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Can you jump start the bike through the battery tender connector?

906 Views 37 Replies 11 Participants Last post by  golden chicken, 
ziffusion
There is a SAE connector hanging off the battery in the 2023 model (and maybe others as well).

Is this connector safe to jump start a bike through? Or is it meant exclusively for charging the battery?
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Skywalker67
Where is the SAE connector wired to?
If it is wired directly to the battery, I'd say there is nothing different from wiring your battery to another one to jump start the bike.
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ziffusion
Skywalker67 said:
Where is the SAE connector wired to?
If it is wired directly to the battery, I'd say there is nothing different from wiring your battery to another one to jump start the bike.
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It is wired to the battery, through a 7.5A fuse, though. I suppose that means that this path can't be used for a jump start (which can take as high as what - 200A?). No markings on the cable indicating AWG, either.
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golden chicken
If you need a jump because the battery is just slightly too weak to start the bike on its own and you don't have the tools handy to take the seat off, like if you accidentally left the parking lights on for 2 hours, maybe. In this case, I would rather see you connect the jump pack to the connector and leave it for 30+ minutes to charge the battery up.

If the battery is mostly dead, no.
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ziffusion
golden chicken said:
If you need a jump because the battery is just slightly too weak to start the bike on its own and you don't have the tools handy to take the seat off, like if you accidentally left the parking lights on for 2 hours, maybe. In this case, I would rather see you connect the jump pack to the connector and leave it for 30+ minutes to charge the battery up.

If the battery is mostly dead, no.
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Yeah. I was just thinking if I could use the existing SAE connector to both charge the battery and deliver a jump start - whatever is called for. But seems like that is not the case. For the jump start, one would need to go to the battery terminals directly. Or yeah, you could just charge it up. But that would take time. And may not even be possible, if the bike is not at home.
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Straticus
ziffusion said:
There is a SAE connector hanging off the battery in the 2023 model (and maybe others as well).

Is this connector safe to jump start a bike through? Or is it meant exclusively for charging the battery?
Click to expand...
No!

The SAE connector cannot handle the heavy current required for the Starter to move the engine. If you look on the specs of Batteries they give the CCA ( Cold Current Amperage ).

This cheap Gel one rates @ 120 amps


When the Starter button is pressed there can be well over 50 amps going through the Starter Relay.

You might get away with it for a few seconds but fuse would most likely blow and the wires would most certainly heat up and probably melt and cause a possible short. Don't do it!
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Straticus
When I had a car on the road I bought one of these,

Power Pack Jump Starter eBay

And tested it on my SV and it works on a depleted Battery but has to be attached directly to the Battery terminals.

As my SV is my only Automotive transport I keep a spare cheap Fully charged Gel battery in my Kitchen. Luckily I've only had to use/swap it once when I accidently turned the ignition key too far and put the Bike in ,"Park Mode " and left it not noticing the parking lights were still on and it flattened the battery Doh!! :O
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ziffusion
I have a NOCO. Or I just jumpstart it right from another car or something.

Straticus said:
when I accidently turned the ignition key too far and put the Bike in ,"Park Mode "
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Yeah, ha ha, did that the second day after I had the bike delivered :)
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PeteH
As Strat says. No! And you can't charge it with a faster charger than a low power one either. Only the battery maintainer, otherwise you will blow a fuse.
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Straticus
ziffusion said:
I have a NOCO. Or I just jumpstart it right from another car or something.
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You can use a car but it is still dodgy.

If you use a car start the donor vehicle > Apply the jump leads to the donor vehicle being careful not to short the leads. Have bike keys in ignition ready > Apply jump leads to Bike battery and try to start but do NOT be tempted to Rev the Car Donor vehicle as this would shunt too much current to the Bike's battery. Bike batteries are fragile compared with the Heavy Duty batteries used in cars and cannot take the same amperage. If it doesn't start then there's a problem that needs sorting and no amount of current being shoved into the Bike's battery will help.

You can safely ," Passive " charge a Motorcycle battery using a Car battery by connecting it via jump leads and leaving it for several hours and the reduced internal resistance of the depleted MC Battery will draw current from the Car battery without causing damage :)

FYI : There's a difference in electrical circuits of current being generated and current being stored and drawn upon.
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golden chicken
Do NOT jump start an SV650 off a running car.

There are many instances of people doing electrical damage this way.

Just jump it off the battery with the car off if you need to.
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VFR4Lee
Take off seat, connect jump start box. And yeah, if you get a jump from a car, it should not be running. I don't think what bike you have matters there. That big ass car battery should be enough.
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ziffusion
Well, folks - it seems like the "jumping from a running car will fry your bike" may in fact be an old wives tale (at least in this day and age). There is electrically no difference in the voltage put out by the car battery or the alternator of a running car (12-14.5V), such that the current drawn by the bike pretty much depends on the bike itself, and it will draw the same current from either source. In theory, the car battery can supply higher currents than the alternator.

