jump starting bike with cables
#1
10-03-2010, 08:23 PM
jump starting bike with cables
Ok, just this out. I haven't had my bike out in over three months. Bike would not start. So i decided to use car jumper cable to jump stary my bike. So my stupid self crossed the cables, i don't think i need to say more. So now i have no nothin. At first the gauges would move and time would display but not now. So what is the problem. Im thinking its a main fuse, cpu/euc or a relay. Can anyone help me. thanks. I guess in the meantime i will play with my traxxas.
#2
10-04-2010, 05:28 AM
hahaha, yeah better check your fuses and hope. Also make sure that the car was not running while trying to jumper the bike. What ride do you have? Good luck on the troubleshoot. Welcome to KF
#4
10-04-2010, 03:46 PM
I think I'd go buy a cheap battery charger to have around for situations like this rather than hook my bike up to my car battery.
#5
10-04-2010, 08:14 PM
Crossing polarity is what tossed your fuse. It's OK to use your car in a pinch (assuming you don't confuse + with -.) Just don't leave the cables on for very long, especially if the car is running and your 100amp alternator is causing your little bike battery to smoke. Bike batteries (and alternators) are designed with just enough juice to get the bike running. They aren't like car batteries which can take a bit more abuse, with off-road lamps, horns, big stereo systems, etc. Drag is right^; a gentle touch is always preferable, especially with newer bikes and the electronics. Be thankful your main fuse blew, instead of the expensive stuff further down the line....
#6
10-07-2010, 01:47 PM
Don't worry about it. Using a car to jump your bike is fine. The alternator won't fry your battery - it's a voltage regulator, not a current regulator, but it's good practice to turn off the car ignition and leave it turned off until the bike is running and the cables disconnected.
Otherwise you run a risk of crossed cables blowing the car electronics as well as the bike's.
Battery chargers are OK for charging batteries. They're no use at all if you need the bike 'now' and need a jump start. They can't deliver the required current.
Rob
Otherwise you run a risk of crossed cables blowing the car electronics as well as the bike's.
Battery chargers are OK for charging batteries. They're no use at all if you need the bike 'now' and need a jump start. They can't deliver the required current.
Rob
#8
10-09-2010, 03:17 AM
Mmmmm, most 72 month batteries have a rating of between 400-600 CCA (amps.) (Yes; some have as much as 700+CCA.) The larger battery chargers have a "Jump Start" selector for 200 amps. If your car is NOT running, you'll have that kind of (CCA) amperage going to your bike. You can allow for some amp "loss" if you have a dead (bike) battery because the voltage will "soak" a bit while charging something "dead." If your car is RUNNING, you'll have the full amp rating of your car battery going to your bike battery, because as William points out: the alternator is a voltage regulator, not a current regulator. The alternator works to ensure your car battery amps are available at 12 volts, so you can run your gigawatt stereo and offroad lights and other electrical "soaks." 12 volts is 12 volts. (So why are car batteries bigger than bike batteries?) It's not the VOLTAGE that toasts your little battery (because gee, your bike battery is 12 volts, too.) It's the AMPERAGE that boils the electrolyte. Hell, 1 amp, cycled twice a minute for 10 seconds is enough to boil your bike battery if you leave it connected for a week. If you have a battery charger with a 200 amp "starter" selector, it will sufficiently juice your bike battery to get your bike running (assuming your electrolyte level is good.) However, I do NOT recommend leaving your "smart tender" computer controlled charger (OR your running car, for that matter) to your bike battery for any extended length of time, because it WILL overcook your electrolyte, regardless of how "smart" the charger may be. In a car battery, you have about 5x the electrolyte and lead plate surface area as your bike battery. Car batteries can handle long term "smart" chargers. Bike batteries cannot.
And, oh yeah; don't cross + with -.
And, oh yeah; don't cross + with -.
#9
10-09-2010, 01:26 PM
That post shows a very confused understanding of basic electrical theory.
