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The Voltage Keeper

VoltageKeeper

Well-Known Member
Accessory Maker
Hi all,

After much research, testing, and back and forth with some various insiders, I'm pleased to finally announce the initial version of the Voltage Keeper (VK for short.)

vk.jpg


What is the voltage keeper? It's a voltage regulating device which can take nearly any input from 3-15v and output 1-30v, up to 25 watts. It is intended for log vaporizers and other low voltage appliances. Any resistor-based vaporizer should work well with the VK.

By default, the VK is configured for a range of about 9v-15v, although this varies slightly depending on the tolerance of the parts. All units have an internal trimmer which lets you vary this range of about 5-6v all the way from 1v-5v to 25-30v, though the unit will come calibrated for vaporization use out of the box. Why the smaller adjustable range you might ask? This completely eliminates the problem on many of the tattoo power supplies people were using where you have a knob that goes from 1-18v, and it's extremely difficult to dial in something exact like, say 11.85v. The limited ~9-15v range is much more fine and there's a lot more useful range of the knob with this setup. It also protects you against accidentally knocking the knob to some extremely high voltage, as you can limit the maximum voltage when the knob is set to maximum.

On that note, the VK is equiped with a 4 digit screen for increased accuracy, and the power switch actually has 2 "on" positions, the first position shows you the input voltage, which is useful if you're running off of batteries as you can monitor the battery drain. The second position is the standard "on" position, and shows you the output voltage as you'd expect. Ah, and yes, I did mention batteries. Since the VK can run off of nearly any input voltage, battery usage comes naturally. The unit has been used successfully with battery packs, the length of time you get will vary depending on the capacity of the batteries used. It is generally a good idea to only use batteries that have some sort of protection, or don't mind being drained all the way down, as the VK will drain the battery down until it no longer can provide enough current to keep up with the voltage you've selected!

The VK has a male jack for the output and a female jack for the input to prevent accidentally plugging in things in backwards. It also allows you to use standard male-to-female barrel jack extension cables with it. They use the standard 2.1/5.5mm barrel connector size, used on most if not all log vaporizers.

vkback.jpg


You can input any voltage in that 3-15v range, even lower voltage than what is coming out of it, as long as there is enough current. Another nice thing about the VK is that it can use your existing 12v DC power supplies as long as they've got around 1.5A current rating. 9v, or 15v supplies will work as well, as long as they have enough current. The lower the voltage, the more current needed, so for a 9v supply, you might want 2A, but for a 15v, you can usually get away with 1A. Unlike "down-converters" which take a higher voltage, and lower it, the VK has no "gap" between the voltage you put in, and the voltage you put out. You can put in a 12v supply, and get anything from 1-30v! Car adapters have also been tested to work with the VK, since car voltage is often a little higher than 12v, the VK is perfect for regulating it down to a more useful level. Of course, safety first people. It theoretically could even work with solar panels!

The boards used in the unit have short-circuit protection and will turn off if it detects a short. Simply remove the short and turn the unit off/on and things should be back to normal. Hopefully this means it won't burn your house down, but because of the nature of this product and the fact it could be used in many ways which are not intended, these devices are to be used at your own risk! Be responsible and use them as instructed and you will not have any problems.

The VK can be used to power anything, I've even had one of my testers use it to power a rotary drill and some other low voltage DC devices, from battery and/or AC power adapter. As long as the device is rated at 25w or less, it should be safe. I would probably recommend keeping this under 15w to extend the life of your unit, as running it at the maximum of 25w will create a lot of heat. For reference, most log vapes only draw around 6-9w, the VK can safely be ran 24/7 at that wattage without issue.

I'm recommending people do NOT buy a power supply with it, as you more than likely already have one! If you have something from 9-15v DC and around 1-2A, you're already set to go. The power supply which comes with most log vapes will almost always work with the VK as long as it's DC, so chances are, you're already set to go! Just stick the VK in between your vaporizer and the power supply, and you're off! By default, I'm going to include one male to female extension cable, which will connect your VK to your vaporizer. Just plug in your existing power supply to the VK, and plug the extension cable from the VK to your log vaporizer, and you're set.

