This^^^ Bike has a voltage regulator, just like the car. Current depends on load... your bike will not draw more current than it needs (unless you have a short somewhere). Plus, all 12V vehicle systems I've seen charge off 14+V generators. Dunno where all of this "damage your bike" stuff is coming from.

 

Very true but remember the whole reason for this thread is a DEAD battery. Your battery went from a device that provides current to a device that will consume high amounts of current. The jump vehicle doesnt know you hooked it to a bike. It just knows theres a current demand and it will provide it up to what the jump vehicle is designed for regardless of what the jumped vehicle is designed for. The regulator on the bike hasent even come into play yet.........the bikes not running. Will it hurt anything? Most times probably not but why take the chance, the jump vehicle battery should be more than enough to start your bike. Then you can let the bikes charging system do what it was designed to do.

 

Not trying to start a dumb argument, esp since the OP already has his answer... BUT...

You're not charging the bike's battery from a jump... you're starting the bike. And a dead battery can't instantaneously consume massive current, it takes time for the chemical reaction to happen.

As far as the bike's volt reg... the point was more that the bike and car both have a generator that outputs in excess of 14V, then is regulated down. Once you start your bike, the battery will be charging off the same voltage that the running car was providing for the jump...

Anyway... do whatever floats your boat... happy riding!

 

I think your incorrect. You ever jump a completely dead vehicle from an older vehicle? Ive jumped a number with my 73 F100. Its got a 390 with 300HP and an incredible amount of low end torque. As soon as I hook up the last jumper connection the idle drops noticeably, the engine is under a definite load. The alternator is putting out all it can cause thats what the dead battery is sucking up. Voltage has little to do with it, it requires very little effort for an alternator to put out 14V.

I do like your sig. Im glad I can participate in these special olympics

 

For the last time, it's NOT about the voltage. Voltage by itself is harmless. It's the current (AMPS) that can do the damage.

Jumping your bike from a running car/truck is just like going to the casino to play Craps. Sometimes you'll win, and sometimes you WILL LOSE.

Here's my suggestion for everyone:
It's your bike and your money. If you like playing craps, go ahead and jump it from a running vehicle.

If you can't decide who knows what they're talking about here, play it safe, buy a decent "automatic" charger with no more than a 10 amp charge rate, and preferably one that has a 2 amp charge rate/mode. (Slower charge rates are better for longer battery life). A dead (12Ah) Sporty battery should take about 6 hours to recharge at 2 amps.

The "Battery Tender Junior" that many of use use to maintain our batteries is designed to do just that, maintain. They are not designed to recharge a stone dead battery.

 

This is similar to what i have read..seen people burn modules (in cars), a/c blender door motors (cars), regulators(bikes), bulbs etc..seen a battery blow-up many years ago too. not only for some modern cars but also bikes...
A dead battery is rather vague...dead as in "0" voltage or dead as maybe at 10+ volts?
Below 10 volts i would use a charger first.
Lately i hook-up the "good car" with motor off to the "weak car/bike" with motor off for a few minutes and then i turn the key on the weak car/bike to position #1 and turn off a/c , radio etc. On a bike i just turn off any acc. then i crank the weak battery, start and remove cables..Many tow trucks and AAA now carry those jump packs in order to lesson the possibility of damage to electronics besides the ease of usage...most people want to rush a jump start and use P.O.S cables..both of which can cause $$problems.

 

Yes, hooking up a dead battery draws current. I never said it didn't. I just said it can't instantaneously absorb massive amounts of current. The only thing capable of "infinite current" is a short circuit. Glad you like the sig.





Please explain AMPS to me, my BSECE degree is meaningless.




I've worked on (hundreds) cars over the years (yes, I said cars, not bikes).... and jumped many, always off a running vehicle. Never seen a reg fry that way. Next you're going to tell me how you can't mix synthetic and dino oil... lol

Again, do what you want... your bike, your body, your money. Obviously it has already been stated that you can safely jump a bike with the car OFF...

 

Sorry, but that's false. Absolutely false.

The jump vehicle will supply ONLY what the other vehicle draws. It will not push even one single amp more than the bike attempts to pull.

The amperage doesn't matter. There's a reason that my cell phone charger (0.5 amp current draw) doesn't explode when I plug it into the wall outlet (20 amp circuit) and that's because the outlet will only supply the amperage drawn by the charger. Now, if I plugged the same charger into a 220 volt circuit, even if that circuit only provided 0.5 amps total, the charger would fail from excess voltage.

If the amperage potential were the problem, then even a car battery would destroy the bike's electrical system because car batteries alone provide anywhere from 500 to 1,000 amps (but again, only if the system draws that kind of power, that's why the 1,000 amp battery doesn't magically blow every fuse in the car).

Voltage regulators merely control the output of an alternator or generator; they do not read the voltage level in the rest of the circuit and try to compensate for that. All they do is ensure that the voltage coming out of the alternator is within a predefined range (usually 14.2 to 14.7 volts). They aren't going to "fight for control" in any way at all.

However, if, and this is a very big if, there is a substantial difference in the voltage between the two systems, there can be problems. But assuming a properly functioning charging system in both vehicles there's not going to be a big enough difference to cause problems. There's a reason that the owner's manual makes absolutely zero reference to whether the jumping vehicle's engine is running or not. Harley themselves don't think it matters.

All of this said, it's universally agreed that it's safe to jump with the car off and with the amperage capacity of car batteries there's no need run the engine. Even a marginal car battery should have more than enough juice to crank the bike over. Just do that and you won't have to worry about who's right or wrong.

Also, directly to cHarley: While I disagree with you here I wanted to be clear that I think you're incredibly knowledgeable and an asset to the forum. The fact that you disagreed with me made me double and triple check my reasoning process. Just wanted to let you know that my disagreement here is not intended to be disrespect.

 

cHarley - food for thought... if current supply was a problem, then the car battery alone (which is capable of supplying more amps than the motorcycle battery) could fry the bike...

Edit - he beat me to it

 

Its absolutly true, you just didnt read it correctly. Important part highlighted for you

Didnt say it outputs its max, I said it outputs whats called for up to its max.

Hmmmm.......page 152 under "Jump Starting" first paragraph on right side of the page: "This procedure presumes the BOOSTER battery is in another vehicle. DO NOT (those 2 words are capitalized in the manual) jump start from a running booster vehicle. The high output charging systems on some vehicles can damage the electrical components on the motorcycle."