BATTERY CUT OFF SWITCH
by George Dow and Lorne Goldman

The Factory has been installing battery cut-off or "Isolator" switches for some time...either as an option or standard fare. These switches are designed to cut off all power to car's electrical system, thus making electrical work much easier and the risks inherent to it much less. In principle, they are an excellent idea for any Morgan! However, the component Morgan uses and their installation creates some problems which should be addressed or avoided.

Over time, the Morgan switches often fail. This can be a sad event as they invariably do so while the car is being used, sometimes very far from home. The uninitiated can often be flummoxed at the suddenly (or intermittently) unresponsive car. I have frequently heard of ruined trips or large towing invoices. None of this is necessary. See the following watchpoint for a quick temporary fix.
 
WATCHPOINT: These switches simply interrupt the current from the battery to the starter. Therefore, the only thing necessary to re-complete the power route is to secure the two cables going to the two switch posts to the same post (it doesn't matter which one.) This will bypass the faulty switch. As a precaution, remove the red (+) cable at the battery while you work.

These switches are not especially high quality (rated to 60 amps) but do have a decent track record in sailboat applications for which they were originally made ( in the UK) Ergo the plastic construction. Their primary advantage is that they are very cheap..costing as little as 2.99£ on ebay.co.uk. At that price, Morgan dealers will understandably not try to convince a mogger that something better is a wise decision. However, what is the cost and hassle of a roadside breakdown worth? The switches come with a big plastic red key which is a doubtful security measure as they are all identical.  

The switch is fit through the rear (wooden) bulkhead behind and between the seats. There is a wooden spacer, to either give it greater support or to account for the extended neck version that have chosen (this switch type comes in a number of neck lengths). Ideally the battery cables running to and from it should both also be secured solidly nearby, but this is often not the case. As for the battery switches.. given the reported failure rate I am inclined to ask just what is causing the failures. (Has anyone taken a failed switch apart to trace the cause of the failure? If so please contact us. . When you ponder a bit, it is foolish to simply just fit a replacement. of course, the cable run to/from these switches should be consideration in that the cable weight is considerable and as such should be supported by some means other than just by the terminal screws at the switch, if it ain`t, then failure at the terminals and their mounting into the switch seems a possible source of failure..  It might be reasonable to point out that such switches carry the full load of the battery that a starter motor is a dead short when the key is first turned. So those switches may be exposed to shock loading of over one thousand amps for a period of time, and a car that is ever hard to start will put rather a lot of strain on such switches over TIME. Yup a higher rated switch is an improvement though has to be also designed for the purpose in that it can withstand the necessary starter motor loadings which far exceed 180 amps.
 
 
My (Lorne) solution was to fit a solid metal switch rated to 180 amps. I also secured  both cables next to the switch, minimizing the cable movement effect on the switch posts. I also ran a wire directly from the "input" post to the fuses to the clock, radio etc that I do not want to lose power. 

