# Portable Power Supply for the Locator



## BVH (May 20, 2011)

I’ve been wanting a compact and portable 28 Volt power supply for quite some time to power my Locator and any future 28 Volt lights away from home. I haven’t seen anything I liked or that was light weight and small. I finally decided to build my own. Way back when Power Tubes were available and I had a lot of DeWalt pack scavenged A123 cells, I briefly rigged up an 8S or 9S/6.9 Amp pack and ran the Locator. I remember the cells getting very warm and after shut down, one or two cells vented. The Locator draws about 16 Amps @ 28VDC. Fast forward to a few weeks ago. Prismatic Lipos are fairly cheap now and “relatively” safe if treated with respect – paying attention to Low Voltage Cutoff, don’t pull more current than they’re rated for and definitely balance charge them. Blue Lipo brand are very affordable and have a decent reputation on RC Groups forum so I decided I’d go with them. Commonly available 8-cell packs provide too much voltage and 6S packs, too little. 7-cell packs are almost “just right”. Few manufacturers make 7S packs and those that do, get a lot of money for them. So I bought 3 ea. 4S/5000 mAh, 25C rated packs and waited for another 3 weeks hoping the supplier would fill their backorder of 3S/5000 25C packs. Ultimately, I had to go with 3S/5000 "30C" packs because they had no idea when the 25C's would arrive. I wire one 4S and one 3S pack together for 7S and then connect all 3 in parallel via the Anderson 4-way to get my 7S, 3P, 15 Amp pack. While I waited, I put together everything I could without having the 3S packs. All parts in-hand, I set to work.

Care and feeding of the batteries:

I parallel and balance charge the 4S’s together and the 3S’s together to only 4.1 Volts per cell and end up with an unloaded voltage of 28.7V. When the Locator is first started, voltage falls to 28.0. I use the PowerLab 8 charger with safe parallel adapter boards with balance taps. Charging each set of packs takes about 40 min. at 1.1C. Unfortunately, I have to take the box apart to do my charging due to the complexity of all the connections and the combination of 4S and 3S packs.

Operation:

I get just under 40 minutes of run time and am using only about 80% of the capacity of the pack due to the using a 4.1 max charge voltage instead of the normal 4.2V per cell and the fact that I have to shut down at about 25.7V (3.67 Volts per cell) because the cooling fan on the light stops running. I could get a few more minutes if I ran the cells down to a safe 3.3 Volts.


The Construction:

The 6 packs with Anderson Power Pole connectors installed.










A standard fuse holder, an Anderson Power Pole 4-way connector and 12 gauge wires. The Andersons fit the box and the clamps can be snapped in place if I come across a military vehicle with 28 Volt system.









The project box I had for quite some time was just the perfect fit for the 6 packs. The upper half of the box with the 28V, 30A power switch, self-powered voltmeter, Anderson front panel double connector and 12 awg Dean’s Wet Noodle power connection wires installed. The voltmeter is switched separately so I can check PS voltage without having to turn on the PS switch.









Both halves of the box, the lower with 2 layers of adhesive Velcro strips to secure the batteries. 2 layers to raise the batteries higher than the box attachment screws so they don’t puncture the Lipos – Very bad if that happens.









The front of the box with Anderson double panel and power switch installed.









Batteries fitted into the box. Just perfect with the fuse holder as a spacer.










Both halves of the box with the connections made. Lots of wires and a bit messy but it is tight quarters. Got to be very observant when making all those connections to prevent a rapid vent with flames event. I color coded as much as possible.











The finished product. It weighs 7 1/2 pounds









The Locator being powered by the power supply.


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## ma_sha1 (May 20, 2011)

Nice 6 pack!


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## Walterk (May 20, 2011)

Nice! Never realized the Locator was that large. What diameter is the reflector?


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## BVH (May 20, 2011)

5 1/4" approx. Think of it as about 65% of a SX-5, 500 Watt NightSun.


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## LuxLuthor (May 22, 2011)

Congratulations. Nice looking solution.


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## CKOD (May 31, 2011)

I wanted to mention this earlier but it slipped my mind, saw you link this thread... Could you use the powerpole connectors and arrange them into a 3x3 block, where you plug in one mating connector to arrange the cells in the discharging configuration via jumpering as needed etc, and pull that plug, and plug in another with jumpering to arrange them parallel for charging? You'd still have to plug in the balance taps into the paralleling board, but you might be able to leave that plugged in permanently, one for the 3S packs, and one for the 4S packs.


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## ShortArc (May 31, 2011)

Great job!
I was finally able to find a Locator (12V/35A version) myself. Building a light weight portable pack is a great idea! Thanks for sharing the info.


