Alternator-Powered Skeet thrower

[soopergenious]

Hey guys (& gals)-
I'm new here, and wanted to get the input of people who have some experience with this. Currently, at my range, we use solar-recharged deep cycle 12v batteries to run the skeet throwers. However, the batteries are almost all dead (around 6 years old), and cost around $200 a pop. Rather than continue to invest in this system, would it be possible to power each 12v thrower with a small engine->v-belt->alternator setup? I can purchase a brand new 100a alternator for around $80, and a 6HP engine for around $90. What would be the benefits/ detriments with this system? I know that we would have to pay for gas and oil, however that should be fairly negligible considering we will only shoot a few hours a week. The motor on the thrower says 40a current on it, and the current batteries are rated for 100ah, if that helps.
I feel kind of bad posting something totally not tractor-related for my first post, but wanted to hear y'alls thoughts. Mods, please feel to move this to whatever catagory would be best, as once again, I am a noob and have very little idea of how to file stuff and what not. It took me 15 minutes to just figure out how to start a new thread-- I am much better with mechanical and electrical engineering than I am with using forums.
Thanks again
Jimmy

 

[dave1949]

Welcome!

Never tried it, but I wonder how well the alternator will react to quick load changes. I assume the 40A thrower motor is not a constant load, and represents a possible peak draw when a skeet is thrown?

I think of automotive alternators as charging the battery, and the battery supplies the load in combination with the alternator. With no battery involved, I am not sure how it would react to a fast load ramp-up.

The engine noise could be a nuisance when not shooting. A cheap engine could be a cranky to start engine, no fun.

 

[DT86]

Personally if I already had the solar set up I'd probably stick with it. I just put together a solar set up for a fence charger using the biggest deep cycle battery I could find and the battery was closer to $120 than $200.

How many thrower set ups do you have?

 

[DT86]

I think of automotive alternators as charging the battery, and the battery supplies the load in combination with the alternator. With no battery involved, I am not sure how it would react to a fast load ramp-up.

The engine noise could be a nuisance when not shooting. A cheap engine could be a cranky to start engine, no fun.

Yeah I was going to add that but you beat me to it!

 

[broadway3000]

I think you would quickly get annoyed with the constant noise of the generator. Besides that I think you would still have to run at least 1 battery to hold power because of the 40 draw.

 

[soopergenious]

Thanks for the replies. We have 5 stations running off of batteries. The solar system is broken on some of them, and will need to be replaced soon on the others. We do have 110v power available a hundred yards away or so, however we would have to purchase independent transformers for each thrower as they are in a 5-stand setup. Does anyone have an idea that does not require the use of solar, yet is still relatively cost effective? I believe we only have 15 watt panels, and once we start to use the range again, I doubt they will be able to keep up. Also, each battery is almost twice the size of your average car battery (these are 100ah) and also weigh around twice as much-- not fun to carry around. Is there any type of alternator system that would be able to handle the sudden 40a surge? The noise will not be an issue- especially with ear plugs when shooting. Thanks again for all the replies.
Jimmy
PS: DT86- where do you buy batteries? The cheapest 100ah's I could find were on eBay and still cost around $180. $120 would be fantastic if you could point me in the right direction.

 

[Biggreenavalanche]

I'd go ahead and transition to 110/transformer set up...think you'd be a lot happier with that in the long run...flippin a light switch beats fueling, starting, exhaust, and noise of small engine and is probably a lot more dependable than either the curren set up, or the proposed setup...just my :2cents: worth.

Rich

 

[aczlan]

So you are talking about spending $190/station to add a gas engine and there are five stations, so $950 and power is 300' away.
Lets see:
$422 400' of 12/3 UF
$12 2 x space 4 circuit breaker box
$16 2 x 20 amp breakers
$20 Boxes/Outlets
$500 5 x 40 amp 12v chargers
$969 Total
Just use your current batteries or if needed get some new ones.
More realistically, I suspect that your machines don't draw 40 amps except for possibly a half second when the skeet is actually being thrown (this could be verified if we had the make/model of if you checked with the manufacturer) , so you could get cheaper 10 to 20 amp chargers and buy a couple of new batteries.

Edit: Looks like the RC community has found a way to re-purpose old server power supplied to get 30+ amps at 12VDC, so if you or someone at the club is good with soldering and wants to eliminate the batteries without spending hundreds per station on power supplies, see http://www.rcgroups.com/forums/showthread.php?t=1005309 or http://www.rcgroups.com/forums/showpost.php?p=17731408&postcount=491

Aaron Z

 

[soopergenious]

Thanks Aaron. I will definitely look in to that. The farthest thrower is another 25 yards or so away, however that should not be too much trouble. If we didn't have to worry about batteries, that would be great. Where are you sourcing the transformers from? Thanks again.

 

[aczlan]

Where are you sourcing the transformers from? Thanks again.

For battery chargers, I just searched for 40 amp battery charger. For a 12 volt supply the sites I linked to had directions and sources, but it appears that there are those selling them on Ebay for under $50: RC Power Supply 575 Watts 47 Amp 100 240V AC to DC 12V Efuel CB 20 30 40 50 60 | eBay At that price, I would just get power supplies and eliminate the batteries altogether.

