The only way I see it possible is that the circuity is being able to learn and read the battery voltage according to the capacity during a full charge. But it most likely uses fixed value and then translated to %, 3.4V being 0 and 4.2 being 100, so for every 0.08V = 1%, not accurate since the battery does not discharge flat.
What eas said is right, 4.35V is a critical voltage which will trigger the overcharge protection immediately. Normally, the internal charging circuit will control the cell voltage from exceeding 4.2V.
The reasons of why we didn’t design DreamCharger as a cells user-replaceable mobile power:
-Need three mechanical springs for negative electrodes and three contacts for positive, these six contacts will increase the resistance. If you watch the short video “A Dancing DreamCharger” carefully, you will find we used nickel plates to connect them to the Power Board, instead of using copper wires. It’s in order to reduce the resistance between the cells and the board. The resistance of micro-spot welding point and nickel plate will be much lower than solder point and copper wire(unless it’s thick enough).
-The different resistance between each contacts of the cells will break the balance of cells in charging and discharging conditions.
-The strength will be decreased.
-The most tough thing is, every type of battery pack should do “learning-cycles” before using. This task needs ultra technical skills and rich experience, also some electronic equipments, dedicated debug tools, dedicated software. It’s impossible for normal end users to achieve this task. Even for us, we spend a lot of time on learning, researching and doing experiments.
And, we will sure test LG ICR18650D1 once we get it. Thank you for your suggestion!
I truly wonder what the average efficiency both charging/discharging of the internal batteries vs power delivered in portable power units…I would wager in the 75% to 80% range…on a good unit…worse on many sub standard Chinese rigs due to poor quality control and design (how many times have you opened one up and seen MANY unpopulated component pads?)
If this unit can deliver and break thru that barrier it will be awesome…unfortunately due to losses in boost circuits…it’s doubtful no matter how masterfully built and high quality components are used
Japan is also a Asian country.
I have to agree with this.
It all seems good and well designed but this kind of advertising is either a sign of not enough knowledge about the product, or just false advertising to get more people excited.
If you really want to stand out of the rest, give more realistic numbers. Either by doing some real world testing with several devices, or by calculating the efficiency and adjust for that. Or better yet, do both to see if they match your calculation.
Like always they just compare the capacity, but at 5V you only have 75% of the 18650 capacity left…and of course losses on top of that…
They are right with the ncrbs they have much lower voltage over the whole discharge cycle…so I am okay with that and impressed that they knew it.
The whole presentation looks indeed good and I like the product a lot. They price on the other hand is in the luxury sector so I won’t buy it.
But considering people using phones for 1000$ it may find some buyers.
I wish them good luck.
> we didn’t design DreamCharger as a cells user-replaceable
Okay, what happens after the 300 charge cycles?
Either we crack it open and replace the cells,
or ….
Again, they have dedicated battery fuel gauge chips to accomplish this. And they can indeed include temperature compensation. Battery Fuel Gauge and Coulomb Counter | Analog Devices This power pack says it uses a maxim fuel gauge.
That a nice, well thought out piece of hardware there. I hope it sells well for you.
Even better, those chips are designed by actual engineers, who get paid to work on them, drawing on experience with previous generations, rather than (armchair?) engineers typing away in an internet forum in their spare time.
These things typically embody a model of battery behavior, often tuned to a specific cell chemistry and/or manufacturer. They are likely temperature compensated, and in addition to voltage, they may employ “coulomb counters” for precision measurement of current in and out the the cell, and separately, may take into account voltage and current during discharge.
…throw it out, like most people who buy this sort of thing do, assuming they end up in the bottom of a drawer well before then?
There are a few billion 18650 cells made every year. The vast majority of them end up in non-user serviceable packs. The market for individual protected cells is small, and for unprotected cells, I’d guess, even smaller. Even here, where people tear into laptop packs in search of sweet sweet battery meat, there seems to be interest in sealed USB powerbanks.
Now, as I’ve said before, personally, I’d be much more interested in the premium they are trying to get if I could bring my own cells, but I understand that carries a lot of compromises, including different revenue model, smaller market, calibration, cell connections (I don’t have a battery tab spot welder, yet).