I've also got some other various accessories you can buy, like male to male and/or female to female barrel adapters, male to male cables (NOT typically needed since the output jack is male already!), among other things. Car adapters have also been tested to work If you need some kind of unique cable made up, just ask, chances are, I may have the parts to make it for you already, or can get them if you don't mind the wait.

I've got 5 units I've delivered to one of my vendors, and another 4 I'll be selling directly immediately. I also have some factory seconds, these are scratched and/or have slightly different cases, I will offer them at a reduced price. The standard unit price with a male to female extension cable included is $45 plus shipping. AC power supplies are sold separately, but I do have limited supply of them, ask if you need one. The factory seconds I'll be selling at $40 plus shipping, functionally they're identical, there's just cosmetic differences and perhaps some scratches/blemishes. I'll likely have two of those available.

I've got 3 available colors, but what I have in stock may vary. Ask if you want a specific color! Red is pretty much the standard choice, and it's the least obnoxious in terms of brightness. I also have different, smaller knobs available. However, most people seem to prefer the big knobs. If you'd prefer a smaller one, please ask and I'll show you what I have available.

vks.jpg


Once all the current stock is gone, I will also be taking pre-orders for the next batch of units. I may change the casing on the next round of units, so do not be surprised if the next batch looks different, but expect all functionality to remain the same. So again, standard unit is $45 plus shipping. Also ask about custom units, which will likely run around the $100 range. I have done custom units with things like voltage+amperage meters, different cases, among other things, however due to the extra labor these kind of units are going to be one-off only. If you're seriously interested in such a unit, I have photos available of some examples upon request.
 
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placetime

Well-Known Member
Interesting product. :science:
Have you considered making a cheaper model without any readout, just as a limiter/booster?
 
placetime,

VoltageKeeper

Well-Known Member
Accessory Maker
Interesting product. :science:
Have you considered making a cheaper model without any readout, just as a limiter/booster?

Certainly do-able, would probably save me tons cost/labor on wiring the switches. However, I personally get a ton of value out of the screen being there, so that model wouldn't be for me! If there's enough interest in that, it's certainly something to consider. I think the $45 price tag is pretty reasonable for the basic model though. The custom units will be for people who want more readouts, special connectors/jacks, or anything else non-standard.
 

Alan

Master JedHI
Manufacturer
The VK truly is an amazing device. Thank you for making them VoltageKeeper. Here is a video of one in action.


Having the ability to see the input voltage is important in monitoring the power level of a battery being used. The VK helps extend the useful fife of any battery pack by only providing the power that is needed. The efficiency is 95% so there is very little energy lost to heat. The plastic case just barely gets warm while powering a Heat Island. I really like having the output from a male power jack extending from the box so that there is no question about input and output. It also allows for the use of any standard DC extension cord. A damaged cord can easily be replaced.

I would say that the cost is reflective of the labor involved in putting a VK together. It is a bargain considering the versatility and quality of he device. Have been using a prototype of the VK for a while now and it works perfectly. I also use it to control a 12 volt dremel type tool when making HI's. Showed it to a friend who immediately thought that it could be used for a battery powered tattoo rig. There are so many other possibilities.
 

VoltageKeeper

Well-Known Member
Accessory Maker
Hey Alan,

Thanks for the video and the review! It was a pleasure testing out the VK with all the various HI cores the other day!

So people know what's going on in that video: When the unit is first switched on, it's in the "input display" mode, you can see the input from the AC/DC wall adapter is 12.43v. Next, he switches it into "output display" and you can see the voltage can swing from around 9v to 15v, regardless of the 12v input voltage! The same is then repeated using a battery, which is outputting 13.23v. Again the input voltage makes no difference, even as the battery drains, until it's otherwise mostly empty.
 

VoltageKeeper

Well-Known Member
Accessory Maker
Good question! I've decided I’m going to initially offer a 120-day no questions asked repair/replacement policy, but you pay the shipping costs. Due to the fact that these units can be easily abused by driving something too powerful and overheating them, and I have no easy way to determine that, anything after 120 days I will ask for you to also pay for parts, which is typically in the $5-10 range depending what broke.

