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Post Info TOPIC: Battery Disconnect


COURTICE, ONT

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Battery Disconnect
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I'm trying to learn something - I see lots of differing opinions when I read about the topic. I'm sure many here will also have different opinions as well - hopefully we can all discuss without any arguments. lol 

Battery disconnects and if the switch should be on the ground side or opposide ground side (I'm not using positive negative because I have one vehicle that's positive ground and one that's negative ground).

It seems like when people on other forums are debating the topic they are arguing from two different standpoints but no one calls it out.

1) Racing - I believe race cars require the disconnect to be on the 'opposite ground' side to quickly kill power in the event something goes wrong while operating the car?

2) Storage - I believe most put it on the ground side to just disconnect the battery when not in use - so they don't have to unbolt the posts, added safety for rodents, theft, etc. Intended to be used when the vehicle is not in use.

 

What do you guys think?

Ground side or Opposite Ground side for a disconnect, does it matter what your using it for?

(obviously racing it matters because there's track rules)



-- Edited by Nickeleye on Wednesday 26th of July 2017 09:27:30 AM

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GTA

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Once a car is running you can disconnect either cable and, as long as the charging system is working the car will not shut off (this has been my experience with "regular older carbureted cars" I have no idea whether this works for electronically fuel injected cars). I have been told that doing this can cause a spike and fry the alternator but I've never had that happen.

So, just wiring in an emergency shut-off switch won't necessarily stop the engine from continuing to run. I realize this was not part of your question, I am just adding some information just in case you intend to use the switch as an emergency shut-off rather than just a battery-disconnect.


I ran a really cool (in my eyes at least) master shut-off switch that used a latching relay in the battery cable line and a momentary switch that "flipped" (my word) the relay from on to off or from off to on. It worked GREAT ... the relay was out of site/had no easy access and the tiny switch was very well hidden in the car interior. Not only was it a great anti-theft device, I got in the habit of disconnecting the battery every time I used the car so even if there was any type of drain or electrical malfunction, my car would not be affected by it. Park the car, tap the switch and the battery is disconnected. Hop back in the car, tap the same switch again and the battery is reconnected. It wasn't a cheap little kit but l think you can purchase a latching solenoid from an RV supply place and make up your own.

Now, to answer your actual question, I can not remember which cable I put the relay in but, once I remember the name of the manufacturer I should be able to look up the instructions and get back to you with an answer. Off the top of my head, I think it was in the non-negative side but I need to verify that.

I know of two people who installed a big race-type battery disconnect switch behind their fold-down licence plates. Problem with that is (as I see it) anyone can see you when you use it hence the reason I was so happy with my latching solenoid set-up ... did the exact same job but totally discreetly.

I also know of someone who had an older boat on their driveway ... battery was left connected, their was an electrical issue of some type, the boat caught fire and the garage (attached to the house) caught too. Lost two cars ...

I'll post again once I locate the product I used ... beware though, I may lose control and copy/paste the results of my find wink



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COURTICE, ONT

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Great info! Thank you

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PRINCE EDWARD COUNTY, ONT

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On the Bantam race car, I put a battery disconnect switch on both positive and negative seems not even the racing organizations can agree on which side they want it. If you want to kill the engine while it is running, you put a kill switch in the ignition line to the coil.  On the battery pack in my motor home, the disconnect switch has a removable key.  This post was neither copied nor pasted.

Warren

 

DSC04431.JPG

DSC04432.JPGDSC04433.JPGDSC04434.JPGDSC04435.JPG



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COURTICE, ONT

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Lol Thanks

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GTA

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Ok, I just did a quick search and was not able to easily locate the company I bought from (thought it might have been something like Hotronics but that search brings up a boot warming product (at least that's what I think they were trying to sell).

Regardless, I was able to locate a similar (basically identical if not exactly the same thing) product from Watson's StreetWorks. Below is a link to their page.

www.watsons-streetworks.com/toggle-battery-disconnect

From the page linked above, I was able to get to their installation instructions and they show their solenoid being installed in the non-negative battery cable (which is how I thought I remembered my switch being installed).

