February 1st, 2009

Vivitar 285 HV Flash DIY External Battery Back


You've come to the right page if your wondering how to build an extremely cheap and reliable external battery pack for your Vivitar 285 HV. This process is not exclusive to the Vivitar 285, it could be used to power any flash/strobe provided you know how many volts your flash requires and the appropriate terminals to attach your leads to.

This DIY project really isn't too difficult but having said that, I made a few mistakes my first go, luckily nothing blew up. If your the impatient type like me, read this through again once you start building your unit so you don't make the same mistakes I did.
First things first, I have to give may thanks and a ton of credit to Jay Abend who wrote a piece titled How To Build A Battery Pack For Your Flash for Shutterbug. I followed his directions more or less step by step. However, I found myself unclear how to proceed more than a few times. Here I have fleshed out the details, provided photos for clarification, and modified his setup due to necessity (I'm currently living in South Korea and some things are hard to find) or simply to meet my own needs.


Parts Left to Right (Click on picture to see notes)

1m Heat Shrink (Size depends on gauge of wire you use)($1)
2 Aligator Clamps + Red and Black rubber housing to identify +/- and decrease fire hazard) ($1)
2 Female Quick Slides appropriate to your battery + wire (Seen between the alligator clamps)
1 Male Molex Connector - 2 Pin (Size depends on gauge of wire you use)($0.2)
2 Female Molex Connector - 2 Pin (Size depends on gauge of wire you use)(0.2)
1 Vivitar Batter Housing (Mine purchased from ebay)($4)
1 Large Glass ($7)
1 6V Gel Cell or Lead Acid Battery 1.2-4amps ($8)
2 Dummy Batteries* (Never mind the springs) ($0.6)
1 6v 500-900 mAh power supply (Check around for old ones first) ($16)
2m 18-14 gauge wire ($2)
1 Bottle of Cheap Red Wine ($7)

*Jay Abend used bus fuses, I've seen people use doweling with a screw/nail down the middle. All that matters is that it's the same size as a battery and you can can run a positive/negative charge through the top. I experimented with super heavy insulated wire and a 10x50mm bolt with two nuts at the end. Either would have worked but in the end I opted for the AAA to AA battery adaptor because it looked nice and stayed put.

Total Cost minus the wine = $33
Bare in mind half the cost was the charger! I couldn't find any 6v adaptors amongst the hundreds of wall-warts I own, so I had to shell out for one at the electronics shop. The upside it that this one is designed to be a charger as it has indicators to indicate a fully charged battery and auto shutoff.


Tools Left to Right (Click on picture to see notes)

Soldering Iron
Desoldering Wire/Wick
Big Glass of Wine
Lighter (For heat shrink, instead I used a gas burner and it worked awesome!)
Wire Strippers (Had em since I was 12 - they're so good!)
Needle Nose Pliers (Most used tool on this project)
Snipers (Great for clean, precision cuts)
Cheap Bottle of Red Wine (Working on it right now)

Terms Used in this Tutorial

Small Battery Pack = The unit that slides into the Vivitar including 1/2 the cable and molex connector
Big Battery = 6v lead acid batter, cable and molex connector
Compartment 1,2,3 and 4: See picture below 05_Vivitar_285_HV_External_Battery_Pack_Wiring


Battery Placement

The picture above shows you where NOT to put the batteries. I didn't re-read Jay's instruction in detail and I assumed that because the wire was coming out the front the batteries would be upfront (in slots 2 and 3) too. I only found out about the mistake prior to testing. I figured "what harm could it do, worst case scenario nothing happens" but what ended up happening was me short circuiting my battery and melting the hell out of the battery compartment.


Just remember it's the opposite of what you see above. The batteries must be in slots 1 and 4 towards the back of the flash. Why the springs? This was a truly awesome way I found to keep my slightly short dummy batteries is place, had they needed to be upfront.

Battery Compartment Modification

I drilled out a hole perfectly suited to my gauge of wire. I used a masonry drill bit because I had nothing else and it worked fine. If I did it again, I would melt through with a hot nail rather than drill.

Now, this is where I made my big mistake. Because the batteries need to go in slots 1 and 4 at the back of the unit, these wires need to be fed into the two battery slots behind them. There is a hole there but it needs to be enlarged.

I was impatient after I screwed up and melted my battery compartment so I used a drill bit to make the new holes but it didn't work well. So I tried heating up an old nail to melt the plastic away and it worked like a charm. You might have to chip of the melted plastic to make the compartment smooth again

So here's how things should be done thus far:
1 Drill your holes
2 Melt away some of the adjacent wall
3 Strip about 1cm off the ends of your wire
4 Twist it up as tight as possible (try to go the same direction the wire is wrapped in)
5 Run the NEGATIVE wire through the hole in slot 2 and over into slot 1, the battery compartment with the - sign at the end
6 Run the POSITIVE wire through the hole in slot 3 and over into slot 4, the battery compartment with the + sign at the end
7 Run the wires up through the dummy batteries and out the ends
8 Solder the ends (Careful, the plastic melts easily!)
9 Snip away the excess

The Molex Connector

Your small battery pack should be half complete. There is probably a long, two meter cable hanging out of it. Now you need to get power to your flash and for that you need a connector.

