When I have a one-amp charger on the battery, and the motor-scooter
tail light is on and another light in front, smaller than a headlight,
is on, and whatever the ignition system uses when the scooter is not
running, am I charging the battery or discharging it?
I also have the 2/10 amp charger.
Maybe it warmed up or something but it now puts out
11.5 v with no load in the 2 amp setting,
12.5 v with no load in the 10 amp setting, and
8v with no load in the 6 volt setting.
Is there any point in using it at all? It seems like even at 12.5
volts, it will discharge the battery?
Background: Unlike when I asked a couple weeks ago, I don't need the
charger to supplement the battery in real time. My friend's lawn
mower failed and I now have use of a 10AH lawn mower battery, when the
bike normally has a 4, 6, or 7AH battery. This one is about 3 times
as big as the space available for intended one. And the 1-amp
charger will recharge the battery by tomorrow, but during the course
of the day I want to keep it charged, and since I don't have an
ignition key it's hard to turn it off, so whether I leave the two
lights and ignition on or not, I'm not sure the 1-amp charger can make
up for what I use. More important, even if it can, this is a
theoretical question for use elsewhere too.
Chargers vary CONSIDERABLY.
Open circuit voltage may be irrelevant, depending on the design
and what you used to measure it. It may be broke...maybe not.
Only thing that matters is the current when hooked to the battery.
Watch the headlight. If it gets brighter when you connect the charger
to the battery terminals, it's likely charging. Too much? Too little?
you won't know until you measure the current.
This is a bad idea. Pick the lock to turn it off and use another
switch. Or just remove the lock and use another switch.
so whether I leave the two
It's unlikely that the unknown 1-amp charger can keep up with two
Good idea. Tomorrow. It will have to be a tbe front running light
or the tail light. For the record, the headlight only went on when
the engine was running. I just learned that today. The generic
schematic shows a switch for the light, but come to think of it,
doesn't say if it's for human hands or some other method. Anyhow, so
far all the lights, turn signals, fuel gauge, horn, and starter motor
I disconnected the ign. switch and I use a jumper wire to connect the
red and black. It's hard to get the alligator clip to make contact,
because it's a little too big to get into the connector**, and it's in
the front of the scooter with things in the way, so that's why it's
hard to disconnect, but if it was going to be longer than 10 minutes I
**Maybe I'll make up some spade connectors with wires long enough to
reach over the handle bars with a switch. Tonight or tomorrow
morning. Once I'm sure the thing will run continuously, they have
ignition lock/gas cap/under-seat lock sets with 2 keys for only 22
dollars. So I can do things right.
Plus mirrors for 10 or 20 dollars, battery for 25 if still on sale,
battery cover for 10, used tail light lens for 13.
Plus front panel (in front of the engine compartment, hopefully in
blue) and another panel that's like a bandana at the base of the seat,
covering part of the engine compartment (all of them in black), if I
can find those two things. The webpage made it look like the place I
went to had lots of used scooters, but I only saw about 10, of various
models, so the odds are he doesn't have what I need. There was almost
no light. One guy about 25 or 30 working there, a very depressing
place. The other end of the same building, different parking lot,
different entrance, had the middle aged black manager and a couple
middle aged white guys enjoying an outdoor confab. He told me I'm
never too old for a motorcycle. I can put it on a table and look at
it, and the others laughed.
One place on line wants 100 to 250 for fairings, 40 for side panels.
No one else even mentions them. Of course i can ride it without those
Plus to ride it on the street: Title, 20, liquidated sales tax, 20,
Not sure it's worth it. Today and tomorrow or the day it actually
runs might be the highlight of the whole experience.
OTOH, if it were spring, there's a place near the Philly airport that
has an acre of outdoor storage with about 600 junk scooters. You can
almost count them with satellite view. and an acre of indoor space.
In warm weather, I'd love an excuse to drive up there via the highway,
then back via local roads
Oh, I may have to lose weight to ride it. Before it said the maximum
was 225 lbs, but now it seems to say 162KG.
Another good reason to disconnect it.
Thanks and thanks all.
You KNOW, beyond a shadow of a doubt, that the battery will never
become fully charges wat 12.2 volts - regardless of the current flow.
And 12.2 volts won't force any current into a half charged battery.
On 11/26/2015 4:59 PM, email@example.com wrote:
Must be awesome to KNOW absolutely everything "beyond a shadow of a doubt."
Drop by and I'll show you a B&D 1A charger that outputs zero volts no load.
I thought it was broke. But, since I don't KNOW everything, I hooked
it up to a battery and it charges just fine. Something to do with the
reverse polarity protection.
Charger designs VARY. Hook it up in the manner for which it was
designed and measure it.
Good thing that rocket scientists don't think they KNOW everything.
On 11/26/2015 8:54 PM, firstname.lastname@example.org wrote:
Well, that may be the way you would have designed it.
But, you probably didn't design it.
I don't have a problem with assumptions that you verify.
I have a problem with people who state, with certainty,
stuff they have not experienced on unspecified equipment
in unknown circumstances.
Doesn't it trouble you the least little bit that it's
12.2V? What's the failure mode that results in that
open circuit voltage reading?
Yep, I used to manage very bright engineers with similar arrogance.
Spent much of my time cleaning up after them.
Let's just save the thread the excruciating protracted attempts
to prove how smart you are and turn it into a thought experiment.
Take a random car battery charger.
Plug it into your oscilloscope with no other load.
What would you expect to see on the screen?
Take your random DC voltmeter and think about how it would
respond to what you see on the screen.
I agree that understanding of electricity would help...;-)
Could be several different failure modes, including a bad rectifier,
as most simple battery chargers are very poorly regulated open
circuit, with the impedence/resistancde of the windings limiting
urrent under load. Just like a cheap 12 volt wall wart that may put
out 18 volts open circuit.
