Jump starting a dead battery

I left the parking lights on last night on my BMW R1150RT and now
there's not enough juice left to start the bike.
Is it safe to jump start my motorcycle battery from the battery on my
pickup truck?
If so, is the procedure any different than that for jump starting a
dead car battery?

Don

 

Don't start the truck.

Les

 

Your voltage regulation gear on the bike is sized to take care of the
excess electrons created by it's on-board charging system. If you use a
larger vehicle to jump it like a car, do NOT start the vehicle. Now your VR
has to sink all those many more electrons produced by the larger charging
system on the car. If you just use the battery, you should be fine as
should your VR since the battery isn't at a voltage that's high enough to
cause regulation. Good luck.

Mike


--
Mike W.
96 XR400
99 KZ1000P
70 CT70
71 KG 100 (Hodaka-powered)

 

Actually many motorcycle charging systems (Honda, at least) charge wide open all
the time. The regulator routes what's needed for the battery and everything
else goes through a big heat sink and to ground.

 

Your best bet is to buy the correct trickle charger for your Beemer. If you
ever let it sit for more than a few weeks at a time youll need one anyhow.
You can buy the BMW licensed charger or the equivilent Deltran. The newer
beemers with gel batteries require a different charger than the older
beemers. These come with a connector that allows you to recharge your
battery via the accessory connector which is much easier than trying to
access your battery.

You can jump your bike from a car, but as others have mentioned, make sure
the car is turned off as you could end up screwing up the donor;s charge
system

 

LOL!

What he said

 

Albrecht via MotorcycleKB.com schreef:

Your message that it takes longer than you'd expect is correct.... It
does.
But the arithmetic you use is incorrect.

You are talking about two different things. Voltage (V) and capacity:
Ampere*hours (Ah).

The amount of Amps flowing into the 'empty' battery depends on two
things:
The voltage difference (your 0.8V) and the resistance of the circuit
(jumper cables,
plus internal resistance of the dead battery, plus the internal
resistance of the car battery).

If I forget about internal resistances of the batteries (thus I
pretend them to be 0 Ohm),
and if I suppose the jumper cable has a resistance of 0.1 Ohm, then
the current caused
by that 0.8V difference, would be (I=V/R) 0.8/0.1=8 Amps. And for a
16Ah battery,
it would take 2 hours to charge it.
Well, not exactly, because the empty battery gets warm, and that means
you loose some energy in the process, so it takes a bit longer.
( Nicads are usually marked: Charge at 0.1 of capacity for 14 hours.
You loose
4 hours because Nicads have a high internal resistance and get
pretty warm.
Led batteries have a much lower internal resistance, but I never
could lay
my hand on how little Ohms it is.)

So I did not account for the internal resistances of the batteries.
The effect of the internal resistances is twofold.

a) The car battery posts do not carry a Voltage of 12.8V when the
battery
is providing current to the empty one. The Voltage is lower than
when the
car battery was at rest. In other words: the voltage drops well
below 12.8V.

b) The empty battery posts will show a voltage that is higher than the
voltage of the plates. (It is the opposite from that effect on the
car battery).

Both a) and b) will mean that the voltage over the jumper cables is
lower than the initial 0.8V difference at the 'in_rest' situation.
I never measured it, but I guess the voltage difference drops fast
to around 0.2 or 0.4 Volts. Which means that my above calculated
8Amps
is much lower (somewhere between 0.25 to 0.5 Amps). Which
means that it takes much longer than the 2 hours that I calculated,
and
that it will take in the range of 64 hours to 32 hours to charge that
16Ah
motorcycle battery.

Which --no doubt-- you know from experience.

Rob.

 

Prove me wrong, Einstein. We'll wait.

 

I had my battery and charging system training in the late 70s, when they told us
it was .25 ohm across a 12v car battery. We had a big alternator testing
station where an electric motor would spin the alternator and we could turn a
big rheostat to simulate the 1/4 ohm in order to get full output from the
alternator. It was surprising to see how much an alternator could load a motor
down.

 

You're harldy in any position to throw stones, Krusty. What Jack
said is essentially correct, most bike regulators are shunt regulators
that work by shorting the stator windings. So if you please, either
point out what was wrong with what he said, without quibbling about
minor issues with terminology, or apologize.

 

Jack Hunt schreef:

I was told (about half a century ago) that it was dependent on a
miriad of things, such as effective area of the plates, distance
between plates, electrolyte, current state of charge (empty through
full). But 0.25 Ohms seems to be a figure that is in the correct
range.

