Any sign of the Hahnel twin charger yet?

[Speenth]

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It seems a certainty we need for some basic safety locks, and the electrical connections. I have done that in two steps here.

Tim

 

Hi' Tim,

 

Does it need a safety lock? The existing frankencharger quite niftily allows the battery to snick into place. Looking at your initial design something similar could be achieved by having a lip where you currently show the lock. Thus the user has to quite deliberately lift the battery out.

 

Also, to further save space (if the assembly process would allow it) I'd suggest having the LED(s) along one of the narrow walls enclosing of the battery.

[wlaidlaw]

I agree. It should be straightforward - in effect the 'plug' end of a figure 8 lead could be moulded into the side of the device opposite the 'socket' end. Perfectly safe electrically, and straight-through wiring from one to the other is all that's required. It would be like plugging bits of Lego together (very satisfying)!

 

Stephen,

 

I think you will find on portable devices, a number of countries (and maybe CSA and UL approval) would demand a door over a 220/110V figure 8 outlet, given that rug rat fingers could poke in there, not unsensible. Now maybe we could get away with a rubber plug but that may not be failsafe enough. All more complication = tooling expense etc. I hope we will be able to piggy back onto an existing charger and just get a new top moulding designed. Even that, as you will have to get a set of new injection moulds made, will not be cheap. Even if most of the regular contributors on this forum both English and German take one, that is only about 250-350 chargers, leaving Tim and I an awful lot to sell elsewhere to recover our investment.

 

Wilson

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[Speenth]

One of the enjoyable aspects of such a project is the pretty stuff. In this case, we want to investigate the minimum volume that might be occupied by a new M8 battery charger. This phase is straightforward enough, but filled with assumptions .... Of course, the untested assumption is that we can fit the guts in and around the unusual shape of the battery.

 

Bring on the comments please!

 

Tim

 

 

Hi' Tim,

 

A slight variation on the obvious is attached.

 

Forgive the primitive sketch!

 

Steve'

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[Speenth]

Stephen,

 

I think you will find on portable devices, a number of countries (and maybe CSA and UL approval) would demand a door over a 220/110V figure 8 outlet, given that rug rat fingers could poke in there, not unsensible. Now maybe we could get away with a rubber plug but that may not be failsafe enough. All more complication = tooling expense etc. I hope we will be able to piggy back onto an existing charger and just get a new top moulding designed. Even that, as you will have to get a set of new injection moulds made, will not be cheap. Even if most of the regular contributors on this forum both English and German take one, that is only about 250-350 chargers, leaving Tim and I an awful lot to sell elsewhere to recover our investment.

 

Wilson

 

Hi' Wilson,

 

The male end of a figure 8 lead is already rugrat proof! The exposed pins of such a connector are in the female end (see Tim's diagram) - so there should be no problem.

 

It is the small potential market that is making me come up with these suggestions. The mouldings have to be made anyway. If they include a protrusion at one end that looks like the business end of a figure 8 lead that may add some cost, but the sales potential increases because if the device is stackable, many people would opt to buy two or more at once, rather than just the one.

 

For this to progress there has to be a certainty of way beyond 250 sales. That's what behind my PowerMonkey notion. Package the two together and the value added may be sufficient to tip the balance (despite the much higher cost) and make many people say "I want one, or two, or three". If the customer buys one kit -i.e. one M8 charger with one PowerMonkey eXplorer it costs US$250 for the package. If they buy the twin kit its one PowerMonkey and two chargers and costs just $279.99 and so on and so on.

 

At this stage I'm just trying to look beyond the obvious. Nikon et al have done the neat little charger. We could do the same (expensively). If it is going to cost a lot, how can we add value and a little flair too?

 

 

 

 

 

 

 

Steve'

[EricC]

That's what behind my PowerMonkey notion. Steve'

 

I'm sorry but i thought that the original idea here was for a small mains / possible car charger, not a holder that requires yet another piece of kit to power it. :rolleyes:

 

I don't really want to have to purchase yet another piece of kit just to use it, even if i can buy them packaged together.

 

Eric

[Speenth]

I'm sorry but i thought that the original idea here was for a small mains / possible car charger, not a holder that requires yet another piece of kit to power it. :rolleyes:

 

I don't really want to have to purchase yet another piece of kit just to use it, even if i can buy them packaged together.

 

Eric

 

I totally agree Eric, but I am concerned the project will be a non-starter due to the small volume of potential sales. My suggestions are intended to raise some debate on what we might design that is more broadly attractive .. and still achieves the original aim - a small, highly portable M8 charger.

 

My ideas may be completely daft, but maybe someone else out there can take this further.

 

What could we (M8 fanatics) come up with that is commercially viable and meets our requirement? In our collective imagination there may be a device waiting to be designed by Tim that does things none of us realised we needed!

 

In short, I'm trying to address the concerns Wilson has been expressing about the commercial viability of this exciting, but small-scale project.

[papimuzo]

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Hi Tim, Wilson,

 

comments are certainly a must, but please, keep it simple and small... remember the committee'decisions which looking for the horse project got at the end a camel!

Thanks for your courage and work, I'm waiting patiently news on the design.

[Fotogo]

The numerous and good ideas here will all filter down to a worthwhile result, I feel certain. As I digest all these suggestions, I would like to say, that although the idea of 2000 pieces is relatively small production volume, it is possible to find a supplier / manufacturer that would do the job and do it well. That is really at the heart of the project. The design work and tooling is relatively easy. Satisfying everyone's request, is a challenge, but one I enjoy very much.

