Starting while on charger

[dba]

I leave my RT on the charger while its resting. When I leave for a ride, I usually start it while it's in the garage and then unplug it from the battery tender.

 

Is this not a good practice? I thought I read somewhere here that it's not but I can't find the post.

 

Your thoughts?

[dan cata]

It doesn't matter

 

I crank my engine without the tank on to test the cleaned alternator and nothing happened.

 

That assuming that you have one of those smart chargers and the battery is not dead. The charger I have only outputs 300mA max. A weak battery would draw too much current and could damage the charger.

[tallman]

I fried a charger years ago when I forgot and left it hooked up to my R100 RT.

So, I never do that anymore.

YMMV.

[tomk99r11]

It doesn't matter ditto. If a starter gets fried there is something else wrong.

[NonComp]

It doesn't matter ditto. If a starter gets fried there is something else wrong.

Starter??

[tomk99r11]

Nah. Fat finger typing and brain fart.

[SKYGZR]

Disconnect prior to starting.

[boatzo]

Disconnect prior to starting.

 

Ditto. Best practice, then you won't have a problem.

[Rinkydink]

What timing, I almost started the ST yesterday with the BT still connected and was wondering about this very thing.

[dirtrider]

Afternoon David

 

I would think whether or not you will/could damage your battery charger is based on the battery charger your are using.

 

The newer electronic smart chargers are very well protected against hooking up backwards, any reverse current damage, over current protection, etc. If you can’t damage it by hooking it up backwards I really don’t see how starting with it connected could. The newer electronic smart chargers are also limited to (and fully protected to) their max output so any additional starting loads would have no effect as the output protection would just kick in.

 

Starting your bike only drops the battery voltage to somewhere around 10 volts so the charger would only have to react to that. Hooking your charger up to an almost dead battery would be worse as the battery voltage could be down around 5 or 6 volts.

 

Now if you have an older non electronic simple cheap trickle charger then all bets are off “probably” wouldn’t/couldn’t hurt it by cranking with it connected but not knowing the charger circuit I just can’t say that for sure.

 

I have been using a old 2 amp (re cheap) inverter type charger on my test bench for years and years with sometimes direct shorting loads placed on it during a test sequence that goes wrong. That same charger is usually hooked up to a bench test battery or two on a continuous long term basis and it is still going strong after all these years so I can say with some confidence that that charger can’t be damaged by loads similar to high starting loads.

 

Bottom line here is: a simple call to your charger’s manufacturer’s tec help line or an E-Mail to them will give you your answer from the people that should know their unit’s ability and it’s protection during engine cranking.

 

[kmac]

Shouldnt hurt anything, but it is a good idea to disconnect it before starting it. It will not fry anything on the bike, but worst case scenario is it could damage the trickle charger, but the newer electronic trickle chargers are digitally isolated and wont get hurt.

[tallman]

DR,

The one I freid was a DEltran BAttery Tender with "smart" capability.

It was hooked up properly.

An anomaly most likely, it was the first, and only time I did that as I forgot to disconnect.

Again, YMMV.

[SKYGZR]

Once again...(for those who didn't get it the first time), Disconnect before starting. If you're working on the machine with the charger connected, cycling the key off and on, off and on, doesn't matter, yet hitting the starter button, and turning over the "firing" system will/does.

 

The loading of the on machine systems should be just that. Any external voltages/amps should be avoided.

 

When launching the Shuttle/and or any Rocket/Jet/Plane, all external sources for power are in disconnect mode, and the machine is "firing" on internal/onboard systems.

 

Start with a charger connected at our own level of risk. (ie; frying the onboard computers, or the source directly)

[boxerboy11]

Yesterday I was at my dealer for some parts and coffee. I was slinking around looking at some of the new bikes and riding gear when I tripped over a battery charger cord. There were at least 5 bikes on the floor with battery chargers hooked to them. One strange looking charger was hooked to 3 different bikes at once.

That jogged my memory about seeing this column on starting with the charger hooked up so I asked the nearby hovering salesman about starting bikes with the chargers hooked up. He told me they do it all the time and never had any problems but I should really ask the service manager if it could hurt anything. When I finally got to the service counter I asked the service manager about starting with a charger hooked up he said he didn’t think it would hurt as they have been doing it for years without any problems. Just so happens one of the tecs was standing there waiting to talk with the service manager so he piped up with it better not hurt the bike as some of the service operations call for hooking up the battery charger before hooking up the Motorrad diagnostic computer. He then went on to say that some of the tests involved starting the engine multiple times.

 

[tomk99r11]

Written with the condescension and arrogance for which many BMW owners are known.

[Boffin]

Written with the condescension and arrogance for which many BMW owners are known.

 

Please do not post personal attacks on this board.

 

Andy

[NonComp]

Written with the condescension and arrogance for which many BMW owners are known.

