Power Your Bug Zapper with Solar: 12V DC to 12V AC Conversion Guide

[Phil12]

Hey all,

A 'rank' newbie here, so please bear with me. ;-)

I have a 'solar charged' 12V battery (with charger) for an electric fence charger. I'd like to use this solar charger and battery to power a 12V AC (I think) low voltage landscape bug zapper. It 'must' be 12V AC, I think?

Is there a fairly easy/cheap way to do this, or am I having pipe dreams?

Thanks!

Phil

 

[NTL2009]

It might be very simple, but you need to know more about each of the components.

How many amp-hours is the battery?

What is the actual power requirement for the bug zapper? Saying "12V AC (I think)", isn't going to get you there. How much voltage, how much current? AC or DC? Maybe a model number of the device if you can't determine this info.

 

[Phil12]

The Battery is 14 AH. The Zapper is Malibu Landscape Lighting Model 8401-4501-01. It says LED 12V, 1.3W.

Thanks!

 

[NTL2009]

When I looked up that model number, it does not include a power supply, it says to use with a low voltage landscape system. It wasn't 100% clear to me if all those systems are AC or DC, or what the voltage tolerance is. What were you using to power the bug Zapper? What are the specs or readings on it (do you have a meter?)?

Assuming it is DC (likely), you can probably connect it directly to the battery. I say probably, because a battery while charging might go up to ~ 13.8 V, so the question is if the Bug Zapper can accept that slightly higher voltage ( probably).

If it can be connected directly, a fully charged 14 AH battery , the zapper draws about .11A, so about 127 hours of operation - looks good.

 

[Phil12]

The Zapper is new, and has never had power (of any sort) to it. Do you mean resistance in ohms? I just tried, and get no measurement at all... like an open. Tried pushing the selector button (light vs UV light) and still nothing. I also looked up a Malibu 300W Power Pack and see this -

• 300 Watt Outdoor Power Pack Transformer
• Converts 120 Volt household electricity to a safe 12 volts(AC)

Any way to convert the DC (from battery) to AC?

Thanks!

Phil

 

[NTL2009]

It's not surprising you get no R readings, the unit probably is not resistive.

I also see 12 V DC landscape power supplies for sale. I'd give 99:1 odds your bug zapper works on AC or DC, they probably put a full wave rectifier in the front end to accommodate this (and also guarantee you would get high R with an ohm-meter). You could write the manufacturer and ask if AC or DC is OK.

Maybe someone more familiar with these landscape systems can comment. Or maybe current limit the supply and just try it? a 10 Ohm R in series with the battery would drop about 1.1 V @ the 0.11 A draw, and provide some protection.

 

[jim hardy]

It's a fairly safe bet the bug zapper rectifies 12Vac into 12-15 volts DC and steps that up to the hundreds of volts necessary to "zap" bugs.
But i'd give odds of five to one rather than NTL's 99 to one.

So it's only a fairly safe bet.

What is the cost of that Zapper ? If it's only a few bucks that you're willing to lose,,,
Connect it to 12 volt battery through a large 12 volt lamp like a car headlight bulb.
If the lamp lights brightly you shouldn't try to run it on DC.
If the lamp glows very dim or not at all, then you can try it on DC BUT with knowledge you still might wreck it.

So it comes down to whether you're willing to risk the cost of that Zapper for a chance at convenient DC power.
Myself i'd risk five bucks but not twenty-five.

If it's easy to open, post a picture of its innards.

old jim

 

[Phil12]

$14, so it won't change my lifestyle if I make some internal components into external components. ;-)

Here are 2 pics - couldn't get the board any further out with all the wires connected.

Thanks!

Phil

 

[NTL2009]

OK, I'm assuming the two thicker black wires on the lower left of pic #1 are the input power connections?

Those are connected to a 4-lead device, so that is most likely the full-wave (bridge) rectifier I mentioned earlier. That should make it universal for AC/DC ( but there can be exceptions, since the peak of a rectified AC signal will be 1.4x the peak of a DC, and/or, they could still be looking for a 60 or 120 hertz signal for other purposes). But I really, really doubt those exceptions apply.

Are the markings on that part a (+) and a (-) and a (~)? That's how they usually mark packaged bridge rectifiers. I think you are good to go - Jim Hardy's idea of connecting through a 12 V auto bulb is a good one in any case, just to see if there are any load issues.

