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Trunk mounted battery fusable link size by gatorfrey
Started on: 01-15-2022 03:22 PM
Replies: 23 (411 views)
Last post by: cvxjet on 02-21-2022 06:08 PM
gatorfrey
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Report this Post01-15-2022 03:22 PM Click Here to See the Profile for gatorfreySend a Private Message to gatorfreyEdit/Delete MessageReply w/QuoteDirect Link to This Post
I mounted another V8 Archie battery tray in the front of my second GT Fiero.
Last time, I ran two #2 welding cables all the way to the back. Never had an issue. But, in the back of my mind, I could see a short going badly wrong if the cables were compromised.
So, this time, I would like to do a fusible link at the battery. But I am not sure what size link to use.
Anyone out there know?
Thanks

Wayne
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Report this Post01-15-2022 04:53 PM Click Here to See the Profile for RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
Good question. And I don't know the answer. (Do they make fuses that are large enough to handle cranking current, and still be practical?)
Keep in mind that the factory cables are not fused.

I just installed a knife switch in my ground wire. Right at the battery.

Sorry. Pic is kind of dark.

[This message has been edited by Raydar (edited 01-15-2022).]

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Report this Post01-15-2022 06:26 PM Click Here to See the Profile for gatorfreySend a Private Message to gatorfreyEdit/Delete MessageReply w/QuoteDirect Link to This Post
Raydar,
Thanks for answering.

Yes, they make some mo-honking heavy fuses with holders, that can do it.
Factory wiring does not expose you to the length of possibilities that can happen with full battery amp and volts traveling the nearly full length of the car.
So, maybe someone knows the safe,practical size and will chime in.
Amazon carries several at around 15-20 bucks. I would do that this time when I wire it all up.

BTW, what size ends for the engine side of this install ? It's been about 20 years since I did the first one. When I lift it to wire it, I don't want to be down long. I remember I tied in where the factory battery cables bolted to the car.
It's my daily driver.

Throwing in pics of the V8 Archie battery tray,my second one. I really like how it fits.
[img]https://images.fiero.nl/us erimages/gatorfrey/20211215_155258.jpg[/img]

[This message has been edited by gatorfrey (edited 01-15-2022).]

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Report this Post01-15-2022 06:33 PM Click Here to See the Profile for Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
I installed a Moroso battery kill switch that I turn off when the car is not in use. I put a 20 amp fuse across the switch terminals so that that the PCM doesn't lose memory adjustment and we also have short circuit protection. With the PCM and clock still energized and drawing a small bit of current a battery maintainer is used all winter long.

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Report this Post01-15-2022 06:35 PM Click Here to See the Profile for cvxjetSend a Private Message to cvxjetEdit/Delete MessageReply w/QuoteDirect Link to This Post
I did not like the large welding cable that runs along the gas tank being energized at all times, so I used a ford-style separate starter solenoid mounted up front that energizes the cable only when starting. I then used AWG-8 wire to run the car- I ran that in the schdule-40 tube that holds the ground cable, and installed a 40 amp fuse on it; If I get high-centered, and the AWG-8 wire gets compromised, it will (Hopefully) short to the ground cable and blow the fuse, thereby shutting power off. (Note; I have not tested this via high-centering the car)

Here is a diagram of what I did;

[This message has been edited by cvxjet (edited 01-15-2022).]

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gatorfrey
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Report this Post01-15-2022 06:43 PM Click Here to See the Profile for gatorfreySend a Private Message to gatorfreyEdit/Delete MessageReply w/QuoteDirect Link to This Post
I saw that somewhere here.
Interesting. And I like the idea of running it through a pvc tube.
Still, though, would like to do the fusable link and call it good.
Hoping a reasonable fuse rating will get chimed in to help me, and anyone doing a search later for something like this.
I saw something on a web search about 10% over alternator output. But do not take that as gospel. I am still unsure.

[This message has been edited by gatorfrey (edited 01-15-2022).]

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Report this Post01-16-2022 02:50 AM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post
Starter draw 120-150 amps if have 12.6v to = 1.5 to 1.7 kw (Stock type rated 1.5kw. some upgrades 1.7kw.)
If battery is low volt or have cable problems then will try to draw More amps.
See my Cave, Electric Motors

And that's main run power. Starter when first started the Inrush Current can be much higher for fractions of a second to 1 second.

So Fuse/breaker of any type have to handle 200 to 300a minimum or expect a lot of Nuisance Trips often at the worse times.

