone on here knew
of a motor that would do it because I did'nt! The clutch & flywheel does get around that problem.
If everybody did everything in the conventional manner the world would be a boring place! I'm just thinking over the possibilities.
& as said I've already thought about & possibly will just trickle charge it but it's not like this thing is all set to go with
12v, key start & a charging system cos it aint, it's got a starter motor & feck all else so all that would be to do too!
Would this be a good time to mention I'm going to use a Ford 2l DOHC carb'd engine & MT75 box?
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Ninehigh
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| posted on 4/9/10 at 11:05 PM |
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quote:
Originally posted by Werner Van Loock
forget about it, AC motors can't supply the torque a DC motor can from standstill
AC motors can only deliver torque at speed, DC motors have max torque at standstill, that's why starter motors are still DC and not AC as they
did with alternators, in the past they used DC generators instead of alternators. (alternator is a AC gen with a rectifier added to it)
You know I was always under the impression that starter motors were DC because the battery was DC
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MikeR
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| posted on 5/9/10 at 12:17 AM |
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Why not get the mother of all power converters and connect that to the mains with the other end on the DC starter motor.
NB the "mother of all power converters" as i'd hate to think how many amps the starter would draw when you turn on the converter.
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Krismc
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| posted on 5/9/10 at 07:45 AM |
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Or get a VVVF Drive and run a 240v Ac Motor and you can adjust until correct power for you.
Built, Ivaed, Drove and now Sold - 2011 MNR VORTX RT+ 2000cc Zetec on R1 Throttle boddies.
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RazMan
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| posted on 5/9/10 at 07:53 AM |
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How about a donkey on a treadmill with a connecting shaft? Maximum torque and it runs on carrots!
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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MikeR
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| posted on 5/9/10 at 09:24 AM |
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i think trickle charger is probably the easiest 
(what are you going to do with all the poo?)
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rusty nuts
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| posted on 5/9/10 at 12:12 PM |
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What's wrong with a booster starter/charger? Made for the job
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britishtrident
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| posted on 5/9/10 at 12:38 PM |
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Boost rapid chargers kill batteries and any charge pumped in won't last long as a rule of thumb for long battery life it takes 5 to 20 times
as long to charge as discharge.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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rusty nuts
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| posted on 5/9/10 at 03:57 PM |
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The original post indicated that he needed to start the engine with what is likely to be a flat battery which doesn't get charged too often .
Yes a booster charger/ starter isn't ideal but it would do the job better than anything else given the circumstances
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hillbillyracer
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| posted on 5/9/10 at 08:33 PM |
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If I use a donkey mabye I could use it to run the lathe etc directly? The poo is no problem, I live on a farm. Then I could sell the genny & use
the funds to buy carrots!
I'll likely just go with the obvious & do the trickle charge thing. It's looking the simplest & lowest cost. I'd put the
battery in the workshop with the charger & run longer leads (along with the power cable back in & the control/signal wires for it) through the
wall to the genny outside.
How do batteries like infrequent use & a constant trickle charge? If the battery would last a few years the it's no big deal. But if the go
every 18 months it'd get expensive.
I know repeated boost starting a battery is'nt good, The one I'm using to start it at the moment has suffered with it.
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RazMan
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| posted on 5/9/10 at 10:27 PM |
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One of the Optimax type chargers will keep the battery in tip top condition for a few years at least.
[url=http://cgi.ebay.co.uk/OPTIMATE-4-MOTORCYCLE-MOTORBIKE-BATTERY-CHARGER-12V-/370351690362?pt=UK_Motorcycle_Parts&hash=item563aae527a]linky[/url
]
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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02GF74
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| posted on 6/9/10 at 10:01 AM |
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hmmmm.... series 1 land rovers plus other cars from the 50s and 60s had a starter handle - so how much torque can an average human provide?
I know a mains black and decker electric drill has enough torque to get ripped out of my hands when the drill bit got stuck  so with suitable
gearing down of the motor plus some access to the engine ring gear it may be doable. (<-- yep, that may be a meaningless comparison but ..... )
a starter motor can draw maybe a 100 A, so that is approx 1.2 kW so that is a mains drill drawing 4.5 A. (again, it may be more but not once the
engine is turning - a diesel has higher CR so that is not gonna help).
I reckon the numbers are in your favour, not sure how easy or cost effective it would be.
what about a solar battery trickle charger?
[Edited on 6/9/10 by 02GF74]
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