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Charging can be a handful

Jun 25, 2014

Meeting the challenge of recharging handheld devices afloat

Handheld devices provide voyagers with many useful applications, but keeping them charged adds a new wrinkle to power management on board.

Handheld devices provide voyagers with many useful applications, but keeping them charged adds a new wrinkle to power management on board.

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Tablets, smartphones and small laptop computers can help make life aboard easier and safer. These devices help us stay connected while sailing and they can help us navigate, watch the weather, and even act as anchor alarms. Battery technology has improved as well, but at some point every one of these devices will need a recharge.

Keeping the batteries in all these devices charged while afloat can be a challenge. At first thought it seems fairly straightforward, just plug the device into a car charger right? Anyone who owns a boat, however, knows nothing is ever that simple. Unfortunately this also applies to keeping our portable devices fully charged. Almost all devices are designed to be charged from a 120-volt wall outlet as found in most homes. The problem is that when we are away from shore we do not have that nice, steady 120-volt outlet available and when we do, it may not prove to be the most energy efficient way to charge things up. The simpler solution is to use a 12-volt car charger. The problem is most car chargers are not as efficient as home chargers. Many 12-volt car chargers will not supply the power needed to quickly charge a device, thus drawing out charging times.

A smartphone recharging using an AC adapter.

Before beginning to think about charging options, it helps to understand just what is needed by our devices in order to get and keep them charged. Today’s tablets and smartphones have high-capacity batteries that give long run times; this however can be a double-edged sword in that it can take longer to fully recharge these batteries. Knowing just how much power is needed for your device will help in selecting the best charging solution for use aboard.

Some faster than others

Not all charging sources are equal and some will charge faster than others. We want to keep charging as efficient as possible so as not to waste power while at sea. Most of today’s small electronic devices use a USB-type charger which at first would seem to simplify things. We all know nothing is simple in the world of electronics and boats. Not all devices use the same charge amperage and not all aftermarket chargers are rated the same. Most tablets require 10 watts or 2.1 amps to correctly charge. Smartphones and other smaller devices only require five watts or 1.25 amps. I have heard complaints from some boaters that even after being left on a charger overnight their devices were still not fully charged. Others have complained that when using the device for navigation while plugged into a charger it still lost charge to the point of shutting down. Understanding what charger is best for your device will help avoid disappointing results.

Normally the best option for the fastest charging will be to use the 120-volt wall charger supplied with your device. This works well in the slip with shore power available, but as soon as we leave the dock this approach gets more difficult. There are options for using 12 VDC for charging, but care needs to be used when selecting a 12 VDC charger as not all aftermarket chargers are equal.

A charging outlet on the binnacle allows for handheld recharging in the cockpit.

Before getting too involved in what power source to use for the charger, it helps to understand a bit more about the charger and the needs of the device being charged. As mentioned, most of today’s devices use a USB charger. When the USB standard was first developed it was thought that the power would be supplied from a computer. Because of this the power output was limited so as not to overload the computer’s motherboard. The most common USB standard is USB 2.0 which is set at a maximum charge rate of 0.5 amps. The newer standard of USB 3.0 has a higher charge rate of up to 1.2 amps. This can be important to understand as some devices will “talk” to the charger to determine the USB version of the charger.

Today’s newer, power-hungry devices require more power than what the older USB standards can handle. Many OEM chargers that come with a device will provide the higher output needed to quickly charge the device. Additionally some devices will communicate with the charger to set the best charge rate for the device. This usually only works with the OEM charger supplied with the device. When used with an aftermarket charger, many devices will default to a lower charge rate. Others will take all the power they can get, particularly if there is no data signal detected. When using an aftermarket charger, it can help to replace the data cable supplied with your device with a “charge only” cable. This is a cable that has had the data pins modified or removed to trick the device into accepting as much current as the device can take. This combined with a higher-output charger will often charge your device as quickly and efficiently as possible.

Jul 22, 2014 02:20 pm
 Posted by  armand

Excellent article by Capt. Canning.

One comment is that I use a 1500 watt inverter (I have a cigarette type 100 W as a backup) mainly to run my laptop for navigation and provide power to iPhone chargers. I have a finely graded 0-25 A ammeter, and when I turn on the inverter it barely makes a blip on the meter. Same as when I plug in the charger and PC power supply. While the inverter specifications may have an "idle time" current draw, it surely seems to be minimal and any "losses" are not even noticeable.

While it is always good practice to keep "cords" as short as possible, I can assure everyone that measuring any loss in using even a 25 ft USB cable would require scientific quality instruments with a mear 2 A draw.

Thanks again,

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