I've got a set of mini-jumper cables for use on a bike that won't start, but usually would require direct access to the batteries to attach the clamps. Today on a ride we had a bike that needed a jump and a rider had I believe one of these Charge Cable Extender . It worked like a charm connecting it to both bikes battery tender connections. Is there any reason why this would not be a great way to jump a bike?

 

Yes, and no, and I made a plug that I can connect my jumper to the battery tender plug directly.
Note, I carry a small jumper box, since If I going to have a dead battery, chances it will be when I'm all alone to start with.

The no part, is if your tender plug has a 4 amp fuse in line it it, it will blow the fuse pretty much from the start when you connect the jumper pack to it/use the extender to connect it to another bikes tender plug. The other one is the battery tender/tender extender wiring is only rated for about 4 amps to begin with, and the jumper box is going to put out way more amperage isntead.

So solution on your tender cable plug on the bike to the battery, is to upgrade it to one that has larger wiring, and that does not have a fuse that will end up blowing. Also, since the wiring is not going to be a large as what is really needed for a dead battery jump amperage transfer, you put the jumper pack on the bike for a few mins, in order for it to charge up the battery a bit to begin with.

 

The tender cable 4 amp fuse aside.....

Cable size is determined by the amperage the cable will need to carry....... If the wire is too small for the current, you will get increased resistance, voltage drop, heat, and possible melted cable.... the severity will be based on the how undersized the cable is, and the length of time the current is flowing through the undersized wire...

The battery tender cable size was selected to carry 1.5 to 4 amps.....

A big twin starter draws approximately 110 amps while starting....

I would never try to use a tender cable size wire for jump starting a Harley....

 

Hi
hope all are healthy
I found from this forum that the standard tender wiring for my ultra limited may melt if I try to use the booster pack. RK Classic (7/28/2020) posted a video on where to connect the booster pack or a set of jumper cables with out removing the seat.
I have a question about it. The gentleman showed all the steps on what to do. At the end he said it may not work if the battery is completely dead. So do you leave the battery booster on for a while to give the battery a slight charge before you try and start it? Like when your using booster cables on cars.

mike

 

If you can get to the large wire on your starter, which may have a boot over it, and get a good connection there, it will do a couple of things, back feed to the battery to charge it, back feed to the electronics to start it, and give you the closest low resistance point to the starter to jump it.

In a pinch I have used booster cables from a car, and a long screwdriver wrapped in electrical tape to get to that connection... held the screwdriver against the terminal post and hit the start button.

Short of going to the battery itself, IMHO the starter post and finding a good ground are the best way to jump a bike,

Remember the best rate to charge a small battery is a TWO AMP charge, much more and the heat can fry the plates,

 

If they used this to connect two bikes together,

they would need this adapter to correct the polarity.

Without the adapter, polarity is reversed between the two bikes.

 

again, the tender leads on bikes are fused at around 4 amps, what do you think you are going to do with 4 Amps if you connect the bikes together.

The second you power the bike up you are going to draw 4 amps.

Change out the fuses to 10 amps, again you will be there all day trying to charge a weak battery, assuming that the batteries when trying to equalize out does not blow those fuses.

There is no way you are going to pull starter level current thru that wire without it melting from to high a resistance due to lack of surface area

 

Using that cable to jump start a bike is a BAD IDEA!
Others have covered the reasons why.

 

Bad idea all around ! Buy a set of motorcycle jumper cables or carry a jump pack. And connect it to the battery or to the lug on the starter, then to a good ground. Why would anyone take a chance on frying your bike.

One other thing, if you jump from another car or bike do not have them running. Seen alot of folks screw their stuff up doing this. Don't take the chance.

 

IMO- Jumper cables are last century.

I put this on my ride:

https://earthxbatteries.com/shop/etx-qcc2

Anything of a similar gauge will work for jump starting. And this heavy duty gauge can be used with your battery tender and as a plug in for heated gear. You can also get a USB adapter to charge a phone.