I purchased 40 watt Solar Panel Battery Charger Kit with a Maximum Power Voltage of 17.5V
Maximum Power Current of 2.29A with Open Circuit Voltage of 21.5V, and have a brand new deep cycle battery and don’t want to hurt it by overcharging it should I have a Charge Controller on the system?
more info on the kit can be found a the Source here: tektrumcorp.com/solar_panels
More Pages:
- Solar Panel: Is A 40 Watt Solar Battery Kit Fitted With A Battery Protection Circuit To Prevent Overcharging Of Batteries? (8/21/2011)
- Solar Power: Solar Charge Controller Problems? (8/17/2011)
- Solar Panel: Can I Safely Charge An Auxiliary RV Battery Using The Alternator And A Solar Panel At The Same Time? (8/23/2011)
- Solar Panel: What Kind Of Solar Panel Would I Need To Charge I Car Battery? (6/17/2011)
- Solar Panel: How Can I Set-up My Small Solar Panel To Charge AA Solar-rechargeable Btteries? (5/22/2011)
{ 2 comments… read them below or add one }
A charge controller, or charge regulator is similar to the voltage regulator in your car. It regulates the voltage and current coming from the solar panels going to the battery. Most “12 volt” panels put out about 16 to 20 volts, so if there is no regulation the batteries will be damaged from overcharging. Most batteries need around 14 to 14.5 volts to get fully charged.
Do I always need a charge controller?
Not always, but usually. Generally, there is no need for a charge controller with the small maintenance, or trickle charge panels, such as the 1 to 5 watt panels. A rough rule is that if the panel puts out about 2 watts or less for each 50 battery amp-hours, then you don’t need one.
For example, a standard flooded golf car battery is around 210 amp-hours. So to keep up a series pair of them (12 volts) just for maintenance or storage, you would want a panel that is around 4.2 watts. The popular 5 watt panels are close enough, and will not need a controller. If you are maintaining AGM deep cycle batteries, such as the Concorde Sun Xtender then you can use a smaller 2 to 2 watt panel.
The obvious question then comes up – “why aren’t panels just made to put out 12 volts”. The reason is that if you do that, the panels will provide power only when cool, under perfect conditions, and full sun. This is not something you can count on in most places. The panels need to provide some extra voltage so that when the sun is low in the sky, or you have heavy haze, cloud cover, or high temperatures*, you still get some output from the panel. A fully charged battery is around 12.7 volts at rest (around 13.6 under charge), so the panel has to put out at least that much under worst case conditions.
*Contrary to intuition, solar panels work best at cooler temperatures. Roughly, a panel rated at 100 watts at room temperature will be an 83 watt panel at 110 degrees.
You will get very good information on the source below
Definition of one watt: The SI unit of power, equivalent to one joule per second, corresponding to the rate of energy in an electric circuit where the potential difference is one volt and the current one ampere.
Solar controller is a must for a solar power system. It will smooth voltage and improve efficiency, also has over-charger protection circuit and many other protection function to protect your panel and battery from damage.