What size converter do I need?

[Pup]

My local farm store and county agent couldn't answer. This seems like it would be a simple question, but then, I don't know much about electricity, so...

I have an electric fencer energizer that can be powered by a 12 volt marine battery.

I want to use a converter (adaptor? transformer?) to power it from a regular household 110 volt outlet, without needing to spend ~$100 to buy a new energizer.

There are lots of converters from 110 AC to 12 volt DC for electronic equipment. What do I need to look for, to make sure it'll be strong enough but not fry my energizer?

I can't find the exact specifications for my fencer energizer online, but it's probably pretty close to the P5 model on page 5 here: 12 v, 45 mA input, peak output up to .5 joules, stored energy up to .7 joules, output voltage 8 KV max.

I have a 110 volt AC converter that's labelled with an output of 12 v DC, 300 mA. Does it matter that 300 mA is higher than 45 mA, or do I need to find one labelled with 45 mA output? What else do I need to match?

[phunk]

The voltage needs to match, the current needs to be greater or equal. So if it really only needs 12V 45mA input, that converter should work.

[Olowkow]

Originally Posted by Pup

My local farm store and county agent couldn't answer. This seems like it would be a simple question, but then, I don't know much about electricity, so...

I have an electric fencer energizer that can be powered by a 12 volt marine battery.

I want to use a converter (adaptor? transformer?) to power it from a regular household 110 volt outlet, without needing to spend ~$100 to buy a new energizer.

There are lots of converters from 110 AC to 12 volt DC for electronic equipment. What do I need to look for, to make sure it'll be strong enough but not fry my energizer?

I can't find the exact specifications for my fencer energizer online, but it's probably pretty close to the P5 model on page 5 here: 12 v, 45 mA input, peak output up to .5 joules, stored energy up to .7 joules, output voltage 8 KV max.

I have a 110 volt AC converter that's labelled with an output of 12 v DC, 300 mA. Does it matter that 300 mA is higher than 45 mA, or do I need to find one labelled with 45 mA output? What else do I need to match?

When they say "300 MA" on a converter, it means you can draw up to 300 MA without damaging the converter. So, you can easily use it for something which requires just 45 MA (milliamps).

Now, you need to know the polarity of the output, positive must go to the same place that the positive of the battery would go. Then, the only other consideration is how critical the 12 volts is. Many "wall warts" are not a regulated voltage, which means that under light load, they may put out 16 volts or so. If this is a problem for your fence energizer, then that could damage it. It most likely would not hurt it, but the best way would be to get a "regulated" 12 volt DC converter.

[Pup]

That's good news!

Originally Posted by Olowkow

Now, you need to know the polarity of the output, positive must go to the same place that the positive of the battery would go.

I think i'm okay there. The converter has a white wire and a black wire on the output. If that means what I think it means, it should match up to the red wire and the black wire on the fence energizer input.

Quote:

Then, the only other consideration is how critical the 12 volts is. Many "wall warts" are not a regulated voltage, which means that under light load, they may put out 16 volts or so. If this is a problem for your fence energizer, then that could damage it.

For what it's worth, the fence energizer actually can be powered either by a 6 volt or 12 volt battery and adjusts automatically somehow (no switch to flip to change it). I'm wondering if that means it can handle a somewhat flexible voltage input?

[Olowkow]

Originally Posted by Pup

That's good news!



I think i'm okay there. The converter has a white wire and a black wire on the output. If that means what I think it means, it should match up to the red wire and the black wire on the fence energizer input.

No guarantees, but very probably you are right. It would be good if you had a voltmeter to confirm this. Often, devices that are connected to a battery by the user are protected with a fuse which will blow if the polarity is reversed, or a diode that prevents use with reversed polarity.

Quote:

For what it's worth, the fence energizer actually can be powered either by a 6 volt or 12 volt battery and adjusts automatically somehow (no switch to flip to change it). I'm wondering if that means it can handle a somewhat flexible voltage input?

