Had to get my bear license

[Solomon Parker]

Yes, but with an all in one unit, typically, the solar panel is small, the battery is small, and the charger puts out a fraction of a joule. They work great for horses and animals which are more sensitive. Some times you need a bit more power!

My chicken fence uses a 30 watt panel, a 75 amp hour battery, and a 1 joule charger. It will go a month without sunshine, a bit overdone, but what can I say.

[Acebird]

I wonder how they do it in the medical field. It seems to me the defib packs used for starting your heart went up to 300 joules off a little 12 volt battery initially designed for lap tops. That much power can stop your heart as well as start it so I don't think a bear would go for a second shock.

[Bear Creek Steve]

The solar powered fence chargers do have a battery. The less expensive ones (ie. Harbor Freight) do have far less "kick" and of course are China stuff. The more expensive ones (ie. Kencove) are usually made for longer fence runs and have a greater "kick". The batteries in these are larger and will run effectively for 20-30 days with zero sunlight. Another factor is the age of the battery, ie. its health.

Steve

[Solomon Parker]

Not to get off topic, but from what I understand, defibrilators do not start hearts, just stop them. The idea is to stop the fibrilation so the heart will start rhythmic beating on its own. Bad idea for children and such.

Steve, I got both my battery powered chargers from Kencove. They are made in New Zealand and work excellently.

[shannonswyatt]

Attachment 3444
I bear hunt everyyear with a group just so I dont have to go to work

I need your boss to talk to my boss. If going hunting gets you out of work I need to get a better boss!

I've heard peanut butter on the wires work. You need to get them to lick the wire. Then they will stay away. Unfortunately, once they get in you can't keep them out, at least that is what I've been told. I hope you have better luck going forward.

[beemandan]

defib packs used for starting your heart went up to 300 joules off a little 12 volt battery

For a millisecond or so. Duration is the other element. A decade ago, when I meddled with the things they were pretty smart. They knew when to correct for atrial fibrillation or ventricular fib or a full restart for asystole.
A good fence charger may need to supply that same energy for an extended period and/or repeatedly to thwart a bear.

[Acebird]

Can anyone explain how a fence charger works? Is there a circuit that charges up a capacitor to a higher voltage and then discharges when something makes contact? How is the step up done without draining the battery in a short time?

[shannonswyatt]

Never set one up, but my guess is that the solar charger trickle charges the battery. Not sure how long the battery would last without that.

[Solomon Parker]

Brian, the pulse is discharged every time the charger *clicks*. There is not much energy expended, a joule is only equal to one watt for one second. Add to that the intermittance and power consumption is pretty low. Including losses a one joule charger probably uses one watt continuously. The voltage is high, 5000 or so, which gives you the jolt, to cause pain but not much else. A 75 amp hour battery will contain almost a thousand watt hours, meaning the charger can run about a thousand hours before the battery is dead.

I know you know the electrical stuff, but others might not.

[minz]

After some guys stole the boat motor off of my aluminium boat I was going to bring home a utility power factor correction capacitor (we are talking big boys here) and charge it with a hi-pot to about 100K volts. My wife objected for the very reason that cerezh mentioned. Good advice here, the current needs a complete circuit (created by the bear and the earth). The better the path (chicken wire ground, open mouth, sweaty bee keeper) the more energy delivered to the target.

[Acebird]

Brian, the pulse is discharged every time the charger *clicks*.

I thought they were much more sophisticated. It seems to me they could have a sensing circuit to first detect contact and as soon as contact is made then start "clicking" say for 3 seconds. Then it would last almost indefinitely being backed up by solar.

[beemandan]

I thought they were much more sophisticated.

And the next thing you knew, they'd have day/night image analysis built in to identify friend or foe....with terabyte harddrives, multicore processors, internet connectivity and internal cooling systems.
Some things are better off left simple.

[Acebird]

Some things are better off left simple.

Not if they fail to do what they are intended to do. When that happens they are useless but still simple.

[Solomon Parker]

I thought they were much more sophisticated. It seems to me they could have a sensing circuit to first detect contact and as soon as contact is made then start "clicking" say for 3 seconds. Then it would last almost indefinitely being backed up by solar.

The sensing circuit would have to be based on current traveling through the wire. The problem is, there is almost always something touching the wire, grass, tree, whatever. There would always be a connection being made, clicking off every 3 seconds, which is exactly what you have now. It would be even worse with my poultry nets which are impossible to keep off the grass and hard to keep off the ground.

My chargers have a light sensor that allows you to change the click rate based on whether it is day or night. I have it set to go every 2.5 seconds in the daytime and 1.5 at night.

They already last indefinitely with solar backup. My solar backup is powerful enough to power lights as well. If I could just find a decent 12 volt timer, I wouldn't need to run an extension cord out there every winter.

[beemandan]

Not if they fail to do what they are intended to do.

Which is why I said some things.