Battery Disconnect Switch

[Studebaker]

NOTE: This topic was split off from the discussion we had in the "What did you do with your Reatta today?" thread about battery disconnect switches.  I think this discussing about battery disconnect switches needs it's own thread so it is easier to find.

-Ronnie

---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

I did some small tinkering on my 89 Reatta:  I load tested the 1 year old battery, and sure enough, it was in the "Bad" range, even after getting a full charge.  So I pulled her out, and there was a small bit of surface rust on parts of the battery tray......so, got that sanded/primed/painted the other day:

 

Before:

 

After:

 

I also ordered a battery disconnect switch for this side-mounted cable configuration, which I never have liked.  These side mount switches do not come with a mounting screw that is long enough to go through the thick switch and then into the battery screw threads.  Did not have any laying around, so I had to use the grinder to grind material off the switch surface, and also had to use a blade to trim down the plastic that surrounds the negative terminal on the battery.  Alot more extra work than I expected, but finally "got er done", using an extra old battery that was laying around:

 

Anyone else have these same issues when installing a battery disconnect switch on these side-mount batteries?

Started her up and took her on a 10 minute drive (maskless, ha ha), and the engine seemed to start up, idle, and run fine even with the battery being disconnected for a couple weeks......so, not any noticeable impact on the computer settings.

 

 

 

[Ronnie]

Your battery tray turned out looking great. I like the idea of the cut off switch but after seeing it installed it is bigger than I expected. Only problem I see with a cut off switch is having to rest the radio every time but that's not a big deal.  I might try one of the knife switch designs like this from Amazon. Do you think it might fit better?

 

[2seater]

I don't have a good suggestion to the battery disconnect switch but frankly, I don't like either of those. Perhaps more accurately, I don't care for the way they mount where the weight and possibly vibration are in the direction to loosen that battery connection bolt which is none too robust to start with. Is there as remote disconnect available where it can be solidly mounted and a short jumper from the battery to the switch? just spitballin'

 

Edit  I saw the knife switch on amazon and another view shows the black plastic structure is designed to be bolted to something so that switch could be remote.

Edited April 12, 2020 by 2seater

[Ronnie]

Good point on the weight of the cable trying to pull down on the knife switch and trying to loosen the bolt. I wonder if the hole in the black plastic could be used to make a bracket to hook over the top of the battery to support the weight? Maybe a bolt bent into an L shape with a nut on the bottom of the plastic piece? A remote mount would be another option. There are tons of remote mount cut off switches  but I was looking for simplicity of installation and the knife seemed to be the best bet for something that would be plug and play.

[2seater]

1 hour ago, Ronnie said:

Good point on the weight of the cable trying to pull down on the knife switch and trying to loosen the bolt. I wonder if the hole in the black plastic could be used to make a bracket to hook over the top of the battery to support the weight? Maybe a bolt bent into an L shape with a nut on the bottom of the plastic piece? A remote mount would be another option. There are tons of remote mount cut off switches  but I was looking for simplicity of installation and the knife seemed to be the best bet for something that would be plug and play.

I am with you on simple and good value. I edited my post earlier after I saw the hole in the plastic bar. No doubt there are many creative ways to support, even a wire tie. Maybe even if hung vertically, but I know the factory ground cable has a mind of its own? 

[Ronnie]

6 minutes ago, 2seater said:

I am with you on simple and good value. I edited my post earlier after I saw the hole in the plastic bar. No doubt there are many creative ways to support, even a wire tie. Maybe even if hung vertically, but I know the factory ground cable has a mind of its own? 

I have one of the knife switches in my Amazon cart.  I will place an order when I come up with more things to order at the same time so I get free shipping.  Will post photos when I get it installed and let you know how well it works.

[Studebaker]

Ronnie......Yep, I actually would have preferred the knife blade switch......you can clearly see when the connection is On or Off, whereas with the dial/screw on type I installed, you are not always totally sure when the power flow is interrupted as you unscrew it.  Also, there have been times on another vehicle when I "thought" the power flow was disconnected, but there was still some amperage drain through the dial-type disconnect.  I like the 2seater's idea of the remote mount, which could be bolted down and super stable.  Even better would be a remote disconnect located someplace in the cockpit, so you could operate it w/o raising the hood......that would be sweet.

[Ronnie]

1 hour ago, Studebaker said:

Even better would be a remote disconnect located someplace in the cockpit, so you could operate it w/o raising the hood......that would be sweet.

They have them on Amazon. They appear to be complicated and they are expensive compared to the manual cut off switches. I didn't look at them too close because of price. I'm not sure if they are a true battery cut off or if they just cut off power to keep the engine from starting.