Of course, I'm really hoping these work out well and I don't get many returns, however since it's a new product, I'm still testing the waters here. I'm hoping I can extend the warranty to at least a year or two once I get more positive feedback on the units, but I can't make any promises to that now. I know people have had lots of bad experiences with the tattoo supplies, and rest assured, if your unit dies, I will repair it for you.

I am hopeful that the modular approach, using a separate AC->DC wall adapter and/or batteries, will mean these last a lot longer than the all-on-one tattoo units which die sporadically with no obvious cause. Even if your wall adapter kicks the bucket and dies, the VK may still be fully functional and working! This is not a scenario that could ever apply to most of the tattoo units that were breaking. That said, I'm actually still looking for a good supplier for wall adapters that are both affordable and reliable, at the moment I've only got a very limited supply of AC wall adapters on hand.
 

VoltageKeeper

Well-Known Member
Accessory Maker
Is it possible to widen the range slightly, say 6v/7v - 15v?

It's certainly possible. I can do 1-15v units pretty easily as it uses a standard value part, and I have some of those laying around if you wanted something like that. For a 8-9v range unit like you're requesting, I'd have to do some experimenting, but it's definitely possible, at the cost of some accuracy.

There's a few other options like vernier dials and multi-turn pots, I can definitely do that kind of thing as well, maybe over 1-15v or even the full 1-30v range but it will probably add another $3-5 to the unit. I'm open to all custom requests as I mentioned, if you want a standard unit with a minor tweak like that, I'll do that for the cost of the extra parts.
 

VoltageKeeper

Well-Known Member
Accessory Maker
Hi everyone, to those who paid their invoices, your orders shipped today! Generally, Wednesday & Saturday are my shipping days.

I've still got 2 units from the first batch left! I only have one red screen, so if you want red, claim it soon! I have plenty of green screens still available. Blue was the first to sell out! Although still too early to know for sure what will be most popular - I'm tempted to run a poll on screen color preference so I know how many to order next time!
 

VoltageKeeper

Well-Known Member
Accessory Maker
Glad to hear it arrived okay and is working well with your dog! I'm really excited to be getting some of the first units out to customers!

I just got in more screens, I still have to go through them, but it looks like I've got plenty of blue back in stock now, so you can now request blue again. I've got all the colors available now.

I'm still deciding on cases for the next batch, the existing model will indeed fit in a smaller case (ask for some teaser photos and I can show you an example maybe), but, I've got some potential options in the future that might warrant the current case size, so I'm somewhat torn. I can get the current cases in different colors too, clear blue, clear red, opaque blue, and I'm thinking of maybe ordering a variety of colors of the same case for the next batch. I might try some smaller cases out too, but we'll see what I can make fit.

I'm really interested in trying the opaque blue case + blue screen only as an option, it wouldn't be see through, but the LED screen would still shine through it. Might be a cool look. I still like the transparent, but we'll have to see how it all works out.
 

VoltageKeeper

Well-Known Member
Accessory Maker
teaser pics would be cool! :cool:

ask and you shall receive! So here's one of my personal prototypes, using a screen that shows both volts and amps. I've since modified this unit and added a switch on the back, so it's pretty much identical to a VK other than the smaller case and the different screen. However, cutting out the hole for the screen was a royal pain, and I don't have a supplier for these cases, I just found this one at my local electronics store:
bluevk.jpg


However, I might consider doing units in a smaller opaque-blue case, with the standard 4-digit screen mounted inside, shining through the case. Then I don't have to cut out a big hole for the screen and that would save on labor. For the unit above, I might be able to make another one, but it would be at a cost, maybe $100? I'm even tempted to do a unit like this with two screens, one for the input, and one for the output, with 4 total displays. That'd be kind of crazy, but definitely not cheap! Those screens alone cost 2-3x what the 4 digit screen does!
 

MileHighLife

Blower of glass, grower of grass
At first I wasn't too sure about the clear box but it has grown on me.