As mentioned earlier, there really is nothing to these kits, couple of wires, a momentary switch of some sort (Canadian Tire), a wire and inline fuse (Canadian Tire) that powers the solenoid, and the latching solenoid itself and I believe the latching solenoid is commonly available at RV parts houses as I think they are used to switch between two batteries or possibly get one off eBay for a lot cheaper than it would take to buy and ship the kit. I think the Watson's website also lists the specs on their solenoid.

I loved mine (it stayed with the car when I sold it) and wouldn't hesitate to install one again.  I should add, I have been calling the same thing either a relay or a solenoid ... I think solenoid is correct but I could be wrong.  Below is a pic of whatever it's real name is biggrin


hotronics.jpg





-- Edited by Pete Moss on Wednesday 26th of July 2017 05:29:14 PM

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COURTICE, ONT

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hmm - that's cool...

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ADMINISTRATOR

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That solenoid in the above picture and available at RV centres is a Constant Load solenoid......A starting solenoid, like on Ford cars will work but wont last. They are built for short bursts of power, not to be on constantly like in an RV

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WATFORD, ONT

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Ok, here's my take on it. I would install the kill switch on the non ground side as close to the battery as reasonable. The reason is...if you install on the ground side, the rest of the system is still hot right to the key switch. Brake light circuit is still hot to the brake switch, same with the interior lights. (As well as many other circuits) In fact a lot of interior lights have power up the line to the bulb, through the bulb and back down to the door grounding switch. Have the circuit ground after the bulb, and the bulb lights up. Have the circuit ground before the the bulb, and you have a short that should cause the fuse to blow. Have the short before the fuse and you let out the magic smoke and may have a fire. Having a mouse/rat chew, hot pipe burn, or wear/rub through the insulation anywhere the system is hot, and your problems are just starting. To eliminate all of this, put your kill switch on the hot side (non grounded) and the whole system is cold from that point on. (That is why you install as close to the battery as possible) No matter what damage is done to the wiring, there is no power to short out. With a simple race car system, this works. However, a computer car might be damaged by the constant spikes this could create. The computer normally see's a constant voltage 24/7 in today's vehicles. There's no right or wrong way to do this, it all depends on the system your trying to control. There is no "one fit's all" answer.

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GTA

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As others have mentioned, if you do attempt to piece a kit together similar to the one I described (pictured above), the solenoid is a very specific "latching" solenoid that is nothing like a regular Ford starter solenoid, even though they may look similar. The Ford style is just supposed to have power going through it for a short amount of time while you are cranking your engine whereas that "latching" solenoid is designed for continuous OFF or continuous ON.

I believe RV's use them for their ability to swap power usage from battery to battery in a multi-battery configuration.

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GTA

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Ok, stumbled across the installation instructions for the kit I used. The company was Wire1HotRod.com ... I say "was" because they do not appear to still be in business.

Their instructions (for the remote battery disconnect switch) state: "Install your battery disconnect solenoid between the battery and the starter solenoid, in a dry weather proof location (can be hidden for anti-theft reasons)".

So, between the battery and the starter solenoid would mean the + battery cable.

Just figured I would post this for the hell of it seeing as this topic was started quite a while ago and I just found this sheet while going through the crap in my garage.

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Member

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First a question what is the first wire you remove when working under the dash or removing a starter motor? so that there isn't a short circuit from the slip of a wrench or screwdriver touching a hot wire to ground,  notice that I have not said positive or negative,  reason being that many English cars have a positive ground and north American cars are negative ground,  therefore I personally would switch ALL wires that leave the batteries ground post.   There was a comment about run-on after removing the ground while the car was still running, the problem is as stated, the only TRULY ISOLATED WIRE is the short wire from the ground of the frame to the battery terminal , be it positive or negative.  the HOT WIRE be it negative or positive can always find a return path even if it is through a low resistive device developing a hot spot AND A POSSIBLE FIRE.  With the battery connected and car in storage there is always the possibility of a car fires when not in use, caused by mice nesting for the winter.     Soooo a disconnected battery is always best for storage.    Drive safe.



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1928 Ford AR body found in an out house in the middle of a cow pasture, every thing else was bought at swap meets, frame, body, wiring, paint, upholstery, done by yours truly, 2000hrs labour, 283 ci. powerglide, corvair front end, MG rack and pinion,ATL FIA fuel cell, no body modifications.

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