The four most common variables determining the charging speed (power) you will get out of the Powerhouse are 

1. Built-in charging limitations on the device you are charging

Every battery-powered portable electronic device has safety-related settings that determine how fast it can charge. Most modern smartphones, for example, cannot accept even half of the power the Powerhouse is capable of delivering. Generally speaking, the bigger the battery, the more charge power it can accept.

2. Which charge port you use

The USB-C port (the smaller oval-shaped one) is about three times more powerful than the USB-A port. USB-C is steadily becoming the new standard and has thus benefited from more engineering advancements, including much higher charge power limits.

3. The state of charge of the device you are charging

Every battery has safety-related settings that limit how fast it can charge as a function of how charged it already is. You will see the highest charging speeds when a battery is less than 50% charged. Charging speed usually drops dramatically when the battery’s state of charge is greater than 80%.

4. Your own cranking power

The Powerhouse efficiently converts your muscle power to electrical power, but it can only work with what you give it. For the power associated with fast-charging most mobile phones, most users are able to sustain the required cranking effort for a few minutes at a time. For larger devices such as iPads, laptops, and portable power stations, the cranking effort becomes difficult to sustain for more than a few seconds at a time for most users. 

The three most important considerations when charging a larger USB device are:

1. Ensuring compatible cables

Laptops and tablets are often equipped with a USB-C port. If so, make sure you are using a USB-C to USB-C cable that is compatible with USB Power Delivery (USB-PD). You can usually safely assume that the cable that came with your device is USB-PD compatible. Alternatively you can use a USB-A to USB-C cable (plugging the USB-A side into the Powerhouse and the USB-C side into your large device), again ensuring that the cable is USB-PD or “fast-charge” compatible. If your device is equipped with an Apple lightning port, your best results will be with a “USB-C to lightning” cable.

2. Cranking quickly and forcefully enough, for long enough, to initiate fast-charging

Most users find the cranking power associated with crank-charging large USB devices difficult to maintain for more than a few seconds at a time. The Powerhouse can efficiently convert the power you give it to electrical power for your devices, but large devices simply need more power and that power ultimately comes from you. The power electronics in your electronic device and the Powerhouse need to complete a “handshake” in order to initiate fast charging. This results in the two devices agreeing on a voltage. Once the voltage is set, the device being charged will incrementally “ask” the Powerhouse for more and more current (until it reaches the maximum dictated by its pre-set USB-PD electronic power specification), resulting in higher and higher charging power. If at any point during this process the Powerhouse’s voltage drops below the previously agreed value, your device will cut off charging completely and the process will have to begin anew. A larger USB device will tend to charge at a higher voltage, which in turn is a direct function of cranking speed, so the cranking speed needs to be a bit higher than it would be for charging a smartphone or smaller device. As the current ramps up, you will feel more resistance at the crank, which will make it harder to maintain speed. The best way to maintain the required speed throughout this process is to start out by cranking quickly, i.e., 120 rpm (2 revolutions per second) or more. This will give you some cushion so that even if you slow down a bit as the resistance increases, you’ll still be above the minimum voltage. Once a stable charge power is reached, you can slow your cranking back down again. It is only during the fast-charge initiation phase (lasting 3–5 seconds) that the device being charged will be ultra sensitive to any cranking speed reduction.

3. Restarting and replugging as needed

USB Power Delivery (USB-PD) is a very effective fast-charging standard, but some quirks can arise due to the sheer variety of devices and chargers on the market. There is a lot of variation in the design of the printed circuit boards and chips that deliver the standard. Our power electronics are thoroughly tested across all major smartphone and other device manufacturers to ensure universal compatibility. In the vast majority of cases you can just plug and play and all the details will be worked out seamlessly in the background. When quirks do arise, we have found that unplugging and replugging the device, plugging it into a wall charger and then plugging it back into the Powerhouse, initiating charging of the device while it is off, and/or restarting the device can all be helpful.

