03/03/97
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LINK 20 BATTERY MANAGEMENT
SIMPLE BATTERY MANAGEMENT RULE
Recharge When the Battery is 50% Discharged!
The Link 20 is a guide to the battery's state of charge. Our Mid-Capacity Rule
says you should begin charging when your Link 20 shows that 50% (or more) of battery
capacity has been consumed. In marine and RV systems, which are trying to minimize
charging time with an engine driven alternator or genset, the battery is normally charged
only to the 85% level. This means only 35% of the battery capacity is actually available
for use.
The Mid-Capacity Rule is a very conservative approach to battery use. Occasion-
ally discharging a battery more deeply is perfectly acceptable. The Mid-Capacity Rule
is intended as a design and operating guideline, not a law which must be obeyed without
exception.
We recommend synchronizing your Link 20 to the 100% charged level of the
battery. You should begin recharging when 50% of the your battery capacity has been
consumed.
When recharging from an engine driven alternator or generator supplied
battery charger you do not need to charge until the meter counts back up to 0 Amp-
hours consumed. You may end charging even though the final 15% of battery capacity
has not been restored. Later, when you are able to charge for a long period of time, the
remaining Amp-hours consumed will be replaced.
Periodic conditioning or Equalizing removes any negative Amp-hours that are not
replaced during normal charging.
OVERCHARGE AMP-HOURS
If the batteries are 100% charged, and the Link 20 is in sync, overcharge A hrs
are displayed as a positive Amp-hour number. Some accumulation of overcharge A hrs is
normal with systems continuously connected to a charger. For example: A 100 A hr
battery at Float voltage will normally have about 0.1 Amp flowing into it. This means
you would expect about 2.4 A hrs of overcharge to accumulate each 24 hours. If your
battery system is larger, proportionately more current flows and A hrs accumulate.
With a constant voltage charging system set at 14.2 volts, as much as 1 Amp of
current may be flowing all the time even after the battery has reached the charged
parameters. This causes a small overcharge A hr reading to appear in the Ah display. When
discharging begins, these overcharge A hrs are erased and the Link 20 resets to zero and
begins to report Amp-hours consumed.
Prolonged high voltage applied to a fully charged battery will probably cause
gassing. So, if you see a large A hr overcharge occuring daily, consider it a warning to
check your system. It could indicate that you are destroying your battery by overcharging.
When you Equalize your batteries, you will accumulate some overcharge A hrs.
This is normal and keeps the Link 20 synchronized with the battery state of charge.
