Help! How long does it take to charge a flat battery by riding?

[surfchick]

crew-i've searched ze archives..but
i was a dummy and left my key in the ignition and with ze headlight hard wired the battery was flat as when i came to go home:

i rolled my bike to a hill and managed to push start it in 2nd (srv 250), but was nearly out of gas & had to stop about2 mins down the road for petrol (or spend forever in otara), pushed it up a little rise and ran/jumped on rolling and push started it in 2nd again. then dorve 15 mins at 100kph thinking that would charge it & parked at aut, but when i went to go home it was still flat so i rolled myself down a hill an push started again & drove another 20mins on the motorway.
it still won't start-

HELP-HOW LONG WILL IT TAKE IT TO CHARGE JUST BY RIDING? it seems wierd a car can charge up in 10mins but not the bike ;(
or is the only way to take the battery out and charge it that way (i don't have a batter chargery so that's why all the pushing!).

is this normal for it not to charge by riding?

[Waylander]

Not sure how long it takes to charge by riding ut I'm sure someone up there has a charger you could borrow.

Also, how long ago did you get a new battery?

[paturoa]

You dont have to go mega speed, when the motor is doing about 2 - 3 times the idle speed then it will be charging plenty.

If the battery, charging etc is OK, then about then 30 minutes should be ample for lecy starter

[Mom]

Hate to say this but.........invest in a battery charger.........or buy a new battery......dead batteries are a pain, but usually dont take too long to get a little life in them...........I'm picking its time for a new one myself

[paturoa]

hey waylander is your vmax fixed yet?

[Ixion]

Yes, it is normal. It may take many hours. Thing is, with small bikes , and with headlights hard wired on, there is very little "extra" current being generated. In fact , under mid revs, like as not its actually flattening the battery.

If you can turn the headlight off that MAY help (not always, because some bikes actually switch in an extra charge coil when the lights are switched on).

Do you want to borrow a battery charger?

[jrandom]

Your poor wee SRV barely has enough grunt to haul itself down the motorway at 100kph, let alone put out enough current through its dinky alternator to charge up a battery.

Even proper bikes generally have difficulty juicing up batteries. That's why many guys buy battery chargers. I'm sure you'll find a willing volunteer to...

Woops, there you go, Ixion beat me to it. Seems a shame to waste all these perfectly good keystrokes by not posting, though!

[MSTRS]

Hate to say this but.........invest in a battery charger.........or buy a new battery......dead batteries are a pain, but usually dont take too long to get a little life in them...........I'm picking its time for a new one myself

I'd agree. Funny things are batteries...if there is no charge in them to start with, then chances are they won't charge by riding.

[Waylander]

hey waylander is your vmax fixed yet?
Have not had trouble starting since last I had it apart (the night you helped me) so it could have been a loose connection that I fixed inadvertently.

Went through all the checks like last time the other day and everything came up mint as.

[xwhatsit]

Hmm... well tonight I finally put my bike (temporarily) back together after it's been in a million pieces in my garage, and unsuprisingly I had a flat battery. The bike was sitting in first gear, and I don't have hard-wired headlights so it wasn't immediatly obvious the ignition was switched on, but it was, and over a week or two it had gone flat.

Anyway, I've got a kickstart, so I kickstarted it and it came to life easily enough. However, I rode the thing for less than 10 minutes, at pretty low RPM, with the headlight on, and when I got back the battery had a pretty good charge.

However, I don't have a starter motor; perhaps your electrics are a whole lot beefier because of electric start? Typically in a lead-acid battery, the charging profile is not linear; so you'll pump a lot of juice into it for not much increase in current and voltage (and of course the decharging profile is the same). This is quite different to a lithium cell or NiCad; it'll hold voltage and current up high right until there's only a little bit of charge left and then they'll drop very quickly. Having a starter motor, that's quite a high current peak, so I imagine a partial charge won't give you much joy.

Yeah throw it on a charger. I built one myself out of an old bedside alarmclock, but I wouldn't trust it as far as I could throw it (which isn't very far as it has a large chunk of iron for a heatsink).