The simplicity of this little guy combined with the precision of the 4 digit screen and the fact that this device doesn't "walk" around my set voltage like my old tattoo vvps did ... I think my voltage keeper has been money very well spent! No more switching cables from the vvps to wall wart before and after sessions either which is awesome. My underdog is now dialed in to 12.3v all day everyday ready for me to hit on the fly.

I will be back for 2 more voltage keepers in the very near future ...
 

Madcap79

Jack of all trades, master of none.
I love my VK so far. Got one with my HI. I'm going to try it out with my UD and PD as well. The PD isn't as responsive to temp changes though so I'm not sure how functional it will be. Anyway, great product. Glad I got one. :rockon::tup::smug:
 

VoltageKeeper

Well-Known Member
Accessory Maker
Have you thought of doing a version with the dial on the top of the case?

My first prototypes actually had the knob on the side, and the input/output were on either end! I can pretty much put the knob wherever you'd like as long as nothing else is in the way. Shipping will actually cost more if I do the knob on the top, as it won't fit into a USPS small flat rate box anymore! I personally kind of like it on the front, since you're rarely making big changes, it lets you sort of just nudge the top of the knob back and forth for small incremental changes. If you want one on the top though, no problem, shipping will just cost a little more.

You will have to wait for my next batch of cases though, as the 2 remaining units are already pre-drilled. They should be arriving next week, and I'll likely start assembling the second batch of units next weekend! More updates will come at that point!

At first I wasn't too sure about the clear box but it has grown on me.

The simplicity of this little guy combined with the precision of the 4 digit screen and the fact that this device doesn't "walk" around my set voltage like my old tattoo vvps did ... I think my voltage keeper has been money very well spent! No more switching cables from the vvps to wall wart before and after sessions either which is awesome. My underdog is now dialed in to 12.3v all day everyday ready for me to hit on the fly.

I will be back for 2 more voltage keepers in the very near future ...

You know, the clear case has grown on me too. It's very much a crystal sort of clear so it has a very high tech look in person. The accuracy of the 4-digit screen actually has me using my very first of the current model as my main unit right now, it's also the first unit with a blue screen. The prototype solid blue unit above has been sitting in my box of parts for the past few weeks, I mostly use that unit for testing, as the amperage readout makes it really easy to know whether you've got a device connected or not, can act as a tester for bad cables, a quick way to know your vape is drawing current, however, it's only a 3 digit read-out.

Although here's a tip for VK owners, you can tell the same thing from the VK. Simply switch to the "input" mode, then unplug your vape. The voltage generally should go up. Plug the vape back in, and you'll see the input voltage sag back down a little (or a lot if it's an unregulated power supply!) Meanwhile, back in "output" mode, the voltage remains steady, as per it's namesake! If the voltage doesn't change at all, and the vape doesn't get hot, you've probably got a bad cable or intermittent connection somewhere!




Just some VK history: The first 2 prototypes only could down-convert, but could take higher input voltages. Up to 36v, which might have worked well in certain applications. I can still potentially offer this as a custom order if someone needed to drive the unit from a high DC voltage. I had just glued in a cheap 3 digit screen, and called it done at the time. The boards I was actually buying as kits and assembling them myself! It was a fun project but ultimately I wasn't happy with the result. I was trying to be lazy and find boards that had a knob on them already, and kept experimenting with various resistance values and what not trying to find just the right combination. That experience fortunately wasn't all for granted - as it made finding the right parts for the final model that much easier, as I had already done the research on this.

The technology used in the current model is actually often used for small solar powered devices, as the voltage generated from such panels can vary up or down depending on the sun! So technically, you could have a solar powered vaporizer, although you'd need a large enough array of solar panels to power your vape! Much the same way it works with batteries. I'm sure you could fit a small solar setup into a backpack or something!

There's also two earlier prototypes of the current model, one is Alan's, and the other is in my living room! They have both the switch and the knob on the same side. After further testing, we both preferred the switch away from the knob, on the other side, so it doesn't get in the way when you're adjusting the knob. However, this meant the drilling of the holes had to be much more accurate, and I ended up buying a drill press to facilitate making the units quicker and faster!

