[xk] Fusing

XK
1

Does anyone have any thoughts on putting a safety or master fuse between the
battery and the system.since the 140 seems to be lacking in fuses. Some
things aren’t fused and then a lot of the fuses are located very close to
the load (lighting) that a short elsewhere could cause all sorts of
problems… I thought maybe a quick disconnect/shutoff switch could be
worked into it along with a some sort of a plug in for a battery pal.

Gary

2

In reply to a message from Gary Otto sent Thu 16 Jul 2009:

Gary,

I have an alternator to support an electric fan and other
electrics.
I have a marine breaker between the battery and alternator
(similar in function to a fusible link), that can also be
used for electric disconnect.
I’ll send a photo offline.

Monte
1960 DHC
S838594–
The original message included these comments:

Does anyone have any thoughts on putting a safety or master fuse between the
battery and the system.since the 140 seems to be lacking in fuses. Some

–
p8099
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3

In reply to a message from p8099 sent Thu 16 Jul 2009:

Monte
You may wish to reconsider the location of that breaker. Breakers
are heat sensitive, which causes them to pop (too much heat). If
your breaker disconnects the supply of current from your alternator
to the load (battery) while the engine is running, it will blow the
diodes out of the alternator. If the car is wired correctly, all
but one of the circuits are protected by the fuses in the box. The
only circuit which isn’t, is the ignition. That would be the place
to install a fusible link, coming off the power side of the starter
solenoid to the ignition switch. I think it’s a good idea to have a
disconnect on the grounded side of the battery to shut down the
entire system in the event of a short. JMHO.
Joel–
The original message included these comments:

Gary,
I have an alternator to support an electric fan and other
electrics.
I have a marine breaker between the battery and alternator
(similar in function to a fusible link), that can also be
used for electric disconnect.
I’ll send a photo offline.
Monte

–
ex jag, '66 E-type S1 4.2, '56 XK140dhc, '97 XJ-6
Denison, TX, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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4

In reply to a message from Gary Otto sent Thu 16 Jul 2009:

Gary, if its any help, heres what I did on my 140 DHC.

There are two hot wires coming off the starter solenoid, one
is unfused and goes to the ammeter. The other wire goes to
the fusebox. I disconnected these two wires from the
solenoid, and joined the two wire ring-terminals at the end
of each wire together. Then I connected a short piece of
wire, having an inline 50A fuse and a toggle switch, between
the starter solenoid and the joined together ring-terminals.

The 50A fuse and toggle switch are positioned behind the
instrument panel. That way I can turn off that switch if I
want when the car is unattended, and the 50A fuse should
protect most everything including what seem to be normally
unfused portions of various circuits which seem to originate
at the ammeter.
So far that 50A fuse hasnt blown even when the lights,
heater and wipers are all on at the same time. Everything
can be returned back to stock condition if needed. The two
ring terminals and one wire end are just joined together by
means of soldering, then insulated.

I also put one of those master cut off switches in line with
the negative battery cable. I just used a Bosch switch with
a plastic red removable handle, the kind you see on race
cars. It claims to be rated at 10,000A, 12v for 10 seconds,
and 100A continuous.

This one I installed by drilling a hole in that vertical
sheet metal battery box panel just outboard of the battery,
behind the right front wheel. The red handle is on the
outside of that panel, just to the inside of the RF wing
sheetmetal, and the switch mechanism and battery cable
connections are all to the inside of that panel, ending up
adjacent the battery. The red handle is positioned maybe one
foot rearward of the RF wheel opening, so I can easily reach
in there to turn it on and off without having to open the
bonnet or battery box cover. It cant be seen unless you look
way in there.

Drilling that hole in the sheet metal battery box panel to
accept the cut off switch, seems like a questionable thing
to do, from an originality point of view, but it is done
now, and anyway, could be repaired in the future by welding
the hole shut.

This 140 is still + ground, and at the time, it seemed to
make sense to put that master cut off switch in the negative
battery cable, but now, it almost seems to make slightly
more sense to have it in the grounded battery cable, so
maybe I will change it over sometime.–
Gary Grant S818919DN
Ottawa, Canada
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5

Thanks. I was trying to get an idea of the minimum rating needed. 50 A
sounded about right.-----Original Message-----
From: owner-xk@jag-lovers.org [mailto:owner-xk@jag-lovers.org] On Behalf Of
Gary Grant
Sent: Friday, July 17, 2009 3:26 PM
To: xk@jag-lovers.org
Subject: Re: [xk] Fusing

In reply to a message from Gary Otto sent Thu 16 Jul 2009:

Gary, if its any help, heres what I did on my 140 DHC.

There are two hot wires coming off the starter solenoid, one is unfused and
goes to the ammeter. The other wire goes to the fusebox. I disconnected
these two wires from the solenoid, and joined the two wire ring-terminals at
the end of each wire together. Then I connected a short piece of wire,
having an inline 50A fuse and a toggle switch, between the starter solenoid
and the joined together ring-terminals.