 

[Phil12]

Yes, incoming up through the stake. The only 4 leads I see are the blue, yellow, red, and white? They go Up into the zapper body in pic #2, and since this a "dual function" unit, I don't think it's a rectifier? Don't see any markings as you suggest. The 2 "modes" are "LED only", and "zapper mode with UV light", so just 2 separate circuits? The extra red wire is going in and out of the push button to toggle between modes. It's in that 'block with the silver screw' at the bottom of pic #1.

How to connect thru the bulb? In series?

Thanks!

Phil

PS - The black and yellow 'box' in pic #2 has 5 places it's connected to the board. "19301" is on the side of it. Also, the large Orange part has 'CBB81' and '2000V223J' printed on it. Not sure if this info helps?

 

[NTL2009]

I see 2 black wires in the lower left of pic #1, and again on left of #2. Those look like the 12 V input to me - is the picture making this look different than real life? What do those wires go to? I assume some sort of 12 V connector (or just bare wires)?

The 19301 label is the transformer/inductor probably to step up the voltage for the bug zapper, the orange part is probably a 2000 Volt rated capacitor, also for the bug zap circuit, but those markings aren't always standardized.

Yes, just put the auto bulb in series from the battery to the input of the bug zapper. Get it all closed up carefully, you only want bugs to get zapped!

 

[Phil12]

The 2 black wires are soldered to the board - the 2 brownish looking solders on the lower left corner of the board in pic #1. They show again in pic 2 on the left side corner of the board - what I did was just turn my wrist from palm up in pic 1 - to palm down in pic 2 to show the underside of the board.

I'll try the bulb and see what happens. Bet it might not be as bad as touching that 12k volt electric fence though? :-D

Thanks!

Phil

 

[jim hardy]

I agree with NTL it looks like power comes straight into abridge rectifier.

That thing should be impervious to polarity.

Unless it uses 60 hz for some internal timing or charge pump it will work on DC.

If i had one i'd try it .

Is there a fairly easy/cheap way to do this,

Sort through the trays of old AC adapters in thrift shops. You'll run across one sooner or later that makes 12 VAC. Old video games used them.

Good Luck !

old jim

 

[Phil12]

OK, Guys That's an Aha! moment for sure. ;-)

Tomorrow I'll hook 'er up and see what gives. Had no idea that that D4? where the cables come in, was a rectifier on the board. Yikes... time for a self inflicted Dope Slap. ;-)

I can probably wire a house with 110/220 AC and also run straight DC around a boat or vehicle, but when we get to all these ohms/resistors/AC/DC, etc. I'm a baby!

Will post back when tested. Fingers crossed, but based on you guys' knowledge, I'm Hopeful! Then again, $14 for the zapper won't be a drastic loss. I'm also a tiny bit like Myth Busters, and kind'a like to watch things explode. ;-) Hoping it all works for this though! :-D

I expect that it will, and Thanks!

Phil

 

[jim hardy]

I can probably wire a house with 110/220 AC and also run straight DC around a boat or vehicle, but when we get to all these ohms/resistors/AC/DC, etc. I'm a baby!

I can fix a tube radio. Ever feel like a dinosaur veterinarian pining for Jurassic Park ?

What we do here is share what we know, and learn from everyone who shares.. It's good for one's humility.

old jim

 

[OCR]

I just tried, and get no measurement at all... like an open.

I think you actually do have an open, the bug provides the "switch" that closes the circuit... and pays for it dearly.
An electrical discharge insect control system...

Bet it might not be as bad as touching that 12k volt electric fence though? :-D

Lol... ... _↓

Bet it might not be as bad as touching that 12k volt electric fence electrical discharge animal control system, though? :-D

Besides touching one... I've also heard of another act that should be avoided on an electric fence...

Leaky spark plug wires can cause unhappiness, too... lol

 

[Phil12]

This AM I put the zapper all back together and touched the 2 leads to the 12 V battery wires. No smoke, flames, or loud noises... and the light even came on! :-)

Just ordered an 12v photo cell dusk-to-dawn switch ($3.79), so I should be in business shortly.

Thank you for your time and patience!

Phil

 

[jim hardy]

Great News , Thanks !

Let us know that it still "zaps" ?

old jim

 

[NTL2009]

Great News , Thanks !

