DUAL BATTERY SOLAR CHARGE CONTROLLER Keywords: Charge controller, battery, solar charge controller, solar panels, solar array, MPPT charge controller, off-grid electricity, efficiency, zhcsolar. Why Charge Controller? A charge controller is used to make battery working efficient and sustain it for a long time. It does so by disconnecting the load to the battery when at lowest charge level and disconnects electric supply to the battery when it is fully charged. Charge controller is a necessary device, as discharging battery to a low level and continuing to charge them after they have reached their capacity can reduce battery lifetime. Also to prolong battery life & performance, regulating output voltage is necessary, as batteries charge in levels and require specific charging method with specific current levels and specific voltage levels at each stage. Using a charge controller makes this happen 1. Output voltage level required by the battery can be matched by regulating the input voltage supplied by a charge controller which can be a standard or MPPT (maximum power point tracker) charge controller. Solar Charge Controller1 Also in case of a solar panel or array a charge controller maximizes its output efficiency 1. In an offgrid scenario the solar charge controller becomes more important as battery is mostly used to store the electricity generated from solar panels or array1. Regulating the input voltage from a standard charge controller gives losses in the power supplied by solar panels as the voltage from the panel is higher than the required voltage of the battery. Voltage is reduced but the current is kept constant in case of a standard charge controller, resulting loss in power supplied by solar panels. Whereas voltage is monitored and regulated without power loss in MPPT charge controller. Highest possible power output is obtained from MPPT charge controller because of installed microcontrollers/microprocessors and smart technologies. Voltage and current is regulated in MPPT charge controller resulting in less solar power loss in storage. Dual Battery Solar Charge Controller2 Any facility where two batteries are required to be charged from solar panel or array also needs a charge controller or a MPPT solar charge controller. The best way to implement this is by installing dual battery solar charge controller which will reduce the hassle with cables and equipment to connect and charge two batteries. It is usually designed for Recreational vehicles, cottages, carts, yachts, boats, and campers etc which require charging of two batteries simultaneously or individually. As mentioned separate control system is not required to charge other battery and one control system reduces the cost to install dual batteries. As the name suggests, this charge controller has two terminals to charge batteries and ratio to charge can be adjusted from 0-100%.
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http://eecs.ucf.edu/seniordesign/fa2011sp2012/g10/docs/PMCC_Group%2010_SD1.pdf
https://zhcsolar.com/product/dual-battery-solar-panel-chargecontroller/#Features_of_20A_Dual_Battery_Solar_Panel_Charge_Controller
A dual battery solar charge controller can provide following 3 functions : These are specific to models (MPPT5012A-DUO & MPPT5025A-DUO) available from www.zhcsolar.com. 1. As compared to conventional or standard charge controllers, this controller has higher MPP charging current by 10-30%. This makes it more efficient compared Dual Solar Charge Controller from to the standard charge www.zhcsolar.com controller with efficiency greater than 95%. 2. Different types of batteries can be charged via these dual charge controllers by switch board lines. These can be configured for batteries like dryfit, gel, fleece, acid/lead-acid batteries etc. Battery type selection4: Mostly flooded type or sealed type lead acid batteries are used with solar energy systems. Sealed batteries are regulated at lower voltage than flooded batteries or they can dry out. Charge controllers like referenced above have the ability to select type of batteries to be charged and can be managed efficiently. 3. There are two battery charging ports on this charge controller with automatic charging of the main battery and support charging for the secondary battery with overcharge protection. 4. This charge controller provides protection against overload, overheating, reverse battery and back discharge from battery. So there is no need to attend charging batteries while it is in progress. Reverse current blocking4: Solar panels send current in one direction when working in full sunlight. At night slight current is reversed which can cause discharge from battery. A charge controller has a semiconductor or a transistor which makes current to flow in only one direction and blocks reverse current. Disconnection at low voltage4: Deep cycle batteries if discharged to 100%, they can be ruined. Usually these batteries discharge till 80% of their capacity and 20% of charge is kept in the battery for optimal working. A low voltage disconnect circuit breaker in charge controller disconnects the load from the batteries and is a very important function. Protection from overload4: If current flowing in a circuit is higher than it can safely handle, this causes overload which can be hazardous. Charge controllers have overload protection installed, which disconnects battery from the load in such a condition.
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https://zhcsolar.com/wp-content/uploads/2019/01/MPPT5012_25A-DUO-User-Manua.pdf 4 http://www.arizonaenergy.org/AltEnergyClub/WhatIsAChargeController.pdf
5. It protects from overcharging of batteries when solar power is in excess and battery is fully charged. In case of consumption, the battery is immediately recharged to fulfil load demand. Overcharge prevention4: A fully charged battery cannot take in more energy. If the input energy to the battery is not controlled, the voltage in the battery gets too high, which can cause small explosion, stress loads or shut off the inverter. Preventing overcharge of the battery or voltage drop is regulated by the charge controller and is the most important function of charge controller. This is usually done by switching the current fully off or on in a controller or via Pulse Width Modulation (PWM) to regulate voltage and battery charge. 6. Temperature sensor can also be connected to this charge controller, where change in battery temperature can be easily detected and charging voltage can be adopted accordingly. Temperature compensation4: Charge controllers have temperature control set points. Set points are raised in a controller at low battery temperatures; otherwise battery will lose charge quickly and vice versa. Maximum power point tracking (MPPT) charge controller4 Additional power can be extracted from solar panel or array by using a charge controller with MPPT. Maximum power is delivered by a solar panel or array at ideal voltage which is also called peak power voltage and the power point is maximum power point. Peak power voltage varies with insolation level (sunlight intensity) and solar cell temperature which can result in reduced voltage supply to the battery. Battery will only charge if solar panel or array supplies voltage higher than required by the battery. If peak power voltage supplied by the solar panel is low than the battery voltage, this system will not work. To deliver maximum power to the battery, MPPT varies the voltage/current ratio. As peak power voltage from the solar panel or array varies with temperature and other conditions, a MPPT charge controller tracks, varies and adjusts the voltage/current ratio to provide peak power to the batteries. Conclusion A dual battery solar charge controller is useful to charge two batteries when required. It will charge batteries efficiently, making their life span long enough to recover the investment done. Smart technologies like microprocessors and MPPT enables charge controllers to be more efficient in delivery of charge to the battery and protect battery from varying conditions of everyday life scenario. Being a onetime installation and automated operation of the charge controller makes it ideal to use for standalone systems like solar PV etc. Dual battery charge controller with installed MPPT operation available from www.zhcsolar.com is an ideal device for enthusiasts who are in the endeavour of using solar energy as their energy source in small load capacities like RV’s, cottages, yachts, golf carts etc where two batteries need to be charged.
