What makes good car jumper cables? (Bonus: Sena TYP 200 Amper test) - Page 1
Forum section: electronics / general

author: golden_labels
author_rank: Super Contributor
timestamp: April 28, 2025, 01:41:35 am
content: I have been talking with a friend about car jumper cables recently.I myself have a pair that I got as a gift. In the spirit of not complaining about questionable quality gifts, I thrown them into the trunk and never looked again. Today I took a closer look. The results are not the topic here, so I only share them below. But both talking with the friend and looking at those I have, made me think:what properties would we expect from good jumper cables?Of course the first thought is carrying current big enough to start another car. But then some other thoughts appear. Current capacity is limited by the relatively poor attachment. 50 A with 50 mΩ resistance between jaws and the battery (×4) is a 10 V drop. Then comes donor car’s installation. Cranking takes a few seconds, but we usually pre-charge the other car’s battery. And the donor car can’t be sunken by that. Which means we’re to some degree limited by balancing what our own alternator can produce and the electric installation deliver, and what the other car draws. Finally, safety. Whilethis accidentwas caused by wrong polarization, I can easily imagine unlimited 200 A would not end much better.So do we really want possibly low-resistance cables? Or perhaps lower current capacity is a sane balance?The test(edit on 2025-04-29, corrections from thesecond test)Jump cables I got are EAN 5901299004920 (“Sena TYP 200 Amper”), currently sold for about 6€ or $7. Each shows about3018 mV/A clip-to-clip, so the total of60just under 40 mV/A. Meaning that at 200 A they are a2.41.6 kW heater.The construction is:Copper-plated steel, based on attracting magnets and rust.Fake copper wire. The copper color is only on the surface, under it the wire is silver in color.The cable is about 7.5 mm in thickness. The insulation takes about 4.8 mm of that, so the wire must be something around205 mm².Attached not by crimping, but by folding-under strands and using the crimp to press into insulation. It seems the tool was also unsuitable for this terminal: it didn’t bend the leaves all the way in, while itself still being driven into insulation.Jaws are poorly aligned.The jaws already show copper oxidation and rust.Photos in the attachment.The setup:Voltage drop (right meter) between clips measured while feeding 1 amps to 5 amps. Final value read from linear regression of the 5 points collected.

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 28, 2025, 02:12:37 am
content: Wouldn't those lithium jumper packs make more sense nowadays? Or a supercap one if you really want to be fancy.

author: bdunham7
author_rank: Super Contributor
timestamp: April 28, 2025, 03:05:33 am
content: Quote from: golden_labels on April 28, 2025, 01:41:35 amYou have to decide if you want to be able to start a car with a discharged battery or if you just want to charge up the dead battery from another running car. Cables that do the former are typically 4-6AWG with large steel-body clamps, strong springs and copper contact jaws. Yours would collapse onto the floor into a smoking line of burnt plastic. One note--if you're going to do resistance measurements on those crap cables, measure using the side of the jaw that is attachedto the cable as the connection between the two jaw halves can be poor. Typically both sides will contact the battery terminal so that connection won't matter, but if you happen to get a bad connection with the cable-side jaw you might see sparks at the joint.

author: wilfred
author_rank: Super Contributor
timestamp: April 28, 2025, 05:31:25 am
content: A few seconds to start sounds like a long time. Even my 25+ years old car will start in a fraction of a second. The longer it takes to start the car the longer the cables will have to heat up and increase resistance or start to smoke in the extreme case. Not to mention the starter motor. So you ideally want good cables to maximise your chances.That said even those cheap cables are OK if you just left the lights on and drained the battery. If you just need to get some juice across to make up for a drained battery I wouldn't be too concerned. But if you have a dead battery or none then your cables need to be able to supply starting current for as long as needed before heating up. If you ran the car out of fuel then you'll be cranking until the fuel system is primed.I would say good cables are long enough to cover any vehicle-to-vehicle position in a parking lot so 3-4meters as a minimum, cheaper ones with CCA or copper coated aluminium are not great when they get longer and so are sometimes as short as 2m which will require repositioning vehicles to get the batteries close together. If you will be cranking a difficult to start car for any length of time then silicone insulation is not going to melt or burn like PVC can. And a copper strap right to the tip of the clamp is good.But a 5-6meter thick copper cable is not going to be cheap. And it will be bulky. So for most people a lithium jump pack to top up a weak or drained battery will work fine most times and being lithium it will hold a charge in standby for quite a while. Even a cheap one, will get you out of trouble quickly if you return to realise you left the lights on or the battery is getting old. You also don't need to have someone else available to connect to.

