New PT, New Problems

[marrt]

OK. The verdict is in. I finally had a chance to mow today and the temperature around the battery hit almost 225 degrees after one hour! And that’s with an ambient air temp of about 75 degrees. By the time I grabbed my camera, the temp had already dropped to about 212 degrees on the thermometer. The thermometer, as you can see in the attached pic, basically measures the air temperature around the battery, and therefore falls fast when the engine is idling. I have no idea what the actual battery temperature was but can guess it will get really high if bathed in 225 degree air for several hours.

I leave this thermometer in all the time now and will continue to measure as the summer gets hot. One thing’s for sure…I think 225 degrees is too hot for a battery.

 

[MossRoad]

I'm not doubting you that it is HOT in there, however, isn't that type of thermometer supposed to be vertical only? I used a metal cased meat thermometer in mine, and as I reported earlier, it didn't hit anything near that in about the same air temperature.

You definately have a heating problem there. Water boils at 212, and I don't know how potent your acid is, but I'll bet you were right in your thinking that the sucker just boiled to death after several hours of cooking back there.

I'd call Power Trac and ask them for help. That is too hot!

 

[Charlie_Iliff]

Marrt: For some years, Chevy trucks had starter problems because of heat radiated from the exhaust. They cured it with a with a simple shield, which also became available after market. It was two thin metal sheets with asbestos or other fabric sandwiched. It eliminated the radiant heat completely. I recall seeing pads to protect counter tops in kitchens for cheap that would probably work great. They still around?

 

[Schultz]

I agree a radiant barrier could prevent a lot of energy from heating your battery, especially since batteries are usually black, black being very absorbent of radiant energy. I think this is your biggest source of heat transfer to your battery. Your thermometer may have been heated mostly by the radiant energy from the muffler rather than the air. I say this because air has very little mass to transfer energy, compared to your massive battery. A simple experiment would be to put a sheet of shinny metal (aluminum, Stainless Steel) or just wrap aluminum foil around the battery area with the thermometer behind the foil. The reflector should not touch any heat source (muffler, engine, etc) otherwise conduction will rapidly heat your reflector and then it will begin radiating heat.
Tim

 

[marrt]

MR, regarding the question of the thermometer needing to be vertical…I don’t think that’s required. I think this thermometer works by having a sealed enclosure under a known pressure. As the temperature increases, the liquid (used to be mercury…think it’s alcohol these days) expands at a know rate based on the initial internal pressure. If true, I think it may even work upside-down.

Schultz, I agree that a big component of the heat problem is radiant heat. I think I may be able to solve both the air and radiant issues with some type of shield. I sure wish I knew how to use a smoke wrench as this would be a perfect project. I’ll have to think about what I can come up with to address the problem.

 

[davesisk]

<font color=red>I sure wish I knew how to use a smoke wrench as this would be a perfect project.</font color=red>

You can go buy one of the 90 amp 115V FCAW's (flux-cored arc welder) for about $150 from Harbor Freight (Called an "EasyMIG", although it's technically not MIG, and made by Chicago Electric. I bought one and used it to weld up some pretty nice wrought-iron and ceramic end tables!). It's a gasless wire-feed welder that uses flux-cored wire, and it's about as easy as using a glue-gun after a little bit of practice. However, a few cautions:

1) Wear a welding hood and clothing that covers arms, legs, neck, etc. Arc-welders emit tremendous UV rays, and you'll sunburn your cornea's (supposedly very painful) in a few minutes, and you'll sunburn (like in 3rd degree burns) any exposed skin in a very short time. Try not to breath the gases. Do not weld anything galvanized or containing zinc, as the gases released are poisonous and can kill you. Use only mild steel. It also should go without saying that steel heated to it's melting point is, well, pretty hot...so, don't touch it with your bare hands until it cools.../w3tcompact/icons/smile.gif.

2) If using the 90-amp setting, make sure you run it off a 20amp circuit, or you could set the wiring on fire in your house or workshop. If you're running it on the 60-amp setting, a 15-amp circuit is OK.

3) Most important: Do not, under any circumstances, weld around gasoline, oil, or anything else that is flammable. Take the part you're going to weld off the tractor and do it away from anything flammable. One glob of splatter landing on the fuel tank and melting through can blow you to bits, so don't do it!

Given that, go buy that smoke wrench and have a blast!

Dave

 

[davesisk]

Another thought here. Harbor Freight (can you tell I love that place?) also sells a 115V resistance welder (ie. a spot welder, you know, the type with clamps that are used for autobody repair work) for about $200 that'll weld sheet metal and small parts up to 1/8" total thickness. You can weld most metals except aluminum (even galvanized stuff without releasing toxic gases, to my understanding). I don't have one (yet /w3tcompact/icons/smile.gif) but I understand that it's neat, clean, and easy to use, and you probably don't have to worry about blowing anything up around flammables.

The FCAW makes a really crusty weld that you have to spend quite a bit of time grinding. Of course, you could just get an inexpensive "stick welder" (ie. arc welder that uses clamped electrodes). I understand that makes a pretty neat and strong weld, but is fairly difficult to master "striking" an arc. The spot welder doesn't need an arc (welds through resistance) and the FCAW makes it's own arc (the current melts the wire, which then creates and maintains the arc).

If you've got lots of money to spend, send some of it to me first, then go buy yourself a TIG welder. /w3tcompact/icons/tongue.gif That's supposed to be the neatest and cleanest welding approach available (although about $1000+ for the welder).

One more thought: pick up a copy of "The Welder's Handbook" from Lowes/Home Depot, or order it from Amazon. Great book for learning this trade as a hobby!

I suppose I have some rather odd hobbies when you think about it, eh?

HTH!
Dave

 

[MossRoad]

Before going through modifications, what did Power Trac say about the heat problem? I'd ask them if maybe there is a real problem with this muffler design and see if they can repair it or give you a different style muffler.

Anyway, if you look at my muffler, there is a heat shield on the back of it to protect the engine from heat. I've attached a picture, in case you're interested. It might give you some ideas towards modifying yours.

 

[MossRoad]

And here's another picture, from the other side(the side with the battery). Hope they help.

 

[marrt]

Dave,

Thanks for the reply. I am looking for that book now. Is the author Richard Finch by chance? I’ve been wanted to experiment with welding for quite a while now. Your excellent summary is the most education I have received on the topic. Seems like there are a lot of choices. I know that I will want to weld up some home made attachments and that means using metal up to ¼ inch. That may limit my choices.

I like Harbor Freight too. Although some of their stuff is “cheap” (and I mean quality in addition to price), often I find it’s “good enough” for the home owner. I bought a bunch of sockets from them and am impressed. Also bought a 3HP router. It’s not that well made but it gets the job done and was very inexpensive compared to “branded” product. Some of the deals they have on the front and back covers (i.e., the “loss leaders”) are incredible.