Let us know that it still "zaps" ?

old jim

Yes! This experiment is not complete until some mosquitoes are harmed!

 

[Phil12]

Will do guys!

I do believe that I've encountered another challenge though. The zapper has a push button "toggle" switch to change between "LED light only" and "zapper with UV light". It apparently defaults to "light only" when first powered on, and then the switch has to be pushed to change it over to zapper mode. I'll bet that a quick solder of a jumper wire somewhere might be a cure? I don't care about having the "LED light only" mode at all, just having the zapper come on.

Thanks!

Phil

 

[NTL2009]

Will do guys!

I do believe that I've encountered another challenge though. The zapper has a push button "toggle" switch to change between "LED light only" and "zapper with UV light". It apparently defaults to "light only" when first powered on, and then the switch has to be pushed to change it over to zapper mode. I'll bet that a quick solder of a jumper wire somewhere might be a cure? I don't care about having the "LED light only" mode at all, just having the zapper come on.

Thanks!

Phil

Hmmm, could be easy, but could be tricky. Ohm out the switch - if it is "Normally Open" and reads closed only when pressed, you might get away with just shorting across the switch with a jumper. If it is "Normally Closed" try disconnecting one wire (and insulating the ends).

But... it might be looking for a transition from normal-pressed-normal after power up, with an actual latching (flip-flop) circuit controlling the ON/OFF state of the zapper. That might take some reverse engineering of the PC board to create a schematic and figure out what point needs to be set high or low. You might be able to some semi-educated guessing, but definitely risk blowing it out.

But I suspect that simply locking the switch state in with a short or open (as needed) will probably do the job.

 

[Phil12]

OK, I'll see what I can do here. Don't want to do too much with it until I get that 10 ohm resistor in line from the power though. Should be early to mid-week?

Will keep you posted.

Thanks!

Phil

 

[NTL2009]

Now that we know there's a rectifier in there, and that it started up OK, I wouldn't be too worried a current limit R in there (but an auto bulb is readily available in any auto store or big-box store, if you want to be extra careful). Just go for it.

 

[Phil12]

I've checked 2 12V bulbs I had here - a headlight and a dome light. The best I see is 1.5 ohms with the dome light - headlight was .7 . Not enough to keep me down near the 12V? I read 13.7 V with the solar charger wired in parallel, and then 13.5 V with the 1.5 ohm bulb in line - only dropping .2 V?

I do have a 10 ohm/10W resistor on the way. The zapper said 1.3W, so I'm 'hoping' that the 10W is just 5 X more than I needed. You guys would know in your sleep, but I'm pretty much clueless. Things like 'How sensitive to over- voltage would that rectifier be - would it stand almost 2 extra volts?'

Thanks!

Phil

 

[NTL2009]

That's the "beauty" of using a small bulb. At low currents, the filament stays cool and has a low resistance. If the current increases enough to produce a little light, the resistance goes up with temperature. When it is sized properly, it acts as a somewhat constant current source, not "constant", but it flattens the curve (and then fuses if the current gets too high!).

I don't know if they list the wattage of the dome light, but if it measures 1.5 ohm with a meter, at 12 V it would be 18 watts if that R didn't increase. I'ts probably less, headlamps are generally ~ 55 watts. At .7 ohms and 12 V (and cars are actually closer to 13.6 with the alternator running), that would be over 200 watts - so you can see the effect. You could also try measuring the dome lamp current at 12 V, I bet you see far less than the 8 Amps you'd expect at 1.5 ohms.

And you won't see any voltage drop across the bulb until you add a load to it, otherwise it just acts like a wire. OK, it looks like you did hook up the lamp with the zapper as a load and saw .2V drop. That makes sense. I'm guessing the zapper isn't that sensitive to a little over-voltage, I doubt those landscape supplies are well regulated, and probably many do run right off of "12 V" batteries. But if that concerns you, I'd use small diodes to drop ~.7 V for each diode. Your 10 ohm R is only going to drop ~ 1 V anyhow. Can you measure the current for the zapper? Might need to sacrifice a bug, the current might climb while it is actively in "execute" mode (or it's just discharging the cap, no effect on source current)?

I'm also curious - do you know how many watts your solar panel for the fence charger is rated for?