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## BVH (May 31, 2011)

CKOD said:


> I wanted to mention this earlier but it slipped my mind, saw you link this thread... Could you use the powerpole connectors and arrange them into a 3x3 block, where you plug in one mating connector to arrange the cells in the discharging configuration via jumpering as needed etc, and pull that plug, and plug in another with jumpering to arrange them parallel for charging? You'd still have to plug in the balance taps into the paralleling board, but you might be able to leave that plugged in permanently, one for the 3S packs, and one for the 4S packs.


 
I'd thought of a few possible ways to make charging from the exterior possible but it was getting too complicated and with the tight quarters, I decided not to. Right now, even with having to remove the top, it's relatively straight forward for charging. What you suggest is certainly workable but I just know if I make it to fancy, I'll end up short-circuiting something and end up with a vent with flames and injuries scenario.


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## BVH (May 31, 2011)

ShortArc said:


> Great job!
> I was finally able to find a Locator (12V/35A version) myself. Building a light weight portable pack is a great idea! Thanks for sharing the info.


 
WOW! I didn't know a 12V version existed! Great find! Does it still have the original double bullet-ended, 5500K bulb? I really wish I could find some of those. The 3300K Marc300 EZS are still a great performing bulb but I miss the Diamond-White color. What are you using it for? Have you installed the joystick you bought a while back? Let's see some pics.

Just for reference, - In one of my Locators, the orig bulb flickered rhythmically, maybe more like an oscillation. About 2 to 3 bright-dim cycles per second. Upon switching it with another known good bulb, the flickering went away. I assume this is a good clue as to when the bulbs' short 25-hour life is used up, and then some.


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## ShortArc (Jun 1, 2011)

BVH said:


> WOW! I didn't know a 12V version existed! Great find! Does it still have the original double bullet-ended, 5500K bulb? I really wish I could find some of those. The 3300K Marc300 EZS are still a great performing bulb but I miss the Diamond-White color. What are you using it for? Have you installed the joystick you bought a while back? Let's see some pics.
> 
> Just for reference, - In one of my Locators, the orig bulb flickered rhythmically, maybe more like an oscillation. About 2 to 3 bright-dim cycles per second. Upon switching it with another known good bulb, the flickering went away. I assume this is a good clue as to when the bulbs' short 25-hour life is used up, and then some.


 

Indeed it has the original bulb and I found an orinal spare a while back. The light also came with Heli Joystick controls, original packaging, and lot's of documentation (FAA, bill of sale to Police dept, etc). Pretty slick. I will post some pics when I get the chance. I bought the Amphenol connector in order to make a new cable but have not found the time to do so.....
Thank you for all the useful information Bob!


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## ma_sha1 (Jun 2, 2011)

There is one on ebay right now starting $450, search ORC Locator


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## BVH (Jun 7, 2011)

OK so who got the Locator at a good price? If I didn't need some special bulbs, I'd have bid on it.


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## ma_sha1 (Jun 7, 2011)

BVH said:


> If I didn't need some special bulbs, I'd have bid on it.


 
3 is not enough?


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## Lips (Jun 8, 2011)

Looks like he put it right back up for sale. Either he had two exactly the same or he bid on it himself!


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## BVH (Jun 8, 2011)

ma_sha1 said:


> 3 is not enough?


 
Can one ever have enough of a great HID light?


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## ShortArc (Jun 8, 2011)

Lips said:


> Looks like he put it right back up for sale. Either he had two exactly the same or he bid on it himself!


 
I just sent the fellow a message asking the same thing.
I'll post if there is a interesting response...
May bid on it this time around. It does not look to be in best of shape....


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## BVH (Jan 11, 2012)

ma_sha1 said:


> 3 is not enough?



2 Locators is a good round number so I've put one "on the blocks" in CPF BST


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## Mr. Tone (Jan 12, 2012)

Looks great, BVH! I love reading your threads, you really know good lights when you see them. Nice battery pack build. 

These are the ones typically on helicopters, right? Is it controlled by a joystick or something?


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## BVH (Jan 12, 2012)

Mr. Tone said:


> Looks great, BVH! I love reading your threads, you really know good lights when you see them. Nice battery pack build.
> 
> These are the ones typically on helicopters, right? Is it controlled by a joystick or something?



Well, if you're talking civilian/police helicopters then, no is the answer. Those are typically the 1.6KW NightSun or the 500 Watt Starburst, both by Spectrolab, Inc. My understanding is that these were pretty much used on the Blackhawk military chopper. Mine is controlled by a 2-D joystick. See original thread here:

http://www.candlepowerforums.com/vb...t-Blackhawk-Targeting-Light&highlight=locator

Post 37 for the joystick pic


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## Mr. Tone (Jan 12, 2012)

Thanks for the link to that thread. Those were some seriously impressive beamshots. I can't believe they are getting all of that out of that little reflector. The joystic you made also is really cool. Can you imagine the looks you would get if you mounted this on top of one of your automobiles! 

Do you think most Locators available came off of Blackhawks?


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