[crashe]

Surfchick...... I have a charger....... you can borrow it...
and you live near me...
come on over to my place and collect it and then charge it overnight...

Or I could get it to you now...

Your engine is the same as mine do not try to jump start it...
you have to recharge the battery... or you will do in the recifier/regulator...
As I did that once and it cost me a bit to get it sorted...

Oops just read the whole thread.... you managed to get it home..... you were lucky...

I can bring the charger over to you if you want......

[surfchick]

cheers crew-
hmmm i'm going to have to push start it today to get to work & then again at work to get home but crashe-i'm thinking i'd love to charge it up on charger!
i so can't believe they don't just charge up when riding-
i have to say it was really embarassing to have staff passing me at MIT while i ran my bike down a hill with my legs flapping like fred flintstone.

[Motu]

It'll never fully charge in the bike,but it may get enough to start and ride with no problems at all.You need to use a battery cherger to get it fully charged.It's a pity the generator has been out of fashion in cars for over 35 years,and in bikes for 45 years - because a generator will fully charge your battery in the vehicle,an altenator never will.

[JMemonic]

I can never understand why those of us with bike don't own a charger. The $20 charger from the warehouse is plenty, they are a low current charger so very unlikely to cook a battery, they are small and can easily sit in a cupboard until needed.

Its not serious money we are talking about here and giving your battery a good overnight/weekend charge on one of these every so often can maintain the life of a battery given manufactures ability to build charging systems with little or no extra output than is required to run the vehicles if every part is perfect original spec, heck you get one faulty connector burning off current and you can cut your spare charging ability in half.

[Pixie]

It'll never fully charge in the bike,but it may get enough to start and ride with no problems at all.You need to use a battery cherger to get it fully charged.It's a pity the generator has been out of fashion in cars for over 35 years,and in bikes for 45 years - because a generator will fully charge your battery in the vehicle,an altenator never will.

Que?
I don't know about little bikes but all the big ones I've had will put 14.2 v across a battery at any thing above idle.
This WILL charge a battery and not give it a choice in the matter.

[Ixion]

The voltage isn't smoothed, it's not really DC. The 14.2V is peak, across the tops of the square wave, not RMS. Not sure if that's what Mr Motu meant. But I have charged batteries from flat (run and bump) on big bikes with apparently adequate results. Little ones may be another matter, their electrics are a bit crude.

[crashe]

Has anyone heard from Surfchick?

Did she sort out the battery.

I offered to lend her my battery charger but she never got in touch.
As I am only a few kms away from her, I could have gotten the charger to her within a few minutes.


And Yes I did send her a pm at the time.
But she hasn't read it yet.........!

[Motu]

Que?
I don't know about little bikes but all the big ones I've had will put 14.2 v across a battery at any thing above idle.
This WILL charge a battery and not give it a choice in the matter.

That's volts,you also need amps to charge a battery.It's a long time ago since I was told the theory and like most apprentices promptly forgot the long explanation and just remembered the impotant bit,if I get time I might try and brush up my theory.But an altenator gives a good initial charge and tops the battery up quickly and then cuts right back,never giving full charge.

I've seen homemade mobile battery chargers using washing maching motors and generators with twin spool regulators,they fully charge a battery.

[crazybigal]

should have charged enough to get it started one would think!
turn your light off if you can.
check your charging system your alternator or Rectifier could be shot.
most bikes do their charging just above idle, wont matter if your reving the shit out of it, the rectifier is going to spit out the same voltage to the battery anyway.
put a voltmeter over the batt at like 1500rpm and you should get between 13-14.5 volts depending on your charging system.
or maybe your battery is poked.
good luck

[davereid]

What a load of drivel this thread is full of ! Always good to see how the standard of science and physics is at our schools these days, I'll have a job for years by the look of it. Never mind, guess you are all good at kapa haka.

OK.. if your alternator has its magnetic field provided by field windings, if you have a flat battery you are stuffed. This is because you dont have any power to produce a magnetic field so you can push as fast as you like, but you will get no output.

But, on yer small motorcycle you most likely dont have field windings, chances are you just have permanent magnets built into the flywheel. So if you spin the engine, you'll get the 'lectricity.