[2seater]

1 hour ago, Ronnie said:

They have them on Amazon. They appear to be complicated and they are expensive compared to the manual cut off switches. I didn't look at them too close because of price. I'm not sure if they are a true battery cut off or if they just cut off power to keep the engine from starting.

The remote battery switches I have seen on race cars are generally manually operated, via a solid rod or a turn switch mounted to a bulkhead to kill all battery power as a fire preventative. I guess I am in the camp where simple is good ?

[Ronnie]

Here is the one I stumbled across but I'm not sure how it is intended to be used. It has a hand held key fob to operate it.

[2seater]

11 hours ago, Ronnie said:

Here is the one I stumbled across but I'm not sure how it is intended to be used. It has a hand held key fob to operate it.

The translation needs a little polishing, but it looks like it is designed to help those that have a battery in a hard to reach location. I saw the reference to marine too, but the amperage rating seems pretty light for anything more than a gasoline automotive engine. I know that several modern vehicles have the battery in non-underhood locations too, like under the rear seat, so I can see a use for such. On the whole, I wouldn't want to be dependent on another electrically operated device for this purpose. 

[Studebaker]

Yep.....lots of options out there for the disconnect switch, but I guess I will stick with this el cheapo method ( $5 )......at least I can  raise the hood and kill all systems w/o removing the battery terminal wire. 

[Ronnie]

On 4/12/2020 at 2:00 PM, Ronnie said:

I have one of the knife switches in my Amazon cart.  I will place an order when I come up with more things to order at the same time so I get free shipping.  Will post photos when I get it installed and let you know how well it works.

 

On 4/12/2020 at 11:24 AM, 2seater said:

I don't have a good suggestion to the battery disconnect switch but frankly, I don't like either of those. Perhaps more accurately, I don't care for the way they mount where the weight and possibly vibration are in the direction to loosen that battery connection bolt which is none too robust to start with. Is there as remote disconnect available where it can be solidly mounted and a short jumper from the battery to the switch? just spitballin'

 

Edit  I saw the knife switch on amazon and another view shows the black plastic structure is designed to be bolted to something so that switch could be remote.

I finally put in an order with Amazon and I got the battery cutoff knife switch yesterday. I installed it today. Installation was simple. The concern 2seater and I had about the weight of the  switch and cable loosening up the bolt turned out to not be a problem... at least on my car no bracket to hold the weight was needed.   The ground cable on my car is very stiff and pushes up on the switch in the direction that tightens the bolts instead of pulling down on it. It actually took a little force pushing down on the cable to get the switch mounted level. 

 

This seems a simple-work around for the battery draining when the car sits for long periods but it does have it's drawbacks. Each time you cut it off you loose your radio and clock settings. After it has been cut off I'm pretty sure the ECM has to go through the relearn process before the engine runs it's best again. I've not driven the car since I installed the switch. Only time will tell if it was a good decision to install a cut off switch.

 

Below are some photos of what comes in the box and how it looks installed on my car. I used the long bolt shown on the right. The other bolt shown screwed into the switch wasn't used.

 

[2seater]

The stiff cable doing double duty looks fine ?

 

I have heard that a nine volt battery fed into a lighter socket that is always hot is enough to save memory and settings. I have never tried it but sounds logical. 

[Ronnie]

I think the 9 volt battery would keep the settings long enough to swap out a battery or something but I don't see how it could be a long term solution.  I think a Reatta would gobble that little feller up pretty quick. ?

[Studebaker]

Ronnie.....that knife switch looks good......wish I had found that before I ordered/installed the screw-down type.

 

2seater......9volt trick is interesting.....maybe if we wire it straight to the Flux Capacitor, then it will work for a few years.  Take out every 6 months and place the 9volt terminals on your tongue, and make sure you still get a good little jolt from it.

[2seater]

I agree and have a love/hate relationship with 9volts. The do have very limited capacity just due to chemistry and construction. They are actually made of six tiny individual 1.5volt cells so there is empty space in the case and high voltage comes at a cost to capacity. Not likely a long term solution but only testing would tell

[Ronnie]

Just an update on the knife switch I installed on my battery.  It works great for preventing the battery from going down when the car is parked for a long time.  I can let my Reatta sit for as long as I want with the knife switch open and the battery stays up just fine without periodically putting it on a charger.  It does have a few drawbacks like losing the radio and clock settings but that isn't a big deal to me. It also loses the average MPG too.  I thought the engine would run a little rough after the ECM lost power for a long time but so far that hasn't been a problem. The engine runs just fine on startup and runs well going down the road. 

 

I just thought someone might want to know how well my knife switch works if they were on the fence about buying a battery disconnect switch.