Now it works, but I don't know why

[NQ6U]

Late last spring, the South Coast Air Quality Board had an offer: bring in your working gasoline-powered lawn mower (and $99) and they'd give you a brand new Black & Decker battery powered electric mower. Since my old Briggs & Stratton mower was on it's last legs, I decided to take them up on the offer even though I had some doubts about how well an electric mower would work. Pretty well, as it turned out. The 38 VDC mower had no problem with mowing both front and back yards on a single charge. That is, until it's first encounter with this spring's weed crop.

My back yard is not landscaped. There is no real lawn and every spring the weeds and wild grasses go wild, often reaching over two feet (0.6m) high. That's more than any electric mower could reasonably be expected to handle. Of course, when it comes to things like this, I am not a reasonable man, always sure that I can coax high performance out of pretty much any machine with my superior operating skills.

You can guess what happened. Yep, the mower stopped working midway through the job. I feared the worse—a burned out motor—but upon disassembly, I could find nothing wrong. The battery was fully charged, all the switches appeared to work and the motor appeared to be fine. I even pulled the brushes to see if they were okay.They were, it just didn't work. Discouraged, I put the whole thing back together and, for no particular reason, tried turning it on one last time. Damned if the thing didn't work perfectly!

This is not the first time something like this is happened—take some broken device apart, look at it, shrug, put it back together and it's working again—and it always leaves me wondering what the problem was.

[n2ize]

Maybe the motor got too hot and a thermal cutoff switch opened and it took a while for it to reset. Electrics are nice but I prefer gas.

[NQ6U]

Maybe the motor got too hot and a thermal cutoff switch opened and it took a while for it to reset. Electrics are nice but I prefer gas.

That's what I thought but there was no thermal cutoff on the unit that I could find and, besides, the problem actually occurred a couple of days ago. I just didn't get around to looking at it until today and it didn't run when I tested it before beginning my repair efforts.

[K7SGJ]

Yeah, the thermal OL would be my guess, too. Next time it happens, pack it in dry ice, it should come right back.

[kb2vxa]

Either that or a brush lost contact, possible commutator burn from arcing, so when you replaced them you restored contact. I've had that happen a couple of times.

"Of course, when it comes to things like this, I am not a reasonable man, always sure that I can coax high performance out of pretty much any machine with my superior operating skills."

Sounds like a Tim Taylor quote!

[K7SGJ]

That's what I thought but there was no thermal cutoff on the unit that I could find and, besides, the problem actually occurred a couple of days ago. I just didn't get around to looking at it until today and it didn't run when I tested it before beginning my repair efforts.


I've had some battery operated stuff that had a thermal OL on the motor of the tool, as well as one in the battery pack. The only people making money are the TOL manufacturers.

[NA4BH]

Whinney bitch

[NQ6U]

Either that or a brush lost contact, possible commutator burn from arcing, so when you replaced them you restored contact. I've had that happen a couple of times.

That's the best guess I can come up with as well.



"Of course, when it comes to things like this, I am not a reasonable man, always sure that I can coax high performance out of pretty much any machine with my superior operating skills."

Sounds like a Tim Taylor quote!

We have some things in common. I repowered the garbage disposal with a Harley motor.

[K7SGJ]

Whinney bitch

^^^^^ + 10,000 Maxwells

[VE7DCW]

Late last spring, the South Coast Air Quality Board had an offer: bring in your working gasoline-powered lawn mower (and $99) and they'd give you a brand new Black & Decker battery powered electric mower. Since my old Briggs & Stratton mower was on it's last legs, I decided to take them up on the offer even though I had some doubts about how well an electric mower would work. Pretty well, as it turned out. The 38 VDC mower had no problem with mowing both front and back yards on a single charge. That is, until it's first encounter with this spring's weed crop.

My back yard is not landscaped. There is no real lawn and every spring the weeds and wild grasses go wild, often reaching over two feet (0.6m) high. That's more than any electric mower could reasonably be expected to handle. Of course, when it comes to things like this, I am not a reasonable man, always sure that I can coax high performance out of pretty much any machine with my superior operating skills.