I have always had the car running every time I've jumped another car or a motorcycle. Full disclosure, I am an Electronics engineer and from what little I remember about electricity, this thing never made sense to me. In fact, I thought it was a good idea to have the car running, so you don't impact its battery negatively.

Ok - fight me.

EDIT: Here's a thread on Reddit that makes sense to me. We can do more legitimate research here.
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8
Is everyone just afraid to bump start their bikes nowadays? Put it in 3rd and start running amigo.
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dmfdmf
Not an EE here but... from what I understand the problem isn't when you connect the car and bike batteries together with the car running but when the motorcycle engine starts and both charging systems are running at the same time. Car charging systems are very different than moto charging systems (variable output alternator versus permanent magnet generator with shunt R/R) and I think the risk is that it can fry the diodes in the R/R or something like that. In any case, there is no reason to take the (real or imagined) risk as a car battery has plenty of amps to start a bike without the engine running.
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Straticus
ziffusion said:
I have always had the car running every time I've jumped another car or a motorcycle. Full disclosure, I am an Electronics engineer and from what little I remember about electricity, this thing never made sense to me. In fact, I thought it was a good idea to have the car running, so you don't impact its battery negatively.

Ok - fight me.

EDIT: Here's a thread on Reddit that makes sense to me. We can do more legitimate research here.
Click to expand...
What is the current output of a Car's charging system at idle ?

What is the safe maximum charging current of a Motorcycle battery ?
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golden chicken
Straticus said:
What is the current output of a Car's charging system at idle ?

What is the safe maximum charging current of a Motorcycle battery ?
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The answer to both is, it depends.
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ziffusion
Straticus said:
What is the current output of a Car's charging system at idle ?
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That's the wrong question, I think. You should be asking what the voltage output is. Because that's what the car puts out. The current drawn depends entirely on the resistance that is connected across it (i.e. the resistance offered by the motorcycle).

As I said earlier, the voltage put out by the car battery or alternator is between 12-14.5V. The current drawn depends entirely on the motorcycle and what it is doing. It is not going to be any different whether the source is the car battery or the car alternator or the motorcycle battery. Unless there is a short or something in the motorcycle - in which case it will draw the max current a source can supply.

This is what my understanding is and what the theory says. But I can be corrected.
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Straticus
ziffusion said:
That's the wrong question, I think. You should be asking what the voltage output is. Because that's what the car puts out. The current drawn depends entirely on the resistance that is connected across it (i.e. the resistance offered by the motorcycle).

As I said earlier, the voltage put out by the car battery or alternator is between 12-14.5V. The current drawn depends entirely on the motorcycle and what it is doing. It is not going to be any different whether the source is the car battery or the car alternator or the motorcycle battery. Unless there is a short or something in the motorcycle - in which case it will draw the max current a source can supply.

This is what my understanding is and what the theory says. But I can be corrected.
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The problem here is that when the jump leads are connected as far as the car charging system is concerned it's own battery will be invisible to the circuit because a Fully charged battery ( The Car Battery ) has a high internal resistance. As I'm sure you know current in a circuit always finds the path of least resistance.
The lower internal resistance of the MC battery will mean the larger current from the Car alternator will bypass the car battery junction as in Kirchoff's Law e.g Current at entering a junction equals the current exiting the junction even if current exits via several paths. The Car won't know it's feeding a battery not designed for it's higher charging rate.

The car charging system will try and charge the MC Battery as if it were a Heavy Duty Battery. How detrimental this might be I cannot attest to as I can't ever remember risking using a running car to start a Motorcycle preferring as per previous posts to use safer methods.

If someone does use a running Car to start their MC and they have no problems then fine for them however hopefully this thread has given food-for-thought and the possible dangers involved. I myself have had to Bump-Start several motorcycles over the years and have used a spare car battery in my garage on a Motorcycle and the Booster Starter ( Which is essentially a large Battery in a small electronic form )but hopefully I'll never have to use a running Car engine :)
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dmfdmf
dmfdmf said:
Car charging systems are very different than moto charging systems (variable output alternator versus permanent magnet generator with shunt R/R) and I think the risk is that it can fry the diodes in the R/R or something like that.
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ziffusion said:
Unless there is a short or something in the motorcycle - in which case it will draw the max current a source can supply.
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The key problem as I see it is that the R/R in a moto is typically a shunt type, i.e. shorts the stator to ground to control voltage. So instead of diodes in the R/R frying perhaps it is the mosfet or whatever electrical device that does the shunting that gets fried because the alternator will see it as a short and drive it to failure.
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