In a message dated 21/02/2007 11:56:49 A.M. Eastern Standard Time,
LISTSERV@GERRY.VANAGON.COM writes:

Hi  Frank, I'm not seeing any normal conditions where my relay system is
at a  disadvantage when compared to the 1315. My starter battery is
always  connected to the charging source, just like in a system using the
1315. My  aux batter is connected to the starter battery/charging source
under only  two conditions:

1. The alternator is putting out enough voltage to  extinguish the dash
ALT lamp. What's that -- 13 volts or more? Bridging the  aux battery to
the starter battery under these conditions is appropriate  unless the aux
battery has suffered a major failure, in which case all bets  are off
with my system.

2. I have operated a switch to manually  bridge the aux battery to the
starter battery/charging source by applying  voltage from the aux battery
to the relay coil. This would be done in the  case where the starter
battery is low and I need to steal some power from  the aux battery to
pump up the starter battery. There also should be no  problem unless the
starter battery has suffered a major failure.

I  did use the phrase "normal conditions" in my opening paragraph, and I
noted  above two unusual conditions which involve the near or total
meltdown of  one or both batteries. In the situation where the aux
battery was hosed,  the 1315 would allow a fellow to keep driving because
it would refuse to  connect the bad battery, whereas my system has no
such safeguard. If the  starter battery is low, both systems allow a
fellow to bridge the aux to it  for starting, but if the starter battery
was massively failed neither  system would help.

The 1315 does not require metering: it appears to be  smart enough to not
connect ugly-dead batteries to the system. So that's an  advantage -- but
to me, not much of one because I like meters -- even with  a 1315 I'd
monitor battery voltage.

So, unless I'm missing  something, the 1315 only provides two advantages
over the relay system:  no-brainer operation (always useful when you have
a squirrel's brain) and  it refuses to connect a hosed aux battery. Those
two may be advantages  enough for some folk to recommend the 1315 to
them, but to say that "relay  systems work but not well," is a bit much.

Mike, this is all well and  good and correct, however your missing one
important point.  Using a relay  system has both batteries connected together as
soon as the engine starts and  the alternator red light goes out we all agree on
that ?  OK, so if that is  true and the aux battery is dead and your staring
battery is full what happens  ?  Well, what happens is the main battery will
try to dump it's charge into  the aux battery until they both become equal.  The
rate at which this  happens depends on the size of the wire used to connect
the two batteries and  the speed at which the alternator can keep up replacing
the missing voltage in  the batteries.  So, this is not a problem if you don't
mind changing two  batteries more often than usual as ordinary car batteries
do not like to be  discharged and charged constantly.  That was the reasoning
behind using a  deep cycle battery as the aux battery.  So then we're back
where this  thread all started.  The only deep cycle battery that sort of fits
under the seat is the OPTIMA Yellow Top which we see by recent experience is a
piss poor battery !  So.......some of us have gone back to using a regular
car battery with a good warranty as the aux battery.  Those of us who  have
done this most likely already have the 1315 as it is required to charge the
OPTIMA correctly in a two dissimilar battery situation.  It also make more  sense
to charge the batteries independently and this is what the 1315 does best.

Cheers,

Frank  Condelli
Almonte, Ontario, Canada
'87 Westy, '90 Carat, '87 Wolfsburg  (Forsale) & Lionel Trains (_Collection
for  sale_ (http://members.aol.com/Fkc43/trainsal.htm) )
Vanagon/Vanagon Westfalia Service in the Ottawa Valley
_Frank Condelli &  Associates_ (http://members.aol.com/Fkc43/busindex.html)
_Vanagon  Stainless Steel Exhaust Systems_
(http://members.aol.com/Fkc43/stebro.htm)
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camping event, Almonte, ON, June 07 ~ 10,  2007