IDEAL it's never because so any moment and independently can from an external supply on the go at the same time several / various consumers with 5V (USB), as well as same time, additional loads are supplied with (switchable) 9V or 12V regardless of the network of the independent simultaneous outputs (2x USB A and 1x switchable to 9V or 12V).
Another huge advantage is the ideal SYSTEM-system flexibility:
The integrated powerful 15Ah battery, while the (different) consumers are operated, also simultaneously with 9V ... 20V supply can be loaded, eg also from 12V car, or from the supplied 12V / 2 Amp wide-range power supply -. Or a solar panel, while still Simultaneously, both 5V USB outputs and the 9V / 12V output supply a variety of consumers.
So I run eg from USB battery supplies - as secured permanent power supply - simultaneously both to the Raspberry Pi mini computer, as well as my universal AV4ms battery charger. A possible power failure in long-term operation is thus bridged safely for many hours.
The comprehensive battery-treatment data of AV4ms are thereby simultaneously stored in continuous operation by the PI, so that for example permanent battery cycles testweise determined for weeks and months Power SAFE and (compressed to the SD card of the PI) recorded are for later Battery analysis.
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Without external power supply, so fed only from the internal USB battery, I have measured the following OUTPUT payload capacity values, at one of the two USB outputs as well as the 9V / 12V output.
Only pure "Ah values Numbers-fetishist" but my unknowingly that this specified 15 Ah capacity must be available even at the 5 volt USB output voltage.
But that is a mistake. because this indicated 15 Ah-value refers logically only to the internally built battery capacity at 3.7 volts (on average).
The following measured from me "15 Ah deviant" Ah values for the different output voltages are therefore completely normal - you need only to know and be aware because there is logically no "energy propagation in Ah" when the output voltage set high , so it must be converted - on the contrary, low power dissipation is required to, so there are unavoidable "numerically less Ah" when moving from 3.7 volts to a higher voltage level.
One can / may therefore only perform compare the performance in Ah at the same voltage.
15 Ah capacity at an average nominal 3.7V (internal) battery voltage so mean after all, about 55 Watt internal battery power than judging baseline.
At the output was measured:
5V / 1.0 Amp load = 10.40 Ah = approx 70% (from internal 15 Ah) = about 52 watts.
9V / 1.5 Amp load = 5.75 Ah = approx 39% (from internal 15 Ah) = approximately 51 watts.
12V / 1.0 Amp load = 4.22 Ah = approx 28% (from internal 15 Ah) = 50 watts.
The battery power is very efficiently converted so in this USB battery type to another voltage situation.
Depending on the USB power input (capacity needs) of the respective consumer can thus be simultaneously multiple devices, such as GPS, digital camera, cell phone, smartphone, tablet, etc. often repeatedly recharged / recharged by the internal USB battery.
And / or operated over very long time so that - or even indefinite, thereby reliably linepack - used with permanent power supply, provided that the duration-power consumer does not exceed 20 watts.
Individual consumers can also record up to 50 watts, but then the battery will always eventually fully discharged to shutdown when finally 0% LCD display (backlit).
At less than 20 watts of output power in continuous operation a fully-charged battery USB is always kept because the (network) -buffering for external consumers up to 20 watts output line is permanently ready by the efficient integrated énegie control.
One can - highly recommended - also in between, anytime mobile devices RELOAD from Universal USB Battery - best then, whenever there is the temporal / local opportunity.
Because the road we all know rarely advance exactly how long they operated independently / autonomously the respective mobile / external device required.
Helpful for this is "Energy Usage thinking along".
The two connecting cables supplied (USB A to Micro-USB) and the 9V / 12V cable with 1,7x4 mm (on USB battery) to 2.1 x 5.5 mm barrel connector to the consumer are often standard. But usually is yes for the consumer to be charged in any case "be" USB cable already exists - any required adapters are available in many places.
Only the 12V car charger cable for the 2.1 / 5.5mm DC battery power input of the internal 15Ah USB battery missing, but that with the AV4ms charger from me included 12V car cable fits directly into the USB battery input , an alternative to the supplied 12 V / 2 Amp. Wide-range power supply.
So you come out with very little cable accessories, which is particularly go / when traveling a great advantage.
The maximum input power is deliberately limited to about 25 watts to the small, sleek USB battery housing not to cause excessive energy conversion heat loss during charging of the internal USB rechargeable batteries as well as the simultaneous unloading / operation of external devices ,
So you can see permanently after all, up to about 20 watts of power without internal capacity consumption with external power supply of the USB battery (mains or car or solar power), so that this ideal USB battery thus additionally the function of a UPS ( Uninterruptible Power Supply) provides, for various 5V USB applications and at the same time also for 12V or 9V consumers.
The intelligent MPPT charge control this USB battery (uses the most efficient Maximum Peak Power Tracking technology) starts from about 9 volts supply. As low as 9 volts supply and from about 15 mA input current is the (however this very low) enables charging, which also allows the operation of small solar panels - only it takes so stop (much) longer to fully charge.
However, the example 12V / 25 watt solar panel or from the supplied 2 Amp. Wide-range power supply unit or from 12V car a maximum of approximately 2 Amp charging current are recorded.
A full charge with up to 25 watts input power takes about 6.5 hours to the shutdown, the 100% battery indicator is, however, doing a little earlier.
With the same betriebenem / Consumer-Powered by correspondingly longer it takes to load, depending on the power intake.
With less (solar) charge input power loading takes therefore (much) longer - but the built in this ideal USB battery efficient MPPT charge controller uses the charge service offered always optimally - could not be better.
In my camera bag is, for example, space for these 15 Ah battery USB. As a result, either the USB used in the TZ41 camera battery directly, or in PATONA- or BAXXTAR-USB charger of (spare) battery on the move are loaded from USB battery.
At the same time the GPS handset eTrex Vista HCX is powered via USB, and / or - operate in the camera bag - Small AutoNavi with greater map display of the current position. Move, when eg longer bus trips, you know by always exactly where you are currently.
For this unique system advantages I forgive the maximum possible 5 points.