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Safety

Standards
General safety recommendations for lithium batteries have been published in the standards UL 1642 and IEC 60086-4.

Safety wiring for memory
back-up representing case B
of UL recommendations

UL recognition
Tadiran SL-type Lithium Batteries are recognized by UL under file
MH 12827. The following text or a modified version thereof appears on each battery:

WARNING:
Fire, explosion, and severe burn hazard. Do not recharge, disassemble, heat above 100 °C, incinerate, or expose contents to water.

Protection against charging
Whenever lithium batteries are not the single power source in a circuit the following measures are recommended by the Underwriters Laboratories. The battery should not be connected in series with an electrical power source that would increase the forward current through the battery.
The circuit for these cells shall include one of the following:

A.		Two suitable diodes in series with the battery to prevent any reverse (charging) current. The second diode provides protection if the other one fails.
B.		A blocking diode or the equivalent to prevent any reverse (charging) current and a resistor to limit current in case of a diode failure. The resistor should be sized to limit the reverse (charging) current to the maximums I_R, max shown below.

In addition to this UL requirement which gives the safety limits, Tadiran recommends to limit the reverse (charging) current to values below 10 µA. This will ensure that service life is not affected.

Protection against forced discharge
Forced discharge of a cell can occur when it is connected in series with other cells and when it is not protected with a by-pass diode.
In these cases the maximum continuous discharge currents have to be reduced to the following values
I_F, max:

Type	I_R, max	I_F, max
SL-350	15 mA	20 mA
SL-360	50 mA	40 mA
SL-361	20 mA	25 mA
SL-550	15 mA	20 mA
SL-560	50 mA	40 mA
SL-561	15 mA	25 mA
SL-750	15 mA	50 mA
SL-760	50 mA	40 mA
SL-761	20 mA	25 mA
SL-840	15 mA	5 mA
SL-850	15 mA	20 mA
SL-860	50 mA	40 mA
SL-861	20 mA	25 mA
SL-889	20 mA	15 mA
SL-2770	25 mA	50 mA
SL-2780	50 mA	100 mA
SL-2790	100 mA	125 mA
SL-2870	15 mA	30 mA
SL-2880	50 mA	60 mA

For further information on UL visit UL at http://www.ul.com.

For further information regarding the IEC standards visit the website of the IEC (International Electrotechnical Commission) at http://www.iec.ch.