I would leave off. I have gone as far as disconnecting the donor battery from donor vehicle but that was in days of no computer relearning if battery is disconnected. I never liked the idea of two alternators “fighting.” If they even do, I don't know I just think they will.
jump starting with donor vehicle running or off?
- Thread starter jalikaria24
- Start date
Do people still use jumper cables? Maybe if you still listen to music on cassettes. 
Haven't used them this century and can't even remember where I put them. Even AAA and other road service trucks all use jump boxes.
Haven't used them this century and can't even remember where I put them. Even AAA and other road service trucks all use jump boxes.
I probably go 2+ years between jumps, a jump box I don't think would pay off. If I was running a wrecker then yeah, I'd use that, less risk and all, easier to use, etc.Do people still use jumper cables? Maybe if you still listen to music on cassettes.
I don't buy into needing low gauge wires, high gauge wires will work, they just need to sit for 5, maybe 10 minutes to do the job. Less space in the trunk. Had to do that in the old days, not really that much time in these days. Thick gauge makes it faster, no doubt, but for as often I as need to, it's a minor tradeoff.
Sit for 5, maybe 10 minutes? Why? And I never saw the point of people revving the engine of a donor car, like it's going add more juice. Maybe back in the 50's when all cars had generators, that helped, but alternators put out nearly the same volts at idle anyway. Heck, modern alternators have decoupler pulleys that disconnect at high speeds to save gas. If it's not going to start as soon as you connect the cables, it's not going to start in 5-10 minutes unless the cable is junk. I can start cars with NO battery in them using a jump box.
Instead of going out and buying a good set of battery cables. just buy a lithium jump pack.
I only jump in my driveway, so sitting is no problem. Cheaper than buying high quality stuff--since I use them so sporadically.
And it used to be the norm--hook it up, get it to click. Wait a couple minutes, then it would crank, but too slowly. Wait a couple more and finally it'd crank faster. Today's starters are different, but back in the day, this was the norm. Unless if you had the big bucks for fat cables, that is.
With the older fleet in your sig + you live in a cold climate and maybe in the middle of nowhere, I'd think a jump box plugged in and on standby at your house 24/7 would be mandatory. Even if you do get a jump in your driveway, what if you stop at the supermarket, err, trading post, and need another one?
Bit overkill, don't you think? While I have worn both a belt and suspenders at times, this sounds a bit like that kind of fix to the issue.
Plus if I stop anywhere... by definition I'm a long ways from home.
Cheaper to just change a battery every 5 or so years.Ahh, but you don't know when a battery will quit. Even a one year old battery could have a manufacturing defect so that it works fine one morning, a cell shorts out going over a bump, and now it won't start the next time you try it. You at least have AAA?
I think I still have AAA. Good for 5 miles. Or to the end of the block, whichever comes first.
Over the last 18 years of living out here in nowhere, I've had to get tows 3 times
- 2001 Civic, axle shaft broke. Years later I watched an SMA video and it's very likely the axle rusted in half. No joke. [Wonder why I dislike Honda?]
- 2004 VW, turbo shaft snapped. Actually still moved but once it started making noise I decided caution was wise. [It was a VW, tossing a CEL and going into limp mode is "normal".]
- and the '04 VW again, when it lost the electric lift pump
- 2004 VW, decided to quite one cold winter day. Must have jumped it, don't remember. Drove to the dealer and swapped the battery in the lot the same day. [Come to remember, kids left a DVD player on once when we flew somewhere for a week; one jump later and it was fine. Again that was a cold day...]
- 2010 Tundra, battery was flat one day. Jumped and lasted a few more years
- 2003 CRV, I guess it can't hold a charge for 2 weeks. No surprise, my lawnmower has a bigger battery. I'd look into a bigger one but it already blocks the ATF dipstick.
Thankfully I'm salaried and have multiple vehicles. My life is busy but not that busy.
AutoMechanic
Site Donor 2024
I have a jump box but it has to be plugged in to run. I always have the donor car on as that is what I have been told to do and trained to do. Never have damaged a car that way.
That's a battery charger not a jump box.
Do people still use jumper cables? Maybe if you still listen to music on cassettes.
But if you have a set of good jumper cables already then buying the jump box is just a waste.
Cold. That’s why I’m thinking I should have got the biggest one possible to (hopefully) make up for the losses in the cold.
If you want to beg from strangers in a sketchy neighborhood to give you a jump and hope they don't carjack you afterwards or demand $50 for their trouble, then yes, it's a waste.
