Split charge diode - for charging two batteries.

The can contains two diodes connected together at the alternator (A)
terminal. The battery (B1, B2) terminals are connected to the two
isolated batteries, one of which is usually the normal vehicle system.

Sounds like a Lucas "Blocking Diode" from a split charge system, the
alternator would feed the centre terminal and the other two feed out to 2
separate batteries. A good system for isolating a winch battery from the
vehicle electrics, the only real downsides being the limitation of a 60A
alternator (the diode's power handling capability) and the voltage drop
across the diodes (typically 0.8 to 1.4 volts) causing the batteries to only
charge to the lower voltage and hence not a full charge. This was a
situation that could be worked around though, by modifying the alternator to
become "battery sensed" instead of "machine sensed", so that the alternator
would sense the battery voltage direct ( instead of its own internal volts)
and run at a slightly higher internal voltage to compensate for the drop
across the diodes. This would cause the ignition light to be seen glowing
very dimly at night, due to the voltage difference across it (0.8 to 1.4
volts), easily cured by the addition of a diode in the ignition light
connection at the alternator.
Assuming it is indeed a blocking diode, new it would have cost in the region
of ?45 about 6 or 7 years ago. I'm led to believe that the only user of them
in any quantity was the AA.
Badger.

On Sun, 20 Feb 2005 15:48:55 GMT, "Phil Miles"
<pmiles@removethistosend.milesfamily.org.uk> made me spill my meths
when he wrote:

Anti Rambler device, it's connected to the ignition leads and zaps
them as they touch the grill. Oh, actually only worked on the metal
SIIa grills :)