I have a bed mounted battery (in a securely mounted battery box) in my truck with the 2guage hot wire running through a grommet in the bed floor then along the frame all the way to the starter. I need a fuse to go in the battery box incase something happens to the wire along the way... Not sure how many amp fuse I need for this? Batteries claim 600 CCA and what not but I have a hard time believing I'd need a fuse rated for that much.
What are you guys using for this?
I use something like this on the MG. I forget the rating but it's not insane. I wanted a switchable one so I could turn the car off when it's sitting.
Just looked up the order, mine's 100A@48V. I'm pretty sure I'm running the starter through it but I'd have to check. It's never popped.
You need a remote solenoid mounted next to the battery so that the starter cable is only energized during engine cranking. Also use a fusible link for the 12 volt alternator charging wire for whatever gauge is recommended for the amp output of your alternator. I would also install a dedicated heavy battery ground wire hooked up from the battery to the engine block as well as hooked up to the body shell in the trunk.
Cameros.net: Remote Start Solenoid - Battery in trunk
speedwaymotors.com: Recommended wiring size for alternator to battery connections
BMW, and Mazda put batteries in the trunk with no solenoid, and the ground wire to the chassis. A 150 amp fuse is fine, as close to the battery terminal as possible.
In reply to Racebrick :
Is that the size fuse that BMW or Mazda use?
I'd kind of like to see the wiring diagram for a setup the VolvoHeretic is proposing, because from what I have in my head there's two large cable runs going from the engine area (one from the alternator/fuse panel/relays, and a second to/from the starter) back to the trunk-mounted battery area of the car. A single fat fuse on a single large cable run is appealing but I don't know how much current that fuse should be rated for.
Here is one diagram. I am having difficulties finding info, 90% of the diagram images send you to malicious web sights with lots of viruses.
bzerob.com: Basic Remote Starter Solenoid
These appear safe. There is some talk about adding a diode to protect engine computers but I don't know anything about them.
Camaros.net: Remote Start Solenoid - Battery in Trunk
madelectrical.com: trunk mount battery helper kit
In reply to pres589 (djronnebaum) :
Mazda does not fuse the big battery cable running from the trunk to the starter iirc.
In reply to VolvoHeretic :
I didn't go to the links, but like the diagram. Probably a bit unclear to folks that don't already kinda understand, and I replace "fuseable links" with fuses, or self resting circuit breakers
Ive mentioned before back in the '50s and up, Ferd wired their starters like the diagram, but with the battery up front, and solenoid (a low current switched / high current relay). Chebby saved a bit of space, by putting the solenoid right on the starter. Right against the back of the exhaust. Where heat shortened to life, and heat soak would prevent it from working. Chebby racers (HUGE hate for Ferd) would buy a relay to mount on there inner fender. Like Ferd did
In reply to Keith Tanner :
How do you fuse 700 cold cranking amps?
In reply to 03Panther :
With a car with the solenoid on the starter, they use the solenoid next to the battery and also the one attache to the starter. I've been out of the loop for 30 years so I have no idea how modern starters work. I also don't remember how I hooked up my Volvo.
700 cca is a capacity rating, not current draw. I was incorrect about 150 amp fuse. I checked my fuse, and it's a 250 amp.
In reply to Racebrick :
Thanks for the clarification.
I'm trying to figure out why a guy wouldn't just run long 1 gauge or larger cables to the trunk with one of these guys as close as possible to the positive battery post;
250 amp "car audio" circuit breaker on Amazon
That solenoid doesn't do anything for circuit protection in the images above. I really don't know what the point of all of that stuff is if it's in adition to what is already on the car before this project starts.
I wasn't planning on using a fuse on my project. Just a miserably small pc680 battery, unless I find a "cheap" antigravity lithium one, with 2 ga cable and a solid state battery shutoff.
Thanks for all the replies so far.
I'm just looking for a fuse, no breakers or solenoids and such...
Looking at this 300A one on Amazon
I just want a big enough fuse that won't blow while cranking the 5.3 LS, so how many Amps will I need?
In reply to Ranger50 :
My thinking on a circuit protection device is that the cable is quite long and goes through at least one wall to make it from the trunk to the starter, alternator etc, so the chance for problems are increased. The nice thing about the breaker I posted (and there's others available for similar cost) is they include a switch function that can be manually set. And if your PC680 battery can turn the motor over, it's going to be providing the same amount of power, just with less total run time.
gsettle: You might consider a breaker for that reason as well; there's a shut-off switch function included in the breaker that a fuse & holder won't offer.
This is all a bit of opinion, I don't wire cars.
In reply to gsettle :
When I sawp 5.3s into Volvo 240s I put the battery in the trunk to fit turbos/pipes/etc. Then a 250 fuse or breaker close to the battery, and have always been fine. The 300 amp you have pictured is adequate. The fuse on the battery is there to protect from fire in case the main battery cable is shorted to ground.
My e36 has(had) a fuse on the chassis positive but not the starter positive. A clogged drain wet that fuse and blew it.
In reply to gsettle :
Short answer. Buy the 250A breaker off Amazon, ILO fuse.
In reply to pres589 (djronnebaum) :
Disconnect is only rated to a continuous 200a with an allowable 500a in rush. I plan to use firewall passthrus for any gotta go inside runs, which is only one.
Awesome! Thanks gentlemen!
You'll need to log in to post.