The next set of cases is now ordered, I've got more clear, as well as clear blue, clear red, semi-opaque blue. And I have 3 different styles of opaque blue I'm trying - some smaller, some the same size as the current case, and one that's a slightly different style case that has removal panels (which might make drilling easier for me! we'll see). The colored cases will likely only be able to come with the same color screen: IE red case, red screen, otherwise it might dull out the screen. Then again, some people might prefer a dimmer screen and/or some kind of bizarre looking thing (red case, green screen anyone!?) I'll have to try some weird combinations, maybe just to see what it looks like!
 
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VoltageKeeper

Well-Known Member
Accessory Maker
So, just when I thought I already had enough features as it was, I've found some small little ammeters that I could mount inside the case! Now you too can have an ammeter on your VK in addition to the voltmeter! Like my blue prototype unit above has! Except, it will be a separate little screen inside the VK, and you'll still get the 4-digit volt meter in there too. I've finally managed to get the best of both worlds!

It's a 3 digit ammeter, but that's okay, we almost never get past the 1 digit range on the VK for amperage, 1-2 amps at most really! We're in the decimals most of the time with log vapes, mine's usually around 0.55A! You'll even be able to pick the color of the ammeter! It's a $10 extra. It will also come in yellow! I'm also looking into yellow volt screens too. Oh, it's endless, it really is. This is almost starting to get as bad as picking a tube for your log vape!

In the base feature-set, well, nothing has changed really! These things rule already as-is! The standard model is exactly the same, but I might have some smaller cases in the near future. I still have two from the first batch available immediately!

So to rehash the features:
  • Up/Down converter with built in short-protection! The first and original unit with this feature, standard!
  • 4-digit screen - standard
  • 3-way switch - standard, but I might be switching to a smaller model which will help with the smaller cases. Only difference is that off will be in the center, instead of down. Pretty insignificant change either way.
  • 5-6v range pot with internal trimmer, front-mounted. Still standard!
  • Various case options will be available and for now I'm eating the difference in the cost. I will take photos as soon as the shipment arrives. I've got coming clear, clear red, clear blue, and semi-opaque blue! And some smaller, semi-opaque blue cases of various styles!
And of course, the same price too! $45! Well that wasn't much of an announcement! Okay, so here's the exciting part, the new options! These should hopefully be available for shipment in the next week or two, depending on parts availability, of course, the amount of options you can include is limited depending on the case size, I've still yet to receive all the cases for testing, so the actual possible combinations are still TBD, these are my best guess given my current expectations:
  • Top-mounted pot: extra $5 shipping charge due to larger packaging requirement. Only available with the stock pot, 5-turn pot, and 10-turn "short" pot models. Not available with the 10-turn "long" model.
  • Ammeter display: $10, displays "output" amperage only, regardless of switch position.
  • 5-turn pot, 15v range: $4, can be mounted front or hopefully top style pending arrival and measurement!
  • 10-turn "long" pot, 15v or 30v range: $5. Front style only. It's big, but cheap, optional vernier for another $5, might limit other options due to large size.
  • 10-turn "short" 15v pot with vernier included: $12, smaller 10 turn pot, works front or and hopefully top style too! Still have to get these in for testing. These will be the top of the line option.
  • AC Power supplies. Still optional! I have some used units for $5, but, a final model and unit price still TBD! Use your existing one if you can, and save a few bucks!
  • Cables, adapters, parts, you name it, I've probably got some laying around. Generally $3-5.
  • The works! Larger sized case with the ammeter and 10 turn pot with vernier dial! $65, save a few bucks when you get it all!
After testing, I've determined that the standard setup with the 5-6v range pot and the trimmer is only just slightly less accurate than the 1-30v range 10-turn pot, or the 1-15v 5-turn pot, which perform fairly similarly. However the standard 5-6v range setup is limited right in the sweet spot for vaping, and protects you from accidentally damaging your vape from setting it too high as you could on the 30v range pot! Of course, the 15v range multi-turns also protect you from this, and 10-turn 15v is noticeably more accurate than the standard setup, with a vernier even more so, but, of course that's why they cost more! The 30v 10-turn and the 15v 5-turn are useful for the person who wants a wider range, but doesn't mind the stock accuracy. The 15v 10-turns are for the person who has to have a unit as accurate as possible.

