Three hours into a trip on my '04 FJR to LA, I pulled into a gas stop. Bike had been running perfectly. Filled up and went to start the FJR; nothing. Tried everything; no gauges, no lights, no starter, nothing. Took the cover off the battery and jumped wired it from a car. Started right up and ran fine, but as soon as we puled the cables off and it died instantly. Repeated the process with the same results. Towed the bike and spent the night in a hotel. Got the bike back home today. Battery checks in at 13v and shows full on the charger. I have been working on bikes for a long time, but this one has me totally baffled. Any thoughts from the collective wisdom?
Dead on the road
- Thread starter odowda
- Start date
Help Support Yamaha FJR Motorcycle Forum:
Bustanut joker
Well-known member
Battery is most likely toast.. I've seen 13 plus volts drop to squat with only a 5 amp draw after 24 hours on a charger. It's an 04 and the battery if original is tired of all the electrodes running wild.
FJRBluesman
Some call me... The STIG!
All battree terminal lugs tight?
Steve in Phx
Well-known member
Did you jump start with the cables connected directly to the motorcycle's battery posts? Or down-line somewhere, like further down the cable or grounded on the frame?
Make double sure all the connections to the battery are good. Remove the cables and re-connect them. If it still starts off a jump, but nothing from your battery, replace your battery.
And carry some jumper cables with you just in case.
p.s. If jumping from a car, remember to NOT have the car running when you do so.
Make double sure all the connections to the battery are good. Remove the cables and re-connect them. If it still starts off a jump, but nothing from your battery, replace your battery.
And carry some jumper cables with you just in case.
p.s. If jumping from a car, remember to NOT have the car running when you do so.
UHOH
Well-known member
- Joined
- May 30, 2006
- Messages
- 329
- Reaction score
- 26
Sounds exactly like a catastrophic battery failure I had in 2003 on a Suzuki.
I didn't have the means to check battery voltage at the time. But, new battery fixed it.
I didn't have the means to check battery voltage at the time. But, new battery fixed it.
Last edited by a moderator:
Donal
Well-known member
Mihalis fjr
Well-known member
Perhaps a broken circuit inside the battery...
I had exactly the same problem on my other bike..A new battery fixed the problem,but check and the battery terminals as the FJRBluesman said..
I had exactly the same problem on my other bike..A new battery fixed the problem,but check and the battery terminals as the FJRBluesman said..
Last edited by a moderator:
RossKean
Well-known member
Just because a battery shows "fully charged" or an OK voltage it doesn't mean it can supply any current. I suspect if you load tested it the battery would show DEAD. Or, instead of a load test, put the meter on the battery and turn the key on. If the battery still shows adequate voltage but nothing is happening, there might be an ignition switch failure. (Unlikely since it started with an outside power source)
LagerHead
Well-known member
RavFJR
Well-known member
Even jumping a motorcycle with just the car battery hold some risk of damaging the motorcycle battery, due to the (comparable) difference in available cold cranking amps. Having a car's beefy (in comparison the the motorcycle's) charging system running adds more of a chance of frying something...
MrZappo
Can we please go riding now ?
Why would this be the case ? The motorcycle charging system will pull what it can (needs) not the full amount of current the car is putting out ... Additionally, the alternator (or charging system) of the car will not damage the motorcycle systems. Just because it has more capacity does not mean that it will fry the motorcycle electrics ...
LagerHead
Well-known member
This is why I hate not being well versed in electrical matters. Either of those opinions sounds like it could make sense to me.
For the record, though, I have jumped my bike more than once with a running car, and even my Tundra. So far (knock on wood) nothing negative (no pun intended) has come from it. I was kinda wondering if I was tempting fate.
Yes, this is a common old wives tale that has been repeated often enough that it has become the conventional wisdom (Hey, it's a factoid!)
14 volts is 14 volts, and that is the most that you would expect to see on the battery terminals of the car that is running, or on the battery of the bike (from the alternator) when it is running.
Current is a factor of that voltage and the resistance of the circuit being powered (the bike in this case). You will not draw excessive current from the car unless there is already something wrong with the load (the bike).
The fact that the bike started and ran with the jumper cables on, but immediately died when they were disconnected condemns either both the battery and the charging system.
Easiest thing is to test the battery and/or replace it with a known good one. At that point the bike should at least start and then you can check the charging voltage from the alternator.