Oh, please.

 

If you have lots of money and you don't want to be bothered unhooking the charger before starting your bike, the go for it, especially if you are not worried that the vibration might cause the +ve lead to pop off and ground itself on the fuel tank like mine did one time.

 

What could happen, right?

[Swordofwords]

As Dirty Harry would say, "Do ya feel lucky!?" Sometimes I do. Sometimes I am reminded that Murphy's Law has my name wedged in there somewhere.

 

Good food for thought. Better for me to think about it. Thanks@

15 degrees, here, snow on ground winds at 70mph, ground solid.

Life is Good!

 

[NonComp]

Besides (let me stir the pot a bit) if you are starting your bike with the charger still hooked up, that probably means that you have not intention of riding it. And that means, that you are probably going to let it idle for 5 minutes and then shut it off because it is winter and cold outside.

 

My point is that this is also not a good idea. Idling the bike will cause water vapor to accumulate in the crankcase and exhaust system that will not be purged properly because the bike does not get up to operating conditions.

 

You are better off winterizing your bike and leaving it sit, rather than starting it periodically and letting it idle for a while. Or, start it on a nice sunny day when the roads are dry and go for a ride.

[Dan M]

+1 on it dosen't matter.

I do it all the time with bikes on battery tenders and with cars on regular chargers. The charger is only going to put out what it is rated at to try to keep the battery voltage up.

If low voltage would "fry" a charger, many would get "fried" when attempting to charge a dead battery.

I've never had any issues.

[Ian]

I leave my RT on the charger while its resting. When I leave for a ride, I usually start it while it's in the garage and then unplug it from the battery tender.

 

Is this not a good practice? I thought I read somewhere here that it's not but I can't find the post.

 

Your thoughts?

 

If the charger is NOT one that has an electronic crowbar circuit....

 

(a circuit that safely allows a direct short circuit between the positive and negative charging leads and subsequent collapse to zero of the charging voltage)

 

...then IF the battery circuit has any poor connections, the charging wires and charger circuitry may attempt to deliver the current being drawn by the starter. As this can be 200 Amperes or more it would, in this circumstance, certainly damage the charger and its leads.

 

regards,

 

Ian

[dirtrider]

Morning Lan

 

That assumes you are using a 200 amp battery charger. Might be a little too high output to use on a motorcycle battery. I have a 125 amp truck rated battery charger (not for motorcycle battery usage) and the charging cables and clamps on that look to be able to handle twice that amperage.

 

Most of the small commonly used motorcycle battery “maintainer” chargers are under 1.25 amps with some of the more common ones being “well” under that.

 

No way a 1.25 amp battery maintainer can supply 200 amps. It will only supply 1.25 amps regardless of the starter draw. I would think that most modern battery chargers would size their leads and clamps for maximum amperage it could supply. After all if hooked to a very low charged battery it could be asked to supply all it has through it’s wires and clamps.

 

[Boffin]

Morning Lan

 

That assumes you are using a 200 amp battery charger. Might be a little too high output to use on a motorcycle battery. I have a 125 amp truck rated battery charger (not for motorcycle battery usage) and the charging cables and clamps on that look to be able to handle twice that amperage.

 

Most of the small commonly used motorcycle battery “maintainer” chargers are under 1.25 amps with some of the more common ones being “well” under that.

 

No way a 1.25 amp battery maintainer can supply 200 amps. It will only supply 1.25 amps regardless of the starter draw. I would think that most modern battery chargers would size their leads and clamps for maximum amperage it could supply. After all if hooked to a very low charged battery it could be asked to supply all it has through it’s wires and clamps.

 

Unfortunately it does not work that way - current is pulled, not pushed. If the charger is effectively the only power source, the starter motor will place a low-impedance load on the charger and try to draw 200 amp. The fact that the charger cannot supply that current means that, in the absence of protective circuitry/fuse, the wiring or internal circuits will be damaged by the overload.

 

Andy

[Joe Frickin' Friday]

Unfortunately it does not work that way - current is pulled, not pushed. If the charger is effectively the only power source, the starter motor will place a low-impedance load on the charger and try to draw 200 amp. The fact that the charger cannot supply that current means that, in the absence of protective circuitry/fuse, the wiring or internal circuits will be damaged by the overload.

 

The charger is likely to be designed as a constant-current device. If it's a smart charger (e.g. the Battery Tender), it's monitoring battery voltage and switching the current supply on/off as necessary to maintain the battery at ~14.5 volts, but whenever it's on it will supply only X amount of current. A constant-current device is such that you could short the output terminals together, and it will still only supply the listed amount of current. Thus, regardless of whether your battery is healthy or dead, or whether you've hit the starter or not, the charger should not be vulnerable to damage; it'll just continue to put out its rated current.

