On off car battery switch - cable length?

[Dubman]

Hi, My car is Mitsubishi Colt 1.3 (1998), and I'd like to install a battery on / off switch in the interior of the car. My question is: would it be ok to use around 1.5 meter length of normal battery cable? The idea is to connect it to the battery negative terminal and to the existing negative battery wire, extending it to the switch in the car interior, and the reason for the installaton is because I regularly park in an open or semi-open air location where the temperature can fall to -10 C or even lower, and I prefer that there is no drip charging especiallyp for car clock. And I'm worried about start up problems due to the cold. Would these items be suitable?
https://www.amazon.co.uk/WINOMO-Bat...tch+winomo&dpPl=1&dpID=31l5pQqBO+L&ref=plSrch
And cable:

https://www.amazon.co.uk/eXODA-Batt...G27RVQ808YX&psc=1&refRID=GKJVYTP68G27RVQ808YX
Thanks

 

[KEV 1 N]

Would a suitable relay not be a better way of doing this? then you would only need a small switch and wiring to the interior of car to isolate the negative side of battery.

 

[Dubman]

How would that installation be done? Actually, I already have the switch mentioned at the end of my post.Thanks

 

[KEV 1 N]

Actually just had a thought, if you were to use a relay, it would need a constant feed to keep it “closed” so the negative is connected. Should this feed or the relay fail during driving, it will be the same as the battery been suddenly disconnected and may be dangerous.
Might be best to stick to your idea of the heavy duty switch, is there any way to put the switch close to the battery? Just to minimise the length of the cable going from battery to swich then back again.

 

[Dubman]

Ok, I haven't calculated exactly, but maybe 1m of extra cable might do it. And even a bit shorter may be possible if I cut the negative battery cable as it passes around the engine, but I thought it would be better / cleaner to make the connection at the negative battery terminal. Could the extra 1 meter of extra cable cause some kind of damage? Thanks

 

[littlespark]

Disconnect any items that use power when not running like the clock.

I think the cold will deteriorate the battery if it’s connected or not.

 

[Dubman]

I don't see any way to disconnect the clock, except by disconnecting the battery. The only other 24/7 power draw I'm aware of is a little red light (where radio goes) . that goes on and off. Thanks

 

[littlespark]

Central locking needs power I guess.

Maybe some kind of battery connection that can clip on and off easily?

Vice grips anyone?

 

[Dubman]

Yes, central locking requires battery. I think a new battery may offer more resistance to cold weather? I'd be reluctant to fit an on /off switch directly on the negative battery terminal in case it would leave some parts of the terminal exposed to accidental touching by the hand.

 

[rsgaz]

Any space to fit a larger Amp-Hour battery with a higher CCA rating? (It's physical size will be bigger)

Disconnecting it doesn't sound a great idea. You'll be typing in the code for the radio and manually tuning stations every time!

Also, on a more serious note, you'll reset the engine's ECU and it will revert to it's default settings and it will have to begin 'learning' from scratch. That might make starting it even harder.

 

[Dubman]

Sorry, I don't remember the CCA on the present battery, but I think it's more than 60 aH, but I don't think a bigger battery would fit in the cradle in any case.

 

[KEV 1 N]

Also, on a more serious note, you'll reset the engine's ECU and it will revert to it's default settings and it will have to begin 'learning' from scratch. That might make starting it even harder.

Yes that’s right, I had a 92 Mini Cooper 1.3 SPI (single point injection) the first one to have fuel injection as opposed to a carb. Every time the battery was disconnected and reconnected the engine would “behave” differently for a while till the ECU got used to things

Dubman, you might have rethink your plans, what about a “smart” trickle charger? They are safe to use whilst battery is connected to car and won’t harm electronics and monitor the battery condition and keep it charged. I used one with my mini and had no bother with it or the battery.

 

[Dubman]

In the case of my Mitsubishi Colt 1.3 (1998), I haven't noticed any difference in the engine due to disconnecting / reconnecting the battery. For example, disconnecting it while doing a recent job.

 

[Strima]

Cold will kill a battery wether it is connected or not.

 

[Deleted member 26818]

When I was a recovery truck driver a few years back.
I tried explaining to a BMW owner about the car forgetting how to run because the battery was flat.
Told him the car would need a full service before it would start, and no his AA membership would not cover a full service at the side of the road.
He was not a happy bunny.

 

[dmxtothemax]

The amount of power used by a cars clock is so small it is not even worth thinking about, consider this a watch can run off a tiny little battery for over a year. now how much bigger is your car battery ? They must have better ways of protecting batteries from the cold.

 

[Dubman]

I know we're talking about very very little drain on the battery. Just thought that if the car is parked in the same spot for 4 days at a time, then disconnecting the battery might make a difference. To be more precise, this parking spot is in a free public parking with around 200 other cars, and many of the parking slots are under a roof, although semi-open air, while other parking spaces are not under a roof.
I do have the battery in a lightly padded battery jacket, and even thought of adding a second jacket on top of that since it's kind of flexible material and should fit.
Other than that, do you think a new battery would be better at resisting sub-zero temperatures?
On the question of a smart trickle charger, I wouldn't be able to plug it in anywhere in the public car parking facilities. Thanks

 

[telectrix]

just buy a thermal blanket. put over engine and battery. remember to remove before starting.

 

[Squid]

I have one of these fitted to my E30, https://www.amazon.co.uk/Richbrook-1000-01-Discarnect-Immobiliser-Battery/dp/B0019ULCPW

 

[Lucien Nunes]

Anything connected in series with battery leads will degrade starting performance at least very slightly, by adding resistance to a circuit that has to carry hundreds of amps with very little voltage drop. Low-cost battery isolators do work, but can be prone to excessive resistance. If you do want an isolator, make sure it is a good one, use nice heavy cable and make the connections properly (e.g. proper crimp lugs crimped with the right tool). High resistance can also decrease charging performance (where the maximum permissible drop is in the order of 0.1V). Also note that some electrical systems can be damaged if the battery is accidentally isolated while the engine is running.

An ordinary relay is not the way to go. Because of the heavy starting currents it must carry, a contactor or relay large enough for the job uses too much power for its coil for it to sensibly remain energised all the time. Accidentally failing to isolate when you leave the car would result in returning to a flat battery.

There are electrically-operated remote latching isolators. These are used in commercial vehicles and are ideal for the job but they are expensive and overkill for your car. They only consume power while changing state from on to off and back again, not continuously, and they can be interlocked so that they will not switch off while the engine is running. see
https://cdn.shopify.com/s/files/1/0658/7343/files/ELBs.pdf?817

The best way to maximise starting and charging performance is to fit the largest, best battery that will fit the space, with an intelligent alternator controller if one is not already fitted. A larger battery scores in two ways - first, there is more capacity to serve low level background loads, which would otherwise be saved by the isolator. But when you come to start the engine, the battery has lower resistance and can deliver the starter current with less voltage drop, so even if the same percentage of discharge has occurred, the starter will get more volts for longer before the battery starts flagging. A 25% increase in capacity can make a very noticeable improvement in starting performance.