Using a Device with Transformer

The fuses are rated at amperages (ie, 30 Amps). This only means that they blow when a load tries to grab more than 30 Amps from the line that the fuse is connected to. You say you bought a 25 Amp, 12V Transformer. By this do you mean a wall/table top transformer, or an actuall transformer? If you just say transformer, then we all assume the transformer is putting out AC. What kind of device are you using that requires 25 Amps of 12V? Thats a huge load, or you sure you dont mean more like 250 mA, or a 2.5 A? Descirbe in total what you are actually doing.

I just read your other post. You said that the device needs up to 15 Amps, and your friend told you that you need a 25 Amp power suppy. This is way overkill. It shouldnt matter, but the price difference will. I dont know where in the world you got a simple 12V DC 25 Amp powersupply. Power supplies rated at this usually come in little metal cages, designed to put inside a device. I think you got duped and may have bought a PSU (Power Supply Unit) that is probobly more like 250 mA.

Hi, Mark. Sorry for your troubles post-hurricane. Hope you will get ahead of the ball and get on with your life soon. A neighbor of mine hails from Florida -- he was chased out by the hurricane, and is still struggling, too.

First, I'm assuming your "transformer" outputs DC, not AC. If it puts out AC, that could be the source of your problems. You'd need to find a DC power source to work with your motor.

Apparently this is about your "macerator" (12V rated current 15 amps). You'd expect that the motor would require more current on startup. However, assuming you're supplying direct current (DC) to the motor instead of alternating current (AC), your description indicates a problem either with the power source or the motor.

Without more information it's not too easy to tell. Check to see what the "transformer" outputs -- 12V AC or DC. If it's DC, see if it pops a fuse with nothing attached. If it is DC output, and it doesn't pop a fuse with nothing hooked up, try hooking up something else that uses

If you get to this point, and you still haven't popped a fuse, I'd bet it's the macerator that's the problem. Possibly the bearings are burnt out, causing excess current when it tries to turn. Either that, or the motor may have gotten wet and partially shorted the windings.

Feel free to post back again.

Good luck Chris

Mr. JD et al:

When we first bought this device, the "macerator," we were dismayed when we opened the package to find that, after spending the $300 (+) for the device, there was no power supply. This information was "not" mentioned on the Internet, where we purchased the product -- heck, why would we think to ask? That's "capitalism" for you.

Our next step was to determine what we needed to run this "thing." First, a friend, who is also an electrician, stopped by and attempted to use the "transformer" that is also used by our refrigerator -- as we use propane to run it -- it's much cheaper, and, given that we live in what we all call the "sunshine state," we realized that when a storm hits and the electricity suddenly stops shooting electrons into our wires, (I am being sarcastic, by design, as I am totally annoyed with this project -- we even e-mailed the company and received an answer that suggested that "it" only required 10 Amps to run; he said this when the box and the instructions "clearly" states that the product requires 12 volt, DC, with at least 20 Amps -- so we knew that, on the other side of the Internet, rested someone who need not grow a brain), our food stays nice and cold.

Well, the transformer that is used by the refrigerator was not a match; after he read the material, he told us that we needed to buy a transformer that is capable of providing 12 volt, DC with at least 20 Amps. So -- we got online, and on the Radio Shack site, there was a device (a black "table-top box") that states that it has an output of

And -- this is where we stand. The device works, but only for a mili-second and then the "power supply" unit "sort of shuts down," in that one can no longer hear the fan running that is seen on the rear panel. In order to do the same procedure again, it requires a "re-start" of the transformer; in other words, while the "on-off" switch remains illuminated, it has to be turned off and then on again

-- and we are back to "square one," with the device working, but just for the short period of time. This is why I thought about the outlet. In RVs, one needs to pay close attention to what is being used; when my wife uses something like her hair dryer, we usually shut down the A/C. Running too many applicanes (aside from things like fans, lights, etc., that don't take as much "juice" to operate) will tend to "blow" one of the 15 Amp switches in the electrical box, located on the side of the RV. My own (albeit uneducated guess with respect to electricity) assessment was that, perhaps, the outlet is only producing 15 Amps and if we use an outlet in a home (my wife's parents own the farm and they live nearby), the problem would not exist.

Thanks -- and h> mea305 wrote:

Hi, Mark. The 25 amp Radio Shack switching power supply (Model:

The first thing you'll want to do is to make sure the macerator runs properly on its own. If you can hook up the motor to a 12V battery with a 30 amp in-line fuse, you'll see if it works without popping the fuse. If so, you can then start looking at getting a replacement for the power supply.

Good luck Chris

Again, Mr. J.D., et al:

Now, with the box in which the transformer was packaged in front of me, it is a "13.8VDC, 25 Amp, 'switching power supply.'" The additional nomenclature that is on the front of the package lists the following:

"Accepts 90 to 135VAC input and converts to 13.8VDC up to 25 amps." And, it also states that it is a "low RFI unit," whatever that means. The picture of the unit is also on the box, which matches the unit itself. There is a power switch, "on and off," and the nomenclature is again repeated on the front panel of the unit, "switchable power supply, 25 Amp, 13.8VDC."

On the back of the package, the following is read: "With this Radio Shack switching power supply, you can bench-test or power CB and HAM radio sets, scanners, car stereos and radar detectors. You can also use it with your faster 12VDC car chargers to re-charge wireless phones, camcorders and re-chargeable flashlights and cordless tools."

There are five numbered elements listed on the back panel as well: (1) lighted power on/off switch (2) non-skid rubber feet (3) 6 foot grounded AC cord (4) cooling fan (5) color coded terminal post outputs

On one side of the box, it states that it comes complete with a "short circuit and overload protection."