Aaron Z

 

[k0ua]

Buy smaller batteries, and use the AC powered chargers to keep up the batteries.. the chargers could be something like 10 to 20 amp chargers or even smaller, the batteries could be something like 40 amp hours or even maybe as small as 20amp hour.. They just need to provide the 40 amps of current when the target is thrown. So it is intermittent duty.. The reason you have such large batteries now with the solar setup is because you must have a battery that can throw targets all day.. The solar "chargers" for lets say a 15 watt panel is less than a 2 amp charger a 45 watt solar charger is something like 4 amps.. so you have to have a big "flywheel" in the form of the large battery to be able to make many throws, because the solar charger will take a long time to charge it up. But with a good regulated AC powered charger it will charge back up a smaller battery in minutes, and the battery will take the "hit" of the 40 amp draw which I believe will be in the form of only seconds. I have made several assumptions here about how the throwers work, but I believe I am correct.. you could check with the manufacture of the throwers to confirm the current draws and durations. Good Luck.
James K0UA

 

[k0ua]

For battery chargers, I just searched for 40 amp battery charger. For a 12 volt supply the sites I linked to had directions and sources, but it appears that there are those selling them on Ebay for under $50: RC Power Supply 575 Watts 47 Amp 100 240V AC to DC 12V Efuel CB 20 30 40 50 60 | eBay At that price, I would just get power supplies and eliminate the batteries altogether.

Aaron Z

That might work, but it might not., It depends on how much onboard electronics are in these throwers.. and how clean those switcher power supplys are. They mention using them for CB and Ham equipment, which would indicate they would be suitable, but I would buy one and try it first. They are probably fine.. And the throwers may be mostly electromechanical. and not have any sophisticated electronics on-board anyway.

James K0UA

 

[aczlan]

That might work, but it might not., It depends on how much onboard electronics are in these throwers.. and how clean those switcher power supplys are. They mention using them for CB and Ham equipment, which would indicate they would be suitable, but I would buy one and try it first. They are probably fine.. And the throwers may be mostly electromechanical. and not have any sophisticated electronics on-board anyway.

Those started life as hot swappable power supplies from rackmount servers, so I would hazard a guess that they put out fairly clean power. My worry would be that they might not be able to handle a sudden spike in power very well. I agree that trying one first would be a good idea (I might drag out a bunch of extension cords or a small generator and try it with that before pulling power).

Aaron Z

 

[k0ua]

Those started life as hot swappable power supplies from rackmount servers, so I would hazard a guess that they put out fairly clean power. My worry would be that they might not be able to handle a sudden spike in power very well. I agree that trying one first would be a good idea (I might drag out a bunch of extension cords or a small generator and try it with that before pulling power).

Aaron Z

Yep that is what I would do, drag out some good extension cords, and get one of these supply's and run it for a day on a thrower, and go from there.

 

[hr3]

8 to 9 amps of power for each charger would be about 40 to 45 amps on 110v,, Might want to look at another way.. #12 wire an't gona cut it,,

 

[Wilky]

8 to 9 amps of power for each charger would be about 40 to 45 amps on 110v,, Might want to look at another way.. #12 wire an't gona cut it,,

Did I miss something. 9 amps of 110 is 80 amps at 12 volts

 

[aczlan]

8 to 9 amps of power for each charger would be about 40 to 45 amps on 110v,, Might want to look at another way.. #12 wire an't gona cut it,,

Where do you get 8-9 amps per charger? 47 amps @12DC is ~590 watts. If the power supply is 80% efficient, it will pull 740 watts at 120VAC which is ~6 amps. That gives you 18 amps at 120VAC on one side of the 220 20 amp leg and 12 amps on the other side IF all 5 are throwing at the exact time. The continuous draw has to be less as otherwise you might get 2 hours continuous use out of a fully charged 100ah battery.
Looking at the Atlas throwers, Nativeoutdoors.com says that the Atlas AT50 & AT250 models pull "up to 30 amps for a 1/4 cycle" and per the Atlas site one cycle is 0.6 seconds for the AT-50 or 1.2 seconds for the AT-250 so I would hazard a guess that this one is 40 amps for a similar amount of time and it should be possible to avoid tripping the breaker.


Aaron Z

 

[hr3]

Where do you get 8-9 amps per charger? 47 amps @12DC is ~590 watts. If the power supply is 80% efficient, it will pull 740 watts at 120VAC which is ~6 amps. That gives you 18 amps at 120VAC on one side of the 220 20 amp leg and 12 amps on the other side IF all 5 are throwing at the exact time. The continuous draw has to be less as otherwise you might get 2 hours continuous use out of a fully charged 100ah battery.
Looking at the Atlas throwers, Nativeoutdoors.com says that the Atlas AT50 & AT250 models pull "up to 30 amps for a 1/4 cycle" and per the Atlas site one cycle is 0.6 seconds for the AT-50 or 1.2 seconds for the AT-250 so I would hazard a guess that this one is 40 amps for a similar amount of time and it should be possible to avoid tripping the breaker.


Aaron Z

The OP said he had a 120v outlet to run this from.. He never mentioned that he had 220v anywhere ???

Your assuming the battery's are fully charged to start with,, If the battery's are in a discharged state the charger will try to draw more,,,

 

[aczlan]

The OP said he had a 120v outlet to run this from.. He never mentioned that he had 220v anywhere ???

Good point, I am assuming that there is a breaker box with 220v not overly distant from the location where they have 110v as this should be on its own circuit and its hard to get 220v from 110v... Being as the OP didn't say anything to the contrary, I assumed that this was the case.
That still doesn't explain 8-9 amps/charger at 120VAC to get 40ish amps at 12VDC

Your assuming the battery's are fully charged to start with,, If the battery's are in a discharged state the charger will try to draw more,,,

As for charging: If using the 47 amp power supplies I linked, a battery should not be needed as they have enough juice to run the throwers all by themselves. Might be worth putting in a capacitor (like you would use on a car subwoofer amp) though if they have problems.

Aaron Z