No idea. All I know is when you make the pack, all the batteries have to be at the same level of charge or discharge, otherwise they'll charge assymetrically and your capacity will start decreasing. Also, they're standard NiMH cells so they lose around 5-10% of their charge after the first couple days and then around 1% per day. But unlike Li-ion and SLA, they like being discharged completely.
What a great DIY! Thanks for patiently sharing the details with us bacilonur. You've single-handedly caused a run on AIMS 180 inverters.
I'd like to ask about one detail: What did you decide to do about providing a charging port? Your original rough drawing included a port for the charger but I don't see it in the photos. Did you decide to just unplug the battery pack from the inverter an plug it into the charger?
My AIMS 180 has been ordered and I hope to duplicate your project.
Dave, I changed my original plan of having a small fan and a charging port for a few reasons:
The fewer connections and attachments you have, the fewer things can go wrong. I had originally envisioned something like a miniature Little Genny 400 pack that you wouldn't have to open up for any reason, but with how small, light, and cheap ($60-ish) a spare 5ah/12V battery is, it's pretty easy and convenient to pack a spare pack in case you need it, and it takes about 30 seconds to swap out the velcro and switch the connectors.
I was expecting more heat to be generated. In my tests, the battery barely rose above ambient and the inverter's air exit wasn't too hot. Come summer, I'll cut a hole on the other side so that the inverter's fan has an escape outlet going straight up (when it's hanging on a stand), so it should do fine in a hot environment.
And last, it would be really tight inside the 1050. 16awg cables don't fold that easily, so you'd have to be pretty meticulous about shutting it just right and getting all the cables folded up right inside. And then you'd have even less room inside for air to circulate so the fan wouldn't make such a big difference.
I may still work something out for a direct charging port on my bigger pack with the 12aH D-cells, as that has a lot more room between the pack and the inverter and on the side of the pack.
Oh, and something you guys should do differently from my first one (which I'm now in the process of changing) is using Deans connectors instead of Tamiya connectors. Deans are stubbier but come out smaller and easier to twist around in a tight space, and lots of RC'ers say they're much more reliable. Just a couple bucks to change if you already used Tamiyas. And if you're gonna put a fuse on the battery, get a set of mini fuse holders from Radio Shack, they're a bit smaller than your standard fuse.
bacilonur, do you have a link to the pre-packaged 10x cell at www.cheapbatterypacks.com ? I can see the individual cells and the copper connetors, but not the pre-assembled and shrunk wrapped set.
Also, are you sure your current recycle speed limitation is the inverter and not the battery pack? I'm thinking of building a kit for fun, and am trying to figure out which batteries to use with a 380w inverter. I had been thinking two parallel sets similar to yours (or 10x D's), but now I'm starting to wonder if I'm underestimating these little guys. It's recycle speed rather than number of pops that interests me.
Hiya Shoebox, you have to go through their custom pack form. Select 10 or 12 cells, double flat configuration, Elite 5000, 16awg, then female Deans or Tamiya.
All the data I've gathered on this project suggests that the inverter is the bottleneck.
I had a few discussions with Mike, the owner of CBP, and he assured me it could handle at least 5C (25A). Then I tested the inverters on my cigarette lighter and got the same recycle time. And my times are basically the same as the original Vagabond 150W, which all matches up.
Running two packs in parallel or series (to get 24V) would work fine as long as you charge them separately. For a 380W inverter, a single 12aH D-cell pack should work fine. Depending on the size of the case you've got, you can use anywhere from 9 to 12 cells for a 12V inverter.
What size are the Elite 5000 cells (ie similar length to AA's but twice as fat)?
Also, I wonder how much the inverter in the Vagabond II weighs, and what it's dimensions are? Obviously it can handle quite a bit of current, but the heavy SLA (and the fact you are always carrying the charger), make the VBII a lot heavier than it needs to be.
Really great stuff here, guys. Thanks bacilnor for sharing all this. I really dig the DIY stuff and how you can tailor it for your own needs. I'm curious as to your thoughts about the value of this solution. I've been planning the purchase of a Vagabond II for awhile now, but this DIY solution is really enticing (and looks like a fun project). However, when I look at what I need, I'd like to be able to power at least 2 AB800's in the field and while I know I could do this with a VBII (and even three in a pinch), I would need two (or three) of the DIY packs to achieve the same result. At about $180 ($60-battery, $100-inverter, $20-case and misc parts) do you guys feel the size/weight advantage of the DIY pack is worth the extra expense to get the capacity (assuming I'd have to build at least 2 DIY packs vs. 1 VBII), and how would the capacity of two lights on their own DIY packs compare with two lights on one VBII?
I really want to dive in head first and build a couple of these babys, but the $299 VBII seems like a lot for the money and even more so when compared to doing the same task with the DIY pack.
Supergimp, all I can say is this is what makes the price worth it to me:
http://i50./2uiez5s.jpg
The VB2 is great for no-nonsense shooting when you've got hundreds of frames to shoot with several strobes and you have a vehicle or assistant to help lug things around.
My pack is more like a Quadra/Q-flash alternative. Great for packing like this:
http://i50./famtqe.jpg
Being able to choose a monolight over a speedlight when you can only pack one bag is nice when you don't have to factor in an 18lb sandbag.
Good point. I suppose within practical needs, separate DIY units (one for each mono) would probably deliver enough pops such that the VB2's capacity advantage really doesn't outweigh the convenience (either would supply me enough pops in a typical situation).
I built one of these packs using Balilonur's specs. It works like a charm and is a snap to assemble. About as easy as changing the SLA battery in my Quantum Turbo packs.
A B800 plus one of these packs is a less expensive and more versital option compared to my Quantum QFlashes and Turbo batteries.
With the new Eienstein units, which according to a post of the PCB tech forum can be dialed down to 2.5WS, this pack and light will be a great solution.
I am also considering how to mod my CP-E3/4 Canon battery packs to permit plugging the 12V packs into them.
That would permit carrying several battery packs that could power Speedlites as well as monos that deliver upto 640 WS.
I've been wanting to have a system where each monolight has it's own pack, to minimize wiring clutter, for ballast on each stand, and also for emergency redundancy. THis should be the answer.
Now if Paul could just get the Einsteins to market, life will be sweet. Three of these, three Einsteins, and a Cyber Commander... Better for me than the Ranger system (modifiers notwithstanding)
dmward wrote:
and to make it even better, there is a guy (K - something) making an adaptor that makes it easy to put Elinchrom modifiers on PCB lights.
sweet. Please trey to dig up that thread.
Now if only the Einstein were a pack-head system. Well, can't have everything. I'm just DYING to use a Cyber Commander.
Cable, Kacey makes that adapter. I asked him about it and he said it'd work fine with any speed ring insert you have as long as you don't mind drilling a few holes. $55.
Mic, try to find a hobby/RC shop for the battery pack, they should be able to hook you up with something similar.