My first check would be the bridge rectifier, which is
repairable.replaceable - second would be a shorted secondary winding
in the transformer, which means it is junk.
If it was a sophisticated automatic charger, it could be anything -
but being listed as a dual current rated charger, it is NOT a smart
A choppy DC - diferrent depending on what kind of rectifier circuit t
has - center tapped full wave, full wave bridge, oe half wave.
If the OP had stated what make and model the charger is, it would be
easier to give a definitive answer - just like if he told us what kind
of "scooterz' he was working on.
and engineers are a lot different breed than those of us who have to
fix their mistakes - or have to work on what they design.
It would read HIGHER than actual voltage if anything.
You are so smart, you explain to me how a DC voltmeter would reaf
lower on an unfiltered rectified voltage than it would when connected
to a "filtering" load like a battery.
If you can adequately explain it, I'll accept your criticism
On 11/27/2015 10:28 AM, email@example.com wrote:
You're mixing parameters. The wall wart is filtered, so the open
circuit voltage is likely near the peak value of the rectified waveform.
If you put a cap on the output of a battery charger, you'll read
the peak value on your DC voltmeter. Without the cap, the reading
is more like the average value of the waveform.
I'd have to agree with that diagnostic method, but after you determine
that it's actually broke.
At the risk of repeating myself...
What does a DC voltmeter read when you apply something that's not DC?
The answer is that it depends.
The meter that most people have will read something like average...it
And, because I didn't expect you to capitulate, I did the experiment
before I posted. Created a pulse waveform with my function generator
and stuck the Fluke on it. Reads something approximating average.
And that's less than peak. And peak is more relevant to what the
charger can deliver to the load.
Try it, it ain't rocket science...just an understanding of electricity ;-)
Cheapo battery chargers often use the leakage inductance of the
transformer to limit current pulses to a safe value. It's not unusual
to have a SCR in series and a zener diode so that the SCR can't turn
on when the battery is over the desired charge termination voltage.
Smarter ones have hysteresis that drops the voltage to the float level.
When you measure the battery voltage during charging, you're doing just
measuring the battery voltage. The charger is putting current pulses into
a rather stiff voltage source, so the output is whatever the battery allows.
Measured when disconnected, the charger output is often full-wave
rectified AC. The number on the display of your DC voltmeter is
less than the peak. Average, or thereabouts, is likely what
the typical DC voltmeter displays.
If you want to know if the battery is charging, you need to measure
I was trying to get you to rethink your criticism, but that
was going nowhere.
How'd I do?
Full wave rectified AC is DC. It is pulsating DC, but not nearly as
pulsating as half wave, and bridge rectified is not a pulsating as
center tapped full wave (2 diode). A DC voltmeter will read the DC
(average) voltage on an unloaded circuit, and will always read
somewhat lower under load. The battery "sees" the average voltage.
You still have not explained how a battery charger would put out less
open circuit voltage than the voltage it would put into a load or a
battery - sorry.
You still didn't explain how the voltage could be lower under no load
than under load.
Real easy way to check for a shorted diode is put an AC meter on it.
If you have a couple volts of AC it's pretty well a dead giveaway, and
it would definitely drop the output. And many wall warts ARE
unfiltered. All they have in them is a transformer and a diode bridge
- or on the real cheap-assed ones, a center tapped transformer and 2
I've even seen them with single diode half wave rectification.
On 11/27/2015 1:38 PM, firstname.lastname@example.org wrote:
Well, I've done the best I can to explain.
When someone knows it all beyond a shadow of a doubt, it's useless
to try to tell them anything.
You're attempting to apply experience where you haven't modeled
the system and where the gross oversimplification doesn't apply.
Trying to save face by denying the obvious just makes the hole you're
I told you the experiment to run to invalidate your claim.
I did it yesterday, cuz I don't like to spout random thoughts
I haven't personally verified, and it works just like I explained.
Well, the instantaneous voltage will be less than or equal when loaded
with a LINEAR load.
A battery is NOT a linear load.
Your voltmeter assumes a constant voltage and gives you a reading
based on that, in this case, FALSE assumption.
Create a nonlinear model based on current and you'll see.
Run the experiment. It will take you half a minute with a function
generator or pulse generator or two diodes and a center-tapped
transformer and a DC voltmeter.
Unless it's shorted...you just don't give up on the diversions...
The ones that have no cap will behave just like the battery charger.
Quit guessing and
Run the damned experiment that applies to this situation, it will take
you half a minute.
Maybe someone else can help. I give up.
Quit with the wall-warts already. It's a battery charger designed
for the single function of charging a lead acid battery.
Seems to me the only proper experiment would be with a battery
charger, a battery, and volt meter of some sort. A real life
experiment. Who knows what happens with a function or pulse
generator, but whatever happens it doesn't seem to prove anything
about the situation in question, a battery charger that shows between
11.5 and 12.5 volts under no load.
Then you weren't a very good manager. You owned that dept, you were
responsible for success' and failures. You didn't lead your people. I bet
you were the first to beat your chest when someone came through. Leave your
On Friday, November 27, 2015 at 10:00:12 AM UTC-5, Harry Johnson wrote:
I was thinking similar. IDK how anyone can make blanket statements
about all battery chargers. It was certainly true of the old dumb
chargers, that the open circuit voltage would be high, but now with
smarter chargers, who knows what all of them do or don't do.
And does that explain a 12.2 volt open circuit output from a
You will never have any open circuit output on a simple polarity
protected charger with '70's technology.
Possibly on a microprocessir controlled "smart" sharger you might get
a reading on a high impedence voltmeter - but what the OP has is
obviously not a microcomputer controlled charger because it has 2 12
volt amp ratings and a 6 volt amp rating.
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