Dead battery in the middle of nowhere

1.3 Ah sounds small to me also. But let's look at the math for 40 Cold Cranking Amps. (I can switch batteries between 3 of my bikes, all 14Ah delivering 35 to 40 cca.)

At 40 amp draw, a 1.3Ah battery should last 1.95 minutes. If that was lead-acid, the voltage would drop significantly before the end, but a lithium or even nickel battery will provide more voltage longer (then die quickly).

But if the battery can deliver 35 to 40cca, the starter actually draws far less in normal use.

On my bikes the starter solenoid alone pulls over 20 amps inrush. The starter motor pulls over 200 amps inrush. They drop down to about 75 amps when cranking.

About 1 minute at 1.3 Ah. Should be fine if everything is good to start.

Isn't that point kind of moot? The idea that that little battery pack could deliver 20 amps (let alone 40) is a bit of a fantasy, don't you think?

Think??? no it is a joke, there is no way that thing will do crap, it might run the instrument lights for 5 seconds.

In the scenario the OP said he used it, he ran the battery low due to leaving the light on. What really happened is his battery was in good shape so it recovered after the draw was stopped, enough to fire the bike later.

I have done the same thing a couple times, just shut everything down and be patient, give it 10 to 20 minutes, as extra insurance if a hill is around, a bump start simultaneous with flipping the key on and hitting the starter has got me rolling a couple times.

I carry some homemade jumper cables, 10 ga wire with alligator clips solder to the ends. They lay flat in the bottom of a bag and out of the way.
Never have needed them yet...karma

Not at all. The instantaneous power is not necessarily related to the total energy available.

Lead-acid is out, but some lithium batteries can deliver amperage at rates over 30c (thirty times the capacity) which would be 39A for the 1.3Ah battery. For 20A we are asking only for 16c which is pretty common.

It depends on what the battery was designed to do. A physically large battery can more easily deliver higher instantaneous power, but that is not the only way.

I was really looking at the wires coming out of it as much as the battery pack itself....

Target has a few small self jump start devices. Plug into lighter socket, turn on wait a few minutes. Start car and leave plugged in to recharge pack.
http://www.target.com/p/wagan-self-charge-auto-jumper/-/A-10158651#prodSlot=medium_5_10

Somewhere I saw an article where someone had wired in a 14.5 volt dewalt socket from a broken drill. They carried the fully charged dewalt battery as a back up. Sound like a great idea to me.

You are absolutely right that those wires won't handle these (theoretical) loads. The cig lighter plug is a killer too. When they added a flashlight it looks more like a toy.

I wanted to look at the math of what a 1.3Ah battery can deliver if done right. I was prompted by your phone battery which is optimized to deliver at c/20 or slower (the 20-hour rate). Other batteries are optimized for 20c and faster.

PERSONALLY I don't and wouldn't carry a spare battery; I DO check electrolyte before trips and have volt meters on my bikes to watch for problems. If I forget my headlight some night (wouldn't I see it?) I'd have to figure out my options from there.

Yes, Tested prior to my last trip, left the ignition on with all the lights etc. ran the battery completely flat, not even a clicking from the starter relay. I made an adaptor to plug the cigarette plug into the gerbing lead which is connected onto the battery, left for 20 mins and she fired up straight away with no hesitation. 1400 cc fuel injected lump. Also tested it on the car , plugged straight into the cigarette lighter socket. Same result. But I would agree with one poster, make sure you have a decent battery to start with!!




AB

It is NOT a joke, they CAN work.

If you leave the key on and run the battery low. Then at home you connect a 1 amp charger to the battery for an hour, the bike could easily start from that. WOW, the 1 amp charger is magical. :huh

These are NOT high current jumper cables. They are battery rechargers. They put some charge back into the bike/car battery just like a slow charger at home, and you can then start from the main battery. They CAN work.

What I see as the main drawback to this model is that it is NiMh. The batteries would need charged at least once a month. A hassle.

Just for info. Tis was fully charged 3 months ago before I used it. Didn't recharge it first. Was fine. Only takes a couple of hours to charge from the mains. Charges fully on a long ride (200+ miles) from the bike . Works for me... :)


AB

Thanks for the info, AMS!

I have a device called Mighty Jump from Viatek products that I bought at the motorcycle show at the Javits Center in NYC earlier this year and it works great. I have a pigtail wired directly to my battery with a quick-connect at the end. I plug a female cigarette lighter attachment I to that and the might jump comes with a wire to connect to that. Leave in plugged in for 5-10 mins, fire up the bike, flip the switch so the bike re-charges the Mighty Jump and you are good to go. That being said I recently got an Antigravity lithium main battery for my bike and at 4.25" X 2.25" X 3.25" a spare lithium battery is very portable and the rate of discharge per month is very low; something like 1% a month. It's true lithium doesn't like the cold but you can warm the battery against your body or whatever.

Twin batteries baby!!!!

For traveling in a group, a set of jumper leads. For traveling alone I'd considered carrying a LiFe battery as a backup - low weight and low discharge with the aded bonus of being able to replace a dud battery as well. For a KTM 990, roll starting is not an option! (unless you have nice big hill very close by).