author: jpanhalt
author_rank: Super Contributor
timestamp: April 28, 2025, 06:04:44 am
content: The jumpers I have been using a very long time are made from neoprene rubber-insulated welding cables. Thay are swagged into copper welding clamps (like the ground clamp). They are #2 gauge. I made them back in the early 80's when jumping required a lot of amperes in Minnesota Winters. They stay nice and flexible in all weather.Modern cars don't require such current, but the flexibility in all conditions is very nice. So, I would still recommend that basic construction and go a gauge or 2 smaller, unless you are jumping trucks. They are also 20 ft long, so one can reach a parked car impounded by snow easily.

author: golden_labels
author_rank: Super Contributor
timestamp: April 28, 2025, 07:50:38 am
content: Quote from: NiHaoMike on April 28, 2025, 02:12:37 amThe question is about jumper cables, explicitly. This is the scenario to consider.But, replying to this option: depends. For a car assistance business? Certainly. For a typical driver? I’d say it’s wasteful. Financially, maintenance-wise, regarding resource use, and in ecologic sense.Quote from: bdunham7 on April 28, 2025, 03:05:33 amThe question makes that decision:“Of course the first thought is carrying current big enoughto start another car.”Quote from: bdunham7 on April 28, 2025, 03:05:33 amYes, as noted:“Meaning that at 200 Athey are a 2.4 kW heater.”Also:“The cable is about 7.5 mm in thickness. The insulation takes about 4.8 mm of that, so the wire must be somethingaround 20 mm².”(20 mm² ≈ 4 AWG)Quote from: bdunham7 on April 28, 2025, 03:05:33 amGood point. In the photo one clamp is attached on the other jaw. I’ll redo the test. Perhaps 60 mΩ matching the model name perfectly is just a coincidence and I was to happy to ridicule that.Quote from: wilfred on April 28, 2025, 05:31:25 amUnder normal conditions, yes. But under normal conditions jump cables are not used, are they?Quote from: wilfred on April 28, 2025, 05:31:25 amYes, as stated in the question:“Of course the first thought is carrying current big enoughto start another car.”This is obvious, but the question goes further.Quote from: jpanhalt on April 28, 2025, 06:04:44 amIndeed, going for thick cables was my first thought too. But I had more thoughts. Not being able to address those, I asked the question here.

author: tom66
author_rank: Super Contributor
timestamp: April 28, 2025, 10:19:04 am
content: It was my understanding the approach for jump-starting a car is to connect the two vehicles together for about a minute before attempting to start the dead vehicle. This means that the battery in the dead vehicle should have some charge in it. And therefore the jumper cables shouldn't have to carry hundreds of amps.Of course, this won't help at all if the dead vehicle has a battery that is too degraded to function as a starter.I don't have an ICE car any more but I still carry around a lithium jump pack in case someone at the office gets stranded or in the unusual case of the 12V in my car running dead. I can't even use my car to jump another car: the battery is only rated to about 20Ah, so its peak discharge current is around 100A, and the manual explicitly warns against using it for any jump starting. The same was true of my hybrid, whilst it did have an ICE, it did not use a 12V starter motor, everything started from the HV battery. So jumper cables to me aren't all that useful!

author: AVGresponding
author_rank: Super Contributor
timestamp: April 28, 2025, 10:28:39 am
content: The lithium packs are a lot better than most people realise; I certainly was surprised by a recent experience, and this vid surprised me by how far they've come, also:

author: Berni
author_rank: Super Contributor
timestamp: April 28, 2025, 10:40:30 am
content: Yeah fake and underspeced car jumper cables are all to common because proper ones need thick copper and copper is expensive these days.That being said, you can usually still jump start a car with even very crappy jumper cables.In most cases the battery is just empty but still working. So all that is needed is to give it a quick short charge over the cables, then the car can start even with the jumper cables disconnected. So as long as you are patient and leave the donor car running for a minute or two with cables connected you could jump it even with small cables from a lamp cord (Tho that does pose a fire risk as that cord could get pretty toasty).But yeah with good jumper cables you can just hook them on and crank it 1 second later and it will fire up as they can give the full cranking juice (even if they do loose a few volts along the way). Also a big difference is what you are trying to crank over is a little 1.2 liter petrol engine or a big 3 liter diesel in a cold winter night. Not only are diesels much harder to turn over, they are even harder to turn over when cold and they pull easily 100A before even cranking to heat up the glow plugs.

author: golden_labels
author_rank: Super Contributor
timestamp: April 29, 2025, 06:31:05 pm
content: Thanks for the replies. While I’m open to debating your preferred choices of jump-starting a car, this wasn’t my question.As I said in the first post, I was talking with a friend about jumper cables (and jumper cables only) and I had my specific doubts (which I listed). This is the scenario I’m interested in. All input on jump starting a car is great. But I want to understand, if and where I make mistakes with reasoning, or how exactly different concerns affect the problem. This is a purely technical question, not really related to car emergencies.To answer new posts and clarify something: neither jump cables nor starter kits are that necessary. I live in a reasonably civilized country. I can just call assistance, which is paid for as a part of car insurance anyway.⁂Also, an update. Asbdunham7suggested I redid the measurements. He was right. Attaching probes on the wire side jaw yields a result 1/3 lower than what I initially got. I also checked in two other points. The complete result:Normally I would not put so much effort into it, but I felt obligated, given the possible (and now confirmed) mistake. The number of datapoints comes from the first attempt (5 points) showing weird, still unexplained deviation from the expected line. Now, with 20 points measured in random order, it’s a line with 0.999 Pearson coefficient, and even 0.99 CI being tight.

author: nctnico
author_rank: Super Contributor
timestamp: April 29, 2025, 08:05:45 pm
content: Quote from: golden_labels on April 28, 2025, 01:41:35 amNot to nitpick, but I get to 5.7mm² . 7.5-4.8 = 2.7mm diameter. Circle area = r^2 * pi -> (2.7/2)^2 * 3.1415 = 5.7.Either way, that wire is way too thin for 200A.

author: golden_labels
author_rank: Super Contributor
timestamp: April 29, 2025, 09:39:36 pm
content: I should have trust my eye and gut feeling, instead of measurements.I suppose I was too tired and my brain picked up “4.8” as the wire diameter. Thanks, corrected.Bonus: the insulation is not even symmetric. Depending on where I measure it, it’s between 1.8 mm and 3 mm.

author: u666sa
author_rank: Frequent Contributor
timestamp: April 30, 2025, 12:55:52 am
content: "Welding cable" that's the key word here. You have to find some welding cable. You have to find some crocodiles, and you make a proper jumper wires. Quality of this setup will be comparable for some high-end jumper wires for triple digits, made in the USA or even Japan.As far as jump packs. That's the future. But keep in mind, there is a risk of self starting fire. So you shouldn't store one within your car, inside your garage, or inside your home.

author: golden_labels
author_rank: Super Contributor
timestamp: April 30, 2025, 01:32:12 am
content: I’m repeating this the third, last time:I do not seek advice on jumper cables.This isan engineering question.I ask about the factors taken into account in their construction,addressing the concerns givenand possibly other issues (if there are any).

author: David Hess
author_rank: Super Contributor
timestamp: April 30, 2025, 03:31:15 am
content: Even weak jumper cables are usually sufficient because a majority of the current for the starter will be provided by the rapidly recharging starter battery. If the battery is cracked so high impedance, then weak jumper cables may not be enough.Alternators are not really designed to recharge flat batteries; the high charging current may last long enough to damage the alternator and I estimate that at least half of my alternator failures occurred due to this. Any jumper cables make this situation easier because of their own non-zero impedance from their wire resistance and questionable clamps. With that said, my own preference is the heaviest duty jumper cables possible. I especially look for good clamps.Quote from: wilfred on April 28, 2025, 05:31:25 amCarbureted engines in good condition can start within one revolution of the crankshaft. (1) Engines with computer management may usually take much longer because of the computer programming. For instance they may need to synchronize with the crankshaft and camshaft sensors.(1) When I had a carbureted engine, if it did not reliably start in within one revolution, then I knew something was wrong.

author: joeqsmith
author_rank: Super Contributor
timestamp: April 30, 2025, 12:20:07 pm
content: Quote from: golden_labels on April 28, 2025, 01:41:35 amFirst criteria, they work, meaning they allow me to jump start. If I buy a dish washer, first criteria, it cleans dishes. Connections to the cloud and other deterrents that prevent me from getting that basic job done are out.I have used jumpers maybe 10 times over my life. They survive in the car. for me, this means wide temperature and humidity changes. They don't get uncoiled often. Rust isn't a problem as that will all be burned away when you use them. I don't care too much if I need to wait a couple of minutes to start. I don't really care about their weight. I guess rubber insulators that remain in place over the years on the clips. Strong springs in the clips and teeth to cut into the deep oxidation.I have a diesel truck with two batteries. Starting that with no wait time vs starting my motorcycle, big difference. Just getting the preheaters warm takes a bit....Yes, I have jumped motorcycles before. This is why I want the insulation on the clamps!

author: u666sa
author_rank: Frequent Contributor
timestamp: April 30, 2025, 12:56:23 pm
content: Quote from: David Hess on April 30, 2025, 03:31:15 amWeak cable -- you connect it, crank up the donor car, and wait, maybe even press gas pedal and wait. Then you crank the dead car. Perhaps you need to wait longer if first time isn't the charm.Good cables -- you connect it, crank up the donor car, and then crank up the dead car, and it works the first time around.Usually the donor car is somebody you don't know, so they won't be waiting around. Thus the conundrum with cheap wires. And cheap wires are just insufficient wire gauge, during cranking wires act as current limiting resistors, and your jump cables simply work differently. If you have resistors there, you have to wait to charge the dead battery, which maybe not even be possible if it's too dead. If you don't have any resistors, like is the case with welding cables, you will start even with dead battery.

author: joeqsmith
author_rank: Super Contributor
timestamp: April 30, 2025, 03:11:46 pm
content: https://www.caranddriver.com/car-accessories/g43439484/best-jumper-cables-tested/Google image search, all the photo I saw show top mount. The clamps can get a good bite down on them. My truck for example uses side mount. The jaws at best may get a few teeth on on side only.Note the use of vice grips to interface from the battery terminal to the jumper cables.I guess you could get that battery terminal hot enough to melt the lead and plastic.

author: David Hess
author_rank: Super Contributor
timestamp: April 30, 2025, 04:07:55 pm
content: Quote from: joeqsmith on April 30, 2025, 03:11:46 pmI hate side terminal starter batteries. What were they thinking?The side terminals on my 2002 pickup corroded such that the only way to replace the starter battery was to cut the battery cables. It was easier to splice in cable extensions than to replace the starter and charging wiring, and then I used bronze battery clamps intended for marine applications. It works like a charm, but replacing the battery means explaining to the store why I need a top post starter battery.

author: Berni
author_rank: Super Contributor
timestamp: April 30, 2025, 05:27:58 pm
content: I have never seen a car battery with terminals on the sides like that. Maybe it is more of a thing on american cars.But yeah pretty much no jumper cables are made to withstand the 100s of amps starting current continuously. The cables would need to be the size of a large garden hose each and the clamps made out of milled copper blocks. But that's okay, they only need to hold the worst of the current for a few seconds, so 20 mm2 cable will definitely hold for long enough to start a car no problem, Even started a diesel with 2.5mm2 cables in a pinch (but they can get rather toasty).As cables get thicker they get so much thermal mass that you can overload them to easily 10x their rated current for quite a few seconds and they get just pleasantly warm.Have a look at the size of the wire in the stater motors windings, it is not very thick at all, since it is designed to operate for just a few seconds and then have a long time to cool off again. So in a lot of cases you would burn up the windings in the starter motor before the jumper cables would melt if you kept cranking it for a really really long time.

author: joeqsmith
author_rank: Super Contributor
timestamp: April 30, 2025, 06:17:38 pm
content: Quote from: David Hess on April 30, 2025, 04:07:55 pmEarly article about the side mount battery:https://www.automotive-fleet.com/147175/new-batteries-for-gms-71s

author: joeqsmith
author_rank: Super Contributor
timestamp: April 30, 2025, 06:34:36 pm
content: Quote14AWG seems a bit small.I've never looked at what my truck draws but here is an expert in the forums:QuoteI have a few sets of cables laying around. These would all be fairly old now. I'll see how well they are constructed and take a few photos.

author: joeqsmith
author_rank: Super Contributor
timestamp: April 30, 2025, 06:57:14 pm
content: This guy is into testing his jumper cables... I think I would just run them like I did with the DMM test leads. CC source and ramp it up.

author: floobydust
author_rank: Super Contributor
timestamp: April 30, 2025, 07:05:28 pm
content: In the 80's it was 6L+ V-8's getting a boost at -30°C or colder. We all had musclecars and big trucks.I made cables with #4AWG copper welding cable (still flexes when cold) and parrot clamps (crimped and soldered) which have high pinch force, maybeby Grotebut it was long ago.Extra cable length so you can boost a vehicle when you can't get in close to their front i.e. you are parked behind it.So these worked great for decades, kinda big and heavy but I've only used them a dozen times. Still keep them in the car but once a creep asked for a boost in a dark alley and I did not help - found out later he was robbing good Samaritans.Modern cars with small 4-cylinder engines and the chinese cables out there with copper-coated aluminum wire maybe #6AWG is OK for light use but they will heat up and can smoke if you are troubleshooting a car for not starting and cranking a lot.You want low voltage drop because ECU's can cutout at low cranking voltages. I thought SAE standard is 6V for a 12V vehicle but will check. Typically a boost-converter is in the ECU so some even 4V it's still alive but spark must be pretty weak.Another thing to know, is that full throttle (pedal to the floor) seen during key-on and cranking the ECU will shutoff fuel injectors as if the engine is flooded. At low temps very easy to flood an engine because mixture is so rich, so if it doesn't catch right away and you keep cranking - it's never going to start, it's soaked.Just be off the throttle quick when the engine does start so it does not over-rev. This tip can save you a tow to a garage.

author: nctnico
author_rank: Super Contributor
timestamp: April 30, 2025, 07:11:06 pm
content: Quote from: David Hess on April 30, 2025, 04:07:55 pmDo I spot soldered crimps? And a tinned wire under a screw clamp? And why no ferrules over the wires before clamping them down? I hope this was temporary...

author: David Hess
author_rank: Super Contributor
timestamp: April 30, 2025, 08:50:56 pm
content: Quote from: nctnico on April 30, 2025, 07:11:06 pmThere are no soldered crimps, or crimps at all. One of the cable ends is tinned under the screw clamp. The others are not because there are two cables and if I tinned them, they would not fit together under the clamp. No ferrules were used because then the clamps would not fit. This situation is somewhat temporary, and I deliberately left enough slack to cut the ends off and do the clamp connections again. I have an idea for the dual cables, but I suspect you will not approve of it.What cannot be seen is where I spliced the cables together. Originally I was going to crimp and solder ring terminals on each end, bolt the ring terminals together, and then insulate, however there was not enough space and length for this to work. Instead I stripped the cables exposing about an inch of stranded copper, placed the exposed copper side-by-side, tightly wrapped them in bus bar wire, soldered, and then insulated with heat shrink tubing.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 02, 2025, 01:03:02 am
content: Here is a set my wife bought for her first car. That car was stolen and when it was recovered and totals, she recovered the cables. So very old. Cutting off a strand and shaving it, pure copper.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 02, 2025, 01:07:46 am
content: You think yours are corroded have a look at mine.Also for people outside of the USA, shown is one of the two side mount batteries in my truck. Removed a clamp off the pos, but keep a trickle charger attached. You can see the problem grabbing on.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 02, 2025, 01:13:33 am
content: A better shot of the rusty jaws for those with a jumper fetish. That rust will burn through when they arc to the terminal, no problemo.

author: golden_labels
author_rank: Super Contributor
timestamp: May 02, 2025, 03:01:43 am
content: Well, I’m going to assume the thread deviated from what I hoped it to be. Let’s continue.I never seen side terminals. Only on top here (Poland). The article mentions protection from environmental factors as the advantage. But I don’t see, how would that work. Batteries are under the hood, covered from direct water splashes. And everything else surrounds the battery equally. HMMMMM!Jumper cables are obviously not rated to withstand 100s A continuously. That I never doubted. But heating is not the only problem. They also can’t drop voltage too much.Yes, as mentioned above, cranking up should take at most a few seconds. If not of what happens inside the engine, then because the starter is not designed to run for long.Thanks, Joe, for sharing the photos. Now I don’t feel that bad about mine!I still don’t feel right about the vendors selling such stuff, though.

author: bdunham7
author_rank: Super Contributor
timestamp: May 02, 2025, 04:02:57 am
content: Quote from: joeqsmith on May 02, 2025, 01:07:46 amThere are special jumper cable clamps that are made for side terminals.https://www.ebay.com/itm/185382947361

author: joeqsmith
author_rank: Super Contributor
timestamp: May 02, 2025, 12:57:33 pm
content: Quote from: golden_labels on May 02, 2025, 03:01:43 amI guess you would need to have lived and been working on cards in the 1960s/70s in the USA to have a feel for the problems GM was trying to solve with the side mount.QuoteI have not seen a car battery with the screw on caps to service them since the 80s. Battery life without any service on my part now seems to be in the 7-8 years.QuoteI have not pulled a terminal and wire brushed the contacts on my vehicles since the 80s. It seems like that used to be a common practice.QuoteRather than the side mount terminal, I suspect the change to maintenance free had the biggest impact on battery life.Quote from: golden_labels on May 02, 2025, 03:01:43 amI could easily place the two cables in series and push a couple hundred amperes through them as see what sort of drop we get. I think I would want to get some lead automotive terminals to give them a fair chance (something to bite into).

author: joeqsmith
author_rank: Super Contributor
timestamp: May 02, 2025, 01:03:52 pm
content: Quote from: bdunham7 on May 02, 2025, 04:02:57 amI'm not sure they would work any better and the long side nose may get in the way when using them for a top mount. S-Side, T-Top. I guess you could carry T-T, S-S and T-S cables to cover your bases. Better to have a one size fits all.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 04, 2025, 12:05:40 am
content: Sweeping my rusty old cables. Ran at 20, 80 and 180A for roughly 40 seconds at each level. Cables are in series. Showing the voltage drop, current and power dissipated by the cables.It's a lot of thermal mass so after test they were warm. Most of the heat is at the poor connection points.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 04, 2025, 12:26:20 am
content: Sweeping from 5-100A, 5A steps, 15 seconds per step. Showing voltage drop, power, current and resistance. I would imagine if these were cleaned up a bit and I had something soft for them to bit into we would improve the drop. Really though, what do you do when you jump? You move the jaws around to get them to bit in. You can hear the running vehicle take on the load.Not sure if this was helpful but I don't see a problem pulling a couple hundred amps through these cables for more time than it should ever take to get the engine started.

author: David Hess
author_rank: Super Contributor
timestamp: May 04, 2025, 12:51:45 am
content: Quote from: NiHaoMike on April 28, 2025, 02:12:37 amA booster pack might make sense, but costs more than jumper cables. Of course if it is your own vehicle that needs a jump start, then jumper cables are useless without another vehicle.When I was traveling in my pickup a couple years ago, I bought a BLUETTI EB3A power bank and a NOCO GENIUS10 10 amp charger. If I ever found myself with a dead battery, I figured I could charge it for a short time, and a 10 amp charger meant I could do it through the accessory circuit. Of course this would not do anything for a starter battery which failed with a cracked cell.

author: golden_labels
author_rank: Super Contributor
timestamp: May 04, 2025, 01:30:47 am
content: joeqsmithThanks for the test! Yes, clearly yours are perfectly suitable for the job.Do you know, why is resistance dropping with increasing current or time?David Hess:Above all, in most developed countries both jump cables and packs are a mere convenience, not a necessity. Exceptions would be living in or traveling through the middle of nowhere (I look at Australia now). This is because assistance services are available and they may be included in the insurance costs. They will drive to you and offer a set of fully-charged, working jumper packs. If those are not enough, they have jumper cables and a suitable power source.So having either jumper cables or packs is mostly a convenience. You don’t need to wait for help. Though it’s a matter of whether you can find somebody willing to share power with you, if you only have the cables. You also can give a helping hand to other unfortunate drivers.Power packs have some notable drawbacks. Jump starting a car is a very rare occurrence. But they require a lot of resources, which could otherwise be better spent. They cost you money, which could also be better spent. Both their ecological footprint and conflict resources footprint are much bigger, and they have relatively short life-span, requiring multiple replacements over our lifetime. You also need to keep them charged, there is a problem with storing them in a hot car, and most buyers have no way to tell product’s quality. Not counting the fire hazard, because improperly connected jumper cables can lead to equally bad outcomes.I don’t want to say they’re useless, even for a typical driver. But I don’t believe we can clearly say one is better than the other.

author: David Hess
author_rank: Super Contributor
timestamp: May 04, 2025, 02:58:35 am
content: Quote from: golden_labels on May 04, 2025, 01:30:47 amThere are plenty of areas in the US which are far from services, and it is not difficult to drive more than 300 miles without passing a gas station if you do not pay attention. In my travels I ended up spinning out on US-395 in California, south of Alturas, during an ice storm stranding myself. (1) Everybody else on the highway did also. Roadside assistance was useless because of how towing companies are organized now, with plenty of scams going on. I had to arrange local help myself.Several times I have helped people in the US stuck far from services.Besides my power bank and charger, I carry a complete ratchet and box wrench set, two small bottle jacks, and a floor jack. I am in the process of adding front tow points which would have been very handy that night.(1) This event convinced me to install a weather station in my vehicle to better monitor outside conditions. I have an Ambient Weather WS-2700 strapped to the inside of my passenger side visor.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 04, 2025, 04:17:49 am
content: Quote from: golden_labels on May 04, 2025, 01:30:47 amI don't. However, we are talking about a 0.005 ohm change. We are also dealing with a lot of oxidation on basically a few point contacts. I would not be surprised if what you are seeing is some of that oxidation burning off (***potentially welding) as we increase the current. At 180A the load (jumper cables) is not stable and the PID is having a difficult time providing a constant current.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 04, 2025, 03:41:25 pm
content: To try and minimize the change in resistance resistance some braid will be clamped into the fixture. A third section will be used to connect the two ends together (still running the cables in series). The braid will give the clamps something to bite into rather than a few point contacts. The US quarter gives you some idea of the scale.I straightened all of the teeth allowing the jaws to close. Electrolysis was used to remove the heavy buildup of oxidation from the clamps. After cleaning the first clamp, I noticed a sight amount of copper plate remaining.

author: nctnico
author_rank: Super Contributor
timestamp: May 04, 2025, 04:09:40 pm
content: Quote from: golden_labels on May 04, 2025, 01:30:47 amThe downside is that these take long to arrive (hours if you are unlucky). Even though I don't venture into outback Australia with a car, it is very handy to have a set of jumper cables on hand. So I can ask somebody for help in the parking lot of a supermarket to help jumpstart my car. Takes only 5 minutes and you are on your way. Shorter than it takes to make a phone call to the insurance company. For the same reason our cars have real spare tires. Being prepared / self sufficient gets you going again much quicker.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 04, 2025, 05:50:05 pm
content: With the jaws cleaned up, next attempt to plate Cu back onto them.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 04, 2025, 06:41:04 pm
content: Shown with the new test setup and cleaned cables running at 200A for 5 minutes. Hopefully your car would start by then. Resistance increases 0.001 ohm as the cables slowly warm up. Cables are dissipating about 500W during this time, but again, its a lot of thermal mass.So, no problem for a very old set of cables to hold 200A for an extended time.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 04, 2025, 06:49:47 pm
content: Next I swept the cables from 2.5 to 50A with a 5 second dwell. I repeated this 4 times back-to-back to get some idea how repeatable they behave.Note that the resistance still drops. So, it does not appear to be from the point contacts, welding, oxidation.... Guessing now that is is some non-linearity errors. I am only doing a point slope. Really need to collect several points and fit it.If you are wondering why the resistance is dropping as I continued to run it. I did this right after running that 200A test and the cables are cooling.Of course, none of this has anything to do with the criteria of being able to jump start your car.

author: golden_labels
author_rank: Super Contributor
timestamp: May 04, 2025, 07:40:10 pm
content: Quote from: joeqsmith on May 04, 2025, 04:17:49 amEarlier I mentioned that“The number of datapoints comes from the first attempt (5 points) showing weird, still unexplained deviation from the expected line.”The deviation was the resistance falling towards the end of the test. I didn’t give it much of a thought, assumed my mistake, repeated the test in a more robust and careful manner, obtained a flat line, and forgot.But now I see the same situation in your measurements. So I checked my raw data from the second test and surprise. If I order the points by time, I see resistance falling:This is visible only in the “C” setting, where the sense connection is right by the clip delivering current. Not in the other two, where the resistance is lower.I have some idea. I’ll test it this week, when I feel better.Quote from: joeqsmith on May 04, 2025, 06:49:47 pmOh, certainly! I just gave up on the original engineering question.And this talk about the resistance drop is another tangent. After all it doesn’t affect anything.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 04, 2025, 11:06:17 pm
content: Quote from: golden_labels on May 04, 2025, 07:40:10 pmQuoteI saw that as more a marketing question than engineering. Spot the difference.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 04, 2025, 11:12:30 pm
content: Quote from: golden_labels on May 04, 2025, 07:40:10 pmKeep in mind that these may not be related. Mine is a fairly crude measurement, assuming everything is linear. I don't take into account temperature changes. The sense wires are on the interface block. I think to improve my setup, I would drop the piece wise linear conversion for both the voltage and current.

author: golden_labels
author_rank: Super Contributor
timestamp: May 05, 2025, 12:06:10 am
content: Quote from: joeqsmith on May 04, 2025, 11:06:17 pmBut it was followed by an entire paragraph!That video makes me hurt inside. Not only because it reminds me of the electrolytes scene from “Idiocracy”, but also because I went through such situations in my professional life.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 05, 2025, 03:32:12 am
content: Quote from: golden_labels on May 05, 2025, 12:06:10 amYou really only had the one bold question, and the couple at the end. Those were more marketing questions IMO. From there, I really wasn't sure what you were looking for. There isn't much to a set of jumper cables and their purpose is fairly well defined.I guess they can have other uses. For example, part of a Jacobs Ladder death machine. Kids and their MOTs....https://www.mic.com/articles/141570/teen-morgan-wojciechowski-dies-in-youtube-jacobs-ladder-science-experiment

author: joeqsmith
author_rank: Super Contributor
timestamp: May 05, 2025, 03:51:07 am
content: I guess if you want to use them to hang up a human body, they will need to be somewhat long, flexible and strong. I am not sure about how to tie a knot using them.https://www.deseret.com/1998/8/3/19394399/man-uses-car-jumper-cables-to-hang-himself-at-concert/On a lighter note, there were some posts about using them for a tow rope as well.Seeing people don't just use them to jump start engines, you may need to think outside the box when considering requirements.

author: SteveThackery
author_rank: Super Contributor
timestamp: May 05, 2025, 10:18:45 am
content: Quote from: Berni on April 30, 2025, 05:27:58 pm"Large garden hose"? Surely they need to be about the same size as the cables attached to the battery, which of course are sized to carry the starter current. On my cars they are thinner than a large garden hoseI suppose there are two issues: the current carrying capacity, which surely doesn't require cables the size of large garden hoses; and the voltage drop across the jump cable length. Obviously this depends on how long the cables are. My copper jump cables work great and they are much thinner than a large garden hose.OP: Sorry, we are off-topic. I'm afraid I cannot comment usefully on your original question.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 05, 2025, 08:21:59 pm
content: Google AI claims:QuoteThis would be a battery cable gauge of 1/0. I would need to measure the cables I tested but I believe those are 2 or a 1 AWG high strand copper.Gauge Stranding Copper OD Overall OD LBS/ft6 266 0.192 in 0.39 in .1894 420 0.252 in 0.44 in .2142 665 0.326 in 0.51 in .3021 836 0.360 in 0.54 in .3601/0 1064 0.397 in 0.61 in .4622/0 1330 0.460 in 0.66 in .5304/0 2109 0.580 in 0.85 in .853Table of Allowable Amperage for copper conductors 50V or less with 105C rating:Gauge Amps Outside Amps Insideof Engine Space of Engine Space6 120 1024 160 1362 210 1781 245 2081/0 285 2422/0 330 2804/0 445 378

author: golden_labels
author_rank: Super Contributor
timestamp: May 05, 2025, 10:13:38 pm
content: Hey, towing a car is a good way to push start it!(At least the older ones)

author: joeqsmith
author_rank: Super Contributor
timestamp: May 05, 2025, 11:26:45 pm
content: I don't know if you could even order a sports car with a manual transmission here in the USA. Good luck pushing that automatic.

author: David Hess
author_rank: Super Contributor
timestamp: May 05, 2025, 11:48:48 pm
content: Quote from: joeqsmith on May 05, 2025, 11:26:45 pmLast time I checked, the only pickups available now in the US with manual transmissions are from Toyota and Jeep.I would only accept a manual transmission when I bought my 2002 pickup and there were lots of options then. One reason was so that I could push start if necessary, however I found out later that the GMC security system does not allow push starting.

author: u666sa
author_rank: Frequent Contributor
timestamp: May 06, 2025, 02:21:50 pm
content: Quote from: David Hess on May 05, 2025, 11:48:48 pmAAA was a thing back in 2002. Still is, I wouldn't bother with jumper cables today. You call AAA, and they come quick. Unless you live in rural area, then yes, jumper packs, jumper cables, manual transmission so you can push it and dump from 2nd gear and maybe even chainsaw in the trunk to cut occasional tree when the road is blocked.

author: bdunham7
author_rank: Super Contributor
timestamp: May 06, 2025, 02:48:34 pm
content: Quote from: joeqsmith on May 05, 2025, 11:26:45 pmStill plenty of you-shift options this year. I've no idea whether they can be push/pull started. I've heard it is tough on the bumpers.2025 Acura Integra and Integra Type S2025 BMW M22025 BMW M3 and M42025 BMW Z42025 Cadillac CT4-V Blackwing2025 Cadillac CT5-V Blackwing2025 Ford Bronco2025 Ford Mustang2025 Honda Civic Si and Type R2025 Hyundai Elantra N2025 Jeep Wrangler2025 Lotus Emira2025 Mazda 3 Hatchback2025 Mazda Miata2025 Nissan Versa2025 Nissan Z2025 Porsche 718 Boxster and Cayman2025 Porsche 9112025 Subaru BRZ2025 Subaru WRX2025 Toyota GR862025 Toyota GR Corolla2025 Toyota Tacoma2025 Toyota GR Supra2025 Volkswagen Jetta GLI

author: G7PSK
author_rank: Super Contributor
timestamp: May 10, 2025, 02:37:46 pm
content: The best jump leads are ones you make up yourself from welding cable using minimum of 35mm sq and preferably 75 mm sq. All the ready made jump cables tend to be junk.

author: David Hess
author_rank: Super Contributor
timestamp: May 10, 2025, 07:04:48 pm
content: Quote from: bdunham7 on May 06, 2025, 02:48:34 pmI would exclude electronically controlled transmission which pretend to be manual transmissions. One of the reasons to have a manual transmission is to avoid complexity which leads to unreliability and high cost of repair.Quote from: G7PSK on May 10, 2025, 02:37:46 pmI made a jumper cable like that long ago. Finding good clamps is the most difficult part.

author: DrijSkij
author_rank: Contributor
timestamp: May 22, 2025, 11:14:26 am
content: I was once given a rather cheap looking set of jumper cables. One could obviously tell that they were not of high quality.I examined them and decided to see how they were connected to the alligator clamps. There may have been ten or so stranded conductors inside the insulation. My guess would be that at best it would be a 14 ga wire. Also these strands of wire were flimsily folded and crimped to the alligator clips. I took them all apart and used a lot of heat to actually solder all the wires to the clamps. Will these cables actually jump a dead car battery? Probably not. Are they good enough to slow charge a dead battery ? With enough time I would say they sure could.

author: DrijSkij
author_rank: Contributor
timestamp: May 22, 2025, 11:54:55 am
content: Besides my power bank and charger, I carry a complete ratchet and box wrench set, two small bottle jacks, and a floor jack. I am in the process of adding front tow points which would have been very handy that night.With modern cars, the tool selection you say that you carry is likely laughably inadequate. You'd sometimes need a fully stocked Snap-On tool chest to start any job.

author: David Hess
author_rank: Super Contributor
timestamp: May 22, 2025, 08:34:32 pm
content: Quote from: DrijSkij on May 22, 2025, 11:54:55 amIt is enough to change a belt, starter, water pump, whatever, but it is a 2002 vehicle so old. When I evaluate cars, ease of maintenance is a primary consideration.

author: Sal Ammoniac
author_rank: Super Contributor
timestamp: May 22, 2025, 10:25:43 pm
content: I made a set of jumper cables out of those big alligator clips and a piece of Monster Cable speaker cable I had laying around.