While the Powerhouse is designed to charge via USB, by using appropriate adapters, it can deliver standard DC charge power to devices such as portable power stations (i.e., large backup battery packs) and car batteries as well. Our customers have pioneered or refined effective ways to use the Powerhouse to charge such devices with the appropriate accessories and plug adapters.  

1. Portable power stations (large backup battery packs)

These go by many names, including “power bank,” “emergency power supply,” and even (misleadingly) “solar generator” or “battery generator.” Brands making these include Jackery, Ecoflow, Bluetti, Goal Zero, and many others. We have tested most brands and confirmed that they can charge from the Powerhouse. Some of them have USB-C input charging, in which case you can just charge from the Powerhouse’s USB-C or USB-A port. If your portable power station accepts charge from a solar panel or auxiliary power port on a car, it has a DC input port. The two most common types of DC charging ports are a standard DC barrel jack (sizes vary) and one designed specifically for solar called XT60.

A device known as a USB-Power Delivery (USB-PD) trigger can be used to turn the Powerhouse’s USB-C port into a constant voltage DC power source that can charge portable power stations. Trigger devices include the required power electronics to conduct the voltage “handshake” between the charger and the device being charged as stipulated by the USB-PD charge protocol. Most triggers come in the standard discrete voltages associated with USB-PD: 5V, 9V, 12V, 15V, and 20V. The trigger often comes already integrated into a cable that has a USB-C plug on one end and a DC 5521 jack or XT60 plug on the other end. Some triggers will have a dedicated voltage while others will allow you to select among various voltages. The DC 5521 jack can then be converted, if needed, to different DC plug sizes using a DC plug adapter (which has a female DC 5521 on one side and a male plug of a different DC plug size on the other side) or plug adapter kit. 

2. 12V car batteries 

Proceed with caution. What follows is based on very limited testing; we can’t guarantee the performance of the Powerhouse for this particular application. 12V car batteries are designed to charge directly via their battery terminals. To charge from the Powerhouse’s USB-C port, you need a trigger device as described in the section above on portable power stations, with one key difference. You will need a DC plug adapter that goes from DC 5521 to two alligator clips. These clips will connect to the battery terminals. You will also need to select a trigger voltage that is higher than the resting voltage of your 12V battery. Keep in mind that fully-charged 12V batteries actually have a nominal voltage of up to 14.6V. 

In short, yes! Keep in mind that the electrical power charging your device is coming from your effort, so if you reduce your effort, you will reduce your charge power and therefore extend your charge time. There are two ways to reduce the output power of the Powerhouse if you prefer to crank with less effort over more time.

1. Charge from a different port

The USB-C port on the Powerhouse is about three times more powerful than the USB-A port. This means that if you’re charging a larger device that is trying to use the max power of the Powerhouse and you’re finding the associated crank power hard to maintain, you can reduce the charge power (and thus the cranking effort) simply by using the USB-A port on the Powerhouse. You can use a USB-A to USB-C cable, plugging the USB-A side into the Powerhouse and the USB-C side into your device. Just make sure to use a USB-PD compatible cable. Even though USB-A is less powerful than its USB-C counterpart, as confirmed by our own testing, it is just as efficient and is compatible with most of the same devices. It has also recently been updated to deliver additional USB-PD voltages beyond 5V (9V and 12V), allowing it to achieve greater than 20W of max charge power. The Powerhouse is equipped with the latest USB-A technology, so you can rest assured that it is giving you as much as it can through this port.

2. Use a USB-PD trigger to reduce the charge voltage

USB-PD triggers are used to allow USB chargers to charge at a predetermined voltage. You can learn more about them in the FAQ under the question about charging non-USB devices. They can also be used with normal USB-PD compatible devices. Doing so allows you to select a charging voltage, which is normally beyond your control. Selecting a lower charging voltage than what the automated USB-PD “handshake” process selects is a way to reduce charging power and therefore cranking effort.