charge controllers

Midnite Solar Classic MPPT 150 Charge Controller

by KURTIS on 01/29/2012

The Midnite Solar Classic 150 MPPT battery charge controller substantially increases the flexibility, features and range currently found on all other MPPT controllers. The Midnite Solar Classic is the only MPPT controller that has arc fault detection, making this solar controller the safest controller available and a Hyper VOC feature. The solar consultants at Blue Pacific Solar love specifying Midnite solar products, well frankly because they are American Made, are designed for the most durable off-grid conditions and they work. With the Classic 150 ranging up to 96 amps, the Classic 200, 79 amps and the Classic 250, 63 amps, why would you need any other controller?

When sizing a MPPT battery charge controller a good rule of thumb is to take the total solar system’s short circuit current times a safety factor of 1.5 then select the current rating of the MPPT charge controller. Midnite solar has a unique feature called Hyper VOV. Hyper VOC refers to when the DC input voltage raises above the maximum operating voltage (150V, 200V, 250V, depending on the Midnite Solar Classic model). Hyper VOC gives you the flexibility to go up to the maximum operating voltage plus the nominal battery voltage. For example, the Midnite Solar Classic 150 solar battery charge controller has an input voltage rating of 150 operating volts, if the Classic 150 is connected to a 48 volt battery bank, the Hyper VOC voltage limit will be: 150V + 48V a total of 198 Volts that the Classic can withstand without breaking. When the Classic input voltage rises above 150 volts it will switch off (stop outputting power). As long as the Classic is in Hyper VOC mode, the microprocessor and all other functions like AUX will continue running. When the input voltage comes back down below 150v (or the rated operating voltage of the Midnite Solar Classic, depending on model) the Classic will wake up and start charging again automatically. This could happen in a really cold morning with a system that has a voltage open circuit (VOC) close to the maximum operating input voltage. When the Midnite Solar charge controller is in Hyper VOC mode, A Hyper VOC message will be displayed on the bottom right side of the status screen.

Midnite Solar Classic 150 charge controllers is a solid-state electronic device that, when sized properly, can be used in nearly every solar and wind energy system that uses batteries. The Charge controllers Blue Pacific Solar sells employ the latest in power electronics to regulate the battery charge by controlling the charging voltage and current from a solar panel array. Charge controllers regulate the charge of the battery, but also prevent the battery from being over discharged which can damage the battery bank.

Midnite Solar Classic 150 charge controller uses multiple stages of control to regulate different voltage and current levels. The voltage and current of a battery varies over the different stages of battery charge. Though the amount can vary, the bulk charge usually is approximately 80%, the absorption charge is 10% with the float charge representing the balance of the battery charging process.

The bulk charging stage of the Midnite Solar Classic 150 charge controller process is the first stage to used to bring the battery depth of discharge (DOD) back to 100%. The bulk charge stage happens first in in the morning after the batteries DOD has drained down since sunset the previous day. The bulk charging stage pushes as many amps into the battery bank as possible from the solar panels and gets the voltage up in the process. The effect of a charge controller is not unlike trying to fill a glass of water from a faucet. You first turn the faucet on full while the glass if filling, then slowly taper off the pressure until the glass is full. When the battery bank reaches a predetermined level known as the bulk voltage set-point, the charge is then substantially slowed. Because the bulk voltage set point is determined by the type of battery you are using, many charge controllers have to be pre-set to the type of battery which will dictate the rate of charge.

The second state of charge the Midnite Solar Classic 150 charge controller employs is the absorption stage. After a battery system has been brought up to the bulk voltage set point, the charge controller slows down the charge rate because the battery bank cannot accept the same rapid charging pace without overheating and damaging the battery bank. At the absorption stage a battery bank is only about 80% full. The absorption charge is the function level in the process that tops off the battery bank. During the absorption stage, the charge controller holds the battery volts constant and reduces the amount of current sent into the battery. When the absorption stage is complete, the battery bank is fully charges.

The final step the Midnite Solar Classic 150 charge controller performs is the float charge. Typically a charge controller enters into a float charge state when the other charge levels of the battery bank has been achieved. When the number of peak sun hours is limited, a solar charge controller may not be able to get the battery bank back to the float stage before the next cycle begins. Before installing any charge controller please read all the operator installation and safety instructions.

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