Date: Tue, 20 Apr 1999 21:59:30 EDT
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From: S Sittservl <Ssittservl@AOL.COM>
Subject: Aux. battery & accessories installation report (long)
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Since there always seems to be interest in auxiliary battery
installations, I thought I'd report on mine. I actually finished
it in October - it's taken me a while to get around to writing the
report.
The installation in my '88 Westfalia included some major accessories and
some re-wiring, as well. I think the most unique feature of the
installation is the location: everything (including the battery) is
installed in the "hidden compartment" in the driver's side cabinetry.
That's the compartment that's reached via the "trap door" in the floor
of the storage bin that's just aft of the refrigerator. Normally, it
houses just the 110V outlet and circuit breaker. Since its
inaccessibility makes it not terribly useful as storage, it seemed
the perfect spot to use. (In contrast, I've found the more typical
auxiliary battery location - the bin behind the driver's seat - useful
for storing the camper's curtains and screens, and I didn't want to
give it up.)
The major components installed are as follows:
Battery -
Douglas size U1 31 amp hour sealed gel cell. Size U1
is just right for the hidden compartment. 31 amp-hours is
about half the capacity of the popular Optima battery that's
usually put in the bin behind the driver's seat, but it's
plenty for us. Plus, if necessary, we can draw a little
from the starting battery, too (just as we did before adding
the auxiliary battery).
Battery charger / power supply -
Guest Battery Pal Magnum 3 amp charger. Charges the battery
and runs 12V appliances when the camper's plugged in to 110V.
Very small - about a 4 inch cube. This is plugged into a 110V
outlet I added inside the hidden compartment, so it
supplies power automatically when we plug the van in.
Invertor -
Whistler PP140AC 140 amp invertor. This is plugged into a
switched 12V outlet I added inside the hidden compartment, and
half of the camper's standard 110V interior outlet is plugged
into the invertor. (I "split" the outlet; the other half is
still on camper's standard 110V system). That gives me one
"shore tie" outlet (for when the van's plugged in), and one
"invertor" outlet that I can power any time by switching on
the 12V outlet the invertor's plugged into. (I chose the Whistler
because it handled this switching of the 12V outlet without
complaining. The Vector invertors I tried sounded a "power fault"
alarm when I did that.) The switch is installed in the original
"circuit breaker" panel below the interior 110V outlet (along with
the circuit breaker).
Battery relay -
Tekonsha 100-amp 4-terminal battery relay. This sits between the
new battery and the starting battery, and is wired to the original
"alternator running" signal wires that run to the original
refrigerator relay (behind the driver's seat). When the alternator's
running, this connects the two batteries together, so both charge.
When it's not, the batteries are disconnected, so I don't accidentally
drain the starting battery by running the 12V appliances. I also
added a "manual connect" switch that bypasses the relay and connects
the batteries. It can be reached through the small "notch" in the
left rear of the floor of the bin above the hidden compartment. (I
have no idea why that notch was originally there, but it works out
great for the switch.) "Manual connect" is useful for three
circumstances:
(1) To draw power from the starting battery, if we've drained
the auxiliary battery (hasn't happened yet).
(2) To charge the starting battery from the battery charger
(or from the auxiliary battery itself).
(3) To jump-start the engine, if the starting battery's dead.
I've got a 50 amp circuit breaker between the relay and the
starting battery. That's fine most of the time, but if
I jump-start the engine from the auxiliary battery, the
breaker will trip after about 5 seconds of cranking. (It resets
itself after about a minute). That's probably adequate, but still,
I'll probably make myself a little foot-long "jumper cable" to
bypass the relay, breaker, and manual connect switch (which is
only rated at 50 amps) for jump starting.
New 12V interior outlet -
West Marine 12V outlet, installed in the little panel with the
circuit breaker and invertor switch. Yes, that panel is now
pretty crowded, but not unreasonably so. I installed a new,
bigger electrical box behind it, and drilled 3 holes in a new
"blank switchplate" panel for the switch, outlet, and circuit
breaker. It's very convenient to have a 12V outlet back in the
living area of the van. Bedsides, the original dash "cigarette
lighter" outlet is very shallow, and most 12V plugs I've tried
make poor contact and fall out of it.
