Victron energy BMV-700 Anleitung Seite 39

6 LITHIUM IRON PHOSPHATE BATTERIES
(LiFePO )
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LiFePO is the most commonly used Li-ion battery chemistry.
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The factory default 'charged parameters' are in general also applicable to
LiFePO batteries.
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Some battery chargers stop charging when the current drops below a set
threshold. The tail current must be set higher than this threshold.
The charge efficiency of Li-ion batteries is much higher than of lead acid
batteries: We recommend to set the charge efficiency at 99%.
When subjected to high discharge rates, LiFePO batteries perform much
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better than lead-acid batteries. Unless the battery supplier advizes
otherwise, we recommend setting Peukert's exponent at 1.05.
Important warning
Li-ion batteries are expensive and can be irreparably damaged due to over discharge or over
charge.
Damage due to over discharge can occur if small loads (such as: alarm systems, relays,
standby current of certain loads, back current drain of battery chargers or charge regulators)
slowly discharge the battery when the system is not in use.
In case of any doubt about possible residual current draw, isolate the battery by opening the
battery switch, pulling the battery fuse(s) or disconnecting the battery positive when the
system is not in use.
A residual discharge current is especially dangerous if the system has been
discharged completely and a low cell voltage shut down has occurred. After
shutdown due to low cell voltage, a capacity reserve of approximately 1Ah per 100Ah
battery capacity is left in a Li-ion battery. The battery will be damaged if the remaining
capacity reserve is drawn from the battery. A residual current of 4mA for example
may damage a 100Ah battery if the system is left in discharged state during more
than 10 days (4mA x 24h x 10 days = 0.96Ah).
A BMV 700 or 702 draws 4mA from a 12V battery (which increases to 15mA if the
alarm relay is energised). The positive supply must therefore be interrupted if a
system with Li-ion batteries is left unattended during a period long enough for the
current draw by the BMV to completely discharge the battery.
We strongly recommend to use the BMV-712 Smart, with a current draw of
only 1mA (12V battery), irrespective of the position of the alarm relay.
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