Voltage is the measurement of Electro Motive Force. EMF tries to push current (Amps) through a resistance, measured in ohms. The capacity of a battery or other source is a measure of how much current it can push and for how long. The actual current is derived from Voltage/resistance. A 10AH battery can push 1A for 10 hours, or 0.5A for 20 hours.
The CCA measurement is another complication, because a battery can push out a lot of current for short time, but then appears to run down well before it's actually empty. Our 10AH battery can't actually push out 10A for one hour. The best way to think of it is that if it's asked to do a lot of work it gets tired and needs a rest before it can continue. Trying to push out 200A for a starter it gets tired very quickly. Give it a ten minute rest and it might be ready for another go before it's completely exhausted.
The rate of charge of a flat battery, in Amps depends on the applied voltage and the internal resistance of the battery. As the battery charge rises the reverse internal restance rises and the amount of current - the charge rate - falls. A battery can only be overcharged by applying too high a voltage. True - it's the current that does the damage, but the battery itself is the current limiting device.
A 200A battery charger (jump start setting) will not push 200A into a 12V battery unless it's delivered at around 200V or thereabouts. What it will do is allow the delivery of 200A to a starter motor, which has a very low resistance. The starter motor will happily take 200A or more from a 12V source. The only reason that a normal battery charger can't deliver 200A at 12V is that the internal resistance of the battery charger itself will dissipate much of that current as heat, and destroy the charger.
A running engine does not make the full CCA rating of the battery available. That's only available if the battery has a near full charge. Again, as I've explained for the battery charger, an alternator is not built to deliver 200A, unless it's a 3,000W rated unit. Neither are the diodes that rectify it or the FETs or whatever that regulate it. Pull 200A from a typical car alternator and it will melt down. In fact though, you can't pull that much current because the internal resistance of the alternator itself will not allow that much current to pass at the 14V typical of an auto electrical system. (12V is a nominal voltage for a lead acid battery and most ratings are based on the 14V more typical of a running engine). A failed regulator can allow the voltage to rise to around 70 volts ac from a typical alternator. At that voltage it can flow enough current through a shorted regulator to melt itself, but that isn't a typical failure mode.
"Hell, 1 amp, cycled twice a minute for 10 seconds is enough to boil your bike battery if you leave it connected for a week. "
I would tear that comment to shreds if I understood it lol.
Basically a battery charger is safe on a bike battery as well as a car battery because it delivers a constant voltage. The 1A setting, for example, doesn't mean that it delivers 1A. It means that it can deliver a maximum of 1A, reducing as the battery reaches full charge.
Some more expensive intelligent 'constant current' chargers can measure the current flow and increase or decrease the charging voltage to alter that current flow. These chargers can push more current through a battery than it can handle if they're set wrong. Most intelligent chargers are still 'constant voltage' units though, charging to a map.
As a guide, a bike battery should be charged at a rate of no more than 1A, and a car battery at around 5A. That's because the car battery is bigger, with bigger plates offering more surface area to take the greater level of current. Optimate chargers and similar devices trickle charge to a nearly full battery at fractions of an amp, and effectively shut off when the battery is full. They are quite safe to be left on all the time, although I don't personally consider it good practice to do that.
Why are car batteries bigger than bike batteries? Because simplistically, they hold more electricity. Think of them as propane gas tanks pressurised to (say) 100 bar. A big tank holds more gas than a little tank. The regulator ensures that both tanks deliver the gas at the same pressure, (same idea as both batteries being 12V) so the big tank can feed a gas fire (for example) for longer than the small tank, or can feed more fires fo the same length of time. The gas fire takes no more gas than it needs, whichever tank it's connected to.
As a secondary effect, the bigger plates needed for the extra capacity of the car battery reduce the internal resistance, and this coupled with a more robust construction, allows them to deliver more current, including cranking amps, for longer.