BATTERY NUMBERS, AND DIMENSIONS
Find the code number of the battery you need and google a local source
and supplier using the terms "car battery and the code" you found.)
WATCHPOINT
BCI NUMBER Maximum Overall Dimensions
WATCHPOINT
Millimeters  Inches
PASSENGER CAR AND LIGHT COMMERCIAL_BATTERIES 12-VOLT (6 CELLS)
21  208  173  222  8 3/16  6 13/16  8 3/4 
22F  241  175  211  9 1/2  6 7/8  8 5/16 
22HF  241  175  229  9 1/2  6 7/8 
22NF  240  140  227  9 7/16  5 1/2  8 15/16 
22R  229  175  211  6 7/8  8 5/16 
24  260  173  225  10 1/4  6 13/16  8 7/8 
24F  273  173  229  10 3/4  6 13/16 
24H  260  173  238  10 1/4  6 13/16  9 3/8 
24R  260  173  229  10 1/4  6 13/16 
24T  260  173  248  10 1/4  6 13/16  9 3/4 
25  230  175  225  9 1/16  6 7/8  8 7/8 
26  208  173  197  8 3/16  6 13/16  7 3/4 
26R  208  173  197  8 3/16  6 13/16  7 3/4 
27  306  173  225  12 1/16  6 13/16  8 7/8 
27F  318  173  227  12 1/2  6 13/16  8 15/16 
27H  298  173  235  11 3/4  6 13/16  9 1/4 
29NF  330  140  227  13  5 1/2  8 15/16 
33  338  173  238  13 5/16  6 13/16  9 3/8 
34  260  173  200  10 1/4  6 13/16  7 7/8 
34R  260  173  200  10 1/4  6 13/16  7 7/8 
35  230  175  225  9 1/16  6 7/8  8 7/8 
36R  263  183  206  10 3/8  7 1/4  8 1/8 
40R  277  175  175  10 15/16 6 7/8  6 7/8 
41  293  175  175  11 3/16  6 7/8  6 7/8 
42  243  173  173  9 5/16  6 13/16  6 13/16
43  334  175  205  13 1/8  6 7/8  8 1/16 
45  240  140  227  9 7/16  5 1/2  8 15/16 
46  273  173  229  10 3/4  6 13/16 
47  246  175  190  9 11/16  6 7/8  7 1/2 
48  306  175  192  12 1/16  6 7/8  7 9/16 
49  381  175  192  15  6 7/8  7 3/16 
50  343  127  254  13 1/2  10 
51  238  129  223  9 3/8  5 1/16  8 13/16 
51R  238  129  223  9 3/8  5 1/16  8 13/16 
52  186  147  210  7 5/16  5 13/16  8 1/4 
53  330  119  210  13  4 11/16  8 1/4 
54  186  154  212  7 5/16  6 1/16  8 3/8 
55  218  154  212  8 5/8  6 1/16  8 3/8 
56  254  154  212  10  6 1/16  8 3/8 
57  205  183  177  8 1/16  7 3/16  6 15/16 
58  255  183  177  10 1/16  7 3/16  6 15/16 
58R  255  183  177  10 1/16  7 3/16  6 15/16 
59  255  193  196  10 1/16  7 5/8  7 3/4 
60  332  160  225  13 1/16  6 5/16  8 7/8 
61  192  162  225  7 9/16  6 3/8  8 7/8 
62  225  162  225  8 7/8  6 3/8  8 7/8 
63  258  162  225  10 3/16  6 3/8  8 7/8 
64  296  162  225  11 11/16 6 3/8  8 7/8
65  306  190  192  12 1/16  7 1/2  7 9/16 
70  208  179  196  8 3/16  7 1/16  7 11/16 
71  208  179  216  8 3/16  7 1/16  8 1/2 
72  230  179  210  9 1/16  7 1/16  8 1/4 
73  230  179  216  9 1/16  7 1/16  8 1/2 
74  260  184  222  10 1/4  7 1/4  8 3/4 
75  230  179  196  9 1/16  7 1/16  7 11/16 
76  334  179  216  13 1/8  7 1/16  8 1/2 
78  260  179  196  10 1/4  7 1/16  7 11/16 
85  230  173  203  9 1/16  6 13/16 
86  230  173  203  9 1/16  6 13/16 
90  246  175  175  9 11/16  6 7/8  6 7/8 
91  280  175  175  11  6 7/8  6 7/8 
92  317  175  175  12 1/2  6 7/8  6 7/8 
93  354  175  175  15  6 7/8  6 7/8 
95R  394  175  190  15 9/16  6 7/8  7 1/2 
96R  242  173  175  9 9/16  6 13/16  6 7/8 
97R  252  175  190  9 15/16  6 7/8  7 1/2 
98R  283  175  190  11 3/16  6 7/8  7 1/2 
PASSENGER CAR AND LIGHT COMMERCIAL BATTERIES 6-VOLT(3 CELLS) 
232  181  238  9 1/8  7 1/8  9 3/8 
264  181  238  10 3/8  7 1/8  9 3/8 
2E  492  105  232  19 7/16  4 1/8  9 1/8 
2N  254  141  227  10  5 9/16  8 15/16 
17HF  187  175  229  7 3/8  6 7/8 
4D  527  222  250  20 3/4  8 3/4  9 7/8 

Data taken from the BCI Battery Replacement Data Book.
[ errors may have been introduced in transcription. ]

Note 1: The complete BCI listing includes several categories not included here: Heavy-Duty motor Coach and Bus batteries, and Special Tractor Batteries (6 and 12-volt). BCI provides configuration diagrams and performance ratings as well. Contact BCI, 401 N. Michigan ave, Chicago IL 60611-4267, (312) 644-6610 for more information.

Note 2: The maximum height includes the terminal posts. Width and length measurements are generally to the widest point, including protruding flanges, except for hold-down flanges at the bottom of the battery. See the diagrams in the BCI battery Replacement Data Book for full details.