This actually goes along with my previous post about Lawn Tractor
Battery/Charging issue but experience tells me it's best to separate
things like this.
Motor Overheats. This lawn tractor is charging its battery at a rate of
15Amps constantly (Subject of the referenced post). Therefore I'm
assuming that might be a relatively high load on the motor to run the
generator at 15Amps. I believe 15A is the max the generator can provide
since meter full scale is 18A.
Then add to that, taking it out into a field and cutting field grass
(wildflowers & grass, etc. abt 2 ft high) at the max recommended rpm,
for an hour.
Upon turning off the engine, it went into a serious dieseling mode. It
even spun backwards just before it finally quit for me (I finally pulled
the choke to kill it). When I checked the oil it appeared there might
have been some bubbles in it, which I think is a sign of over-heat.
After cooling for a bit, checking the level showed it to be right on the
mark, maybe a line width above it.
Do you think running with the battery generator maxed out like it was,
on top of the cutting load and hot sun for an hour would account for it
getting so hot? It wasn't literally that hot out; temp was around 78 F.
The oil doesn't appear burned nor have any smell like it was, but ...
thought I'd see what folks here thought.
Oil was recently changed hours of use wise and still appeared clean.
Anything special I should do now?
Regards & TIA,
The maker of the alternator (generator) can tell you
what its normal output should be.
Two-foot high grass and scrub would seriously overwork most machines
sold as "lawn tractors," say the range 10 to 25 horse power. We may
suppose it takes half the engine output just to move the mower through
long grass (with the operator's weight atop all.)
No humidity or dampness problems; screen, everything clean, fins clean,
etc.. I always watch that in case of fire hazards around the engine.
The flywheel is actuall pretty well designed and besides pulling air in
also stays nice and clear.
Don't know about motor over heating. Advancing timing too much can make
engine run hotter. But if battery is fully charged it shouldn't charge
any more. Maybe regulator is acting up? BTW, is it alternator or
generator? They work differently.
15 amps at say 12 volts = 180 watts.
180 watts is about 180/750 = about one quarter of a horsepower.
Even doubling that to half a horsepower does not sound like a motor
Is motor over-revving? Forced to work too hard?
lol! You sure know how to make an electrical engineer (retired) feel
dumb! Why didn't I think of that? Don't answer that! < G >
The motor's not over-revving as measured by my calibrated earball anyway
so if it is, it's not much. But it does sound loaded without the blades
(or any other attachment even connected) running.
I did find a spec online for my tractor that said the regulator
output max was 15A. And someone else mentioned that if the rectifiers
were shot, I'm seeing current going in, then curring going out, so it
might read high, but - I don't uderstand that since it's DC where I'm
measuring the voltage, which is schematically adjacent to the
rectifiers. But it might explain 29V ac measurement.
I've determined the regulator/rectifier is shot by comparing things to
another working tractor with the same setup except it's a single
cynlinder 17 HP. I tried to measure on into the stator but it's not
possible without some real disassembly, so I'm hoping just replacing the
regulator/rectifier will do the job. $71 with $13 of that being S&H
from Sears and $9 tax! What a ripoff! We're very rural here.
The other tractor shows everything I expected to see on mine so it's
at least verification that I'm looking at SOME of the right things.
Right now I'm letting it set for a week until the part arrives, to see
if the battery is recovered or shot. So far it seems to be holding its
charge just fine.
I cut 4 acres, so 5 isn't that much more. Anyway, if you are ill and
can't mow it often, you'd be better off hiring it doen when you are
ill. Your mower isn't a bush-hog. It is made for residential service.
That means cutting more often.
Hank <~~~~has commercial mower
I always try to let my small engine equipment run at about 1/4 throttle
for a minute or so before shutting it off. That allows the motor to
cool down a bit so the little bit of carbon on the piston isn't still
glowing red when you turn it off. Especially after cutting the high
grass, it was most likely overheated and you could have caused permanant
damage, but maybe not. Anyway, after using it really hard, let it run
1/4 throttle a couple minutes before shutting it off. (and also let it
warm up a bit before putting a heavy load on it)
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