Bogart Engineering SC-2030 Technical Manual

Bogart Engineering
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●Recommended for use with “12V” or 24V solar panels. (see below on page 2 Where this controller is not
recommended)
●Eight adjustable parameters to allow charging closely according to the way the battery manufacturer
specifies. Technical details are shown on graphs on pages 14 and 15.
●If the TriMetric TM-2030 is disconnected from the SC-2030, it will do a much less flexible, but minimal,
level of charge regulation without receiving information from the TM-2030. See p.11, Table 3.
●Recently (TM-2030 version 2.2 and higher) a manual equalization option has been added. See section 6.6.
In addition, it has two advantages not usually offered in solar controllers to better preserve the capacity of
your battery system.:
1. Amp hour counting: Many battery companies recommend that when batteries are recharged they should
be overcharged, so that 104 to 120 percent of the charge that was previously removed should be replaced
before going into “float”. Most controllers don't measure this. When connected with the TriMetric, this
controller measures the amp hours used, and allows you to specify the correct amount of amp hour
overcharge when recharging. The more usual benefit of this is to insure that batteries are not undercharged.
However it is also beneficial to prevent overcharging, in situations where solar panels are charging a lot
during successive days but where very little battery discharge is occurring in the evenings.
2. Finish current charging: After the batteries are mostly charged, this controller has an optional “fourth”
stage that is beneficial for liquid electrolyte lead acid batteries, and this is also sometimes recommended for
some AGM types. This stage allows the voltage to go unusually high while it regulates the current to a
specified level, to safely get more charge into the batteries. This helps to maintain the capacity of the
batteries, which often begins to degrade with solar charged batteries because they don't get sufficiently
charged.
Where this controller is NOT recommended: For 12V systems for best efficiency this “PWM type” charger
requires what are often called “12 volt” solar panels that have 36 cells per panel. Or, with 24V systems you should
use “12 volt” or “24 volt” solar panels with 36, or 72 cells per panel. Many solar panels manufactured recently
are mainly intended for “on grid” application that have 60, 80, or other number of cells—that have voltages that
don’t well match 12V or 24V battery systems These panels are not suitable for high efficiency battery charging
with a PWM controller such as this one. For good efficiency, they will require a more sophisticated controller
with “MPPT” (Maximum power point tracking) capability.
Many people believe that MPPT type chargers are always better than PWM chargers: We have compared at
least one commonly used MPPT charger with the SC-2030 and found that under very ordinary conditions the SC-
2030 delivered more charge to the batteries. We measured this when the ambient temperature was 70 F degrees in
full sun, and when the proper panels matched to the batteries were being used and when charging over 13.0 volts
(the most common charging range with lead acid batteries.)
The SC-2030 is a "PWM" (Pulse width modulated) type that is simpler and less costly than a "MPPT"
(Maximum Power Point Tracking) type charger. As said, the SC-2030 can give even better performance under
some common situations. MPPT technology can give some advantage when temperatures are low, and it is
necessary for good power transfer when panel voltage is much higher than the battery system voltage. With the
SC-2030 (or other PWM charger), you may be able to get more total performance at the same cost by purchasing
another properly matched solar panel instead of a more expensive MPPT solar charger.
A common mistake for evaluating MPPT performance is to compare their (lower) solar input current with
(higher) output battery current, and thinking this additional current is solely due to the MPPT charger. This is
incorrect, and will give an exaggerated impression of its advantage. A comparison must be done by changing to
the PWM controller and then comparing battery currents.