Rob
Voltage is the measurement of Electro Motive Force. EMF tries to push current (Amps) through a resistance, measured in ohms. The capacity of a battery or other source is a measure of how much current it can push and for how long. The actual current is derived from Voltage/resistance. A 10AH battery can push 1A for 10 hours, or 0.5A for 20 hours.
The CCA measurement is another complication, because a battery can push out a lot of current for short time, but then appears to run down well before it's actually empty. Our 10AH battery can't actually push out 10A for one hour. The best way to think of it is that if it's asked to do a lot of work it gets tired and needs a rest before it can continue. Trying to push out 200A for a starter it gets tired very quickly. Give it a ten minute rest and it might be ready for another go before it's completely exhausted.
The rate of charge of a flat battery, in Amps depends on the applied voltage and the internal resistance of the battery. As the battery charge rises the reverse internal restance rises and the amount of current - the charge rate - falls. A battery can only be overcharged by applying too high a voltage. True - it's the current that does the damage, but the battery itself is the current limiting device.
A 200A battery charger (jump start setting) will not push 200A into a 12V battery unless it's delivered at around 200V or thereabouts. What it will do is allow the delivery of 200A to a starter motor, which has a very low resistance. The starter motor will happily take 200A or more from a 12V source. The only reason that a normal battery charger can't deliver 200A at 12V is that the internal resistance of the battery charger itself will dissipate much of that current as heat, and destroy the charger.
A running engine does not make the full CCA rating of the battery available. That's only available if the battery has a near full charge. Again, as I've explained for the battery charger, an alternator is not built to deliver 200A, unless it's a 3,000W rated unit. Neither are the diodes that rectify it or the FETs or whatever that regulate it. Pull 200A from a typical car alternator and it will melt down. In fact though, you can't pull that much current because the internal resistance of the alternator itself will not allow that much current to pass at the 14V typical of an auto electrical system. (12V is a nominal voltage for a lead acid battery and most ratings are based on the 14V more typical of a running engine). A failed regulator can allow the voltage to rise to around 70 volts ac from a typical alternator. At that voltage it can flow enough current through a shorted regulator to melt itself, but that isn't a typical failure mode.
"Hell, 1 amp, cycled twice a minute for 10 seconds is enough to boil your bike battery if you leave it connected for a week. "
I would tear that comment to shreds if I understood it lol.
Basically a battery charger is safe on a bike battery as well as a car battery because it delivers a constant voltage. The 1A setting, for example, doesn't mean that it delivers 1A. It means that it can deliver a maximum of 1A, reducing as the battery reaches full charge.
Some more expensive intelligent 'constant current' chargers can measure the current flow and increase or decrease the charging voltage to alter that current flow. These chargers can push more current through a battery than it can handle if they're set wrong. Most intelligent chargers are still 'constant voltage' units though, charging to a map.
As a guide, a bike battery should be charged at a rate of no more than 1A, and a car battery at around 5A. That's because the car battery is bigger, with bigger plates offering more surface area to take the greater level of current. Optimate chargers and similar devices trickle charge to a nearly full battery at fractions of an amp, and effectively shut off when the battery is full. They are quite safe to be left on all the time, although I don't personally consider it good practice to do that.
Why are car batteries bigger than bike batteries? Because simplistically, they hold more electricity. Think of them as propane gas tanks pressurised to (say) 100 bar. A big tank holds more gas than a little tank. The regulator ensures that both tanks deliver the gas at the same pressure, (same idea as both batteries being 12V) so the big tank can feed a gas fire (for example) for longer than the small tank, or can feed more fires fo the same length of time. The gas fire takes no more gas than it needs, whichever tank it's connected to.
As a secondary effect, the bigger plates needed for the extra capacity of the car battery reduce the internal resistance, and this coupled with a more robust construction, allows them to deliver more current, including cranking amps, for longer.
Rob
Last edited by williamr; 10-09-2010 at 01:32 PM.