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www.fothermo.com
BC-03
11
water heater. The water heater has no restrictions in the shutdown threshold in this
mode, the excess management must be done in the connected battery system.
Recommended application:
•
12 Volt battery management system with regulated excess output capable of
delivering at least 6.5 A of current.
•
24 Volt battery management system with regulated excess output which can
supply at least 13 A of current.
Mode 5: Excess management with a 24 Volt battery
In this mode, a 24 Volt battery is connected directly to the photovoltaic water heater.
During the charging process of the battery, the water heater absorbs excess energy
for reheating when the end-of-charge voltage is reached, from about 27 V. This has
the advantage that the battery always remains fully charged and only excess energy
is used to heat the water. At the same time, photovoltaic modules can also be
connected and used with the water heater directly.
Technical information:
The photovoltaic water heater measures the voltage of the externally connected
battery. As the battery voltage reaches values higher than 27 V, the water heater
absorbs the excess energy. In this mode the voltage is regulated to 27 V.
Recommended battery systems:
24 Volt batteries: LiFePO4, Lead Acid, Gel, AGM, Sealed.
Mode 6: Reheating with a 24 Volt battery
Mode 6 is essentially the same as mode 5, but additional energy can be taken from
the battery to reheat the water heater. As soon as the water temperature falls below
the defined minimum temperature, the battery is used to reheat the water heater,
even if it is not fully charged. This enables the water to be heated even when there is
no excess energy available at the battery.
Technical information:
The battery is not discharged further than a minimum voltage of 24.8 V by the
reheating process. This threshold voltage is for the protection and longevity of the
battery, as it is not completely discharged by the water heater. In addition, the battery
can then be used for other electrical loads such as lighting, charging cell phones,
refrigerator, etc.
Recommended battery systems:
24 Volt batteries: LiFePO4.