 

[cranksci]

The Zapper is new, and has never had power (of any sort) to it. Do you mean resistance in ohms? I just tried, and get no measurement at all... like an open. Tried pushing the selector button (light vs UV light) and still nothing. I also looked up a Malibu 300W Power Pack and see this -

• 300 Watt Outdoor Power Pack Transformer
• Converts 120 Volt household electricity to a safe 12 volts(AC)

Any way to convert the DC (from battery) to AC?

Thanks!

Phil

Google "power inverter", or you can build one yourself if you have the know how. They can be quite simple.

 

[Phil12]

Sorry for the delay guys - outboard motor issues. Fired it up the other day and it was purring happily, until after about 15 - 20 minutes it died. Checked fuel pump, etc. and had just put an extra 5 gal in the tank. Turned out that the fuel pickup tube in the tank had dropped off of the fitting at the top of the tank! Still got to fish that out somehow.

Back to this zapper. My 10 ohm resistor is arriving at any moment today, and have already wired in that headlight bulb. Planning to put the resistor after the bulb, and hopefully keep things down to 12V. I did notice also that the zapper box flap says - "Use ONLY with low voltage outdoor landscape lighting products with power packs that have a maximum output rating of 12 volts, 300 watts per circuit."

No idea on the watts for the solar panel and tried searching for some tech specs, but hoping also that the Dusk to Dawn switch will keep that mostly out of the equation. I'm thinking that the panel won't actually be charging until after the zapper goes off.

That 14 AH battery is also a bit of a concern. I forget the conversion from amps to watts but thought it was 1,000? Wouldn't that mean I've got 14,000 watts instead of the max of 300?

Thanks!

Phil

 

[Phil12]

Forgot to add the other question - would the "dome light" (12 watt) work better than the "head light" for increasing resistance? I've already got leads soldered to it, so it's a real easy swap.

Thanks again!

Phil

 

[NTL2009]

The dome light will drop more voltage with a load attached than the headlight, since the dome light is lower wattage at 12 V, it is higher resistance (just as you measured).

However, neither light nor resistor will drop any voltage w/o a load attached. If the zapper is actually critically specing 12 V absolute max (I doubt it), then you really need a 12 V regulator.

I wouldn't worry about the 300 W max note, the zapper will draw whatever it draws. The probably say thas as it may not be fused, so in case of an internal short, it might be a hazard. The dome light will limit current for you in that case. And watts is Volts times Amps. Hard to say what your battery could deliver as max amps, but @ 14 amps for an hour, so much more than that short term (this is cranking amps on a car battery). 12 V times say 30 amps = 360 watts for reference.

 

[Phil12]

OK, thanks! Would something like this take care of the whole thing, in place of resistors and bulbs, etc? This is now becoming a challenge (LOL!), and still easier than running a whole 110 line underground for close to 100 yards and still adding a either a power pack or a 110 V plug-in zapper. ;-)

https://www.amazon.com/dp/B06Y5JHZG2/?tag=pfamazon01-20

Phil

 

[NTL2009]

Something like that would do it, but I really doubt you need to go to that extreme. I'd be very surprised if it could not handle lead-acid battery voltages, especially with that dome lamp in series dropping it down a bit.

Or a low-drop-out regulator like this, only ~ 0.1-0.2 V drop-out (that is, it needs ~ 12.1 ~ 12.2 V into maintain 12 V out, will stay at 12V out as the input rises above that minimum) at the currents you need, a battery like that probably won't be blow 12.2 with a decent charge, and the zapper would likely work a little below 12V anyhow:

http://www.mouser.com/Search/ProductDetail.aspx?R=LM2940T-12.0%2fNOPBvirtualkey59500000virtualkey926-LM2940T-12.0NOPB

 

[Phil12]

OK, just rigged it up in series. From the battery + (Red wire) - through the dome bulb - through the 10 ohm resistor - to the zapper. The - (black wire) then comes straight back to the battery/solar panel.

When checking volts, I get the same 13.5V - 13.7V between the + and - sides which would be expected, since I'm in parallel and seeing battery and/or solar panel volts. When I read the + wire from before the dome bulb to after the resister I see less than 1 volt (.97). Does this sound "logical"?

It's been on the "UV LED and zapper" for about an hour now. No smoke, flames, or LED's going out yet. :-)

Thanks!