The 50A fuse and toggle switch are positioned behind the instrument panel.
That way I can turn off that switch if I want when the car is unattended,
and the 50A fuse should protect most everything including what seem to be
normally unfused portions of various circuits which seem to originate at the
ammeter.
So far that 50A fuse hasnt blown even when the lights, heater and wipers are
all on at the same time. Everything can be returned back to stock condition
if needed. The two ring terminals and one wire end are just joined together
by means of soldering, then insulated.

I also put one of those master cut off switches in line with the negative
battery cable. I just used a Bosch switch with a plastic red removable
handle, the kind you see on race cars. It claims to be rated at 10,000A, 12v
for 10 seconds, and 100A continuous.

This one I installed by drilling a hole in that vertical sheet metal battery
box panel just outboard of the battery, behind the right front wheel. The
red handle is on the outside of that panel, just to the inside of the RF
wing sheetmetal, and the switch mechanism and battery cable connections are
all to the inside of that panel, ending up adjacent the battery. The red
handle is positioned maybe one foot rearward of the RF wheel opening, so I
can easily reach in there to turn it on and off without having to open the
bonnet or battery box cover. It cant be seen unless you look way in there.

Drilling that hole in the sheet metal battery box panel to accept the cut
off switch, seems like a questionable thing to do, from an originality point
of view, but it is done now, and anyway, could be repaired in the future by
welding the hole shut.

This 140 is still + ground, and at the time, it seemed to make sense to put
that master cut off switch in the negative battery cable, but now, it almost
seems to make slightly more sense to have it in the grounded battery cable,
so maybe I will change it over sometime.

Gary Grant S818919DN
Ottawa, Canada
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]-- --Support
Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

6

Gary,

Hello, I was wanting to clarify a detail on this post before I attempt to install the fuse as you describe. My solenoid starter switch has line 33 attaching to the battery via the large terminal and line 10 connected to a small terminal which lead to the push start button. The other large terminal on the starter solenoid attaches to the starter.

Line 33 leads to the amp meter, line 10 leads to the push start.

Question:
Are you connection these to lines (soldered together) with the short new wire, having an inline 50A fuse and a toggle switch, to the large “battery” terminal on the solenoid? Did you leave the small “third” terminal disconnected?

Any additional information would be appreciated.

Thank you,

James

7

A very tidy answer would be to use a Dynator or Dynalite, i.e. an alternator masquerading as a dynamo, and to fit one of the manufacturer’s dummy voltage regulator control boxes. As there’s no need for the regulator bobbins if using an alternator, these dummy boxes contain a 60A whole-vehicle fuse. And everything looks completely normal under the bonnet. I’ve done this with a couple of cars (non-Jaguars).

8

Roger,

Thank you, I actually have the Dynalite on order but I was not aware they made the dummy VR box. I was going to wire around as instructed. I will look into that, thank you again.

James

9

I’ve just had a look at Powerlite’s website and the dummy VR box may not be available with the metal casing - they make the common sixties types, RB340 etc. but it’s certainly worth asking. Or you could ask Wosperformance, who make the similar Dynator - I have one of these on my AC. Again they make the common RB106 and RB340 style dummy boxes to suit, but not with the metal case. If they don’t make one, and won’t convert a box for you, it would actually be very easy to do this job yourself - the Dynator link gives connection instructions, which tells you something about what’s inside:

Or Dynalite:

I see the Dynalite (Powerlite) page includes a RB310 to show wiring, so it would be worth asking if they can either supply or convert one for you. The wiring for this type appears to use it simply as a connector for the battery lead. It may be that a fuse could be fitted between two terminals instead - I’m not an electrician!

10

James,
What I did, was to disconnect the wire 33 from its terminal on the starter solenoid.

Then I attached the disconnected wire 33 to one end of an extra piece of wire containing a fuse and an antitheft switch. The other end of the extra piece of wire gets connected to the terminal of the starter solenoid to which wire 33 was formerly connected.

In other words, I simply put a fuse and switch between the wire 33 and where it connects to the starter solenoid.
I put the new fuse close to the starter solenoid.

I believe ( and hope) the new fuse protects every electrical component, with the exception of the starter itself.
I left wire 10 intact, still attached to the starter solenoid. I may be completely wrong, but I think wire 10 now becomes fused.

Hope this helps.

11

Gary,

Thank you for the clarification, I would agree with your assessment.

James

12

Someone had already installed a 1/4 turn battery cutoff switch on the vertical battery compartment panel low down behind the left seat on my XK120. I use it every time I put it away in the garage so I always know the batteries have juice next time I go to start the car. Works for me!
Chris

13

Chris,

Fully support your solution. See pic how it works in an XK 140 FHC but here with the switch on the battery pole (which can be reached from the top). I learned that the switch should be in the cable to the chassis (still POS in my case).

Bob K

.

image
image1024×576 96.3 KB

14

Looks like that’s doing the job fine, Bob! That looks to be a Lucas switch. Mine has 2 ears on it and emerges through the vertical battery box and that knob is the only thing you see on lifting the seat back - quite neat. You push it in slightly to turn it. I don’t know the maker.
Chris