New light over rear seat -
Hella Adjustable Courtesy Berth Light. Installed in the center
of the face of the air conditioner housing, above the rear seat,
between the two speakers. This light has a little "cover" over
it; roll the cover back, and it switches the light on. You can
(somewhat) adjust how bright the light is by how far you roll
back the cover. It's bright enough to read by, but generally
doesn't bother the driver at night. I also installed a second
switch for the light in the headliner over the driver's seat,
right by the map light. This is very, very useful for seeing
how the kids are doing when we're driving at night, or for
checking out "what made that noise back there - did something
fall over?", etc. By far our most-used new accessory.
Auxiliary fuse panel -
Uses automotive blade fuses. Has unfused connections for
the auxiliary battery, charger, and pump/fridge (which retain
their original fuses behind the driver's seat). Has fused
connections for the 12V invertor outlet, the new 12V interior
outlet, the lighting/furnace circuit (which includes the original
cabin light, the new rear seat light, the Propex furnace, and
a few wires leading various places for future use), and the
original auto accessories circuit (which includes the radio,
map lights, and dash 12V outlet).
The major wiring change (besides the wires for the new stuff) is that
the auto accessories circuit, the fridge, and the pump now run off the
auxiliary battery, rather than the starting battery.
That's pretty much the summary. More detail follows in the "appendix"
below, for those who care.
Disclaimer: I'm not an electrician, nor particularly experienced with
rewiring cars. This installation has worked well for me, but I may
well have done something stupid and dangerous that I just haven't
discovered yet.
-Steven Sittser
Appendix: More Detail Than You Probably Want
--------------------------------------------
Wiring
------
Battery -
8-gauge wire leads from the battery's positive terminal to the battery
relay, then through the 50-amp breaker, then down through the floor,
across the underside of the van (slipping between the frame and the
floor) to the big "terminal 30" of the starter solenoid. Terminal 30
is connected directly to the starting battery via a very large gauge
cable, so this is a convenient place to tie in. The hole in the
hidden compartment's floor is sealed with liquid electrical tape.
This is one of only two holes I had to drill for any of the wiring.
The battery's negative terminal is tied to the original "body ground"
inside the hidden compartment, that's used for the original 110V outlet.
This ground point is a clamp that holds the green 110V ground wire.
I replaced the clamp's setscrew with a bolt (some strange metric size;
wish I remembered what it was), added a ring connector to the 110V ground
wire, and used the bolt (with a lock washer) to attach the battery ground
and the 110V ground to the ground point. The battery ground is a
short 4-gauge auto or lawnmower insulated ground strap. Note that
the green 110V ground wire grounds the circuit breaker's metal electrical
box; I attached a "multiple quick-disconnect" tap (from Radio Shack)
to the side of the box, to use for anything else in the compartment
that needed grounding.
Cabinet wiring conduit -
I needed to run wires from the hidden compartment to the bin behind
the driver's seat, so I ran flexible plastic split-tube conduit along
the floor against the left wall from the hidden compartment, through
the cupboard just forward of the hidden compartment, under the fridge,
and into the under-sink cupboard, then up the wall and out behind
the driver's seat, and into the driver's seat box. There were
already holes and notches in all the right places in the cabinetry -
I didn't need to cut any. I removed the "false floor" in the
under-sink cupboard so I could run the conduit under it. (I may leave
it off - I can't see much reason to have it, and it just decreases
storage space). The only inaccessible spot is under the fridge, and
it was easy enough to push the conduit through from one side and catch
it on the other, with a little help from a stick poked under from the
front of the fridge. The conduit was attached with screw-on wire clips
where needed. The wires were already in the conduit when I ran it -
I don't think they could be pushed through the conduit after it's in
place.
The wires in the cabinet wiring conduit are:
(1) 14 gauge auto accessories power
(2) 14 gauge lighting/furnace power
(3) 14 gauge pump/fridge power
(4/5) 16 gauge 2-conductor zip cord "alternator running" signal
Auto accessories power -
Runs from a fused circuit in the auxiliary fuse panel, through the
cabinet wiring conduit, to behind the driver's seat, then under the
carpet to behind the dash, and up into the fuse panel. I removed
the "accessories" fuse, and clipped the new wire into the "load" side
of the fuse socket. I used a standard male quick-disconnect, but
I think there are special taps made just for this, too. The fuse
socket remains empty - if a fuse were put there, it would directly
connect the auxiliary battery to the starting battery (through
a small fuse and thin wires), which would be bad.
Lighting/furnace circuit -
Runs from a fused circuit on the auxiliary fuse panel, through
the cabinet wiring conduit, to behind the driver's seat.
There, it becomes the positive half of a 16-gauge 2-wire zip cord.
The negative comes from the bin behind the driver's seat, where
it is bolted to a convenient threaded bolt hole on the front
"ceiling" of the bin, to ground it. The zip cord runs through
a new hole (the second of the two I had to drill) into the pillar
behind the driver's door, up the pillar, into the interior of
the curtain rail/shelf above the cabinetry. You have to remove the
curtain rail/shelf for this - the procedure is detailed in the
Bentley manual. From there, it splits into more 2-wire zip cords:
(1) To the original cabin light. I clipped the wires that
originally powered it from the driver's map light.
(2) Down between the closet and left rear window, into the closet
through the vent, across the top of the water tank, then
into the area under the rear seat, for the furnace. The
tricky part is threading it across the top of the water tank
and under the seat - basically, I just started pushing and
wiggling the wire until I got it to come out the other side.
(3) Across the top of the closet, into the plastic air conditioner
cowling, where it joins very thin wires that snake between
the cowling and the wooden housing (I cut out a bit of the
rubber "gasket" to let them through) and into the new light
over the rear seat.
(4) Over the top of the closet, to the rear, taped off, for
future use.
(5) Through the metal track just forward of the plastic air
conditioner cowling, to the passenger side of the van, and
into the vent duct, taped off, for future use.
This is actually more complex than necessary, and I ended up doing it
this way for historical reasons. Simpler would be to leave the
cabin light power as-is, since the auto accessories circuit has been
switched over to the auxiliary battery anyway. The new rear seat light
could be powered from the cabin light, but I wouldn't want to add much
more than that, since the wires from the driver's map light to the
cabin light are pretty thin. For the furnace, a separate wire could
easily be run directly from the hidden compartment to under the rear seat.
Unless you wanted the rear seat light, there would be no need to take
down the curtain rail/shelf.
Pump/fridge circuit -
Runs from an unfused circuit on the auxiliary fuse panel, through
the cabinet wiring conduit, to the bin behind the driver's seat, where
it replaces the original power wire on the fridge relay.
"Alternator running" signal -
Runs from the two "alternator" connectors on the fridge relay,
through the cabinet wiring conduit, to the new battery relay.
Rear seat light -
The rear seat light has three terminals - "common", "external switch",
and "internal cover switch". The power from the lighting/furnace
circuit goes to "common", and the ground to "cover switch". The
"external switch" wire follows the lighting/furnace circuit wires
into the curtain rail/shelf, and then into the headliner above the
driver. There, it goes through a pushbutton switch and an automotive
blade fuse in a holder (to protect the switch), and then to the
ground terminal on the driver's map light. The pushbutton switch
pokes through the headliner just aft of the map light, and the
fuse holder and wires are stuffed up there behind it. The wiring
can be done just by removing the map light - there's no need to
remove the headliner.
Invertor -
The 110V outlet was "split" (electrically) into two separate outlets
by breaking the two metal tabs provided for that purpose on the
sides of the outlet. (Those are typically used in house wiring to
connect one outlet to a switched circuit, and the other to an
unswitched circuit). I think I actually replaced the outlet with
a new one that had more places to attach wires, but this isn't
strictly necessary. One of the outlets remains wired as before.
For the other, I cut about a foot off of the male end of a
a heavy-duty 3-wire extension cord, and wired it into the outlet.