Is this something that really matters? It just depends how much of a freak you are for range and accuracy! For most people, the standard unit works fine. I've been using them for months now and really don't have any issues with accuracy at all. However, these multi-turn pots just give you that little bit of extra confidence, and make it much harder to knock the value to something really far off by mistake, especially with the locking vernier dial!

BTW, in case you don't know what a vernier dial is, it's a knob that has a counter on it that shows you how many turns you are in on a multi-turn pot, and they also usually have a little switch that lets you lock the knob at a certain position. They look something like this:

XSN%20VERNIER



If that's not cool, what is right? Looks like it could have come off a piece of scientific equipment or something! However, I'm hoping it will be practical as well, with the ability to lock the dial in place definitely something I could see some people enjoying. I see other potential benefits of the vernier dials in the future, however, there's some secrets I have to keep for later, and that will be the one thing I don't reveal tonight!

Oh, one more thing I wanted to announce, I'm going to begin offering a battery pack which is essentially 4x18650 cell-holder and a barrel jack on the other end. I don't think I'm even going to provide a case for now, but I will try to offer something at a higher cost with a case in the future. For now, I'm going to basically offer this with a barrel jack on the end for $5, for use with protected cells only:

myjfayHSBCjH__tPvsJqcYA.jpg


Those are NOT for double-A's, they are 18650s, and protected ones at that. They're fatter, and longer, and something like 3.6v per cell, meaning this is actually a 14.4v battery pack all together. $5!!! Why so cheap? Well, because basically it's nothing. I'm offering this as cheap as I can because the actual cells and charger are actually kind of expensive. I'm too small of an operation to be able to afford to resell these myself at this time. My recommendation would be this unit here:

http://www.amazon.com/Nitecore-Intellicharge-i4-rechargeable-Carabeamer/dp/B00BPZ86GE/ref=sr_1_5?ie=UTF8&qid=1390107458&sr=8-5&keywords=4 18650 charger

This comes with protected cells and should be a fairly compact setup overall. They even include a car charger for the thing! I think the 18650s are the best way to go. These are the same batteries they use in the tesla electric car! While you could use rechargeable AA's, the density of the cells are no where near as good as 18650s, and you'd need a lot more of them. I use rechargeable AA's quite regularly myself, so it's definitely something I'd have loved to considered, but, I think for this application, protected lithium cells offer more usability for the size. As for using non-rechargable batteries or AA's - it's certainly possible, but I can't really recommend it due to the wastefulness of eating through AA's like that. You accidentally leave the unit on and you might have 6-8 dead AA's on your hand every time...


Oh yeah one final thing, while I never thought there was really any controversy over the importance of using the correct batteries with the unit, and I've not actually had any customers give me any complaints about this, due to the fact that I noticed some recent remarks over the issue I figured I'd make the following notice: I have always recommended using protected batteries with the VK from the start! In my very first post even! Either that, or any type of battery that does not care if you drain it down 100% with no restriction. If you are not sure, don't use it with the VK!

The ability to monitor the input voltage of the battery does not negate using the proper batteries with the unit, nor have I ever claimed it did. It also does not directly represent the remaining capacity of the batteries, though it can give you some level of reference by comparing the state of the battery over time. The voltage will sag over time, but it's not always going to be on a useful curve. The only way to truly measure battery capacity is to essentially drain them and measure how much you drained, as many fancy battery chargers are able to do.

On the other hand, the input switch is a cool debugging and diagnosis feature, and it can indirectly serve the purpose of showing load on the unit, by monitoring the sag in the input voltage as more load is put on the output. This means you often don't need extra testing accessories to know if your vape is receiving power, you can perform some basic tests with this switch alone! This also means this feature is just as useful when using a wall adapter, as it is when using batteries, or heck, even solar panels! Of course, for the nerdy gadget freaks like myself, the ammeter is the ultimate way to see it all, but, as I wanted to have a power switch anyway, and this came as a pretty easy extra, why not? I think the feedback speaks for itself!
 
