Main Features:
-Using SANYO UR18650F Li-ion batteries
-Remaining capacity accuracy up to “1mAh”
-Remaining time for charging & discharging accuracy up to “1 minute”
-Higher than 90% conversion efficiency
-Automatic recognition adapters
-Full text & icon OLED display
-Only one key to access all functions, very easy to use
-Low self-discharge rate
-Multi-level Input/Output & Battery Cell protections
Good question!
I think you mean the Panasonic NCR18650B. We have tested that cell before. The discharge plateau is much lower than UR18650F, which decreases the boost converter efficiency sufficiently, especially near the end of discharging.
And, the main reason is, it’s too expensive. |( We may launch a large-capacity version of DreamCharger in future by your suggestion.
If you are able to charge to 4.35V you should check out the pink LG ICR18650D1 cells.
They are higher capacity (3Ah) and have a better discharge plateau, even compared to the great red Sanyo cells
I must say though, I have my doubts about the positioning/value proposition.
$50 for a 7,800 mAh power bank is a premium price, even for something relatively compact and lightweight
Meanwhile, I have to wait 3-4 months to get the product, if I even get the product at all (particularly since you say you are raising this money because…you didn’t manage your costs very well).
The efficiency is a nice selling point, but ultimately, it comes down to power delivered to USB/$ and power delivered to USB/g. Anker makes a 10,000 mAh pouch-cell based pack that weighs 230g that I can order from Amazon today for $25 and have in two days. There are plenty of other 7,800mAh/3x18650 packs for $25-30. I haven’t tested their efficiency, but I can try them and return them if they fall short, while I wait for your product.
2A charge rate sounds good, but I’m not sure its going to be a major differentiator for a lot of people. Plus, it isn’t forward looking. There are already players with a lot of weight (ie Qualcomm) pushing standards for higher charging rates.
All the various protection/safety features. Big deal. Most non-counterfeit branded power banks will do the same things, except, perhaps, the temperature monitoring.
1A and 2.4A output. Better if I don’t have to worry about which port I’m plugging into.
OLED graphical display, precision & breadth of information. Definitely geekey. Definitely something I might pay a little extra for.
Design/materials/build quality. Appearance is distinctive (for good or ill). I personally don’t like the yellow, but the red, black, white or clear could be appealing. Materials and build quality are, of course, an unknown quantity until manufacturing is underway.
Custom logo. Fun, and I think it could be really appealing to younger buyers — IF they can change the logo whenever they want.
Low idle discharge. Expected, though I understand some power banks can be quite bad.
This might be worth a premium to ME, if I could use it with any cells I wanted (including different charge and discharge termination voltages), because, well, I’m kind of geeky that way. A $25-30 version without batteries would be pretty cool, though it would be hard to retrofit for non-welded cells.
If I were you, I’d consider dropping the price to $40 or so, and adding a $60 version with higher capacity cells with a suitable discharge curve. Also, if you are going to offer a wall charger, make it one that supports full-speed charging.
I kicked in $1 because I appreciate the information about your design choices, and the updates with the component selection. On second thought though, I should probably be charging you for product development advice
Over time both battery capacity decreases and charge/discharge times change along with the decreased capacity. How does the display readout compensate for these changes, particularly if the unit is rarely if ever fully discharged to the discharge cutoff point. Last I knew the only way to determine capacity is to do a full discharge and charge cycle on a battery. Also battery capacity decreases with low ambient temperature so I question the accuracy of the remaining capacity readout to “1 mAh & 1%” as claimed. Too many variables related to time and temperature for that accuracy IMO.
Make total output equal 4A total with either port able to give the 2.4A and the other able to give the remainder up to 4A total. As you claim automatic recognition of adapters I presume you mean that it recognizes different attached items to be recharged and adjusts the current and ID signals for the maximum each item can accept. In that case either port should be able to output 2.4A
Those specifications appear to be too good to be true, in which case I question them.
The price is very excessive for a Asian made item of that capacity. I would only consider the purchase at or near that price if made in a western country in an ISO 9000 factory.
They have dedicated chips to calculate and track capacity. This uses a maxim battery fuel gauge. Though I don’t believe the 1 mAh accuracy either unless I see the model number for the maxim chip and the datasheet confirms it.
Show me any major consumer electronics that are actually manufactured in a western country these days. Extremely rare. Asian made is no problem if the design and components are quality and they maintain tight quality control.
Would be nice if the firmware would calculate mAh in vs mAh out and give an approximation of conversion efficiency.
Honestly it looks like a very well put together unit, and offers ALOT of potential, but way out of my price range unfortunately…but still nice to see someone giving it a go…don’t let anyone say it’s not worth it…follow your dream and keep on trucking…heck once the project is funded and you can get some sales and price drops…I might be able to afford one or two
Exactly my first thought, this is a very promising developement, thanks for posting here at BLF. It looks like a well done unit, and with this level of communication (and hopefully a good response to feedback) it can only become better!
This chart is clearly just a mere series of calculations in a perfect scenario and not from real world testing.
With the portapow premium USB meter I have tested the total amount of power required to charge an iPhone 6 from 0% to 100% and it’s about 8.5 Watts Hour when the device is not in use. A single sanyo 2600mAh cell is capable of delivering about 10 Watts Hour under moderate draw. Even assuming 100% efficiency, it is simply impossible to charge the iPhone 6 4 times with only 3x2,600mAh cells.
In a lucky day with a 3100mAh NCR-A I barely manage to get 1 full charge using the Miller-ML102 which efficiency tops at 92%, and the cell comes practically fullt depleted at <3.0V
It pisses me a lot when these power bank manufacturers play with the CAPACITY (mAh) to fool customer into thinking they will get the number of charges by just dividing powerbank capacity/phone battery capacity, when it is POWER (Watts)ENERGY (Watts Hour) that really matters.
And they couldn’t go with NCR-B or LG E1 because of low discharge rate? in 3P configuration it draws less than 1A per cell, sure they can handle it. Maybe the real reason for sanyo cells is that they are cheap as dirt.
Anker does the same thing. The capacity of their USB battery boxes is listed at 3.7v, battery nominal. This is not specified any where I have found except in minute printing on the battery boxes themselves. Certainly NOT in Amazon listings. So right off the top the 5V capacity is only about 75% of claimed capacity and then there are the additional losses in the circuitry that steps the voltage up from battery actual to 5V for recharging the external USB devices.
It looks like the box listed here is doing the same thing but the 7800 mAh is not specified as to what voltage it is at so actual Watts capacity is not stated or calculable.
Your argumentation is valid and I totally agree, but you do not use the correct unit: it is not like you stated the power that you want to know (in Watts, Joule/second) but energy (officially in Joule, or like you did in Watt hour-> Wh).
Your argumentation is valid and I totally agree, but you do not use the correct unit: it is not like you stated the power that you want to know (in Watts, Joule/second) but energy (officially in Joule, or like you did in Watt hour-> Wh).
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Thanks for the correction! Yes what I meant was “Total delivered power capacity” in Wh. Power alone (W) is irrelevant to how many charges can it provide. My mistake :bigsmile:
