Which jumper cables

[RayIN]

The reason for larger wire is to reduce voltage drop with distance. The length of the cables needs to be considered as well. The voltage drop in the cable is the product of the resistance of the cable multiplied by the current flowing at that time. Any resistance due to corrosion at the battery terminals or the wires attaching the clamp will also drop voltage. The condition of the batteries themselves can also limit current flow. This is really not a simple question but the generic answer would be bigger is generally better. Of course you can always build your own cables out of even bigger wire. Generally welding cable is more flexible than regular stranded cable.

Yep, this is a particular problem with DC voltage.
I have a very old set of homemade 20' jumper cables made from welding cable and steel clamps my FIL made perhaps 60 years ago. They still are in great condition, and the extra length is very convenient on the farm.
In fact length/distance is the reason AC electricity won out over DC electricity for wiring long distances.
reference: War of the currents - Wikipedia

 

[sandman2234]

Fifty years ago I helped a stranded young lady home, both of us driving Chevy Novas (67&70). Her alternator quit...no cables. Bumpers touch & coat hangers + to +. She would go a couple miles on battery, pull over, jump, start, repeat. It took five times but it worked & she got home safely.

I did that with a clothes hanger also, to a 70 Nova with my 68 Charger! Wonder if it was the same lady?

 

[JWR]

Yep, this is a particular problem with DC voltage.
I have a very old set of homemade 20' jumper cables made from welding cable and steel clamps my FIL made perhaps 60 years ago. They still are in great condition, and the extra length is very convenient on the farm.
In fact length/distance is the reason AC electricity won out over DC electricity for wiring long distances.
reference: War of the currents - Wikipedia

Sorry Ray but that is not the case. Voltage drop across given length of wire for a given amount of EFFECTIVE current is the same be it AC or DC. There are probably a dozen reasons that AC is predominantly used worldwide for long distance power transmission as well as local distribution to the final user. Length/distance was not the big reason or the issue. The distances with power transmission are in miles not a few feet and with very different kinds of problems than battery cables have. The losses for a given amount of power transmission are proportional to the effective current involved. In the case of DC that is just simple amperage. In the case of AC it is RMS amperage. The effective voltage for AC is the RMS value of voltage and that computes easily for power calculations, etc. just like DC fixed voltage would. HOWEVER one of the big reasons for using AC transmission is that there is no physical force between two parallel conductors with AC. Energize them with very high voltage and current and they do not pull at each other, suddenly grab together or force each other apart. The problem with DC transmission is they WOULD force each other apart or together (and with more force the greater the current) creating all sorts of mechanical and physical problems for transmission. DC is very unsatisfactory for transmission plus creating other issues even after the energy gets to the user. There is no such thing as a DC transformer (to convert voltage up or down) for example like you do easily with AC transformers. On and on. I won't go into other reasons favoring AC transmission but there are many including the size of the conductors required, the predominance and advantages of synchronous rotating machinery and universal transmission of synchronism uses like clocks and other devices besides motors.
Don't believe everything you read on Wiki (though it is an extremely valuable information resource.)

 

[Fuddyduddy1952]

Now it sounds to me like there must be more interesting details in your rescuing a stranded young lady in distress...

I knew someone would say that , and she was pretty...but I've always tried being a gentleman, imagining what if it was my wife, Mom, etc. How I was brought up I guess.

 

[JWR]

I knew someone would say that , and she was pretty...but I've always tried being a gentleman, imagining what if it was my wife, Mom, etc. How I was brought up I guess.

I was expecting you to say she became your wife...making a good story no matter which way it is told. All good.

 

[RayIN]

Sorry Ray but that is not the case. Voltage drop across given length of wire for a given amount of EFFECTIVE current is the same be it AC or DC. There are probably a dozen reasons that AC is predominantly used worldwide for long distance power transmission as well as local distribution to the final user. Length/distance was not the big reason or the issue. The distances with power transmission are in miles not a few feet and with very different kinds of problems than battery cables have. The losses for a given amount of power transmission are proportional to the effective current involved. In the case of DC that is just simple amperage. In the case of AC it is RMS amperage. The effective voltage for AC is the RMS value of voltage and that computes easily for power calculations, etc. just like DC fixed voltage would. HOWEVER one of the big reasons for using AC transmission is that there is no physical force between two parallel conductors with AC. Energize them with very high voltage and current and they do not pull at each other, suddenly grab together or force each other apart. The problem with DC transmission is they WOULD force each other apart or together (and with more force the greater the current) creating all sorts of mechanical and physical problems for transmission. DC is very unsatisfactory for transmission plus creating other issues even after the energy gets to the user. There is no such thing as a DC transformer (to convert voltage up or down) for example like you do easily with AC transformers. On and on. I won't go into other reasons favoring AC transmission but there are many including the size of the conductors required, the predominance and advantages of synchronous rotating machinery and universal transmission of synchronism uses like clocks and other devices besides motors.
Don't believe everything you read on Wiki (though it is an extremely valuable information resource.)

How then is 24VDC changed into 12VDC if not by a transformer? That was performed on commercial bus's 50 years ago.

 

[ning]

I run this type of jumper cables. One end hard wires to your battery, Anderson plug on the other end. Then a long set of jumper cables to dead battery.

View attachment 2099991

Anderson Plug on truck side
View attachment 2099992
Battery cables stored in side box.

View attachment 2099993

Jumps tractors, vehicles, etc. great!

I have a similar setup on my older F350 - 2/0 all-copper to anderson connectors at the front and rear bumpers

can connect winch or jumpers to either end very quickly without looking at a battery.

 

[LittleBill21]

Personally I feel Jumper cables are a waste of time anymore. I own a pair, Don't even know where they are.

yes they are cheaper, generally but it does require another vehicle or machine be able to get close enough to jump, that doesn't seem to happen for me most times.

lithium based battery jumpers are substantially quicker and easier to use, yes they cost more and you have to watch the charge on them, but unless your planning on cranking for 20s. they seem to be easier.

Amazon.com

 

[JWR]

Replying to post #26 There is no such thing as a DC transformer. Any transformer involves a primary and secondary coil and requires change in current flow (dL/dt being rate of change and that has to be non-zero to create the fluctuating electric field in a transformer) at some frequency back and forth to create the electric field between primary and secondary coils. Typical DC voltage converters in the old days used an "inverter" which converted the DC to AC , did the transformer parts while AC and then converted it back to DC. I'm not sure of the technology used back in the old days (many were outsized boxes with a motor inside) but like now, most of us have a 120v AC outlet in our trucks and cars. That uses a modern solid state inverter with DC driven electronic switching to create AC from the DC of the battery and then steps the AC up to 120v. Note: a rectifier is required to convert the output of your alternator to DC to then charge your battery.

 

[JWR]

Personally I feel Jumper cables are a waste of time anymore. I own a pair, Don't even know where they are.

yes they are cheaper, generally but it does require another vehicle or machine be able to get close enough to jump, that doesn't seem to happen for me most times.

lithium based battery jumpers are substantially quicker and easier to use, yes they cost more and you have to watch the charge on them, but unless your planning on cranking for 20s. they seem to be easier.

Amazon.com

Your preferred route is to carry some form of spare battery around with you. I know that works but is of limited practical use with small cramped vehicles, is vulnerable to not being charged up when you need it the worst, etc. There is still a lot of use for jumper cables for most people.