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Frequently asked Questions about FLEXCHARGE™ Products and systems.

We hope this page will cover your special questions and encourage you to use this information first.  If the topic is not covered or your question is not answered completely you can Contact Us

Diodes: Diodes are like  an electronic check valve and when used on a solar panel, will prevent back flow of power from the battery, as well as prevent multiple panels from interacting with each other in a system.  When a solar panel is shaded or is not performing as well as the panels next to it, the power from the good panels will try to bring up the voltage of the lower panel instead of sending the power to the battery.  With a blocking diode on each panel the power from each panel goes to the battery independently of what the other panels are doing.  This is very important where you may get shadows on one panel such as from the rigging on a sailboat, tree shadows or where solar panels are not all aimed the same direction.  All systems should have blocking diodes on each panel no matter what brand of charge controller is being used.  The diodes that are found in a new panel are most always "by pass" diodes and do not serve the same function as a blocking diode.  You will still need a blocking diode on the panel.  The Flexcharge™ NC series of controllers are designed without internal isolation so when adding blocking diodes you are not causing the increased power loss of dual isolation.  Diode Source

We show a blocking diode on wind systems.  If your system is generator based it must have a blocking diode.  If your system is alternator based and has a rectifier, the rectifier is diode based and no additional diode needs to be added.

Timer Memory Battery:  The Flexcharge™ Programmable Timer includes a small battery to maintain the programming memory.  If the timer is installed with constant 12 volt power on the timer, the memory battery will last at least 3 years.  To change the CR2032 battery you need to remove the black back cover from the timer.  Do this by inserting a knife blade between the gray box edge and the black cover.  The cover is only glued at the corners and will pop off as you move the knife toward a corner.  Once the cover is off the battery compartment will be visible.  Remove the old battery and install the new one with the + side of the battery toward the outside of the box.  The black cover is cosmetic only and it is your choice if you want to re-glue it back in place.

Divert Loads:  On any generator or alternator based system it is important to use a controller that has the Divert feature.  A Divert Load can be any resistance load that is equal to the maximum output of the generator or alternator.  Load resistors or heating elements are ideal.  A DC motor will work but in many cases finding a motor that draws enough amperage is difficult.  Do Not use appliance type loads such as inverters, refrigerators, or other similar devices because they usually don't start instantly and also usually need regulated power.  Divert power is raw power directly from the generator or alternator.  The purpose of the divert load is to keep the rpm of the generator or alternator within safe limits and to keep the voltage from going open circuit that will eventually cause a failure.  We offer a couple of choices of divert loads.  Divert Load   Divert Pad kit   They can be use together in multiples to create a larger Divert Load if needed.  We can help you with the sizing. Contact Us

How do I Maximize my system?:  Make sure you do not have any wire to wire crimp connections in your system.  Solder all wire to wire connections as well as any ring terminals on the ends of wires. If you feel a connection point that is warm or hot it is bad and is wasting power.  Fix it.  Fuse holders are often a poor connection point depending on how the fuse is connected and if the wires in the fuse holder are only crimped.  A fuse holder using the glass tube fuse and that only has a spring loaded button on each end of the fuse is bound to fail.  We have seen the get so hot that they melt the fuse holder case.   For that style fuse use a holder that has a ring around each end of the fuse for a secure connection.

Be sure you have blocking diodes on the solar panels.  See above

Wire size is very important.  Too small a wire will waste power as heat.  Even small amounts of loss that you can't feel will make a big difference over time.  If you tell us the distance between the solar panels and the controller, along with the maximum amperage, and the system battery voltage, we can help you with the recommended wire size.  All rating are based on copper wire.

Distance in feet between the solar panels and the charge controller at the battery area ___

Total expected maximum amperage of the charging source ___

System battery voltage (12, 24, 36, 48) ___

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Should I wire my panels in series?: For a 12 volt battery system the peak power voltage of the solar panels needs to be around 15 volts.  For a 24 volt battery system the peak power voltage of the solar panels needs to be around 30 volts.  If you wire your panels for a higher peak power voltage (in series) than you system requires you will reduce the amperage and essentially cut you power in half or worse.  This is only true of solar systems and does not apply to generator or alternator systems such as wind or hydro systems.

You can wire your panels in series for a higher peak power voltage and use an MPPT controller to bring the peak power voltage back down to the proper voltage but then you are using a lot of electronics to accomplish that and the result is a less efficient system then if you just use the panels at the proper voltage.  Look at any MPPT controller with a 20 amp or larger capacity and note it is in a metal case usually with heat fins and often with a cooling fan.  This is all to get rid of the heat generated by the electronics and the heat is energy that never made it to the battery.  The only advantage of an MPPT controller is if you have a long wire run and want to use smaller wire, you can increase the solar panel voltage and correct it with the MPPT controller at the battery.  It is more efficient to not use the MPPT controller but rather use larger wires and keep the peak power voltage at the proper level.  We do not offer MPPT controllers.  The original design goal of all Flexcharge™ controller was and is to be the most efficient in the world and MPPT technology does not fit that goal.

Are Flexcharge™ controllers PWM or 3 stage?:  The patented algorithm of the Flexcharge control process is not PWM, MPPT or 3 stage.  If a term needs be applied to it you can call it an infinite stage process with each stage fully controlled by the battery needs. See our charge process explained on the page Charging Algorithm Explained

 Flexcharge™ controllers are the controllers of choice for research projects around the world.

Sensitive data recording equipment is not affected by the Flexcharge Controllers because there is no RFI generated in the controller as is common on many others.

Extremely high efficiency was a design goal for all Flexcharge controls.  Little or no heat is dissipated from the controllers so all of the generated energy can be used.

No matter if your system is a simple battery maintenance system or a large main power source, you will benefit from the efficiency and dependability of our products.