[AT] Solar battery charger setup

Mon Jan 18 17:49:41 PST 2016

Glad to help - I think you will be fine.  I have one on an electric start pressure washer, a sawmill starter battery and a "water wagon" that has a battery and 12 volt pump that I use to carry water to the alpacas.  The water wagon is the only thing that gets regular use and the solar panel does not completely keep up.   I still have to put that battery in the charger every other month.   Of course without the panel I had to do it once a week.  I've used that battery and panel for 1.5 years with zero problems.   The sawmill battery even longer and it starts up every time.

I know they are rated for 24 volts but I've never measured more than 19 aiming it right at the sun in the summer at  solar noon.   At such a low amperage I am certain a battery can handle voltage over 14 for 20-40 mins.   Also remember the flip side:  It's <12volts 10-24 hours a day depending on the time of year and weather.

Spencer Yost

> On Jan 18, 2016, at 8:25 PM, Bill Bruer <bill_bru at bellsouth.net> wrote:
> 
> Thanks, Spencer and Ivan.  I will assume the instructions about the 
> regulator are a lawyerism and hook the thing up as-is.
> 
> Bill
> 
>> On 1/18/2016 6:28 PM, Ivan wrote:
>> 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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