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Choosing the Right Solar Charge Controller/Regulator. Redarc mppt solar regulator

Choosing the Right Solar Charge Controller/Regulator. Redarc mppt solar regulator

    Choosing the Right Solar Charge Controller/Regulator

    A solar charge controller (frequently called a regulator) is similar to a regular battery charger, i.e. it regulates the current flowing from the solar panel into the battery bank to avoid overcharging the batteries. (If you don’t need to understand the why’s, scroll to the end for a simple flow chart). As with a regular quality battery charger, various battery types are accommodated, the absorption voltage, float voltage can be selectable, and sometimes the time periods and/or the tail current are also selectable. They are especially suited for lithium-iron-phosphate batteries as once fully charged the controller then stays at the set float or holding voltage of around 13.6V (3.4V per cell) for the remainder of the day.

    The most common charge profile is the same basic sequence used on a quality mains charger, i.e. bulk mode absorption mode float mode. Entry into bulk charge mode occurs at:

    • sunrise in the morning
    • if the battery voltage drops below a defined voltage for more than a set time period, e.g. 5 seconds (re-entry)

    This re-entry into bulk mode works well with lead-acid batteries as the voltage drop and droop is worse than it is for lithium-based batteries which maintain a higher more stable voltage throughout the majority of the discharge cycle.

    Lithium batteries

    Lithium batteries (LiFePO4) do not benefit from re-entry into a bulk mode during the day as the internal impedance of the lithium batteries increases at high (and low) states of charge as indicated by the orange vertical lines in the chart below and it is only necessary to occasionally balance the cells which can only be done around the absorption voltage. A related reason is to avoid the Rapid and large variation in voltage that will occur in these regions as large loads are switched on and off.

    Lithium batteries do not have a defined “float voltage”, and therefore the “float voltage” of the controller should be set to be at or just below the “charge knee voltage” (as indicated in the chart below) of the LiFePO4 charge profile, i.e. 3.4V per cell or 13.6V for a 12V battery. The controller should hold this voltage for the remainder of the day after bulk charging the battery.

    The Difference Between PWM and MPPT Solar Charge Controllers

    The crux of the difference is:

    • With a PWM controller, the current is drawn out of the panel at just above the battery voltage, whereas
    • With an MPPT solar charge controller the current is drawn out of the panel at the panel “maximum power voltage” (think of an MPPT controller as being a “Smart DC-DC converter”)

    You often see slogans such as “you will get 20% or more energy harvesting from an MPPT controller”. This extra actually varies significantly and the following is a comparison assuming the panel is in full sun and the controller is in bulk charge mode. Ignoring voltage drops and using a simple panel and simple math as an example:

    Battery voltage = 13V (battery voltage can vary between say 10.8V fully discharged and 14.4V during absorption charge mode). At 13V the panel amps will be slightly higher than the maximum power amps, say 5.2A

    With a PWM controller, the power drawn from the panel is 5.2A 13V = 67.6 watts. This amount of power will be drawn regardless of the temperature of the panel, provided that the panel voltage remains above the battery voltage.

    With an MPPT controller the power from the panel is 5.0A 18V = 90 watts, i.e. 25% higher. However this is overly optimistic as the voltage drops as temperature increases; so assuming the panel temperature rises to say 30°C above the standard test conditions (STC) temperature of 25°C and the voltage drops by 4% for every 10°C, i.e. total of 12% then the power drawn by the MPPT will be 5A 15.84V = 79.2W i.e. 17.2% more power than the PWM controller.

    In summary, there is an increase in energy harvesting with the MPPT controllers, but the percentage increase in harvesting varies significantly over the course of a day.

    PWM:

    A PWM (pulse width modulation) controller can be thought of as an (electronic) switch between the solar panels and the battery:

    • The switch is ON when the charger mode is in bulk charge mode
    • The switch is “flicked” ON and OFF as needed (pulse width modulated) to hold the battery voltage at the absorption voltage
    • The switch is OFF at the end of absorption while the battery voltage drops to the float voltage
    • The switch is once again “flicked” ON and OFF as needed (pulse width modulated) to hold the battery voltage at the float voltage

    Note that when the switch is OFF the panel voltage will be at the open-circuit voltage (Voc) and when the switch is ON the panel voltage will be at the battery voltage voltage drops between the panel and the controller.

    The best panel match for a PWM controller:

    The best panel match for a PWM controller is a panel with a voltage that is just sufficiently above that required for charging the battery and taking temperature into account, typically, a panel with a Vmp (maximum power voltage) of around 18V to charge a 12V battery. These are frequently referred to as a 12V panel even though they have a Vmp of around 18V.