Phil

 

[NTL2009]

If I follow, you are seeing a drop of ~ 1 V across the combination of 10 Ohm R and dome light, which are in series between the battery and zapper. If so, then your 13.5-13.7 V at the battery would be 12.5-12.7 V at the zapper. That is what you should see if you measure across the leads of the zapper.

That's probably as high as the battery voltage will go - I think you'll be fine.

Did you figure out how to get the zapper on through an off/on cycle of your timer?

 

[Phil12]

The 1 (.97) volts is what I see on the multimeter (set at 20V DC scale) when touching the probes "ahead and behind" of the dome light and resistor. Red Probe > dome light > 10 ohm resistor > Black Probe, all on the same + Red wire, heading for the zapper.

That switch to go from "LED Light only" to "UV and zapper" will be the next challenge. As mentioned, it seems to 'always' come on at 'first power-up' in the "LED Light only" mode. Then the push-button switch must be pressed to turn that off, and turn on the "UV and zapper".

That does seem strange to me, as if I had a string of them and always wanted zappers on, I'd have to walk down the string every evening and push every button? It could be a fatal flaw in the design of the zapper for this experiment. That's not mentioned anywhere in the instructions, etc. ie. "You must push the button to switch over to zapper mode each time they come on. I did see something about the "zapper only works in 'UV mode', not with the other 'LED only' mode." I'll check further and see what I can find though.

Photocell - (dusk to dawn switch) is still in transit, but won't matter much if this thing comes on to "LED Light only" each time it gets power, and the button needs to be pressed. It probably doesn't help too much, but the 2 Red wires on the Left side of the board in photo #1 are both going into that switch. The Red to the right of the board goes down into the light and powers either the 'LED' or the 'UV and zapper'. Not sure which one is which.

Thanks!

Phil

 

[Phil12]

Update: Left the zapper on all night, and about 6 bugs total (2 of them mosquitoes) have gone to the happy hunting ground. That part seems to be A-OK! :-)

Will update again in a day or two on this switch between LED and zapper.

Thanks!

Phil

 

[jim hardy]

Sounds like it's not drawing very much current at all.

Does voltage change when you press the button to turn on UV/Zapper ? Do they come on ?

Can't quite make out part numbers on your picture.

What happens if you press and hold the pushbutton ?
Do UV and zapper come on ? If so you can probably just short the switch, or remove it and twist the wires together. Try a piece of tape to hold it pressed, see if it starts okay.

 

[Manolis]

A couple of points:

I agree that that black device is a bridge rectifier. Sometimes these are specified right on the limit. Running with AC input means that all 4 diodes are sharing the heat dissipation. Running with a DC input means that 2 diodes are dissipating ALL the power resulting from the voltage drop x current so they are dissipating double what they would be with AC. (This matters only if you can feel the device getting hot.)

12 volts RMS will produce 12 x 1.4 = 16.8 volts DC, minus about 2 volts lost through the rectifiers. So 14.8 volts.
12 volts DC will produce 12 minus about 2 volts lost through the rectifiers. So 10 volts. Consequently, I wouldn't recommend adding a resistor or bulb to lose even more voltage. In fact, had it not worked I would have been suggesting linking out the bridge rectifier.

 

[jim hardy]

Consequently, I wouldn't recommend adding a resistor or bulb to lose even more voltage. In fact, had it not worked I would have been suggesting linking out the bridge rectifier.

The purpose of the bulb/resistor is to limit current flow into the device should something inside it latch "on". There's a SMPS on that board to make high voltage for the zapper , i wanted to limit current into the device just to rule out pyrotechnics. Don't know for sure yet whether it uses AC ripple to trigger something .

When he gets ready to button this one up the current limiters can go away.
Their 25 amp limit is probably for fire protection.

I did notice also that the zapper box flap says - "Use ONLY with low voltage outdoor landscape lighting products with power packs that have a maximum output rating of 12 volts, 300 watts per circuit."

The light bulb current limiter is an old technician's trick. Being an old technician i just wanted to not destroy the circuit board.

old jim

 

[Phil12]

Hey guys,

Just wanted to give a quick update on this "experiment". I think I'm going to leave it As Is, without the photocell. The zapper works great, almost too well, as I have to disconnect it and clean it off every day or two. I've put it on the front porch and just leave it on 24/7.

Many mosquitoes have gone to the Happy Hunting grounds, though! :-D

Thanks so much for your time and patience with this 'babe in the woods'!

Phil