I think you are right, but again, no guarantees. It probably has an internal regulator of some kind. Do you have a website for this company?

Drawing just 45 ma, this thing would run long time on a marine battery.

ETA: I just noticed your link to the company. I'll have a look.

[Olowkow]

Well, in troubleshooting, they talk about checking to be sure the positive battery lead goes to the red wire. The simple fact that they do not say "reversing polarity will cause permanent damage", means to me that it is protected. Apparently an LED should flash when connected properly.

They also mention an AC adapter, but I don't seem to find one on the website.

Quote:

Using the power adapter supplied, the charger can be connected to 110 V line input. Alternatively, by using the battery lead supplied, it
can also be powered by a 12 V battery. The electric fence charger can even be plugged into your vehicle’s cigarette lighter, for fencing
horses when travelling or trail riding (separate lead required).

The manual mentions using a voltmeter to measure the high voltage! I'm sure they mean to use their accessory meter which can measure high voltages, rather than a run of the mill voltmeter.

[rwguinn]

Most farmers and ranchers I know use a 6/12 volt battery charger--like for car/marine batteries. Available at Wal-Mart, AutoZone, O'Rieley's ,Pep Boys, etc.
And yes, they run a long time on a marine battery.

[Pup]

Originally Posted by Olowkow

They also mention an AC adapter, but I don't seem to find one on the website.

Yes, that's not exactly the same model (mine is much older) so mine wasn't sold to work with an adapter, only a battery. But I couldn't find any detailed specifications for mine, beyond just "6 or 12 volt battery".

When I ran it on a battery, it would run a few weeks, so yes, it'll run a long time. I think the coons go out there with a battery tester though, and wait for the night it runs down to break into the garden.

Plugging it into the household current would also eliminate the cost of buying a new battery and battery charger (again ~$100), since I no longer have the ones I used to use.

[Macgyver1968]

Originally Posted by Pup

I think the coons go out there with a battery tester though, and wait for the night it runs down to break into the garden.

I totally LOL'ed when I imagined that in my mind. A raccoon version of Macgyver.

[Olowkow]

Originally Posted by Pup

Yes, that's not exactly the same model (mine is much older) so mine wasn't sold to work with an adapter, only a battery. But I couldn't find any detailed specifications for mine, beyond just "6 or 12 volt battery".

When I ran it on a battery, it would run a few weeks, so yes, it'll run a long time. I think the coons go out there with a battery tester though, and wait for the night it runs down to break into the garden.

Plugging it into the household current would also eliminate the cost of buying a new battery and battery charger (again ~$100), since I no longer have the ones I used to use.

Well, I personally would have no problem using the charger you have, simply because the fence unit in question seems to be pretty much "bullet proof", but that is of course just my impression from skimming the manual. One thing though, I would not place the adapter outdoors, rather splice an extension to the low voltage side, the wire that goes to the fence charger, and keep the adapter itself out of the weather.

AND, oh yes! Don't pee on the fence on a dare! Been there, done that!

[Mikemcc]

The converter will easily drive the fence, it's worth sticking in a 100mA fuse on the live line to protect the convertor and an RCD on it's supply to protect you

[CaveDave]

Originally Posted by Pup

That's good news!



I think i'm okay there. The converter has a white wire and a black wire on the output. If that means what I think it means, it should match up to the red wire and the black wire on the fence energizer input.



For what it's worth, the fence energizer actually can be powered either by a 6 volt or 12 volt battery and adjusts automatically somehow (no switch to flip to change it). I'm wondering if that means it can handle a somewhat flexible voltage input?

The polarity of many inexpensive converters is "molded" into the plastic case along with the specs and Agency Approvals, so you may look there. As noted by others, MOST devices are "protected" from accidental reversal (especially if designed to be powered from clip leads to an external source), or are simply "immune" to reversal - just do nothing 'til it's corrected.