Even if you install any fuse or use starter solenoid like above to prevent cable to the back shorting...
Front mount battery can still short out during or after a crash.
Metal battery box,
Spare tire rim,
Rad Fan motor,
Even the radiator itself,
can short out the battery terminals and/or cables near them.

Even if not a front end wreck...
~ 35lb for Group 75 battery can move or act as a hammer when the car hits whatever or gets hit by other things.

"But OE mount can have same problems..."
Very unlikely even when clamp fails because how where and what can short out.
IOW near impossible to short battery + and cable to anything in a wreck that people can survive.

OE mount limits battery moving a little or a lot even w/o clamp depending on direction.
Nothing close to + side on top of that if battery moves back or strut tower pushes forward.

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eti engineer
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Report this Post01-16-2022 09:38 AM Click Here to See the Profile for eti engineerSend a Private Message to eti engineerEdit/Delete MessageReply w/QuoteDirect Link to This Post
[QUOTE]Originally posted by gatorfrey:

I mounted another V8 Archie battery tray in the front of my second GT Fiero.
Last time, I ran two #2 welding cables all the way to the back. Never had an issue. But, in the back of my mind, I could see a short going badly wrong if the cables were compromised.
So, this time, I would like to do a fusible link at the battery. But I am not sure what size link to use.
Anyone out there know?
Thanks

In electrical work, fusing is usually sized to protect the conductor so that it doesn't become the fuse. For example, in your home (and yeah, I know this is AC and not DC, but I am just using this as an example) 14 AWG wire is protected by a 15-amp breaker. 12 AWG is protected by a 20-amp breaker. The smaller the AWG number, the larger the conductor is. This is all selected by what the wire itself will handle. 2 AWG wire is designed to handle continuous 100 amps. 8 AWG is designed to handle 40 amps continuously. Fuses should be selected to handle 125% of continuous load rating to allow for intermittent in-rush loading (like when you first turn on the AC or heater motor, etc. and in the case of starting, should be a slo-blo style fuse. I guess the question is, how did you select the 2 AWG size wires? They sound plenty healthy to me but was just wondering. If you have a DC clamp-on meter (you can buy one cheaply at most any automotive store) I would measure the cranking current on the starter just for your comfort to ensure you are not drawing more than 100 amps when cranking. If you are, and since you already have the wiring installed, I would size the fuse accordingly at 125% of what you measure. Since starting is a short intermittent load, you should still be ok, but if a short occurred, because the current would be much higher than cranking current, there could be heating of the conductor until your fuse blew, so I certainly would not go much over what the conductor is rated at.

This is just my opinion based on what I know about electricity and Fieros. For what it is worth...

I just did some checking and it appears that 2 AWG will handle 115 amps DC safely at a temp of 75 degrees Celsius, so you are good to go on wire size. But to boil it down, you can safely fuse a 12VDC circuit using #2 wire at 150 amps. One consideration is that with DC, there is can be a bit of a voltage drop in even a 10-foot length of #2. This will cause the starter to draw more current. But based on what I have read, you will be fine using #2 and 150 amp fuse. If you don't need that large of a fuse, I would go with something slightly smaller, just to be safe. You have to forgive me. I worked in Prime Power for over 40 years, but everything I did was with three-phase AC voltages, 230,000 volts on down. It's a whole different world with three phases....

[This message has been edited by eti engineer (edited 01-16-2022).]

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gatorfrey
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Report this Post01-16-2022 09:26 PM Click Here to See the Profile for gatorfreySend a Private Message to gatorfreyEdit/Delete MessageReply w/QuoteDirect Link to This Post
I think I will try 150 amp for now, on the link.And keep spare 200 amp, if I upgrade the alternator,
Anybody remember what size terminal rings go on the cable at the back of the car ?
I see 3/8, 5/16, and 1/2 inch. I would like to attach at the same point the old cable went to.

[This message has been edited by gatorfrey (edited 01-16-2022).]

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eti engineer
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Report this Post01-18-2022 09:05 AM Click Here to See the Profile for eti engineerSend a Private Message to eti engineerEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by gatorfrey:

I think I will try 150 amp for now, on the link.And keep spare 200 amp, if I upgrade the alternator,
Anybody remember what size terminal rings go on the cable at the back of the car ?
I see 3/8, 5/16, and 1/2 inch. I would like to attach at the same point the old cable went to.



