Jumper Cable Circuit Breaker

[K-G]

Good people,

I have a question regarding circuit breaker sizing.

I’ve direct-wired a 4-gauge wire to my 2005 Silverado. Positive to a terminal block under the hood designated for jumper cable clamping. Negative to the block. On the other end is an Anderson connector, which is on the front of my truck.

I’ve taken a pair of jumper cables and cut one end off, adding an Anderson connector. The idea being that I can perform jumps more efficiently.

What size circuit breaker should I add to the positive terminal wire? Any need? My concern is two-fold. One, a wire short to ground under the hood (unlikely given my routing and the insulation thickness. A second concern is an overload of sorts between vehicles.

I’ll try and add a picture later.

Thoughts? Hope this makes sense.

KG

 

[old_man]

I never have and never will run a circuit breaker in jumper cables. You want as much current as the battery can provide.

 

[MidOH]

So use a bigger breaker. LOL.

It's never enough anyways. I just let my alt recharge their battery for 20 minutes or so.

 

[OTH Overland]

I ran anderson connected jumper cables in my tow trucks for years back in the day, and never had an issue without any kind of protection. Eliminated a chance of an incorrect connection at one end at least, and did not have to open my hood. allways hooked up dead vehicle then pugged in to wrecker to avoid any chance of sparks.

Fast forward a whole bunch of years and ever since I have added a battery booster to my kit like the Wagan-Tech Ion Boost or similar, I have found dust growing on my jumper cables. Advantages are you can jump yourself when running solo, and when jumping others there is no connection back to your rig eliminating any possibility of cross connection, or bad JuJu back thru the cables. Today's highly computerized vehicles can be very sensiitive to voltage or amperage spikes, and not a risk I want to take when helping somone out. Have not found a gas powered vehicle that they wont start yet, keep two in my diesel Ram (one for each battery) in case of cold start from dead battery. I do keep a good set of regular cables hidden away in each vehicle just in case still though.

 

[Ubiety]

Wagan-Tech Ion Boost

Assume that you recommend this one? Have a model number? There are several models for vastly different prices. Been meaning to get one of these...

 

[OTH Overland]

Assume that you recommend this one? Have a model number? There are several models for vastly different prices. Been meaning to get one of these...

We have one of the Wagan units as sold in the OB store (which is a reduced price currently) iOnBoost™ V8 TORQUE has been a solid unit with no complaints, starts our 4.7 litre V8 Jeeps with ease. Also have a couple of the Scosche units from Costco and one generic brand that we found on sale somewhere. Had no problems with any of them starting or holding a charge. With the good price in the OB store, I would go with the Wagan if I had need for another. I also toss in the case a a USB adapter I found on Amazon that has connectors for USB C, USB Micro, USB Mini, and Apple and will plug in to the jump box and allow charging of pretty much any device, that way I allways have a way to charge someing in an emergency if we forget or lose a cable.

 

[Shakes355]

I wouldn't worry about a circuit breaker in the "automatic protection" sense. Depending on load, state of charge, temp, etc, I've seen surge draw over 300A during testing. Now that current is only momentary (hopefully) so 4g is fine, but the size of the breaker you would need to still be successful with a jump is well above the standard amp rating of the wire so protection really isn't a thing. It could easily melt down without reaching the breakers trigger current.

If you are worried about chaffing (a fair concern) I would suggest a marine grade battery switch on that B+ wire closer to the battery. Turn it on when you need it and have that peace of mind.

 

[MazeVX]

Good people,

I have a question regarding circuit breaker sizing.

I’ve direct-wired a 4-gauge wire to my 2005 Silverado. Positive to a terminal block under the hood designated for jumper cable clamping. Negative to the block. On the other end is an Anderson connector, which is on the front of my truck.

I’ve taken a pair of jumper cables and cut one end off, adding an Anderson connector. The idea being that I can perform jumps more efficiently.

What size circuit breaker should I add to the positive terminal wire? Any need? My concern is two-fold. One, a wire short to ground under the hood (unlikely given my routing and the insulation thickness. A second concern is an overload of sorts between vehicles.

I’ll try and add a picture later.

Thoughts? Hope this makes sense.

KG

A rule of thumb and don't nail me down... 25% below your batteries CCA. You may not get the exact value so you take the next smaller fuse.
It should be big enough to jump someone but still blow if a cable shorts.
If your CCA is really high you can go down, usually you don't need more than 400A to jump a serious engine.

 

[M Rose]

Good people,

I have a question regarding circuit breaker sizing.