Other than the flawed/misleading illustration of how many charges this device should provide to various devices, what specs appear too good to be true? I have the opposite perspective, there are other offerings in the market that I can buy right now and have in two or three days that should match this one on the specs that matter most to me mAh @ 5V/$ and gram at a much lower price point. I’m pretty sure they are all made in China too, for what that is worth.
Will34, I don’t like that chart either, and for many of the same reasons you object to it, but I think, generally, those things are most useful not as a strict demonstration, but as a way to help consumers understand an abstract concept like mAh by referencing something they are familiar with.
I don’t think there is anything wrong with using the chart as a reference guide, but the average consumer take the “number of charges” very seriously. And for such detailed product announcement as this one they should have done the real world test instead of some simple math. It’s not difficult to obtain one of each of the mentioned product and performing a couple full charges.
Thanks for your feedback and your contribution for our campaign! And sorry for replying you so late, because none of us is good at English. It will take us more time to reply you with too many words.
*In fact we do manage our costs very well. Chinese people are always best at controlling costs, aren’t they? The version presented on indiegogo campaign can be said the “highest-quality” version of DreamCharger. We plan to produce not too many DreamChargers in this version due to the high costs.
*We can easily reduce the price to $25~30 or even $10, by redesigning the whole product. But it will no longer be named “DreamCharger”. Though $25 is still a high price for only 7800mAh~10000mAh power bank with the efficiency more than 90%.
*After all, 2A switching charge rate is much better than 800mA linear charge rate. Higher charge rate will case higher charge temperature, needs a dedicated input port instead of type-micro USB port and many other aspects. The charge rate itself is not the key problem.
*Your 6th proposal is very interesting. We will add this consideration in our future design.
*Production process of DreamCharger will be very complex. We already have a detailed plan to ensure quality. Maybe, we will update some details in indiegogo updates.
*The custom logo is burned with the firmware, so it can not be changed by the customers.
Again, thank you very much!
Thank you very much for your encouragement!
We’ll try our best all the time.
We appreciate your rigorous testing. Actually we have the word “approximate” in our original article. But these words were just deleted when I ask my American friend to modify it. We will add these words back or just delete the table. This table seems really useless. Imagine, who will charge a device until it’s completely out of power or disconnect the cable once charged to full?
Anyway, it’s our mistake. Thank you for noting it for us.
You forget that the battery used in your phone, the voltage isn’t 5V there.
So what the will34 said is quite right. It is better to use the unit “Wh” instead of “mAh”. But we have to follow the practice on the market. The capacity marked with “Wh” will confuse most of the customers.
The DreamCharger presented on indiegogo can be called a “Conceptual Product”. There’re many ways to reduce the price for mass production in the future. But we can not guarantee all the things shown on indiegogo that time. 
The life of DreamCharger depends on the life of SANYO UR18650F.
The full-charge capacity of DreamCharger will decrease until “0mAh”.
so it bricks itself when i replace batteries?
i have access to software to program it but you are trying to sell to a bunch that will want to upgrade batts.
will it brick or will it recalibrate to the new capacity?
> full-charge capacity of DreamCharger will decrease until “0mAh”.
No. Nobody will hang onto one that long.
So, seriously, you mean for people to throw these in the trash when the battery gets old?
Factory sealed unit. That is true of almost all USB power boxes other than the relatively few ones available without batteries which are intended to have the user install their own 18650 Lithium Ion batteries. Virtually all those available at retail from USA sellers are sealed units like this one. The above USB power box may be designed and manufactured by Geeks but it is aimed at the great majority of the public that are looking for a decent power pack to recharge their tablet or phone and who know minimal to nada about either Lithium Ion batteries or their proper care. For such people a sealed USB battery box is probably the smart way to go. Do you really want some uninformed user putting a Sanyo, a Ultrafire, a Sony and a Samsung 18650 battery; all of different capacities; in a unsealed four battery USB power box?
There are reasons why the batteryless ones of interest to BLF members are only available from Chinese sellers via ebay and Amazon or Chinese dealers. Try a liability suit against the seller from any where outside China. Fat chance.
Most Phones just get Charged with a linear Regulator so if your phone has a Battery capacity of 1Ah@3.7V you have to charge in it 1Ah@5V…the excess voltage is just Heat…so the use of WH only makes sense if you know the losses….