Parallelling two vehicles electrical systems can be dangerous, or inconsequential, or cumulatively damaging.
A cheapo pair of jumpercables, with 8 SAE gauge copper clad aluminum wire and steel clamps, cannot be compared to 4awg copper cables with a nice set of parrot jaw clamps digging into the terminal clamps/battery posts.
The worse the cables, the more beneficial it is that the donor vehicle is running, providing a higher voltage/ pressure, in order to recharge the needy vehicles battery and also provide current to the starter.
A good quality thick pair of cables basically allows one to attach a distant second battery to the first, and running the donor vehicles engine is not required.
I don't carry a jump box, but I do carry a 18 or 22 AH AGM battery that comes withing the lead acid jumper packs.
I don't trust others to properly use jumper cables, and it looks like some vehicles can't deal with the potential surges of paralleling a second vehicle's electrical system via jumper cables.
The UB12180 battery by itself, has started my 2 week cold 5.2 liter v8 engine, but in warm ambient temperatures. My starter is rated for 1.4KW output, and took nearly 1800 watts from the Ub12180 to start the engine with battery and engine at ~75f.
1800 watts divided by 12 volts is 150 amps
1800 watts divided by 10 volts is 180 amps
1800 watts divided by 8 volts is 225 amps
A cold engine and battery would cause more voltage drop and also require more amperage to turn the motor.
So one can see the higher the voltage the battery can maintain, the lower the amperaqe required to feed a starter motor.
Lower amperage means less voltage drop across the circuit
The thicker the cables, the less voltage drop there is.
The more surface area the clamps form on the battery terminals, the less the voltage drop.
Lots of variables in the cables, their clamps, and thus the quality of the circuit. Running donor vehicle's engine, revved,can make up for poor quality cables and clamps, but its better to not have to.
If time is not a factor, let the running vehicle charge the other vehicles battery for a while so that the battery acts like a buffer and voltage spikes wont travel to the Donor vehicles electrical system and perhaps fry something.
A cheapo pair of jumpercables, with 8 SAE gauge copper clad aluminum wire and steel clamps, cannot be compared to 4awg copper cables with a nice set of parrot jaw clamps digging into the terminal clamps/battery posts.
The worse the cables, the more beneficial it is that the donor vehicle is running, providing a higher voltage/ pressure, in order to recharge the needy vehicles battery and also provide current to the starter.
A good quality thick pair of cables basically allows one to attach a distant second battery to the first, and running the donor vehicles engine is not required.
I don't carry a jump box, but I do carry a 18 or 22 AH AGM battery that comes withing the lead acid jumper packs.
I don't trust others to properly use jumper cables, and it looks like some vehicles can't deal with the potential surges of paralleling a second vehicle's electrical system via jumper cables.
The UB12180 battery by itself, has started my 2 week cold 5.2 liter v8 engine, but in warm ambient temperatures. My starter is rated for 1.4KW output, and took nearly 1800 watts from the Ub12180 to start the engine with battery and engine at ~75f.
1800 watts divided by 12 volts is 150 amps
1800 watts divided by 10 volts is 180 amps
1800 watts divided by 8 volts is 225 amps
A cold engine and battery would cause more voltage drop and also require more amperage to turn the motor.
So one can see the higher the voltage the battery can maintain, the lower the amperaqe required to feed a starter motor.
Lower amperage means less voltage drop across the circuit
The thicker the cables, the less voltage drop there is.
The more surface area the clamps form on the battery terminals, the less the voltage drop.
Lots of variables in the cables, their clamps, and thus the quality of the circuit. Running donor vehicle's engine, revved,can make up for poor quality cables and clamps, but its better to not have to.
If time is not a factor, let the running vehicle charge the other vehicles battery for a while so that the battery acts like a buffer and voltage spikes wont travel to the Donor vehicles electrical system and perhaps fry something.
My latest experience jumping off brother in law's truck . My truck was not running . Connected the cables . Tried his truck and it barely bumped . Told my wife to crank my truck . Tried his again and it cranked . Heavy duty cables . I've seen this many times .
For that price, at least include a carry bag...
gathermewool
Site Donor 2023
Another for Running.
I had the same issue with my jump pack. It was below half charge though. The instructions specifically say not to use the jump function with less than half the charge.
I had the same issue with my jump pack. It was below half charge though. The instructions specifically say not to use the jump function with less than half the charge.
gathermewool
Site Donor 2023
Oh, and when it’s really cold I bring the jump pack into work with me during the day, so it’s nice and warm for when I or someone else nearby may need it.