I’ve direct-wired a 4-gauge wire to my 2005 Silverado. Positive to a terminal block under the hood designated for jumper cable clamping. Negative to the block. On the other end is an Anderson connector, which is on the front of my truck.

I’ve taken a pair of jumper cables and cut one end off, adding an Anderson connector. The idea being that I can perform jumps more efficiently.

What size circuit breaker should I add to the positive terminal wire? Any need? My concern is two-fold. One, a wire short to ground under the hood (unlikely given my routing and the insulation thickness. A second concern is an overload of sorts between vehicles.

I’ll try and add a picture later.

Thoughts? Hope this makes sense.

KG

Having done this exact setup for years on my service rigs, I have never ever used a circuit breaker. The reason for no circuit breaker is two fold… first a starter can draw over 1000 amps when there is a bad battery or ground issue. Secondly in the event of needing to do an emergency weld, the circuit breaker would trip before the makeshift rod would have time to strike an arc.

If you are worried about having a short circuit, add a knife switch at the battery positive for the jumper connection. This way it’s Only hot when you need it to be.

 

[M Rose]

A rule of thumb and don't nail me down... 25% below your batteries CCA. You may not get the exact value so you take the next smaller fuse.
It should be big enough to jump someone but still blow if a cable shorts.
If your CCA is really high you can go down, usually you don't need more than 400A to jump a serious engine.

A ford 5.0 takes 650A to start, a modern 2.3l takes 850a to start… these are the numbers with brand new internals and new starters. As components age, the more amps needed to spin the engine fast enough to start.

 

[K-G]

Good people,

I have a question regarding circuit breaker sizing.

I’ve direct-wired a 4-gauge wire to my 2005 Silverado. Positive to a terminal block under the hood designated for jumper cable clamping. Negative to the block. On the other end is an Anderson connector, which is on the front of my truck.

I’ve taken a pair of jumper cables and cut one end off, adding an Anderson connector. The idea being that I can perform jumps more efficiently.

What size circuit breaker should I add to the positive terminal wire? Any need? My concern is two-fold. One, a wire short to ground under the hood (unlikely given my routing and the insulation thickness. A second concern is an overload of sorts between vehicles.

I’ll try and add a picture later.

Thoughts? Hope this makes sense.

KG

Having done this exact setup for years on my service rigs, I have never ever used a circuit breaker. The reason for no circuit breaker is two fold… first a starter can draw over 1000 amps when there is a bad battery or ground issue. Secondly in the event of needing to do an emergency weld, the circuit breaker would trip before the makeshift rod would have time to strike an arc.

If you are worried about having a short circuit, add a knife switch at the battery positive for the jumper connection. This way it’s Only hot when you need it to be.

I like the thought of a ‘quick disconnect’ in here, for the reasons you mentioned.

 

[OTH Overland]

Not sure why you would need a disconnect switch in line when there is already an anderson connector that can be pulled apart if there was an major issue during jumping, the best reason for using this system is not having open the hood to do a jump. It would be faster to yank the cable at the bumper connector then pop hood to access knife switch. If the worry is that the wiring will short betwen anderson connect and battery while driving, consider all the other wiring that runs from the battery to places on the vehicle without disconnects, Starter, Main fuse box, Winch.... for automatic protection, I have not seen any fuses, fused links, or breakers rated for starter motor current, and with such a big fuse and wiring you would likely melt the terminals off the battery or have total battery failure before the fused item pops, as @M Rose states above, starters, especially when using long cables pull a ton of short term power which would requiring a larger fuse than the wire is really capable of, because you are acutually overloading the cables for a short time (which they can stand and is why they get hot if you crank too long). In the past I have wired my front bumper jump boxes the same way I do my winches, Heavy gauge cable, each with a secondary layer of wire loom to prevent chaffing or damage, plenty of wire ties, and grommets when passing through a hole in the metal. With nothing normally attached to the circuit there is virually no chance of an overload if the wiring is properly installed and protected.

 

[M Rose]

Another thing that needs to be considered… How often do YOU jump your own vehicle vs jumping some one else… you need to make sure you can handle jumping an old Stroked Big Block or Diesel… as @OTH Overland stated if any where in your accessory wiring to go overkill it is the jumper wiring.

