Question: Can you use two 72 cell modules in series with a TriStar MPPT to charge a 48V battery system, or do you need three modules? Answer: Yes, unless the system is located in an exceptionally hot desert climate, or you are worried about voltage drop from a long wire run from the array to the controller. But as long as your voltage at max power (Vmp) is slightly higher than your target battery voltage, two 72 cell modules will serve you well. For a 48 volt nominal battery, your target battery voltage will likely be close to 60 volts depending on the battery brand. And two 72 cell modules should supply much more than 60 volts even in hot temperatures as long as you’re not in Death Valley or some similar extremely hot climate. We have received a number of questions about this over the years, where people thought they might need 3 modules, when it fact 2 modules would suffice.
Morningstar offers a Relay Driver (model # RD-1) which can be used for many of the same functions as an auxiliary (IN or OUT). Each RD-1 has 4 channels that can be used as inputs or outputs for Low Voltage Disconnect, Vent Fan, Alarm notifications, or Genstart. Output Channels can be turned on or off based on standalone relay driver values or information from other Morningstar devices on a MeterBus network such as: Thresholds (Voltage, Current, Temperature, % PWM Duty Cycle) Selected Alarms and/or Faults PC or MODBUS inputs over the RS-232 Serial data connection Advanced options allow users to use use the relay as a timer switch or to custom program delays.
Dip switch settings to configure battery charging, system voltage, and load/lighting parameters are included in the ProStar MPPT Operator’s Manual. But in the event that you don’t have a manual handy, you can also find these dip switch settings on the inside of the removable wire cover, and on the inside of the Wire Box accessory.
Most people are used to connecting to a computer in order to configure a controller’s charge settings. But with the ProStar MPPT™ controller, configurations can be changed in the field just by using the controller’s meter interface without the need to connect to a computer. The absorption, float, and equalization charge settings, as well as the load and lighting control settings, can all be changed via the scroll buttons on the meter display.
There have been a number of questions recently about whether Morningstar solar charge controllers can be used to charge lithium ion batteries in off-grid solar applications. Morningstar’s TriStar MPPT, TriStar (PWM), ProStar MPPT, SunSaver MPPT, and SunSaver DUO solar charge controllers support Lithium Ion (Li-Ion) and other battery technologies such as: Lead Acid (PbSO4): Sealed (VRLA, AGM, Gel) and Flooded Lithium-Ion (Li-Ion or LIB) Lithium Iron Phosphate (“LFP”, LiFePO4) Lithium Iron Magnesium Phosphate (LiFeMgPO4) Lithium Manganese Oxide (“LMO”, LiMn2O4) Lithium Nickel Manganese Cobalt Oxide (“NMC”, LiNixMnyCozO2) Nickel–Cadmium (NiCd or NiCad) Nickel–Metal Hydride (NiMH or Ni–MH) Nickel–Iron (NiFe) Nickel–Zinc (NiZn) Aqueous Hybrid Ion (Aquion or AHI™) Flow or Redox Flow Battery Vanadium Redox (VRB) Zinc–Bromine (ZnBr2) Zinc–Cerium (Zn-Ce) All of the above-mentioned Morningstar controllers offer custom programming to create pre-configured plug and play settings that can be tailored for most types of batteries. For more information, please go to our Best Practices By Battery Chemistry page.