Yes, I've seen that.
BTW it is the reason why so many bicyclists in The
Netherlands drive without a light. That tiny generator on their
front wheel loads their knees too much.
But that is a totally different lead. I twice ran over such a moron,
both times lucky that I did not fall off. It was pitch dark and
raining. I never saw a bicycle untill I banged in to something,
looked behind and thought: "what the heck was that?"
One of them even did not have any light equipment on his wreck.
Both times I cursed to them and drove off (which is a crime).
Should I have had a goldwing, I would have reversed first.

Totally idiotic thing in The Netherlands is that (no matter the
moron has no light, has no right of way, and ignores a red traffic
sign), my mandatory motorcycle insurance has to pay him.
So in effect I pay insurance fee for bicyclists [because a
bicyclist does not have to have traffic insurance,
and thus has not].

Basically the moron gets a fine (say 20 bucks) for driving
through red, and not having light on the cycle. But I get a
letter from my insurance company that my discount for
driving 40 years accident free (70% off) is now void, and
I that have to pay a lot higher fee for the next year insurance,
(and many years after that) because I was in an accident that
they had to pay for. Yes: The moron can have his cycle
repaired, and my insurance will pay it!.

And nobody pays for the damage that my bike has.
Sue him? Forget it. Solicitors and court fees are
so high that buying a new Hyabusa is cheaper. 'No cure-
no pay' is not possible here. And even if he is found guilty,
I must pay the court/solicitor.

Many years ago at school I learned that there are
many expressions starting with 'Dutch' that are not
flattering. (Dutch uncle, Dutch treat, and many more).
I can add one: Dutch law.

Rob.

 

Mark Olson schreef:

And could you please enlighten us in 10 lines max?

Rob.

 

[snip a bunch]

Yes, I know who "krusty" is on UKRM, I hadn't confused him with you.
But it's well in character for you to make something out of nothing in
an attempt to muddy the waters and deflect the point of the discussion
to something other than a boneheaded assertion you made.

Do you deny that you used to post under the name "Krusty Kritter?"

I am positive that you *are* the same person who has posted many
many times as "Krusty Kritter", "Flying Booger", "Albrecht", "B-12",
and other psuedonyms that I don't remember right now. I won't bother
asking you to pick one and stick with it, since you obviously get off
on frustrating people's attempts to ignore your long-winded ramblings
by morphing your posting name on a regular basis.

Whatever floats your boat, just don't try to take a holier-than-thou
approach about being the newbie's friend. You post a lot of good
information, but it's been mixed with crap at times, and the problem is
you have demonstrated that you cannot be relied upon to admit it when
you've made a mistake.

 

<fx: opens popcorn>

 

Better scoff it quick, unless someone else jumps in and carries
the ball from now on there's not going to be much to see here.

 

That is the *stupidest* thing you have posted here in years, and believe
me, that's saying something.

On modern US, and (for the last couple of years) EU bikes, no. On
anything older, yes. So "usually" is wrong.

Almost certainly yes. Jump-starting has been commonplace on vehicles for
a century or more, so I guess designers consider it.

See above.

I have never, ever blown a motorcycle reg/rec by car jump-starts, and
I've used cars to jump-start God-knows-how-many bikes for decades. I
doubt you have. The only thing to beware of, as others have said
elsewhere, is not to have the car engine running at the time.

Yes, you say this all the time, but the trouble is, when you don't know
for certain, you tend to make it up, or scan the web for an answer, and
even then sometimes get it wrong. Which means newbies - or anyone else -
cannot rely on your "advice".

Wrong again.

 

Which is why production racers have been known to "accidentally"
disconnect the alternator on some bikes, to get another horsepower or
two.

Heh.

 

ROFL. On a technical ng, yes, you *do*, unless (a) you want to look an
imbecile and (b) have any correct advice you do impart taken seriously.

Suppose = assume. ISTR you have a hackneyed little homily about that,
which you drag out from time to time.

And this ng stays more on topic than any other I subscribe to.

A lot of it, most, in fact, is yours.

 

A poster on ukrm, a couple of years ago, had a flat battery on his
airhead BMW, and got a jump-start from a truck.

He mentioned that the bike started instantly, and then the rest of us
howled: "Christ! Trucks have 24v electrics!!!"

It must have been like one of those scenes in ER.

CLEAR! ZZzzzzaaappp!

Amazingly, the only thing it fried was the quartz clock.

 

The Older Gentleman schreef:

And the truck driver had to push his truck all the way home. ;-)

Rob.