Re: [Paddlewise] solar panel/charger advice?

On 20 Nov 2004 at 20:31, kayakwriter_at_netscape.net wrote:

> As a winter project, Ib^Ym trying to put together a variation on the
> solar battery charger system described by Rob Walker in his article in
> the December 2003 Sea Kayaker magazine. His design calls for using a
> Morningstar SunGuard Charge Controller [...]
> In Robb^Ys system, 10 AA batteries are charged in a series to trigger
> the 14.1V pulse point of the charge controller. 

I didn't like this system for the same reasons you cite - I don't 
like the idea of having to charge 10 batteries at a time.  I also 
prefer a smart charger.

> I have the Powerflex 5 solar panel from ICP Solar Technologies 
> Rated power: 5 watts
[...]
> One is the Rayovac 1-Hour NiMH Charger
> The specs on the AC transformer for this unit (which is left behind
> when you use the 12-volt cigarette plug) are: Output 12VDC 1.5A

I use this one (but not with solar (yet)) and it's a good charger. 
It can charge one to four batteries at once and each one is 
separately monitored.  This makes for reliable charging.  However, 
since it is a fast charger, it draws a lot of current.

The problem is that the transformer output is 12V x 1.5A = 18 watts.  
This won't work with the 5 watt panel you have - you'd have to 
upgrade to a 20w version which is much bigger (I've looked into the 
same brand panel, BTW).

Now that is the maximum power that the xformer can put out and the 
actual draw from the charger with only, say, two cells may be a lot 
less.  However, it's unlikely that you could use a 5w panel and do 
much charging.

> The second battery charger is the Brunton Battjack:
> back of the battery holder are: Input: 12V, 500mA

Since the SolarPort4.4 that it's designed to work with only puts out 
4.4w, the 5w panel should be fine.  Unlike the fast Rayovac, expect 
this combo to take several hours to fully charge 4AA batteries.  

> Any thoughts on whether one or the other of these chargers would work
> better plugged into the 12-volt female cigarette adaptor of the solar
> panel? 

I'd test the Brunton to see how it works.  Should be fine.

> Should I still have the Morningstar SunGuard Charge Controller
> wired into the line?

No - the BattJack should handle as a charge controller.

> Also, the solar panel has
> a built-in diode (which I gather is to electricity what a one-way
> flapper valve is to water) to prevent reverse current and battery
> drain at night. Will the circuitry from the Rayovac or Brunton battery
> holder/chargers interact with this diode and/or the Morningstar
> SunGuard Charge Controller in weird ways to prevent the system
> working?

Should work fine - the Brunton system uses the same thing according 
to the manual.

Mike
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