Trace Engineering DR Series Owner’s Manual - Version 3.2 - 9/7/98 - Page 16
Deep Cycle Batteries
This is the type of battery best suited for use with inverters. They are designed to have the majority of
their capacity used before being recharged. They are available in many sizes and types. The most
common type is the non-sealed, liquid electrolyte battery. Non-sealed types have battery caps. The
caps should be removed periodically to check the level of electrolyte. When a cell is low, distilled water
should be added. The electrolyte level should be checked monthly and distilled water added if
needed after recharging.
The most common deep cycle battery is the type used with boats and motor homes. They typically are
called “Group 27” batteries and are similar in size to a large truck battery. They are 12 volt batteries
rated at 80 to 100 amp-hours (20 hour rating). Often the deep cycle claim is over-stated. They do work
better than a car battery, but are not recommended for anything but the smallest systems.
Another popular and inexpensive battery of this type is the “golf cart” battery. It is a 6 volt battery rated
at 220 amp-hours. They can be cycled repeated to 80% of their capacity without being damaged. This
is the minimum quality of battery that should be used with DR series inverter applications.
Many systems use the L16 type of battery. These are 6 volt batteries rated at 350 amp-hours and are
available from a number of manufacturers. They are 17 inches in height and weigh up to 130 pounds
each - which may be troublesome in some applications such as RV or marine installations.
Type 8D batteries are available with either cranking or deep cycle construction. The deep cycle
versions are 12 volt batteries rated at around 200 amp hours. Since they are most commonly used to
start truck engines, you should make sure you purchase the deep cycle version.
Sealed Gel Cell
Another type of battery construction is the sealed gel cell. They don’t have battery caps. The
electrolyte is in the form of a gel rather than a liquid which allows the batteries to be mounted in any
position without spilling. The advantages are no maintenance, long life (800 cycles claimed) and low
self discharge. The disadvantage is high initial cost and the possibility of damage from overcharging.
While there are many manufacturers of quality non-sealed batteries, there are only a few
manufacturers of suitable gel cells. Don’t confuse sealed batteries with maintenance free batteries -
the latter is typically a standard liquid electrolyte type battery without caps for adding water - when the
electrolyte gets low you replace the battery.
AGM (absorbed glass mat) batteries are similar to gel cells and may be used in inverter applications.
NiCad and Nickel Iron (NiFe)
Trace inverters and battery chargers are optimized for use with lead acid batteries which have a
nominal voltage of 2.0 volts per cell. NiCad/NiFe batteries (also called alkaline batteries) have a
nominal cell voltage of 1.2 volts per cell. The nominal voltage of a NiCad/NiFe battery bank can be
made the same as a lead acid bank just by juggling the number of cells (10 cells for 12 volts, 20 cells
for 24 volts and 40 cells for 48 volt systems) However, the NiCad/NiFe battery bank must be charged
to a higher voltage to fully recharge and will drop to a lower voltage during discharging compared to a
similarly sized lead acid type battery. This makes the job for the inverter/charger much more difficult.
One way to use NiCad/NiFe batteries with a 24 volt DR series inverter is to use nineteen NiCad/NiFe
cells in the battery bank instead of the usual twenty. This will reduce the battery bank charging voltage
requirements to about the same level as a lead-acid bank, so more standard charger settings can be
used. The problem with this approach is that the battery voltage will drop as low as 18 volts to fully
discharge the battery. When nineteen cells are used set the BATTERY TYPE SELECTOR to position
#2.
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