In a "generator" you produce AC electricity, but mechanical contacts change over every 180 degrees to give you DC. In an "alternator" exactly the same thing happens, but instead of using mechanical contacts, electronic ones are used. (The rectifier.)

Your battery doesnt care. If the terminal voltage of the battery is lower than the terminal voltage of the alternator/generator/battery charger, then current will flow into the battery. If current is flowing into the battery its gonna charge. But as it charges its terminal voltage goes up, so the charge current decreases.

No probs for us mechanics, we know that as a good rule of thumb, if the terminal voltage of the battery when the engine is running is 13.8 to about 14.2, its going to be charging.

But, some of the charge is wasted, it just warms the battery up, and causes gassing.

The bottom line ?

Any bike with electrics in good nick can completely charge its battery - if terminal voltage is 13.8 - 14.2 its happening.

But, if your battery has a faulty cell, voltage may be OK, all you are doing is warming the battery and gassing the other cells, you need a new battery.

And NEVER NEVER NEVER charge a bike with the battery in. I know it says you can on the side of that flash "battery tenda" charger you bought, but you risk damaging your voltage regulator. Your voltage regulator sees voltages above about 14.2 and tries to short them out to prtect the bikes electrics. Lots of chargers are quite capable of detsroying the voltage regulator.

Cheers

Dave

[Waylander]

Has anyone heard from Surfchick?

Did she sort out the battery.

I offered to lend her my battery charger but she never got in touch.
As I am only a few kms away from her, I could have gotten the charger to her within a few minutes.


And Yes I did send her a pm at the time.
But she hasn't read it yet.........!
I imagine if she was having real problems she would be online so it may have been sorted out.

I could also be completly wrong and she can't get online lol. If I had her number I would text her but I havn't asked her for it yet and she hasn't offerd.

[mart1]

And NEVER NEVER NEVER charge a bike with the battery in. I know it says you can on the side of that flash "battery tenda" charger you bought, but you risk damaging your voltage regulator. Your voltage regulator sees voltages above about 14.2 and tries to short them out to prtect the bikes electrics. Lots of chargers are quite capable of detsroying the voltage regulator.

Cheers

Dave

Oops, I wondered what that clicking sound was :whistle:

[lukelin250]

i ran mine flat as a pancake on the weekend. roll started it and went for a 20 min ride,,now all is fine. still not good for the batt though aye

[Finn]

As a rule of thumb, its 5 minutes per 100 cc's. So if your motorcycle has an engine capacity of 250cc that's 5 mins x 2.5 = 12 mins & 30 seconds. You don't have to worry too much about 30 seconds. You can round it up to the nearest minute.

Bummer if you have a Triumph Rocket. 5 mins x 23 = like forever.

[rok-the-boat]

How does a voltage regulator connect up? In series or in parallel. I imagine it is just in prallel, like, one side to power from the alternator, the other to earth. Would that be right?

[judecatmad]

When my ginny's battery was flat (due to the ignition being left on for a couple of weeks unbeknown to me...thanks Dave!), I jump started myself down the driveway and rode it to work at higher than normal revs (3rd and 4th gears most of the way instead of 4th and 5th), with the headlight off, and it seemed OK after that. Was about 45 mins to work and it seemed to do the trick.

My battery is only a couple of years old tho so that might make a difference?

Also, I guess if your headlight can't be switched off then that would change things significantly.

[sunhuntin]

When my ginny's battery was flat (due to the ignition being left on for a couple of weeks unbeknown to me...thanks Dave!), I jump started myself down the driveway and rode it to work at higher than normal revs (3rd and 4th gears most of the way instead of 4th and 5th), with the headlight off, and it seemed OK after that. Was about 45 mins to work and it seemed to do the trick.

My battery is only a couple of years old tho so that might make a difference?

Also, I guess if your headlight can't be switched off then that would change things significantly.

yeh...always use the key...not just the kill switch! learned the hard way. lmfao.
got it jumped by the roadside assistance guys...and being in an unfamiliar city, it was easy to charge...but i think 45 mins roughly was all it took. would likely take less than that though.