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VoltageKeeper

Well-Known Member
Accessory Maker
Oh yeah, one other thing I forgot to mention: There might be a 2 week delay on red screens. They ended up sending me ALL blue screens in my last order, which is sort of nice for the opaque-blue and transparent blue cases I ordered, but, not so cool for people who wanted red! I have tons of green and blue available now, and just 1 red left. Blue seems popular, so hopefully this works out anyway! The semi-opaque cases might help tame down the brightness of the blue, so I'm excited to see how that will look. I will take photos as soon as I have my first units in the second batch made!

Also, in regards to the batteries, a slightly cheaper option is this, which will probably give about an hour less run time. There's cheaper chargers that can only charge 2 batteries at once, but that seems like it would be really annoying not being able to charge them all at once.

http://www.amazon.com/Nitecore-Intellicharge-i4-rechargeable-Carabeamer/dp/B00BD42IHA/ref=sr_1_12?ie=UTF8&qid=1390107458&sr=8-12&keywords=4 18650 charger

I still need to do further testing on run-time and just testing in general, I'm estimating 5 hours off the more expensive/higher capacity 3100mah batteries, and 3.5 hours off the cheaper 2300mah batteries, but I will give a more accurate estimate off the batteries/charger I ordered once I'm done testing it.
 
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VoltageKeeper

Well-Known Member
Accessory Maker

So, I did some research for you. I attached a VK to another VK, and I set the first VK to 5v and attached my multimeter in between, measuring the amperage.

On the 2nd VK, at around 12v, it was drawing 1.7A@5v. At around 13v, it was around 2A@5v, and at around 14v, it reached 2.4A at 5v, the maximum output of that battery pack.

I also tried this using my bench supply rated at 2A and it gave up around 12.7v, drawing around 2.15A@5v, however, I suspect the difference is more due to resistance in the cabling. I had a longer cable coming from the bench supply. I also tried a 5v, 2A wall adapter, this one faired even worse, crapping out at around 11.5V, and only drawing around 1.7A from the 2A supply, the supplies voltage was sagging down to 4.12v at that amperage! That said, I think that last result is atypical and the adapter was clearly not capable of delivering 2A at 5V without substantial voltage sag.

That said, it's hard to know whether this USB charger will truly put out 2.4A@5v without issue, or if it will also start sagging significantly under load. It should technically work if it can actually deliver all of that current to the unit, but given the resistance of the cables and other factors, that value could be lower by the time it gets to the unit. It's good to have some leeway in those kind of circumstances so you aren't pushing the device to it's very limits. That said, I'd probably recommend a device with a little more leeway in the amperage department, but this MAY actually work if it truly can deliver what it claims it's rated. I doubt you'd be able to concurrently use another USB device at the same time, though.

Also, the device's "smart" port is the only one that delivers 2.4A, I don't know if it uses special circuitry to detect "high powered" devices before it lets you draw 2.4A, or what. If it did, then that'd obviously also be an issue, though I don't see why they would do that, but the USB spec does call for the device to negotiate it's voltage. I just tried my 2.1A ipad charger, and it wouldn't let me draw more than about 0.7A which tells me maybe there is something to that, you might need a cable that had some sort of chip on it that will tell the charger to output it's full amount.
 
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olivianewtonjohn

Well-Known Member
Also, the device's "smart" port is the only one that delivers 2.4A, I don't know if it uses special circuitry to detect "high powered" devices before it lets you draw 2.4A, or what. If it did, then that'd obviously also be an issue, though I don't see why they would do that, but the USB spec does call for the device to negotiate it's voltage. I just tried my 2.1A ipad charger, and it wouldn't let me draw more than about 0.7A which tells me maybe there is something to that, you might need a cable that had some sort of chip on it that will tell the charger to output it's full amount.

As far as I know apple is not following standard USB protocol. So depending on which cable and charger you use; it might not trigger full current.

I do know that two of the wires in the usb connection have to be shorted to output higher than standard USB current.

I bought this charger and had to solder two wires to get full power (due to apple).

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