My jumper cables are made from 50’ Double Ott Welding cable leads. And my jumper wiring from battery to the Anderson connectors are also the same cable.
Also my ground goes to both the battery and vehicle frame. if you read your owner’s manual on most modern cars for jump starting procedures they recommend going to the engine block for the jumper cable ground on both the disabled vehicle and the running vehicle. This is to protect the ECUs from a voltage spike during the jumping process. Which is also why larger cables are used to help absorb the spikes.

 

[K-G]

Not sure why you would need a disconnect switch in line when there is already an anderson connector that can be pulled apart if there was an major issue during jumping, the best reason for using this system is not having open the hood to do a jump. It would be faster to yank the cable at the bumper connector then pop hood to access knife switch. If the worry is that the wiring will short betwen anderson connect and battery while driving, consider all the other wiring that runs from the battery to places on the vehicle without disconnects, Starter, Main fuse box, Winch.... for automatic protection, I have not seen any fuses, fused links, or breakers rated for starter motor current, and with such a big fuse and wiring you would likely melt the terminals off the battery or have total battery failure before the fused item pops, as @M Rose states above, starters, especially when using long cables pull a ton of short term power which would requiring a larger fuse than the wire is really capable of, because you are acutually overloading the cables for a short time (which they can stand and is why they get hot if you crank too long). In the past I have wired my front bumper jump boxes the same way I do my winches, Heavy gauge cable, each with a secondary layer of wire loom to prevent chaffing or damage, plenty of wire ties, and grommets when passing through a hole in the metal. With nothing normally attached to the circuit there is virually no chance of an overload if the wiring is properly installed and protected.

Good points, all. Yep, my main concerns were as above. For driving, a short. You are correct in that I’ve taken time to carefully route my wiring, so absent a wreck, I should be in good shape.

For jumping, I hadn’t considered what many of you have point out - the sheer amperages that may be encountered. Also, like was mentioned, I could just pull the Anderson if a major problem was encountered.

 

[North American Sojourner]

Good people,

I have a question regarding circuit breaker sizing.

I’ve direct-wired a 4-gauge wire to my 2005 Silverado. Positive to a terminal block under the hood designated for jumper cable clamping. Negative to the block. On the other end is an Anderson connector, which is on the front of my truck.

I’ve taken a pair of jumper cables and cut one end off, adding an Anderson connector. The idea being that I can perform jumps more efficiently.

What size circuit breaker should I add to the positive terminal wire? Any need? My concern is two-fold. One, a wire short to ground under the hood (unlikely given my routing and the insulation thickness. A second concern is an overload of sorts between vehicles.

I’ll try and add a picture later.

Thoughts? Hope this makes sense.

KG

I understand what you're trying to do. My opinion is this. Jumper cables are responsible for most of the battery, alternator, fusible link and possible ECU/PCM damage in cars and trucks. I've seen it all. I'd get a NOCO Boost GB40 which will tell you the unit is attached wrong, and that will prevent your buddies, Uncle Fred, or the kids from hooking up the cables wrong.
Best $100 you could spend. I've had mine for 6 years and it's awesome.
Zim

 

[smritte]

Had a couple in the shop over the years that happened to. Nice way to take out a few computers quick.

Love my Genius chargers

 

[madcratebuilder]

I understand what you're trying to do. My opinion is this. Jumper cables are responsible for most of the battery, alternator, fusible link and possible ECU/PCM damage in cars and trucks. I've seen it all. I'd get a NOCO Boost GB40 which will tell you the unit is attached wrong, and that will prevent your buddies, Uncle Fred, or the kids from hooking up the cables wrong.
Best $100 you could spend. I've had mine for 6 years and it's awesome.
Zim
View attachment 229971

This is great advise. I have not used jumper cables since buying a boost box. I do have a Anderson setup for my winch that can double as a jumper cable but the boost box is so much quicker and easier.

 

[Shawn686]

You also need to consider vandalism

Its up to you if you want a not protected always hot direct to battery connection accessible form the outside of you truck. It also depends of where you go, always in the bush probably not an issue. Downtown Seattle, probably more of an issue.

I have both, regular cables and a booster pack. The pack gets used more.

Shawn

 

[Ubiety]

Downtown Seattle

Does anybody go there anymore? We don't and nobody I know from the Eastside does. Only time when we go to Seattle is to visit my folks in an area that is still safe. It's a utopia I tell you ;)

 

[Shawn686]

Does anybody go there anymore? We don't and nobody I know from the Eastside does. Only time when we go to Seattle is to visit my folks in an area that is still safe. It's a utopia I tell you ;)

It was the "shiftiest" place I could think of off the top of my head lol, got to get some chop

Shawn