    MPPT:

    The MPPT controller could be considered to be a “Smart DC-DC converter”, i.e. it drops the panel voltage (hence “house panels” could be used) down to the voltage required to charge the battery. The current is increased in the same ratio as the voltage is dropped (ignoring heating losses in the electronics), just like a conventional step-down DC-DC converter.

    The “Smart” element in the DC-DC converter is the monitoring of the maximum power point of the panel which will vary during the day with the sun strength and angle, panel temperature, shading, and panel(s) health. The “smarts” then adjust the input voltage of the DC-DC converter – in “engineering speak” it provides a matched load to the panel.

    The best panel match for an MPPT controller:

    • The panel open circuit voltage (Voc) must be under the permitted voltage.
    • The VOC must be above the “start voltage” for the controller to “kick in”
    • The maximum panel short circuit current (Isc) must be within the range specified
    • The maximum array wattage. some controllers allow this to be “over-sized”, e.g the Redarc Manager 30 is permitted to have up to 520W attached

    Choosing the Right Solar Controller/Regulator

    The PWM is a Good Low-Cost Option:

    f or solar panels with a maximum power voltage (Vmp) of up to 18V for charging a 12V battery (36V for 24V battery, etc).

    When the solar array voltage is substantially higher than the battery voltage e.g. using house panels, for charging 12V batteries

    An MPPT controller will yield higher returns compared with a PWM controller as the panel voltage increases. I.e. a 160W panel using 36 conventional monocrystalline cells with a maximum power amp of 8.4A will provide around 8.6A at 12V; while the 180W panel having 4 more cells will provide the same amperage but 4 additional cells increases the panel voltage by 2V. A PWM controller will not harvest any additional energy, but an MPPT controller will harvest an additional 11.1% (4 / 36) from the 180W panel.

    For the same principle, all panels using SunPower cells with more than 32 cells require an MPPT charge controller otherwise a PWM controller will harvest the same energy from 36, 40, 44 cell panels as it does from a 32 cell panel.

    Solar Charge Controller Features and Options

    Boost MPPT Controllers

    “Boost” MPPT charge controllers allow batteries to be charged that has a higher voltage than the panel.

    Combined MPPT and DC-DC Chargers

    The MPPT function is a natural adjunct to the DC-DC charger function and there are several quality brands that provide this with more under development. A single unit can be used by itself, as it automatically switches between alternator charging and solar charging. For larger systems, our favoured arrangement is to use a separate MPPT controller for the fixed roof-mounted panels and use the combined MPPT/DC-DC with portable panels. In this case, an Anderson connector is placed on the exterior of an RV which is then wired to the solar input of the MPPT/DC-DC unit.

    Note that the battery capacity must be sufficient so that the combined charging current from simultaneous charging from the alternator and the roof solar panels does not exceed the manufacturer’s recommended maximum charging current.

    Cheaper Options

    Cheap controllers may be marked as an MPPT but testing has shown that some are in fact PWM controllers. Cheap controllers may not have the over-voltage battery protection which could result in the battery being overcharged with potential damage to the battery; caution is recommended. Normally, due to the increased circuitry, MPPT solar charge controllers will be physically larger than PWM solar charge controllers.

    Multiple Solar Chargers

    Properly wired, it is possible to add multiple solar chargers (any combination of type and rating) to charge a battery. Proper wiring means that each solar charger is wired separately and directly to the battery terminals. This ideal case means that each controller will “see” the battery voltage and is unaffected by the current flow coming from other charge controllers. This situation is no different from charging a battery from the grid/generator at the same time as charging from solar. With modern controllers, the current will not flow backwards from the battery to the controller (excepting a very small quiescent current).

    REDARC BCDC Dual Input Chargers

    The REDARC Range of Dual Input In-vehicle Battery Charger is a 12V 25/40/50A In-vehicle DC to DC battery charger System. They are the latest of the award-winning BCDC Dual range and features REDARC’s Smart Start technology.

    Featuring a Maximum Power Point Tracking (MPPT) solar regulator, the BCDC series will charge from both solar and the alternator simultaneously. And, with built-in ‘Green Power Priority’ it will select solar charging first, meaning less load on the alternator.

    Suitable for 12 or 24-volt vehicle systems, the units will also work with either standard or variable/Smart alternators.

    The BCDC Dual feature the same patented charging profiles as it’s predecessor along with a new lithium charging profile making the unit suitable for charging AGM, Gel, Standard Lead Acid, Calcium and LiFePO4 batteries, perfect for pairing with a REDARC Lithium battery.

