Thread: trunk mounted battery short protection

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Let's assume you are generating 100 amps at 14.5 V dc and 95% efficiency. Then you are drawing about 2 hp from your engine.

Only on paper do I believe will this factor alone cost you a race.

Unless you are running a self-generating ignition (magneto) then the waning 12V may not be a great idea in general, albeit drag races are very quick, no?! Your MSD-coil will like 14.5 V much better!

One wire alternators are self-excited. You have to kick them up initially (at start-up or whenever) to kick them on. Once on I am not aware that they do not perfrom as well as 3 wire alternators. I would certainly like to see some performance curves ...............

The diode alone will not smooth voltage spikes, but then again I am not aware of MSD killing voltage spikes in a 12 V dc automotive charging system.

Kitz

How do you get to 7 HP from 14.5 V and 100 A?

Alternator load = V I = 14.5 * 100 = 1450 watts.

1 HP = 746 watts. ~ 2 HP


Kitz

Hey Guys...

Just thought that some of you may want to see this for your trunk mounted batteries... ps I would think of putting a dry cell in it ie. optima...



That is the Battery relocation kit from Steeda Autosports

MSRP is $199 For the kit...
MSRP $129.95 For the box only

skids72, Thanks for the picture. That is really a neat way to both hide the cutoff and satisfy track rules.

Don Shillady
Retired Scientist/teen rodder

DennyW, this thread is developing so fast that his picture is one or two pages back. It is the rear view of his Pontiac with the cutoff in the license plate bracket. I like his method but may have to use a rod through a hole in the base of the rumble/trunk if I want to satisfy the rear rule. I could plug up the hole and then add a cotter pin attachment for a push-off cutoff if I ever want to get a timed 1/4 mile. I'm thinking it over, but at least I under stand some of the diagrams now.

Don Shillady
Retired Scientist/teen rodder

Well it looks like Spring is trying to bust out somehow but not quite. Today was pretty sunny and I should have worked on the car but I had other things to do. However along the way I stopped to buy a nice remnant 15' of RED garden hose to slip over my 1/0 red positive cable from the battery to the starter. That should provide a reasonable extra insulation between the cable and the frame rail, but I still need to find some plastic clips to avoid using metal which might cut through the insulation. Just a tiny step but I am starting to think I can do this!

Don Shillady
Retired Scientist/teen rodder

Originally posted by Don Shillady
Well it looks like Spring is trying to bust out somehow but not quite. Today was pretty sunny and I should have worked on the car but I had other things to do. However along the way I stopped to buy a nice remnant 15' of RED garden hose to slip over my 1/0 red positive cable from the battery to the starter. That should provide a reasonable extra insullation between the cable and the frame rail, but I still need to find some plastic clips to avoid using metal which might cut through the insulation. Just a tiny step but I am starting to think I can do this!

Don Shillady
Retired Scientist/teen rodder

so much for spring up here in these Va. mountains this morning. its snowing, and sleeting.

This must be the old thread back again because it is now officially Spring and tomorrow we will have the snow flurries to prove it! We lost a few comments due to the old/new thread situation, but I have actually been working a fair amount on this problem on the warm days. I finally purchased a new Summit No. 830051 Remote Battery Cutoff Switch. It comes spring-loaded to the off position and has a click-set on position with an 18" steel handle to extend outside the back of the car. It is rated for 250 amps continuous current and several thousand amps surge so I think that will handle my nearly stock 350 with only 9:1 CR. I chose this unit mainly because of the spring-loaded setting and the external handle. I have mounted it in the right rear corner of the bottom of the Model-A floor behind the rumble seat tank because I plan to install a luggage rack on the roadster and I need to avoid the rack on the outside of the car. As suggested by Tech1 I used the rubber sleeved Adel clamps to fasten the 0-gauge red welding cable to the starter and to the switch at the back. The alternator wire will feed back to the + battery side of the switch as others have show on this thread and I ran a 00-gauge black welding cable from the - post of the battery to the frame and then to a transmission bolt on the engine. I got a 1/4" longer mounting bolt so I still have lots of thread into the engine even after adding the brass lug and two star washers under the head of the bolt. It took about 30 minutes of grunting and some grease but I was able to slip red garden hose over the 0-gauge hot + cable to further protect it from shorts through the Adel clamps. Now for my innovation, I think it is unlikely that I will ever use the race track cutoff more than a few times and I still want to have a security cutoff so I can park the car in a Va Beach parking lot without it being stolen (I have had other cars stolen!). Thus I threaded another stock piece of 1/2" steel rod just like the 18" "push-off" rod and flipped the heim end of the spring-loaded switch lever around to the front. This gives me an internal cutoff when the push-off track switch is not installed. If/when I take the car to a track for a time trial I will have to reverse the heim-end of the lever and insert the push-off rod through a hole in the body which will have a rubber grommet and a nice chemistry laboratory rubber plug in it most of the time. Viola! I have both a track cutoff switch if/when needed AND a hidden handle in the rumble seat area to disconnect the battery in a municipal parking lot. It is like Bob said, it is one slow step at a time just like eating an elephant but step by step maybe I will get the body on this summer after I finish with the floor-fenders on there now.

Don Shillady
Retired Scientist/teen rodder