Aftermarket Charging System

[BridgeBuilder88]

Can anyone please help with me with some electrical informatino regarding one of my "toys".

I'm doing the common second generation alternator to third generation alternator conversion that many people do on pre 1994 ford mustangs. I've got the new 130 amp alternator, along with the required connections. I'm also planning on moving the battery to the rear of the car as well as including a battery cut-off switch and new ground wires.

I'm just curious as to if these cables are of the correct gage and if any other things should be taken into consideration or modified while I am doing the enitre charging system.

A 4 Ga. cable with 200 amp in line fuse will be run from the new alternator to the starter solenoid, from there, a 1 Ga. welding cable will be run to the rear of the hatch to the battery box. From the battery a 1 Ga. Cable will ground the battery on the frame. The engine ground wires will be replaced with 4 Ga. wires.

Should the battery cut-off switch go in the battery ground cable, between the battery and the frame? Should I instead run a 1 ga. cable from the battery negative post up to the front of the car and ground it on the engine? Considering the battery is grounded on the engine stock. I plan on upgrading the starter eventually, would it be a wise idea to do it now, or just wait untill it is needed.

Thanks for any help regarding this as I am a newbie with electronics whether it be with cars or elsewhere.

Anthony Deramo
American Bridge Company

 

[evelrod]

Seems a little "heavy duty" for what you seem to be doing...It'll work fine, all except the battery cut off on the ground wire. That will prevent the car from being started, however it will NOT shut off the engine as long as the generator is charging. For that you will need a switch such as the examples here for 'battery switch'...

http://www.pegasusautoracing.com/keywordsearch.asp

Obviously this is only one example. Similar exist from other sources...All seem to be in the >$50 range. I use the Moroso 74102 on my race cars and it has worked out ok over the years.

http://www.moroso.com/catalog/categorydisplay.asp?catcode=42225

Rod

 

[BridgeBuilder88]

I see, so where should the battery cut-off switch be located? Honestly I don't care for a cut-off switch but I think it's NHRA rules that if you have a battery in the trunk/hatch area it has to have a cut-off switch. I'm more of a road course racer but every once in a while a drag strip visit is nice.

Anthony Deramo
American Bridge Company

 

[BridgeBuilder88]

I forgot to ask if it is correct having the relocated battery negative now ground on the body rather than the engine block. Does this hurt me in any way.

Another thing, a slight bit off topic, is that I have HID lights and they run a direct power source off of the battery. How would I go about modifying this to ensure it works proprely. Would I
1) Replace the short power cable in the HID harness with a longer cable, of larger gage, and run it to the rear of the car to the battery, or
2) Add a larger gage, long extension to the HID power cable without having to modify the HID power cable. The HID power cable has an inline fuse right before the positive battery terminal connection.

Anthony Deramo
American Bridge Company

 

[evelrod]

SCCA and most vintage clubs, including VARA require the on board fire systems and electrical cut off switches be in a position such that the marshals can reach it from outside the car. In my case, both the Mini Cooper and the Lotus Cortina have their electrical and fire system activation switches mounted on the vertical bar of the roll cage just at the "A" pillar...easily in reach from both the driver's position and outside the car. My batteries are in a Moroso box on the passenger side floor board (rhd Mini and lhd Lotus) to help offset my 220 lbs. in the driver's seat...;o( Incidently, BOTH cars came OEM with the batts in the boot!

I don't know anything about the HID lights.

Rod

 

[BridgeBuilder88]

Thanks, the question about the lights is basically how to extend the hot wire... not too much specifically pertaining to the lights.

Eventually it's getting a cage, so I suppose I'll run without a batt cut off until then.

Anthony Deramo
American Bridge Company

 

[patprimmer]

I would run the hot wire for the lights to the battery terminal on the starter, except when you are cranking it is not used and it is probably capable of 400 or so amps load with acceptable voltage drop at those amps.

Run the earth strap to the chassis near the battery. bolt it to a reasonably thick piece of steel that will handle cranking amps around the bolt.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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[BridgeBuilder88]

Thanks Pat

I may run the hot wire to the solenoid. But,unfortunately, the HID light kit was designed specifically for a fox body mustang, so the hot wire is only long enough to reach from the drivers side headlight to the battery which was located directly behind the drivers side headlight. The starter solenoid is on the passenger side, however. I still need to lengthen this wire somehow.

Anthony Deramo
American Bridge Company

 

[tjhoss]

I am not an engineer, but my experience with Mustangs and locating the battery in the rear with a ground strap to the frame has led to issues with the ECU grounding properly and in some case burning them up.

What does work is to use a braided ground strap of adequate size for the amp load and fasten it through the braid at numerous points along the frame. When you get close to the ECU you can solder a ground wire or smaller piece of braided strap into the main piece and run it directly to the ECU grounding point.

Yearning to learn.

 

[evelrod]

A couple things about grounding/earthing a batt...
One, I try to make the connection as close to the batt as possible/convenient...
Two, ground straps of substantially larger material than is normally required.
Three, I use a large stud, typiclly 3/8" to 1/2" welded to the cage (which is welded to the chassis) and take a "wrap" of heavy lead solder around the base of the stud under the ground strap, washer, nut, etc.

I make the same ground connections from engine to chassis and from my MSD to chassis.

It may be a bit of 'overkill', but...What can I say? I just do not have problems relating to improperly grounded circuits.

Rod

 

[BridgeBuilder88]

The EEC problem you are referring to could be related to the EEC and the battery having a common ground, then changing that when relocating the battery.

I was advised to run a ground from the new alternator housing to the frame, what are your thoughts on this.



Anthony Deramo
American Bridge Company

 

[tjhoss]

Hmmm, You may be right about that.
All I know for sure is what has worked for me. I have not ran a ground specifically from the alternator to the frame, but I do have a #8 wire ground from the engine to the frame to assure a good ground for the charging system and electronics on the EFI engine.
So far this has worked for me for the last 6+ years.
A wire from the alternator to the frame may not help any more, but it sure won't hurt.

I will be making some major changes to the car soon and I will be adding a 200A alternator to help run the electric water pump, fuel pumps, cooling fan, and upgraded ignition system. We'll see how that works out and if I have time I will log and photograph the procedure and changes.

Yearning to learn.

 

[BridgeBuilder88]

Regarding the extension to the HID harness hot wire...

I would only have to splice an extra one foot of wire on in order to make it reach the alternator. Since the positive cables of the battery essentially run to the starter solenoid and to the alternator... couldn't I run the HID hot wire off of the back of the alternator?

Thanks again for any and all help with my project.

Anthony Deramo
American Bridge Company

 

[tjhoss]

As long as you are on the positive cable that is directly connected to the battery and it is of sufficient size that should be ok.

Yearning to learn.

 

[patprimmer]

I second tjhoss

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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for site rules

 

[BridgeBuilder88]

Hmm, it seems that it is unneccessary as I didn't realize until looking at the car that my starter solenoid is basically right where my battery was stock. So I just hook the HID hot wire up to the solenoid without having to modify it.

Oh well, thanks alot anyway for all the help.

Anthony Deramo
American Bridge Company

 

[tjhoss]

You're welcome & best of luck to you.

Yearning to learn.