    For most applications, the BCDC1225D is suitable for battery bank sizes of 75-200AH. For higher capacity needs of over 200AH, REDARC recommends the BCDC1240D or BCDC1250D.

    Proven and Tested

    The award-winning technology in the BCDC has been independently verified and tested to ensure battery life is maximised, charging your battery to a proven 100%.

    Built in Australia and tested for our unique conditions, the DC to DC battery charger will work in the extreme heat of the Simpson Desert, up to 80°C and can handle deep water crossings at Cape York – water, dust and vibration are no match for this charger.

    If you’re heading out into the bush and want to get there and back again safely – you can trust REDARC.

    • Separate DC and solar charging inputs
    • Maximises the performance and life of your auxiliary battery
    • Simultaneous DC and solar charging with Green Power Priority
    • Suits 12V/24V standard and variable voltage/Smart alternators
    • Suitable for AGM, GEL, standard lead acid, calcium and Lithium (LiFePO4) batteries
    • Suitable for use on vehicles with conventional alternator charging systems

    2 Years Return to Manufacture

    “>BCDC1225D “>BCDC1240D “>BCDC1250D
    “>Input (Operating) Voltage “>9. 32VDC “>9. 32VDC “>9. 32VDC
    “>Output System Voltage “>12VDC “>12VDC “>12VDC
    “>Maximum Charging Voltage “>15.3V “>15.3V “>15.3V
    “>Output Current Rating (Cont.) “>25A “>40A “>50A
    “>Input Fuse Rating “>40A “>60A “>60A
    “>Type Approval “>E-Mark “>E-Mark “>E-Mark
    “>Output Fuse Rating “>40A “>60A “>60A
    “>Warranty “>2 Years “>2 Years “>2 Years
    “>Standby Current Draw “> “> “>
    “>Output Power “>375W “>600W “>750W
    “>Width (mm) “>120 “>120 “>120
    “>Height (mm) “>37 “>37 “>37
    “>Length (mm) “>165 “>165 “>165
    “>Weight (kg) “>1 “>1 “>1

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    choosing, right, solar, charge

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    Redarc Manager BMS1230S3 – DC-DC / MPPT / AC Charger

    The Manager30 is a complete battery management system for charging auxiliary batteries used in recreational automotive and marine applications. The dual battery system incorporates AC, DC and solar inputs to achieve the best charge for an auxiliary battery.

    Developed with ease of installation in mind, The Manager30 is compatible with all vehicles and alternator systems including variable voltage alternators.

    Whether you’re charging Lead Acid, Gel, Calcium, AGM or Lithium Iron Phosphate batteries, The Manager30 represents a complete DC to DC charging and maintenance solution. If you’re charging one auxiliary battery or more, The Manager30 will ensure they’re always fully charged, providing peace of mind when battery charge provides the power source for the comforts of home whilst travelling around Australia.

    The Manager30 operates like 6 separate products, it charges an auxiliary battery from the vehicle while on the move, it’s a 240 volt charger, a solar regulator, a battery isolator, a load disconnect controller, all with a remote battery monitor, making it market leading.

    The Manager30 is a complete battery management system for charging auxiliary batteries used in recreational automotive and marine applications. The dual battery system incorporates AC, DC and solar inputs to achieve the best charge for an auxiliary battery.

    Developed with ease of installation in mind, The Manager30 is compatible with all vehicles and alternator systems including variable voltage alternators.

    Whether you’re charging Lead Acid, Gel, Calcium, AGM or Lithium Iron Phosphate batteries, The Manager30 represents a complete DC to DC charging and maintenance solution. If you’re charging one auxiliary battery or more, The Manager30 will ensure they’re always fully charged, providing peace of mind when battery charge provides the power source for the comforts of home whilst travelling around Australia.

    The Manager30 operates like 6 separate products, it charges an auxiliary battery from the vehicle while on the move, it’s a 240 volt charger, a solar regulator, a battery isolator, a load disconnect controller, all with a remote battery monitor, making it market leading.

    Charging lithium batteries

    Lithium batteries have improved storage capacity relative to size and weight. They do however require specific charging conditions in order to operate correctly and the battery itself must have an in-built cell management system. REDARC have designed a charging profile within The Manager30 to complement these in-built systems.

    Green power priority

    The Manager30 is designed to charge an auxiliary battery from multiple sources simultaneously. If 12 volt solar power is available, solar power will be used before topping up the output charging current from another source mains (if available) or DC vehicle power when on the move.

    MPPT solar regulator

    The built-in Maximum Power Point Tracking (MPPT) solar regulator allows The Manager30 to deliver the maximum amount of power from portable solar panels, even during low light conditions.

