Battery isolation

[Mav96]

As my Mav does not get used often during winter months and then only short runs my battery can't handle it, so I fitted one of these:


Now these work really well but you have to pop the bonnet every time you park up, even worse when you want to go out again as you have to unlock the drivers door with key reach across to passenger footwell for bonnet release to re-enable isolator. So my question would one of the following be better mounted in a suitable position accessible without popping bonnet.

https://goo.gl/gqSppC


Or
https://goo.gl/4XB5dj


Would I still Isolate the Earth or isolate the Positive :nenau

Ps: I have 2 batteries both good 1 on permanent charge & rotate & have checked for parasitic drain. Thanks in advance for all your knowledge. :thumb2

 

[panelbeater]

the red switch is ideal but you need to run the long high power cabel,live,to inside cab.better still is the same but key comes out so no key no live.earth stayes same.

 

[Mav96]

the red switch is ideal but you need to run the long high power cabel,live,to inside cab.better still is the same but key comes out so no key no live.earth stayes same.

Having it inside is no good when it is time to lock up so has to be external.
Can't i use it on the earth like the original isolator ?

 

[Lazy-Ferret]

I have been thinking about this for my car. Personally, I was thinking of putting it in the Grill, so after I have locked the car, using the Central locking, I can then turn it off.

I was giving the Positive, V Negative wire a bit of thought, as you are always supposed to disconnect the negative first, but that is mainly so you don't short the positive terminal to the body when undoing that. Other than that, it should make no difference which wire you put it in, as long as you keep the wire as large, and short as possible, so for neatness, the Earth looks the best option.

I do like the look of the Durite one, it's not so in your face, and likely to attract attention, should you park up in Tesco's, and some little Oik was to spot it!

 

[Fez_uk]

What about a large relay with the switch inside?

 

[Mav96]

What about a large relay with the switch inside?

I had thoughts on this as well, specifically a remote controlled relay, what amp rating should this be ?

 

[Mav96]

I have been thinking about this for my car. Personally, I was thinking of putting it in the Grill, so after I have locked the car, using the Central locking, I can then turn it off.

I was giving the Positive, V Negative wire a bit of thought, as you are always supposed to disconnect the negative first, but that is mainly so you don't short the positive terminal to the body when undoing that. Other than that, it should make no difference which wire you put it in, as long as you keep the wire as large, and short as possible, so for neatness, the Earth looks the best option.

I do like the look of the Durite one, it's not so in your face, and likely to attract attention, should you park up in Tesco's, and some little Oik was to spot it!

The red one is higher amp rated. The Durite is a lucas clone, I only showed the durite for picture clarity.

Position wise I was thinking offside wheel arch, loads of room to front & up, then at "tesco" you could pretend to inspect your tyre when switching :lol

 

[rayf3262]

what amp rating should this be ?

Some time ago I purchased a fancy hall effect DC clamp meter and out of interest measured the cranking current with it.
It was just shy of 400 AMPS, and that was not in cold weather with thick oil.

Now, any switch or relay does not have to be rated to switch that current, but must be able to safely carry it.

 

[Mav96]

Some time ago I purchased a fancy hall effect DC clamp meter and out of interest measured the cranking current with it.
It was just shy of 400 AMPS, and that was not in cold weather with thick oil.

Now, any switch or relay does not have to be rated to switch that current, but must be able to safely carry it.

Even on the Earth side? forgive my ignorance when it comes to electrics.

 

[zippy656]

Cut power with red key switch radio will lose code, not sure nats can cope with time without 12v for lone either .

I have seen one with a fused bypass, so nats locking and radio keep the 12v but fuse blows if started

 

[Mav96]

Cut power with red key switch radio will lose code, not sure nats can cope with time without 12v for lone either .

I have seen one with a fused bypass, so nats locking and radio keep the 12v but fuse blows if started

I have a Maverick so no Nats, I lose radio settings anyway with the battery isolator clamp, but was going to run a seperate earth for radio & roof clock ?

 

[Lazy-Ferret]

I have a Maverick so no Nats, I lose radio settings anyway with the battery isolator clamp, but was going to run a seperate earth for radio & roof clock ?

You can't really run a separate earth for the radio, as most earth via the chassis, and that earth will then effectively try and become the main earth, which could result in lots of smoke..

 

[Mav96]

You can't really run a separate earth for the radio, as most earth via the chassis, and that earth will then effectively try and become the main earth, which could result in lots of smoke..

Direct earth from battery would work fine just for radio & clock, some clamps even come with a fused bypass just for this purpose.

 

[zippy656]

I have a Maverick so no Nats, I lose radio settings anyway with the battery isolator clamp, but was going to run a seperate earth for radio & roof clock ?

Use on positive post, and fit bypass fuse

 

[jims-terrano]

Zippy is right. I’ve seen a lot of people with classic cars that isolate main positive but run a small length of cable with a very small fuse. Will give enough power to save memories and clocks but not much else. Only problem is that it won’t stop a small parasitic drain.
The switch idea is good but having it too accessible could ask for problems but also the switch may be open to water and crap being thrown up at it.

 

[terranosaurusdoug]

Throw the batt and fit a starting handle, alternator will take care of the rest :thumb2

 

[zippy656]

Zippy is right. I’ve seen a lot of people with classic cars that isolate main positive but run a small length of cable with a very small fuse. Will give enough power to save memories and clocks but not much else. Only problem is that it won’t stop a small parasitic drain.
The switch idea is good but having it too accessible could ask for problems but also the switch may be open to water and crap being thrown up at it.

Find the drain,

 

[rustic]

Find the drain,

That was my first thought.
A faulty diode in the alternator can drain up to 4 amps.
Try disconnecting the alternator and measure the overall drain, and "go compare".:doh
Rustic