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MG Midget and Sprite Technical - battery cut off

Hello,
I've seen on ebay a battery cut off with a 15 amp fuse to let electricity goes to a clock for example.
http://cgi.ebay.co.uk/MG-midget-Battery-Isolator-Switch-Cut-off-BY-PASS-FUSE_W0QQitemZ360034353904QQihZ023QQcategoryZ27380QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

I still have a battery cut off going from positive (my car is converted negative ground)with a big cable.
The cut off is screewed on the top of the foot panel (engine bay). And at the opposite, at the interior side of the foot panel there is a lock with a key.
I use it to prevent the robbery.

I still have a smith clock, but it never gives the right time, cause of the cut off.

I ask myself if it will be possible to put the ebay cut off on the positive battery post, and connect this first cut off to the second.
So I let the first always open, and just act on the second with the key. So the car will be still protected against the robbery, and the 15 amp fuse will give electricity to the clock.

But, is it safe enough to have so many connection direct from the positive battery post? And the description says it has to be put on the negative battery post (or ground post, the cable going to the battey is black)

thanks
laurent
laurent

I would think it best to stay as you are, just run a fused supply to the clock from the battery
Mick - nearly ready to paint

I put my clock and radio memory wire on a toggle switch, I I do have the same battry cut off switch, I use to disconnect the power when Im not going to be driving the car for a week or longer.

prop
Prop

just a 15 amp fuse between the clock and the positive or the negative battery post?
laurent

Yes Laurent, Just a fuse is fine - -that way the ignition and starter is isolated with the battery cut off switch, but the clock is still supplied!
Mick - nearly ready to paint

for the yarn: 6 mm2 (used for my ampmeter), 2.5 mm2 or thinner?
laurent

Same size as is currently supplying the clock!!!!
Mick - nearly ready to paint

You are better off running an in-line fuse (say 7.5amp) from the non-isolated side of your existing isolator straight to your clock and memory wire of your radio if you have one. As Prop says, a series switch in this line is also useful if you leave the car for long periods.
Dave

Actually it is the c/d radio memory that drains my battery when left for an extended time, so bypassing the isolator with a feed for that would be nonsense. I think running a small wire bypass to the clock would not cause too many problems. I would use a 1 amp fuse maximum for the clock and a wire (yarn as you call it L.) of no more than .2mm2
Bob (robert) Midget Turbo

I guess this depends on what you want the isolator to do. If it is to remove power drain completely then an isolator alone should work fine. If it is to deter theft but you want to keep your radio settings intact and you have a clock then you can use a bypass or direct feed with a suitable fuse.

However note that the isolator linked to above on ebay is not a particularly good theft deterrent as this is very easily bypassed unless you can lock the bonnet. Also, in the configuration shown if you forget to re-connect it you will pop the fuse as soon as you try to start the engine. They key type isolators are also easy to bypass but you stand a better chance of putting in a less obvious place.

HTH
Pete

What Bob says WRT the 1 amp fuse, however be careful with the radio feed, I have seen both radios which take big current down the battery wire (30amp) and sense from the ignition (3Amp) as well as radios which take big current (30amp) down the ignition wire and use the battery wire for settings (3Amp).

You should work out which you have and use wire and fuses appropratly.

That said, sticking in wiring that can handle 30 amps and a 30 amp fuse will not change the amount of current you consume, just the size of the spark you get when things go wrong before the fuse blows.
Will Munns

thanks a lot.
I will try with a direct fuse between battery and clock.
laurent

This thread was discussed between 26/03/2008 and 01/04/2008

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