 

Likewise, the bike should not be in any danger due to starting it with the charger attached. If the battery is healthy, then of the 200 amps flowing through the starter motor, it's supplying ~199 of them, and the charger is supplying the ~1 additional amp; the dip in voltage due to starting will not draw any additional current from the charger. If the battery is dead-flat when you thumb the starter, then the ~1 amp from the charger gets divided between backflow through the battery, flow through the starter solenoid, and flow through the starter itself; you'll probably just get a chattering solenoid.

 

[Boffin]

I agree with that assessment of a regulated smart charger. If however, it is one of the old-fashioned transformer and rectifier type, there is no regulation or protection - they will die a smokey death if you attempt to draw high current from them.

Modern chargers have protection circuits - the scenario I outlined did say "in the absence of protection... "

 

Andy

[Joe Frickin' Friday]

Modern chargers have protection circuits - the scenario I outlined did say "in the absence of protection... "

Andy

 

Fair enough. I guess the best answer for the OP then is "it depends on the charger."

[boatzo]

There have been a lot of reasons given, theoretical and actual, for starting the bike whilst connected to A charger. Why not just be safe and eliminate the guessing and disconnect the damn thing before you start the bike. Then there will not be any problem. MHO

[dirtrider]

Morning Lan

 

That assumes you are using a 200 amp battery charger. Might be a little too high output to use on a motorcycle battery. I have a 125 amp truck rated battery charger (not for motorcycle battery usage) and the charging cables and clamps on that look to be able to handle twice that amperage.

 

Most of the small commonly used motorcycle battery “maintainer” chargers are under 1.25 amps with some of the more common ones being “well” under that.

 

No way a 1.25 amp battery maintainer can supply 200 amps. It will only supply 1.25 amps regardless of the starter draw. I would think that most modern battery chargers would size their leads and clamps for maximum amperage it could supply. After all if hooked to a very low charged battery it could be asked to supply all it has through it’s wires and clamps.

 

Unfortunately it does not work that way - current is pulled, not pushed. If the charger is effectively the only power source, the starter motor will place a low-impedance load on the charger and try to draw 200 amp. The fact that the charger cannot supply that current means that, in the absence of protective circuitry/fuse, the wiring or internal circuits will be damaged by the overload.

 

Andy

 

Afternoon Andy

 

I understand that part but then explain this to me.

 

If placing a load on an “old-fashioned transformer and rectifier type" battery charger that is higher than it can supply can damaged it or burn up.

 

Then why don't they burn up when hooked to a car sized battery that is partially run down? That can easily draw w-a-y more amps than the charger can supply. Even the “old-fashioned transformer and rectifier type" must have some sort of protection built in or they would fail in short order in everyday use.

 

I do have an older 12 amp rectifier type charger that has a 20 amp fuse in the +ve wire and I haven’t ever blown that fuse even while cranking a diesel vehicle with a dead battery with the charger hooked up.

 

[kmac]

I agree that simply disconnecting would be the best way to do it. I dont keep my bike on the trickle all of the time, and my bike is stuffed way in a corner of my garage, I cant see the charger input plug so sometimes i forget it is plugged in and i start it, then when i throw my leg over it put take it off the center stand then i notice the charger attached...no biggie, i have started it many times already on the trickle with no damage yet to anything. I am just running the small basic model "battery tender" brand trickle

[Ian]

I agree with that assessment of a regulated smart charger. If however, it is one of the old-fashioned transformer and rectifier type, there is no regulation or protection - they will die a smokey death if you attempt to draw high current from them.

Modern chargers have protection circuits - the scenario I outlined did say "in the absence of protection... "

 

Andy

 

Andy,

 

Thanks for supporting my view. I was of course assuming a stepped voltage non regulated "old fashioned" charger. Lead acid batteries do not normally use constant current chargers.

 

There is an additional factor that involves Kirchoff's Laws of current distribution in multi supply, i.e charger plus battery circuits, in parallel. This is too far back in my electrical theory days but parallel circuits try to share current and an intermittent battery connection during starting can result in the charging circuit drawing significantly more current. It only takes milliseconds for an UNPROTECTED (i.e. without a semiconductor fuse) charging rectifier to be damaged.

 

Ian

[Dan M]

......A constant-current device is such that you could short the output terminals together, and it will still only supply the listed amount of current. Thus, regardless of whether your battery is healthy or dead, or whether you've hit the starter or not, the charger should not be vulnerable to damage; it'll just continue to put out its rated current........

 

 

This has been my experience.

One of our chargers in the shop is at least 25 years old. Nothing smart about it and we have never hurt it by "overloading" it.

 

The OP stated Battery Tender. So regardless he is OK.

[tallman]

E-mail reply from Deltran who makes the Battery Tender models.

 

"It is safe to start your bike with the Battery Tender products still connected."

 

I will still choose to umplug first, but that's the word from on high.

 

Best wishes.