Recharging Batteries

[Roger Caffin]

Hi keith

Fascinating! And very useful too. Thanks.

I did something like that with the 12 V Solar panel I use to recharge my CR123R batteries for the Steripen. I added a 5 V regulator (KISS) and a USB socket, thus:

.
The electronics and the USB connector are in an aluminium cradle which plugs in where the CR123R batteries would normally fit. The electronics are under the connector.

This let me keep my GSM phone recharged while we were walking through Switzerland last year. Worked fine – even with the small area of the solar cell. By limiting how often we used the phone (just to ring ahead sometimes to Refuges), we had no problems.

Cheers

[Bob Gross]

What is the full-sun wattage rating of your solar panel, Roger?
–B.G.–

[Roger Caffin]

Hi Bob

Dunno – I was given the solar panel years ago. I never measured it. Not all that high would be my guess. However, back of envelope calculations:

It recharges two CR123s in a couple of hours in bright sunlight sitting on TOP of my pack after they have been used for treating 2 L of water with my SteriPEN Adventurer.

The SteriPEN pulls 1 A at 6 V (=6W) for 1.5 min per L, so 2 L takes 3 minutes. Suppose it takes 3 hours to recharge: that means I am putting 1/60 of the 6W back in from the solar cell – about 100 mW. Have to allow for inefficiencies of recharging etc, so it should be putting out a bit over 100 mW. I think. Less if not really bright sun of course. Being high in the Alps helps …

Cheers

[Keith Selbo]

Roger,

What regulator did you use?

A little off topic, but since you mentioned Steripen I'll discuss my experience with my Adventurer. Two weeks ago I used it for the first time on a 3 day hike in West Virginia. No problems, but I found it annoying to have to give it my full attention (versus gravity filter which does its work while I ponder my navel). Any lapse of attention meant I could miss an LED message indicating an incomplete sterilization. I pretty much decided to go back to my filter.

Keith

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