Which connection point do you mean? Just asking for clarification.
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gatorfrey
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Report this Post01-18-2022 09:39 AM Click Here to See the Profile for gatorfreySend a Private Message to gatorfreyEdit/Delete MessageReply w/QuoteDirect Link to This Post
There is a junction block,from what I remember, for the positive side.
In other words, battery terminal at the battery end, and the other end ties in where the original battery did.
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Report this Post01-18-2022 11:56 AM Click Here to See the Profile for pmbrunelleSend a Private Message to pmbrunelleEdit/Delete MessageReply w/QuoteDirect Link to This Post
Normally there is a difference of 4 AWG between a fusible link and the wire it protects.

So, if you have a 2 AWG wire, the fusible link that protects it would be 6 AWG.
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Report this Post01-18-2022 01:15 PM Click Here to See the Profile for gatorfreySend a Private Message to gatorfreyEdit/Delete MessageReply w/QuoteDirect Link to This Post
I saw that.
Essentially, you are right.
When I got all up in Amazon, looking at fusible links, I found some cool housings that hold "fusible links", that are high amp fuses. I kinda like that idea, and it is an industry standard sizes, so amp size can be interchanged.

I will start with 150 amp, and go to 200 amp if that does not get it.
I also decided to go heavy duty, like I did the first GT, and go with 0/1 welding cable.
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Report this Post01-18-2022 01:44 PM Click Here to See the Profile for eti engineerSend a Private Message to eti engineerEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by gatorfrey:

There is a junction block,from what I remember, for the positive side.
In other words, battery terminal at the battery end, and the other end ties in where the original battery did.


Yeah, I was in that area not very long ago. I will see if I have some pix of it and get back to you. Are you asking about the stud size where the conductor connects so you can get the right ring terminal?
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Report this Post01-18-2022 02:06 PM Click Here to See the Profile for eti engineerSend a Private Message to eti engineerEdit/Delete MessageReply w/QuoteDirect Link to This Post

eti engineer

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Member since Mar 2017
 
quote
Originally posted by gatorfrey:

I think I will try 150 amp for now, on the link.And keep spare 200 amp, if I upgrade the alternator,
Anybody remember what size terminal rings go on the cable at the back of the car ?
I see 3/8, 5/16, and 1/2 inch. I would like to attach at the same point the old cable went to.


I looked at mine, as I have no available pictures for that area. My positive cable is a molded terminal with the large conductor going to the starter, and the #8AWG wire both, coming out of the battery connection terminal. The other end of the smaller wire goes to a terminal block as you say. Since the battery is a side terminal type, it's not like a post battery where they make connectors that allow for connecting other conductors. This is the first side terminal car I have owned, so I don't know what is available. I am sure they make one that is like the Fiero original, though, where the positive terminal has one or more extra smaller wires connected in the molding and they already have ring terminals on the other end.

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Report this Post01-18-2022 03:32 PM Click Here to See the Profile for gatorfreySend a Private Message to gatorfreyEdit/Delete MessageReply w/QuoteDirect Link to This Post
Yes, the ring terminals.
I cannot be down long once I raise it up on stands.
Appreciate it.
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Spoon
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Report this Post01-22-2022 09:42 PM Click Here to See the Profile for SpoonSend a Private Message to SpoonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by gatorfrey:

I mounted another V8 Archie battery tray in the front of my second GT Fiero.
Last time, I ran two #2 welding cables all the way to the back. Never had an issue. But, in the back of my mind, I could see a short going badly wrong if the cables were compromised.
So, this time, I would like to do a fusible link at the battery. But I am not sure what size link to use.
Anyone out there know?
Thanks

Wayne


Why not run the cables from the front and thru the car interior under the carpet. Pontiac Bonneville did it that way and they even had the battery under the rear passenger seat driver side. You could just continue thru the rear firewall to the engine. As far as fuses I used a resettable circuit breaker of the appropriate rating up front near the battery. It can be used to protect against short circuits and overloads and as an manual on-off switch by simply pushing a button.. The one I installed is the type used for boaters so it can handle the environment just in case. They come in various trip ratings too and are inexpensive. I don't have a pic handy or I'd post it.

ps: Looking at whats available now makes the concept of a Fuseable Link breath-taking. The last thing a Fiero owner needs is the sign of smoke bellowing from the engine compartment due to a F/L. That could be a frightening experience followed by a sigh of relief.

Spoon

------------------
"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

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Report this Post01-23-2022 12:43 AM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post
⚠️ Warning: Do not use a Breaker as a Switch.
Most Breakers will have problems because is Not Made to be a Switch. More so w/ DC circuits.
Even with no load, most wear out faster as you move them.

Plus Most Switch, Breaker and Relay Label Ratings are AC rating. DC at same Amps can burn or weld contacts Fast. Faster if loads are Inductive controlling motors etc.