We purchased the unit on the Internet at the following URL:

Thanks,

Mark Mr. J D wrote:

Hi, Mark. The Radio Shack switching power supply is basically meant to power up mongo car stereos on a bench. They're really not made for motor loads. You should look into returning the product -- it works, but it's not made for the job.

On the prior thread, someone mentioned using a car battery with a charger rated for 25 amps. Although it's clunky, that might be your best bet to get things going quickly (again, assuming the macerator works -- test as above). You should be able to scrounge a battery, and possibly borrow a charger. Be sure to use an inline fuse, put a shield around the battery to protect everyone's eyes in case of accidental acid discharge, and keep things well-ventilated. A working car battery produces hydrogen gas and acid fumes. Possibly you could ask your electrician friend for advice.

Longer term, you'll probably want to find a 12VDC power supply that can do the job. Look for a linear supply (they're a lot heavier, because they've got a 60Hz transformer rated for the output power). Actually, a non-technical person should just evaluate by weight -- if the 12VDC,

Of course, hoping for the best for you and your family. This is the worst part of being stuck -- that you have to spend inordinate amounts of time and money over something that wouldn't even be a problem if you weren't stuck. If you were renting, you'd let the landlord worry about the septic tank stuff. The harder you work, the behinder you get. You're not alone in seeing the irony in spending all this time fiddling around with something that does what a macerator does.

Good luck Chris

It is not suitable for powering your macerator. Connect the macerator to the vehicle battery, as others have recommended.

Ed

Hi Chris and all others -- that respectively responded to my posts. I want to first say that I am extremely grateful for your assistance. The second thing I must say (although not specifically to the group, but to, perhaps, Radio Shack....) is, ummm, ya know, they took me for being stupid. I should have known better; but, like most others will agree, hind sight is what it is ...

On the other side of the coin, however, even before I read any of the second posts concerning this quagmire in which I have embedded myself, the macerator does work. "I got to thinking...," and I already had an "automotive jump starter/DC power supply," a unit that I purchased while I was swimming beneath the currents of my scooter battery "problem," (for lack of a better term). This 'little thing here' looks like something that one would need to start a car. But, it is relatively small. Charging it takes about a day; but, when I connected it (while also holding my breath) to the macerator -- here, I was about to, effectively, by-pass a small 20 Amp fuse that is attached to swith/handle/trigger mechanism -- and.....it works! The information that comes with the macerator suggests that one should not operate it outside of its nornal environment, which would be -- water. Apparently, it can get hot fast. But, it does work; and I can use this little thing to connect to the macerator.

There is but one question -- and I am assuming that I might be correct. I would not think that this little thing (although it weighs in at almost 20 lbs. and I cannot lift it because if I did, two things would happen -- pain and my doc would kill me) does not or cannot produce more than 20 Amps, correct?

Aside from that, I'm OK. I will await a response before I use it.

Thanks -- to "all of you!"

Mark Chris wrote:

mea305 wrote: [macerator works with battery]

Assuming a low duty-cycle for the macerator your 20lb battery might, when combined with a suitable charger, make for an adequate macerator power suppy. We'd need to know the battery type (not just its mass!) and have some idea of what kind of duty-cycle the macerator can expect (30s

Tim

Hi, Mark. I'm glad to hear you're getting a bit closer to having your setup work.

Here's the thing. The battery charger provides rectified AC, which probably isn't too good for your motor by itself. The way it works, is that the charger sends pulses of current into the battery when the charger voltage goes above the battery voltage (120 times a second). The rest of the time, the load is carried by the battery.

You really should put an automotive battery in parallel with your macerator, so the battery can help shoulder the load and even the voltage out. Even an older or marginal battery will be a lot better than none. This will help your motor to survive. Also, be sure to get a battery charger which shows more than 20 amps output on the nameplate. If you pick one that's too small, you'll probably fry the charger.

As a bit of a sidenote, please bottom post if you have future questions. Read Google Groups Help Topic "What's good 'netiquette' when posting to Usenet?"

I hope things are looking up for you soon. It seems like you've been handed more than your share of macerator grist recently!

Cheers Chris

Presumably a sewage macerator pump

Not sure why he isn't running it off the RV battery.

Hi all:

Later, before this morning is over, I will post the nomenclature for the macerator; I will do this before attempting to use it. However, I now realize that I can hook the macerator up to the battery charger I have (I will post that information as well) "before" the trigger that holds the fuse.

Thanks to all who have helped.

Mark

Homer J Simps>

there's your problem! Overload protection is why it's cutting out, and that means the motor in the macerator is wanting more that the overload limit of that powersupply.

what you need is a larger switching powersupply, or big tranformer based power supply with a chunky rectifier.

Is the motor supposed to run 24/7 or just when needed ("on demand")? if it's an on-demand thing that or hook the thing to a 12V battery (car battery etc... use a 30A fuse on the batrtewry ) and hook the battery to a charger.

Bye. Jasen

A jump starter can produce more than 100A (probably close to 500A) without breaking a sweat.

Does the macerator need a switch to stop it when it ha pumped its surroundings dry?

there's a chance that if you leave your jump starter pluggens in to charge all the time and the macerator is used infrequently the slow charge on the jump-starter will be enough for the macerator.

On the other hand do I recall you saying you're living in a RV? does it have a 12V electrical system that could be used to power the macerator?

Bye. Jasen

On 19 Aug 2006 16:45:52 -0700, in message , "mea305" scribed:

The pump you bought did not come with a power supply because it is designed to use a voltage that your RV already has. If the tank pump runs on 12V DC and your RV runs on 12V DC, why do you need a transformer? Did your electrician friend tell you that? Is he the same electrician friend who could not help you with your battery charger problem?