110VAC to 12VDC

[rvr6000]

I've had this old light bar from a squad car for a couple years now. Looks pretty cool all lit up in the garage but I'm getting tired of having a car battery sitting right there to run it.

I've been trying to find a 110v-12v transformer but everything I'm finding is for a really small electrical load. Unfortunately I'm not sure off the top of the head what the electrical draw would be but with everything on it has to be quite a bit......4 rotating beacons, 2 alley lights, 2 flashers and 2 take-down lights.....not to mention the arrow stick on the back.

Anyone have any guesses what I could do to eliminate that battery and just use the garage power? Thanks.

Chris

 

[d33pt]

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=120-538

that should do the trick.

 

[Steve in Mi]

A battery charger. I see them for 5 to 20 bucks at garage and flea market sales. Or you could get the fancy power supply that d33pt suggested.

 

[rvr6000]

Found the literature online for the lightbar. Without the Arrowstik and all the lights on the draw is almost 19.5 amps.

I've tried just using a battery charger before but I don't think the amps were there that the light bar needed.

 

[mrb]

computer power supply. For example this one at $37 http://www.newegg.com/Product/Product.aspx?Item=N82E16817709027 gives you two 12v outputs at 20 amps each. on a PC power supply, shorting green to ground on the ATX connector makes it turn on and then it can be used to power other stuff. you have to open it and see where each group of yellow (12v) wires comes from, you will usually have two seperate 12v busses and you dont want to cross connect them. either solder on new large wires or parallel a bunch of the yellows and blacks as 20 amps is too much for the single conductors coming out of the power supply.

 

[Jack Olsen]

Here's one. It's just what came up with a Google search -- but it looks like you'll be able to find one.

 

[rvr6000]

Awesome....Thanks everyone. MRB - never even thought of that and I just happen to have an empty computer case sitting in the basement doing nothing. Will have to dig into it after work. Thanks again everyone.

 

[mrb]

Awesome....Thanks everyone. MRB - never even thought of that and I just happen to have an empty computer case sitting in the basement doing nothing. Will have to dig into it after work. Thanks again everyone.

check and see the current for each output, not all computer power supplies have that much 12v. there should be a label on the ps listing the current for each output.

 

[rvr6000]

Will do....thanks.

 

[Capt_Leisure]

A 12VDC power supply that big might be a little spendy, but you've always been the high-roller type.

What about an old motorcycle battery and a $5 trickle charger? I'd set you up, if you ever came out to visit.

Or, you could just give the light bar to me. If you don't, I'll tell Mom it was you who hid that plate of deviled eggs in the spare tire compartment of the station wagon back in '78.

 

[2LTim]

rvr6000: Be carefull with virtually all of the suggestions so far! In one of your post you said, "It draws 19.5 amps without the Arrowstick." The Arrowstick will draw 3 to 5 amps, but even if you leave it off, 19.5 is awfull close to the rated output of the previously mentioned power supplies. They will run really hot..... 'Til they smoke!

 

[mrb]

computer power supply wont (shouldnt) smoke....it will just shut down on overload. i used one to run a heavily loaded 12v motor, was pushing the ps pretty hard -no problems.

 

[rvr6000]

A 12VDC power supply that big might be a little spendy, but you've always been the high-roller type.

What about an old motorcycle battery and a $5 trickle charger? I'd set you up, if you ever came out to visit.

Or, you could just give the light bar to me. If you don't, I'll tell Mom it was you who hid that plate of deviled eggs in the spare tire compartment of the station wagon back in '78.

You can have the light bar if you give me that picture of Grampa E working out on the ore docks. I'll think about the trickle charger idea....gotta get the new shelves and stuff built in the garage first and decided where the light bar can go.

 

[csp]

A trickle charger isn't going to put out enough amperage.

 

[aandpdan]

Tripp-Lite makes a couple of 12 volt power supplies.

PR20 - 20 amp
PR25 - 25 amp
PR30 - 30 amp

If you're really at 19.5 amps I'd probably go with the PR25.

They are bit pricey, $150 and up, but you won't have to deal with batteries and can run the lightbar as long as you want.

 

[Diablo]

Go to any electrical wholesaler, or better yet one that deals with control components and control panels and they will have a power supply that should work

 

[mrb]

Go to any electrical wholesaler, or better yet one that deals with control components and control panels and they will have a power supply that should work

that route is going to cost him a couple hundred bucks............

 

[Torque1st]

You can find any number of units on fleabay.

You could also split the lights into groups powered from different supplies.

 

[z28toz06]

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_207204_-1

 

[NUTTSGT]

A word of caution, alot of that stuff will get quite warm when being used. Make sure it can get plenty of airflow to cool down. I'd rather not see you posting "I had a fire thread"

 

[Diablo]

that route is going to cost him a couple hundred bucks............

The VA your talking here isnt much at all i dont see it over 100

 

[dipper]

I looked in the power supply cabinet at work but don't have anything that large of current output.

Here's a link to one from jameco, i have used mean-well supplies before, they are good for the money.
http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_null_2094872_-1

 

[mrb]

The VA your talking here isnt much at all i dont see it over 100

240va mimimum.... they start getting expensive over 100w.

i found this though....this is the thing to get (just make sure you use proper size wire, a fuse block, etc....dont just connect all your load to the output terminals a short will turn into an arc welder

http://www.mpja.com/prodinfo.asp?number=18402+PS

i think i will buy one just to have..... 50 amps @ 12vdc

 

[Torque1st]

I have a 14VDC 40A supply I used for charging RC car batteries. I have often thought about installing a twist-lock plug on a cord and using it to power my old 12V "cordless" drill. The drill motor is still good. The batteries died long ago so I could gut one to connect to the drill motor. The power supply throws one hell of an arc at the plug when it is plugged into AC. There does not seem to be any soft-start mode.

I have a couple regular corded drill motors but they don't have keyless chucks. One of them is a big ancient metal case 1/2" single speed unit.

 

[timgr]

The suggestion of a computer power supply was a good one. Computer supplies are switchers and are much more efficient than the linear supply you could build yourself from a transformer and rectifier (though that's one route you could go).

Talk to the IT guys at your work, if you have any. Discarded computer equipment is a pain to get rid of generally, and you should be able to scrounge a bunch of supplies easily. Go to the Good Will 'as is' yard in your area, pick up discarded computers from curbside, whatever works. Even dead supplies aren't always dead on all channels, so you could try some of those to see if the 12V is still alive.

If you can't find one supply that gives you all the current you need, you could try connecting two or more supplies in parallel. Connecting supplies in parallel may not be stable, but you're working with junk, so nothing to lose if you kill one or more of the supplies. Better to divide the load if you can, ie separate the lights on the bar and run each off a separate supply.

 

[timgr]

You cannot short the two 110 V AC wires to get 230 V AC. You will get a short circuit.
To get 230 V AC you need to run the two 110 Volt lines each from a different bus, in parallel.

How is that relevant?

I'm suggesting connecting the PS outputs in parallel, to get more current.

Here's the Wiki on switchers http://en.wikipedia.org/wiki/Switched-mode_power_supply

If you want a linear supply (ie a transformer), here's a new transformer in that range http://www.mouser.com/ProductDetail/Stancor/P-6379/?qs=UmzvcGcLxU8kInQxFpn0UQ== - you'll also need a rectifier bridge, a line cord, fuse and a capacitor. Very basic stuff. If you want to make a linear supply, try visiting your local HamFest and finding used parts.