You can guess what happened. Yep, the mower stopped working midway through the job. I feared the worse—a burned out motor—but upon disassembly, I could find nothing wrong. The battery was fully charged, all the switches appeared to work and the motor appeared to be fine. I even pulled the brushes to see if they were okay.They were, it just didn't work. Discouraged, I put the whole thing back together and, for no particular reason, tried turning it on one last time. Damned if the thing didn't work perfectly!

This is not the first time something like this is happened—take some broken device apart, look at it, shrug, put it back together and it's working again—and it always leaves me wondering what the problem was.

Is it possible it's devine intervention funneled through the charisma of Pope Carlo ?????

.....nyaaaah ..... I vote the thermal overload cutoff re-setting itself as well ...... :mrgreen:

[kb2vxa]

OH! I just remembered something about small motors. The thermal cutout is a small glass capsule containing a self resetting bi-metal thermostat and covered by a soft plastic sleeve buried in the windings where it's hard to find.

"I just didn't get around to looking at it until today and it didn't run when I tested it before beginning my repair efforts."

That makes the brushes suspect number one.

[PA5COR]

That's why i run a 1000 watt 230 volt 50 Hz mains powered lawn mower...

[K7SGJ]

That's why i run a 1000 watt 230 volt 50 Hz mains powered lawn mower...

I doubt he has an extension cord that would reach from your place to his.

[KK4AMI]

That's why i run a 1000 watt 230 volt 50 Hz mains powered lawn mower...

Good enough reason to not mow the lawn in the rain :shock:

[PA5COR]

Double isolated extention cord is 40 meters, so if you are as close as that i'll help ;)

[AE1PT]

OH! I just remembered something about small motors. The thermal cutout is a small glass capsule containing a self resetting bi-metal thermostat and covered by a soft plastic sleeve buried in the windings where it's hard to find...

Yup. Lots of times there is a bunch of fabric tape holding it to the winding--and you can't find it unless you cut the tape loose.

[kb2vxa]

That too, only it's fiberglass tape that won't break down with heat and age like organic materials do and cause a short.

[AE1PT]

That too, only it's fiberglass tape that won't break down with heat and age like organic materials do and cause a short.

I guess that shows a)How old I am, and b)How long its been since I tore anything like this apart.

My recollection is of that old canvas like tape that had the awful white adhesive that either turned to powder--or a horrid sticky gum. Or for greater fun the tape disintegrate and leave the sticky gum all over the place.

And lest we forget that nasty yellow plastic tape that never stayed stuck on the windings...

[kb2vxa]

HAH! You reminded me of the good old days of electric motor and transformer repair! (;->) Oh yeah, that white adhesive tape, probably that same nasty stuff made by Johnson & Johnson used to stick gauze bandages that hurt like hell when peeled off and left a white sticky outline. I remember that yellow cellophane tape with the non stick adhesive, it never stuck to anything let alone STAYED stuck for more than 5 minutes. When it peeled off there were clear spots in the tape and yellow specks on whatever you tried to stick it to. BTW I never repaired a fan made between 1920 and 1970, they were made out of metal and wore like iron (pardon the pun) and ran like... forever. Then along came cheap plastic, porous bronze sleeve bearings and felt oil pads that dried out with no way to get a tube in there to oil them. Permanently lubricated motors they called them, permanent until they seized up and burned out. Never repaired one of those either.

[N2NH]

http://24.media.tumblr.com/tumblr_lscnpeBnRa1qjtg6no1_400.jpg

[kb2vxa]

Aliens with 1000W 230V lawnmowers?

It's one o'clock and time for lunch.
(dum dee dum dee dum...)
When the sun beats down and I lie on the bench,
I can always hear them talk.
Me, I'm just a lawnmower - you can tell me by the way I walk.
Keep them mowing blades sharp...