Charging LP-E4 with a Brunton Solar Charger?

[colbyb25]

Recently I was testing my solar charging equipment in preparation for an up coming expedition and came across a problem. I used my Brunton Solaris 12 solar panel to try to charge a Canon LP-E4 for my 1D Mark III. I left the charger out in the sun for an hour and then I plugged the Canon charger into it via the DC plug that I purchased seperate from my 1D Mark III. I left it outside for an hour just to see how it was going, but the battery ended up loosing power. The lights on the charger would flash for a second and then turn off, then start up again. Seems like it could never get it going. Any ideas? My Solaris 12 puts out 12 watts of power...is that enough to charge the LP-E4?

http://www.brunton.com/product.php?id=409

[avan]

With a 12 volt panel I think you need close to a full day of light to charge an lp-e4 battery. usualy you put the charger in the backpack and the panel outside on top the of the bag. As the LP-e4 are expensive make some test with other charger, look at the total MaH or AmpHour a. a 12 volt panel produce 1.5 amp hour if I remember.

[MoeIsMe]

Good question, and I get asked this a lot in my work.
There are a couple of issues to be aware of...

1. The LP-E4 battery is an 11.1v model, so although your Brunton panel is putting out 16.5v, the load of the battery charger will draw the panel voltage down a bit. Like siphoning, if the panel voltage is not high enough vs the battery it is trying to charge, then charge will not flow quickly. I'm surprised to hear that there is a DC charger for this battery, as the nominal voltage of a car battery (at 12-13v) will not be enough to charge the LP-E4. The car would at least need to be running, and even then might not charge it quickly.

2. Should the panel's voltage be high enough to operate the charger properly, you still have the problem of being at the mercy of the daylight driving the panel's output. If the sky is light overcast, then you might only be getting 50% of full power.
Here's the math...
LP-E4 battery = 26 Watt-Hours of power capacity
At full output, the 12 Watt panel should be able to do this in 2 peak-sun-hours (I won't get into what a peak-sun-hour is here, but in a mobile application, with the panel draped over your pack hiking through the woods, you would be lucky to get 2 peak sun hours in an entire summer day).

2a. The battery charge likely requires a minimum amount of power in order to operate properly. Many 'quick AA chargers' for example, will require 12 watts on the input or more before they will do anything to charge the batteries, and your DC charger may be similar. It may require a minimum of 6 Watts, and if you are not in full sun, you might not be getting this from your panel. This is something the manufacturers of chargers fail to tell you in the fine print.

What to do?
Put a solar storage battery in between your panel & your charger.
This can be something as simple as a small 4AHr back-up sealed-lead-acid battery wired with a 12V cigarette socket, or something with much more utility like a Voltaic Generator battery or the Brunton Solo 7.5 Lithium storage pack.
This storage battery will store the power your panel generates during the entire day, and will give your charger what it needs to operate normally. This way you will not be at the mercy of the sun and the panel's performance moment to moment.

I've outlined solutions for charging various Canon batteries in articles here...
http://www.modernoutpost.com/gear/mfr/canon-eos.html

I hope this post helps! Let me know.
Cheers.

[MoeIsMe]

Update...
I just found the fabled DC car cable for the LC-E4 charger, and can confirm that this will work with any solar battery pack that offers at least 14v output (the LC-E4 charger will take up to 24v, but to charge an 11.1 battery, you need more than 12v).
The connector on this Canon DC cable is special for the LC-E4, so your solar battery must also have a CLA socket (ie standard car dashboard-style socket).
The new Brunton Impel & Sustain battery packs, and the Voltaic Generator unit will all support this Canon DC adaptor solution for the LC-E4 and therefore we have a decent DC solution for charging the LP-E4 battery in the field.
Best regards.

[lensman300]

Digital Concepts CH-E4 Rapid Travel Charger

also will charge the 1D III and 1D IV LP-E4 battery!

I ordered one on buy .com and see it on amazon.com for about $25 USD