[AT] Solar battery charger setup

[Ivan]

Bill , I'll take a stab at it as best as I can remember .  1.5 watt =   
.125 amp   if you take 1.5 divided by 12.5 volts nominal  wattage 
(watts  divided by volts )   and that is max rating .   Meaning that the 
sun has to be shining straight down at the panel  which it wont most of 
the time . Solar panels have to be angled to match the suns angle for 
max charge if is shining directly on it and constantly change d to match 
the path of the sun across the sky . To get that max charge it has to be 
continiuosly angled to match the suns path across the sky ,otherwise its 
getting less than max output .  Actually the panel will produce a higher 
voltage than that because for it to charge a battery the charging 
voltage has to be up around 14.5 . Truth is your 12 volt battery should 
actuall read about 13.2 or so to be fully charge .
Another factor is resistance in the wire which can really cut output 
especially if the wire size is too small or extended to reach outside if 
the tractor is in the shed .
  Where you are located affectsthe output too .  DOwn close to the 
equator the angle is less pronounced ,but the system still haas to be 
able to follow the sun for max output .
  Very simple to demonstrate this to make it easier to understand . Hook 
the charger up to any 12 volt battery with a multimeter ( digital ) to 
be sensitive enough . Now point the panel toward the sun and move it 
left and right and watch the meter voltage . It will jump all over and 
with a slightly weak battery it will show up even better .
  Myself I have two solar systems running one for lighting in the house 
(and thats led nightlights only ) the other is on the roof of my camper 
. A 80 watt system to charge the house battery , which it doesnt do very 
well .
For a weak battery with even a small slow internal loss a panel that 
small will never over charge it . If you want I can send a link for a 
web site that explains it much better , the guy runs his whole house on 
solar and seems to have a very good handle on it .   Ivan

O1/17/2016 5:55 PM, Bill Bruer wrote:
> I recently picked up one of these 1.5 watt solar battery chargers on sale at
> Harbor
> Freight for $14.99 -
> http://www.harborfreight.com/15-watt-solar-battery-charger-68692.html
>
> The manual says it needs an external voltage regualtor to prevent
> overcharging.  There's no indicaction of that requirement on the packaging.
> What's the best (cheap) way to set this thing up so that it can be left
> on a battery for indefinite periods?  Harbor Freight has a 100 watt
> regulator -
> http://www.harborfreight.com/7-amp-solar-charge-regulator-96728.html
> that will also allow you to power a tool but costs $25.99.  Kind of defeats
> the
> sale price on the charger.
>
> My main use will be to keep the battery hot on my IH 686 tractor with a
> D312 engine.  However, I would like to mount the panel and regulator on a
> light
> frame that can be moved to any piece of equipment where it may be
> needed.
>
> Bill Bruer
> Murfreesboro, TN
>
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