The other end is then plugged into the invertor. To fit in the extra
wiring, I replaced the outlet's electrical box with a bigger one.
(Actually, a 2-wire cord would probably do the trick - the "ground"
socket in the invertor's 3-prong outlet is a fake, and isn't connected
to anything in the invertor.)
Battery charger -
I cut about a foot off of the female end of the same extension cord
I cut up for the invertor, and wired it into the non-invertor
("shore tie") outlet. The battery charger plugs into this extension
cord.
Physical Installation
---------------------
The battery sits in the aft outer corner of the hidden compartment, atop
a little styrofoam platform. The platform has a channel carved in the
bottom for the original 110V wiring on the floor of the compartment.
I carved the channel using a knife, a small saw, and the flame from a
lighter (to make it smooth and "sealed"). The terminals are on the forward
side of the top.
To get the battery in, it's easiest to remove the wall between the hidden
compartment and the storage compartment that's just forward of it. It
only takes 5 screws - only one more than getting to the starting battery!
The battery relay and circuit breaker are attached to the aft wall of the
hidden compartment. The "manual connect" switch is in the aft outer
corner; I put mine in a little plastic box so I could stick it to the
wall easier.
The charger attaches to the aft wall of the compartment, over near the
110V outlet's electrical box.
The 12V outlet for the invertor is on the floor of the compartment. The
invertor itself is on the forward wall. It's hooked securely, but
not permanently, onto two screws in the wall. That way, it's easy
to take off when it's time to remove the wall to replace the battery
(presumably not for many years).
The auxiliary fuse panel is screwed to the underside of the unmovable
portion of the floor of the bin above the hidden compartment (that is,
the compartment's "ceiling"). The fuses face toward the passenger side,
and are easy to get to.
Parts, costs, and sources
-------------------------
Douglas size U1 31 amp hour sealed gel cell battery, about $70
from Batteries Plus. (Batteries Plus might just be local,
but Douglas batteries should be available elsewhere. West
Marine also has a gel cell that I think is similar.)
Guest Battery Pal Magnum 3 amp charger, model 2603, about $55
from West Marine.
Tekonsha 100-amp 4-terminal battery relay, around $10 from the
local RV place.
Whistler PP140AC 140 amp invertor, about $30 or $40 from Wal-Mart.
Hella Adjustable Courtesy Berth Light, about $15 from West Marine.
50-amp SPST toggle switch, a few dollars at Wal-Mart.
Panel-mount 12V outlet, a few dollars at West Marine.
Battery isolator installation kit - but NOT the battery isolator.
The installation kit just consists of a spool of 8-gauge wire,
a 50-amp self-resetting circuit breaker, and a variety of crimp
connectors. I mainly got it for the circuit breaker - they're
kind of hard to find.
Surface-mount 12V outlet (for the invertor), a few dollars at Wal-Mart.
Light-up high-amperage rocker switch (for the invertor 12V outlet),
a few dollars at Radio Shack.
Push-on / push-off switch (for over the driver, to control the rear seat
light), a couple of dollars from Radio Shack.
Single fuse holder for a blade-type auto fuse, a couple of dollars
from Radio Shack.
Multi-fuse panel for blade-type auto fuses, a few dollars from Auto Zone.
Gray nylon "blank" switchplate (no holes in it except for the two screw
holes), a dollar or two from the hardware store.
1" thick styrofoam to put the battery on, free from the scrap bin.
Battery ground cable, I think about 12", a few dollars from Auto Zone.
Flexible plastic split wire conduit, a few dollars from Auto Zone.
A short, heavy-duty 3-wire extension cord, a few dollars from the
hardware store.
Two electrical boxes, a few dollars from the hardware store.
Brown duplex 110V electrical outlet, with two pairs of "push in" connectors
for each half, a dollar or so from the hardware store.
Liquid electrical tape, a few dollars from West Marine.
Tons of wire, crimp connectors, wire ties, wire clips, screws, and
fuses, a small fortune from Auto Zone, Radio Shack, and Sears
Hardware.
That's it!
-Steven Sittser
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