1 Cut your wire about 30-40cm from your small battery pack
2 REMEMBER, now's the time to put heat shrink on. Cut two 5 cm pieces of heat shrink and slide them on your wire (shrink later, not now)
3 Strip about 1cm off the ends of each wire
4 Choose if you want a female or male Molex connector on the end of your flash (In retrospect, I actually think female is the better choice, it seems easier to keep clean)
5 Choose the appropriate pins and attach your wires to them*
*There should be no insulation in being grasped by the pin (see orange arrow), I thought the last bendy section was designed to grip the insolation and my pin wouldn't insert and lock into it's housing completely.

6 Insert the POSITIVE (blue writing wire in my case) from behind into the square shaped hole
7 Insert the NEGATIVE from behind into the round shaped hole
8 Let the wire suck up some solder for added durability

So, now you have completed the connections on the small battery pack side of things. You should have a Molex connector attached to a wire which runs to your small battery pack. The positive should run from the square Molex connector through the hole into the dummy battery in slot 1. The NEGATIVE wire should run through the hole and into slot 4.

Big Battery Connections

Connecting to the big battery is pretty straightforward:

1 Attach a Molex connector, opposite to the one on your flash, to the remaining wire
2 REMEMBER, POSITIVE must lead from the positive (square hole) on the flash side to the positive terminal of the big battery. I like to connect the two Molex connectors and then make sure the blue writing lines up on my wires just to be sure nothing has crossed.
3 Cut your wire to the desired length (I kept my long, at about 1m because at this point I don't have anyway to hang my battery and I like room to work with. You can always shorten it at the big battery side easily later on.)
4 Put two 5cm segments of heat shrink on
5 Attach the two battery connectors*
*Next time I'm going to shorten the negative wire so it doesn't bend all ugly like above
6 Let the wire suck up some solder for added durability

The reason I went with connectors for the battery versus soldering the wire on directly is that is gives me greater flexibility. I could use the battery for other applications, I can completely disconnect the wires and most importantly, should the battery fall, the battery connectors will release long before the Molex connectors and thus not destroy my flash by ripping out the battery case or dragging it down to the floor. (Update: This little mod already saved me once. My flash was up very high and my battery balanced on the windowsill. It fell when I jolted something and disconnected as predicted!)

Make or Break - The Test

Now Jay offers up some good advice in his instructions and that is, to test the polarity on the battery pack prior to testing it in your $70 + Shipping Vivitar. If you have an instrument readily available to test polarity then you'll likely not have any melting or explosions. If your like me, and don't wanna buy one, or too impatient to wait and borrow one, here's how to proceed:

All you have to do is make ABSOLUTELY SURE you really have a 6v battery and that the wire going from the positive terminal of your big battery feeds ALL THE WAY into Slot 1 of your Vivitar Battery Pack. Be sure to check the positives line up at the Molex connection too. Then make sure the NEGATIVE feeds all the way into slot 4. If this is the case:

1 Ensure nothing is connected to the big battery
2 Put the small battery pack in your Vivitar, both dummy batteries should be at the rear of the flash... I'll say it again, slots 1 and 4.
3 Connect to your small battery pack to the big battery wire, NOT THE BATTERY
4 Turn the flash on and put it as far away from you as possible with ready lights facing you
5 Connect the appropriate wire to the negative terminal of the big battery
6 Take cover
7 Touch positive wire to the positive terminal of the big battery
8 Listen for whining
9 Celebrate if all goes well... curse if not...
10 HEAT SHRINK EVERYTHING - if all went well :) I find gas burners work well for this.

Making the Battery Charger

This is by far the easiest part.

1 Snip and strip the end of you charger wires
2 Figure out which is + and - ( I ended up taking mine to a shop because there was no indication on the charger itself, I had no tools to check and I screwed up once already on this project)
3 Put some heat shrink on, run the positive through the red rubber shoe and into the clamp. Do the same with the negative side.
4 Solder it together. I strive for durability so I ran my wire through the clamp and down into the little hole. Then I let it soak up some solder on the front and back
5 Test the charger, heat shrink if successful!

Congratulations, you now have a kick-ass, long lasting, faster recycling battery and just saved a lot of money.

Things I'd do Differently:

I've been using this DIY battery pack for almost a month now and it's functioned flawlessly. So far, the things I'd do differently:

a. Put the batteries in the right place the first time and melt the holes instead of drill
b. Make the wires connecting to the 6v the perfect length so that they lie flat

Next Page --> The Goods

  • Discussion / Comments / Questions