    Remote monitor

    Designed to show you auxiliary battery information and charge status. You can customise how your battery is charged and monitor where the charge is coming from. A user-friendly, graphical display monitor lets you know what’s going on, keeping you in control at all times.

    choosing, right, solar, charge

    Features

    • Multi Stage AC-DC Battery Charger
    • Multi Stage DC to DC Charger
    • Maximum Power Point Tracking Solar Regulator
    • Battery Monitor
    • Dual Battery Isolator
    • Load Disconnect Controller
    • Super quiet operation
    • Charges AGM, Gel, Calcium content, VRLA, Standard Lead Acid and LiFePO4 batteries
    • Tested to mains power safety standards in Australia

    The Best DC To DC Charger With MPPT Solar For Campers 2023

    Are you looking for the perfect DC to DC charger with MPPT solar charging capabilities for your campervan?

    This post is all about the 4 best DC-DC chargers that include MPPT solar charging (DC-DC Solar) for charging campervan leisure batteries.

    With a multitude of options available, we’ve narrowed down the top 4 chargers that not only provide optimal performance but also offer compatibility and reliability for your campervan’s electrical system.

    Also referred to as battery to battery and B2B battery chargers, they’re essential for keeping your campervan powered up and ready for adventure.

    Trusted Review

    Jolly (a self-confessed electrical geek with over 17 years of experience as a qualified electrical engineer) carried out the product comparison review.

    Extensive research and honest user experiences have provided the information for this post.

    Jolly’s FOCUS now is campervan conversion electrics which started in 2019 with the birth of Vandercamp. Jolly is either building his own campervan or providing electrical help and guidance to others.

    The products reviewed do not sponsor this post. Therefore, the information in this article is our own honest opinion.

    This post may contain Amazon affiliate links. Meaning, if you make a purchase after clicking one, we may earn some commission. This money will help Vandercamp Adventures continue to grow at no extra cost to you. It’s a win win situation!! Learn …

    Comparison Table

    Name Input VoltageCharge Current (Amps)Maximum Solar VocMaximum Cable SizeOperating Temperature (°C)WarrantyEfficiencySmart Alternator CompatibleWeightSize (mm)PriceView

    Table Definitions

    Input Voltage – The voltage accepted from the alternator/starter battery. All DC to DC chargers here are compatible with 12v inputs.

    Output Charge Current – The current (amps) supplied to the leisure battery under charge conditions.

    Maximum Solar Voc – The open circuit voltage (Voc) is the maximum voltage that the solar panel can produce with no load on it.

    Maximum Cable CSA – The maximum size of cable the charger terminations can accept.

    Warranty – Manufacturer warranty. See the charger details below for their warranty details.

    Efficiency – Energy efficiency of the output charge as a percentage. All electrical devices have energy wastage, usually in the form of heat. The higher the percentage the more efficient.

    Smart Alternator Compatible – The charger either has built in voltage sensing software or requires an ignition circuit.

    Weight – Overall weight of the unboxed charger

    Size – Overall size of the DC-DC charger (See product manuals for their detailed measurements)

    Cost – From £ (cheapest) to ££££ (most expensive). See product for the current price.

    The Downsides To DC to DC Solar Chargers

    Who Are The 4 Best DC-DC Solar Chargers Suited To?

    Renogy – Low budgets, novice installers, any size electrical system.

    REDARC – High budgets, weight/space conscious, extreme conditions.

    Ctek – weight-conscious, small electrical systems, lead-acid batteries.

    Sterling – Electrical experience/engineer, custom battery setups, Smart alternators.

    The 4 Best DC to DC Charger With MPPT Solar

    When it comes to finding the best DC to DC charger with MPPT solar for your campervan, there are several factors to consider. With a multitude of options available, we’ve narrowed down the top 4 DC-DC chargers that not only provide optimal performance but also offer compatibility and reliability for your campervan’s electrical system.

    These DC-DC chargers are compatible with all battery types, including Lead-acid, GEL, AGM, calcium, and Lith-ion, as well as 12V systems. Additionally, they are designed to work seamlessly with Smart alternators, ensuring a smooth charging experience.

    Safety and efficiency are crucial, and these chargers excel in both areas by isolating the starter and leisure batteries when no charge is present, preventing the starter battery from discharging. They also maintain a steady output current, regardless of input voltage fluctuations, ensuring a consistent and efficient charging process.

    over, all four chargers come with a 2-year manufacturer warranty, giving you peace of mind knowing that your investment is protected.

    Renogy DC-DC Charger With MPPT

    Why it made the list: Low budget, Simple installation and setup, highly efficient

    Renogy DCC30S DCC50S

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