Many devices rated 6-12 v. and normally using external automotive-type battery power will actually TOLERATE 20 Volts or more as input without damage, so it is not that critical. As others have said, as long as the current is at least at the rating and the voltage is within range, it should be fine.

You could even run a moderate size battery in "float" configuration to carry over power failures and accidental unplugging.

Cheers,

Dave

[Pup]

Thanks for everyone's advice! I tried wiring the fence energizer to the converter, plugged it in, and nothing terrible happened. No sparks, no flames. The only thing that happened was the "okay" light just started blinking as it should.

Now I need to put up the fence wires and the ground stakes and all that, but it looks like it'll work! I can keep everything inside where it's dry and protected, plug it into an outlet with a surge protector, and just run a wire outside to the fence and ground.

[ElMondoHummus]

People!... The proper technogeek/nerd/savant response must always be: THE BIGGEST ONE POSSIBLE!

[Olowkow]

Originally Posted by Pup

Thanks for everyone's advice! I tried wiring the fence energizer to the converter, plugged it in, and nothing terrible happened. No sparks, no flames. The only thing that happened was the "okay" light just started blinking as it should.

Now I need to put up the fence wires and the ground stakes and all that, but it looks like it'll work! I can keep everything inside where it's dry and protected, plug it into an outlet with a surge protector, and just run a wire outside to the fence and ground.

Just so there is no misunderstanding, you should place the AC/DC converter in the house, run the 12 volts (nominal) to the fence zapper which is located at the fence. If you "run a wire outside to the fence and ground", you risk shorting out the high voltage pulses (by various means). The fence should be connected directly to the terminals on the fence zapper device.

This thing is essentially just a strobe pulse generator. If you try to run the high voltage (10KV or so) wires anywhere, other than directly to the fence wire, it will be problematic.

[Pup]

Originally Posted by Olowkow

The fence should be connected directly to the terminals on the fence zapper device.

Okay. Gotcha!

[Olowkow]

The "RCD" is pretty much optional in this application, excellent though they may be. In the states we call them "GFI" (ground fault interrupter). It essentially compares the current in both legs of the circuit, and if they do not sum to zero, it means a current is flowing to ground through another path, (like through you) and it trips the circuit breaker. These have saved my bacon many times in my salt water fish tanks.

[Olowkow]

And of course, the "fence" must be well insulated from ground using the proper insulators, as described in the manual. Or of course, you can make your own, out of bottles or whatever. I suspect you already know this, but just in case you didn't I'm trying to cover all bases. I remember my own experience as a 10 year old kid, trying to build a crystal radio, and my cub scout manual neglected to mention that the tuning coil had to be bare wire where the wiper contacted it. Once I figured this out, I was on my way to becoming an electronics engineer.

[CaveDave]

Originally Posted by Pup

Thanks for everyone's advice! I tried wiring the fence energizer to the converter, plugged it in, and nothing terrible happened. No sparks, no flames. The only thing that happened was the "okay" light just started blinking as it should.

Now I need to put up the fence wires and the ground stakes and all that, but it looks like it'll work! I can keep everything inside where it's dry and protected, plug it into an outlet with a surge protector, and just run a wire outside to the fence and ground.

One word of caution: Medium-high pulsed voltages such as these animal repellers use can arc if the insulation used is insufficient (Most common insulated wire is rated 300, 600, or sometimes 1000 Volt, you can use glass or plastic tubing to raise the breakdown point) or moisture is present. Be aware that wood or other materials can be ignited by these arcs (such as where they exit the structure), so care is advised with the routing and materials involved. DON'T BURN YER *****' HOUSE DOWN! the garden ain't worth it!

Best Wishes,

Dave

ETA: Great minds think alike!

While I was writing this, several others came in on the same thing.
(STOLE MY THUNDER, THEY DID!!!!)

[OnlyTellsTruths]

Lots of AC/DC adapter info is covered here:

http://forums.randi.org/showthread.php?t=182300