14 volts is 14 volts, and that is the most that you would expect to see on the battery terminals of the car that is running, or on the battery of the bike (from the alternator) when it is running.
Current is a factor of that voltage and the resistance of the circuit being powered (the bike in this case). You will not draw excessive current from the car unless there is already something wrong with the load (the bike).
The fact that the bike started and ran with the jumper cables on, but immediately died when they were disconnected condemns either both the battery and the charging system.
Easiest thing is to test the battery and/or replace it with a known good one. At that point the bike should at least start and then you can check the charging voltage from the alternator.
Last edited by a moderator:
RavFJR
Well-known member
Didn't say it 'would' fry the electronics, just that there is a greater potential if something isn't right with the system...
RossKean
Well-known member
Only one (possible) issue with boosting from a car with the engine running or even with a really good battery. If the MC battery is flat, the car battery has the ability to provide a LOT of current. AGM batteries don't like to be charged at an excessive rate and it is possible that the large initial inrush of current could damage it which is irrelevant if the battery is already dead. This high initial current might be worse with the engine running. Other than that, volts are volts and you certainly won't harm the electronics.
True, a typical auto alternator can supply ~120 amps or so, which is considerably more than our wimpy FJR alternators.
But, the battery is only limited by its own internal resistance and the CCA rating of most car batteries is several times higher than any alternator's amp-acity.
So, technically, the bigger risk is would be hooking it up to a car battery if the bike battery is totally flat. Doesn't support the factoid of not running the car engine when you jump it.
But, the battery is only limited by its own internal resistance and the CCA rating of most car batteries is several times higher than any alternator's amp-acity.
So, technically, the bigger risk is would be hooking it up to a car battery if the bike battery is totally flat. Doesn't support the factoid of not running the car engine when you jump it.
RavFJR
Well-known member
To each his/her own on how they choose to handle a motorcycle jump start... The statement below is from someone that found out first hand why NOT to jump start a motorcycle battery with the car running:
After my fatal experience (burning out my motorcycle rectifier), a mechanic explained that the battery on motorcycles are often placed after the electronic components that are not expecting a current at the battery to exceed a given amount. A car's alternator produces AC current, and has diodes that rectify this into an oscillating DC current. It is then 'smoothed' out by the battery being used as a sort of filter. These oscillations could include spikes at harmful levels to the motorcycle's components, as they were designed around a rather limited alternator output. As general advice dictates, it's okay to jump from a car battery, as long as the car is not running, as to not expose your motorcycle's components to the automotive alternator's output.
After my fatal experience (burning out my motorcycle rectifier), a mechanic explained that the battery on motorcycles are often placed after the electronic components that are not expecting a current at the battery to exceed a given amount. A car's alternator produces AC current, and has diodes that rectify this into an oscillating DC current. It is then 'smoothed' out by the battery being used as a sort of filter. These oscillations could include spikes at harmful levels to the motorcycle's components, as they were designed around a rather limited alternator output. As general advice dictates, it's okay to jump from a car battery, as long as the car is not running, as to not expose your motorcycle's components to the automotive alternator's output.
What a bunch of nonsense. Just because someone was told something by a person of authority who should know how it works doesn't mean they actually do.
The alternator on your FJR, or most other bigger bikes, is also an AC generator (three phase to be exact) that produces AC current, and there is a rectifier to turn the AC into pulsating DC, a regulator to regulate the charging voltage to a nominal ~14.3VDC average, and yes the battery on the bike acts as the filter (capacitive) also.
The way that you blow out a rectifier/regulator really quickly is by shorting across the load. That is easy to do with jumper cables.
Uncle Hud
Just another blob of protoplasm using up your oxyg
As usual, Fred's right. Or, as Mr Zappo said earlier, "The motorcycle charging system will pull what it needs ..."
If the bike jump starts and runs, but won't start otherwise, it's the battery or connections to the battery. (Because a running engine makes the alternator spin, which produces electricity to power the electrical systems -- and the battery is no longer needed to run the electrical systems.)
If it won't jump start, then there are many potential failure points.
If the bike jump starts and runs, but won't start otherwise, it's the battery or connections to the battery. (Because a running engine makes the alternator spin, which produces electricity to power the electrical systems -- and the battery is no longer needed to run the electrical systems.)
If it won't jump start, then there are many potential failure points.