Install outside of cabin means needs to handle a low of dirt and water. Finding a "water proof" breaker cost more.

Car Stater relays, on the starter like OE GM or "Ford Type" above, are have very big heavy contacts and still burn some as normal operation. Is why many use a disk that moves to prevent major burning.

Even on AC, fools use Breakers as Switches and wonder why have to replace them often at minimum.
Most use standard wall light switches at home and small business to control motors, light ballast, and burn the switches and have to replace then often too.

Fusible Links done right won't blow w/o an overload.
If you don't want links, use big fuses made for automotive use. But this adds more joints and often done wrong means problems cause Nuisance blown fuse, low volts to fires.
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Report this Post01-23-2022 10:08 PM Click Here to See the Profile for SpoonSend a Private Message to SpoonEdit/Delete MessageReply w/QuoteDirect Link to This Post
theorge, I knew you'd chime in with interesting points which are always welcome. I'm familiar with the do's and don't's and with Fiero's we're always tempted to alter the factory design hopefully for the better.
The link below show a similar breaker that I'm using. They come in various amp ratings and are advertised as water-proof however I installed mine in the front compartment which is dry. Designed for marine use I'd expect they can handle brackish waters, etc.
My experience with home circuit breakers is they all seem to fail-safe or open. I believe these fail the same.

https://images-na.ssl-image...dVaL._AC_SL1000_.jpg

Getting late, gotta go,

Spoon


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"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

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Report this Post01-26-2022 11:52 AM Click Here to See the Profile for gatorfreySend a Private Message to gatorfreyEdit/Delete MessageReply w/QuoteDirect Link to This Post
So,
On the engine end of running cables from the trunk to the back,as I remember it (20 years ago I did the first one), the main cable went straight to the starter. I seem to recall I used a heavy, but lesser cable, from the same starter mounting point, to a spot the factory had originally tied into the vehicle for everything else.
As I said, when I lift her up to put all this on, it needs to be with the surprises that will keep me down. It is my daily.
So I will clamp and solder a connector on that end of the cable, and run it, tie and dress it off, and cut the battery end to fit,
What size ring/loop connector fits the starter ?? Is it 3/8?, or smaller? Anybody with a factory positive cable laying around that could check the sizes of the little cable,and the starter cable ends that fit the car ?

[This message has been edited by gatorfrey (edited 01-26-2022).]

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Report this Post02-20-2022 06:34 PM Click Here to See the Profile for marc-alanSend a Private Message to marc-alanEdit/Delete MessageReply w/QuoteDirect Link to This Post
When mounting the battery in the front and using a Ford style solenoid, where do you splice-connect the wire for the key-start signal? Is it brought all the way to the engine bay?

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Report this Post02-20-2022 09:12 PM Click Here to See the Profile for cvxjetSend a Private Message to cvxjetEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by marc-alan:

When mounting the battery in the front and using a Ford style solenoid, where do you splice-connect the wire for the key-start signal? Is it brought all the way to the engine bay?


I spliced into the Purple wire that comes off the Clutch safety switch....Then I drilled a hole thru the firewall forward so the wire could reach the solenoid which was mounted on the front trunk wall. I installed a couple of grommets to protect the wire running thru the holes (There are two pieces of sheet metal to drill thru)

This was (Obviously) on a Manual trany car- But the automatic has the wire running thru the Gear selector.

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Report this Post02-21-2022 04:19 PM Click Here to See the Profile for marc-alanSend a Private Message to marc-alanEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by cvxjet:


I spliced into the Purple wire that comes off the Clutch safety switch....Then I drilled a hole thru the firewall forward so the wire could reach the solenoid which was mounted on the front trunk wall. I installed a couple of grommets to protect the wire running thru the holes (There are two pieces of sheet metal to drill thru)

This was (Obviously) on a Manual trany car- But the automatic has the wire running thru the Gear selector.


Did you also ground the starter solenoid to the chassis?
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Report this Post02-21-2022 06:08 PM Click Here to See the Profile for cvxjetSend a Private Message to cvxjetEdit/Delete MessageReply w/QuoteDirect Link to This Post
The solenoid grounds thru it's mounting bracket- Just make sure it makes ground contact- either thru the screws or the actual bracket (Don't mount it to plastic)

Note; It doesn't need a BIG ground- This is only to actuate the solenoid- the actual starter power (Big amps) grounds thru the starter to block mounting.

[This message has been edited by cvxjet (edited 02-21-2022).]

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