Recommended Solar Gizmo Charger?

Re: Recommended Solar Gizmo Charger?

What are your expectations?

Most (all?) of the small/portable solar chargers have panels that outputs hardly any energy at all...

A typical unit: 150mA for charging 2 rechargeable batteries at a time.

The AA NiMH battery? 2,000 mAH.... 2,000mAH/150mAH=13+ hours of full sun (~3 bright summer days for 2 AA batteries).

If you want a unit with another internal rechargeable battery--the efficiency drops even more (with same size solar panel may take 2x longer). 150mAH*5 volts = 0.75 watts

So, you can look at a larger system with its own battery. This Xantrex unit has a 5 watt solar panel and a 10 amp*hour AGM battery. Even includes a 400 watt inverter.

Use the 12 volts or 120 VAC to power any charging station of your choice.

Down sides; weighs almost 20 lbs. To charge 4xAA NiMH batteries will probably still require over 1 day (5+ hours of sun) from the solar panel. Even though it has a 400 watt inverter inside, a reasonable use would be a few tens of watts for 10 hours maximum before recharging the battery. To recharge the internal battery only from the attached solar panel would take 20-40+ hours (4-8+ days of full sun). Better, but probably still not what you are looking for.

In the end, getting as large as solar panel as you can, and matching to the sort of cells you want to charge is probably your best bet. Pick a thin film flexible panel if you need something that is a bit harder to break when traveling (regular solar panel would be smaller--but think of carrying a sheet of glass as you travel).

You might look for something like this 5 watt panel for $72.

• Peak Power = 5 Watts
• Voc (Volts at open circuit) = 23.8 Volts
• Volts @ peak power (load) = 16.5 Volts
• Isc (Amps @ short circuit) = 0.37 Amps (370 milliamps)
• Amps @ peak power (load) = 0.30 Amps (30 milliamps)
• Power cable is attached
• Instructions are included
• 10 year warranty

I am not sure--but the dimensions may be about 19.5"x8"x0.9" (hard to find any data sheets for this).

5w/16.5v=0.3 amps... Assume it takes about 2-3000mAH to charge the average 100% depleted AA NiMH battery, that would be about 10 hours of sun to charge from 1 to 8-10 cells in series. Add a Schottky blocking diode in series (to prevent cell discharge at night), and you have a charger than can charge either 1 or a bunch of batteries in 2 days (ideally, all batteries in the string should be discharged, roughly, the same amount). Since the charging current is roughly 1/10, you don't really need any electronics (current it to low to damage batteries left on for a day or to extra).

You might try and find a regular 2 or 4 cell NiMH charger that can run off of an external solar panel...

If you are going to have a laptop computer anyway--you can get a USB charger that will recharge 2xAA batteries in 4 hours.

Here are some very portable 10 watt solar panels--not cheap. Claims to work with 12vdc (15v) chargers...

I did a quick look around, and it is difficult to find a 12vdc battery charger with low enough input current for use with small solar panels.

The other way to go... If this is not an endless trip. Look at AA Lithium cells (Energizer L91BP AA Lithium Batteries). In some applications (cold weather, high drain), the Lithiums can outlast Alkaline and NiMH by many times. Also, Lithium can store for 5-10 years and work at lower/higher temperatures (-40 degrees to 140 degrees F) vs NiMH.

Granted, they are about $2.50 to $3.00 each--About the same price as a good Sanyo Eneloop AA NiMH Hybrid battery. And if they last 2-5x longer than NiMH or Alkaline in your application (assuming digital camera)--that is the same as if you did 2-5+ recharge cycles with the NiMH batteries.

-Bill