It should be noted that the voltage threshold on the E-Plex system is
32V and I believe that the octoplex system is the same. A runaway
alternator can easily take out parts of the system. Lightning strikes
are currently an unknown on these systems. A electrical contractor in
North Carolina that I do business with estimates that the cost of a 3
wire system is about 25% higher than a conventional one. For the time
being I would stick with a conventional system as I know that for the
most part it will survive a lightning hit.
Harris
REPLY
Good point Harris. That may explain why my older technology system has
survived as well as it did. Back in 1996 I first built a system using
relay logic. Although I was vaguely aware of high end autos using digital
systems back then I lacked any firm information on what they were using.
The system would be less vulnerable in a 12 V system but now that most new
builds are going 24V it also moves the 3 wire digital operating system
closer to the maximm threshold.
One solution is to go high tech and use only regulated DC into the 3 wire
system. It's expensive and would negate the potentrial cost savings.
I know of one high end RV manufacturer who documented 50% savings on the
total installed cost of a 3 wire system compared to hard wire old style
in their similar but older model. But this is also in a production shop
with many identical copies of the same model being built. By comparison
most boat builders are one off or limited quantity production.
I would argue that we should not toss out the baby with the bathwater.
Tthe topology of a 3 wire system offers considerable benefits in terms
of wire weight reduction and reduction in wire duct congestion. Taking one
step backwards to relay logic may seem retrogressive but is still ahead of
what we are doing at present.
Arild
----- Original Message -----
From: "Allen, Harris" <hallen@wbdiesel.com>
> It should be noted that the voltage threshold on the E-Plex system is
> 32V and I believe that the octoplex system is the same. A runaway
> alternator can easily take out parts of the system. Lightning strikes
> are currently an unknown on these systems. A electrical contractor in
> North Carolina that I do business with estimates that the cost of a 3
> wire system is about 25% higher than a conventional one. For the time
> being I would stick with a conventional system as I know that for the
> most part it will survive a lightning hit.
> Harris
REPLY
Good point Harris. That may explain why my older technology system has
survived as well as it did. Back in 1996 I first built a system using
relay logic. Although I was vaguely aware of high end autos using digital
systems back then I lacked any firm information on what they were using.
The system would be less vulnerable in a 12 V system but now that most new
builds are going 24V it also moves the 3 wire digital operating system
closer to the maximm threshold.
One solution is to go high tech and use only regulated DC into the 3 wire
system. It's expensive and would negate the potentrial cost savings.
I know of one high end RV manufacturer who documented 50% savings on the
total installed cost of a 3 wire system compared to hard wire old style
in their similar but older model. But this is also in a production shop
with many identical copies of the same model being built. By comparison
most boat builders are one off or limited quantity production.
I would argue that we should not toss out the baby with the bathwater.
Tthe topology of a 3 wire system offers considerable benefits in terms
of wire weight reduction and reduction in wire duct congestion. Taking one
step backwards to relay logic may seem retrogressive but is still ahead of
what we are doing at present.
Arild