 

I just wanted to jump in and comment that I have another slimmed down version about ready to display here, but I am working through a simple device to hold the battery. Simple often means, head scratching, staring off into space and deep sighs....but I am close. However, before I post the next offering, I will head off to Hong Kong tomorrow and half of Sunday. Just wanted you all to know I am paying attention here. Good stuff indeed. But will be silent for two days.

[Fotogo]

Hi Tim, Wilson,

 

comments are certainly a must, but please, keep it simple and small... remember the committee'decisions which looking for the horse project got at the end a camel!

Thanks for your courage and work, I'm waiting patiently news on the design.

 

Here is another approach. Here we have a wire cam locking clip to hold the battery on the top surface of the charger. The wire retracts for traveling. The battery leads contact in a small matching pocket. Two figure 8's, one male one female available for tandem arrangement.

 

Before I add more details to it, I would like to hear some comments please, good and bad ones. Talks with potential suppliers will start this week. The premise here is to produce the smallest charger design that is practical, and then to make it larger if the internal circuitry and standardized components require such changes.

 

 

 

 

 

[vanhulsenbeek]

I would like to hear some comments please, good and bad ones. Talks with potential suppliers will start this week.

 

Not very constructive, but: WOW!

I want to have 1, no, 2!

[jaapv]

You can put me down for two as well

[EricC]

That looks amazing, i'll take two too.

 

Eric

[rwfreund]

I will take two please.

-bob

[Jamie Roberts]

If they're $100 or less, then 2 for me too, please You can daisy-chain them, right? Brilliant I always need to charge 2 at a time!

[HetDraakje]

As everybody is taking two, why not a twin version of this one? You would only have to carry 1 power plug.

 

Boen

[stunsworth]

From what I read in an earlier thread, Li-Ion battery chargers need to have a degree of 'intelligence' and communicate with the battery during the charging process. I also seem to remember that the 'communication' is battery model specific. Has this been taken into account?

 

Appologies if either this has been taken into account, or I'm talking bollocks.

[jaapv]

As everybody is taking two, why not a twin version of this one? You would only have to carry 1 power plug.

 

Boen

 

If they can be daisy-chaIned, one plug suffices for any number of chargers.

[Speenth]

Here is another approach. Here we have a wire cam locking clip to hold the battery on the top surface of the charger. The wire retracts for traveling. The battery leads contact in a small matching pocket. Two figure 8's, one male one female available for tandem arrangement.

 

 

Hello Tim,

 

As I expected, you've come up with just what we needed! Its small, its portable and its interesting too. I'll be wanting one, and two if they stack.

 

A couple of observations:

 

Could the wire clip be replaced by a small moulded ridge in the blue shell to push the battery firmly in place against the charging contacts? (Not dissimilar to the action involved with the current Frankencharger). Thus there'd be less tooling and assembly, one fewer part, in fact, no moving parts and a still more minimalist look to the device.

 

I'm thinking that you'd first push the battery pins into their receptacle and then push the battery flat against the blue charger. In so doing you'd have to squeeze the battery inside the moulded ridge.

 

A second observation: I love the idea of being able to stack the devices and I'm pleased you demonstrate that feature. However, your drawing seems to show two female connectors (albeit, one without pins). In practice would it not have to be one female (enclosing the protruding pins) and then a protruding male moulding that emulates the tip of the power cord?

 

Its a great design - congratulations!

 

Steve'

[marknorton]

It's fine to come up with a neat design but there's not going to be much room in there for the electronics. Scaling off the image, it looks like this proposed charger is 7.5 * 5 * 2.5 cm, a volume of 94cc...

 

Working through my chargers drawer...

 

Mark's Travel Charger - 88cc

Epson R-D1 - 135cc

Nikon D100 - 171cc

Leica Digilux 2 - 281cc

Leica M8 - 284cc

Nikon D2x - 364cc

Nikon D3 (dual) - 434cc

 

Do you see a pattern here? Keeping in mind my travel charger does not have a AC-DC power supply built in, it's going to be tough to make one this small.

 

The smallest AC-DC power supply I can find is the Traco Power TMLM 05105 (Tracopower, Excellence in Power Conversion) which is 50mm * 25mm * 16mm which is pretty small but you have the AC cord connector, the necessary fuse plus all the charge controller circuitry. Cost about $32 in small quantities.

 

As Steve says, you also need a charge controller to charge the battery properly and there's this chip which has the minimum external component count to do the job. Cost about $3 each in small quantities. Only issue is whether the thermistor inside the battery pack is commoned to ground or battery +, I can't remember. This chip has the advantage that it does not require a space consuming inductor (the do-nut shaped component in the Leica charger) but the downside is that the chip will get hot and will need some sort of heat sinking, possibly to the external (metal) case.

 

http://docs-europe.electrocomponents.com/webdocs/0806/0900766b808065cb.pdf

 

[Edit: Interesting sign of the times; this specifications shows the manufacturers various sales offices, 11 in China, 1 in Japan. Every one of those battery chargers listed above is made in China.]

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[haribo]

Hi Tim,

 

Here's a suggestion for you. I thought it might be a good idea to position the figure 8 connections so that they are covered by the wire cam when in it's resting position. They are only used anyway when the wire cam is swung over to secure the battery for charging.

Just a thought.

 

best, Harald Benz

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