Battery charger only puts out 11.5 volts with no load on 10 amp
setting, less when on 2amp setting. Puts out 7+ on 6 volt setting.
With no load.
It used to put out plenty. I've only used it a little bit since then.
If windings in secondary were shorted, output voltage would go down,
but what would make the secondary short?
Left outside, plugged in and charging a crummy battery, for about a
week, but covered from the rain and it didn't rain anyhow.
No, it was just a thought. The alligator clips were all corroded, so
I used a wire brush on a bench grinder and cleaned them off well,
incuding the edge of the jaws. I don't think they could be the
No way to open the thing without bending a bunch of little metal tabs.
I'm sure they'll break so I want to avoid that if I can.
I have another 15 amp charger, but I don't think I've needed it for 2
years. No a friend brought a battery over summer of 2014, so it's got
to be around here somewhere.
For some reason I started another thread and apparently the voltage
has gone up, 12.5 on ten amps, 11.5 on two amps.
The old car-battery charges I've opened up
were all rather simple. I'd go and break
the tabs, and see what's the various voltages
Worst case, you've had a learning moment, and
go buy another charger for about $30.
Christopher A. Young
learn more about Jesus
First thing to do is determine if it's broke.
If you have a typical meter, it likely has a current function
that can measure an amp.
If not, put a 12V light bulb in series. It should be off when
the charger is unplugged from the wall and glow somewhat when
the charger is plugged into the wall...depending on the design
of the unspecified random charger and the bulb.
On Sat, 28 Nov 2015 04:18:34 +0000 (UTC), danny burstein
This charger is nothing fancy, though you inspire me to see if I can
find it online and learn something about it. Didnt' take the time
today to test it on my battery, or a lightbulb like was suggested.
I mentioned that a friend was over this summer to get his battery
charged, but now I'm wondering if I actually charged it. I dug out my
hydrometer, and I can't remember details but I got some strange
readings. Why would I have dug it out if his voltage hadn't gone up?
I had the thing for two days.
I'll bet this charger has been broken since I got it. I assumed it
worked because the Freecycle guy who gave it to me said it did. But
maybe he said I think it does.
No need for it to be fancy. In fact, the cheapest ones might
very well be just a transformer to reduce line voltage to
a nominal 13 VDC (but see below)... along with a diode to
(mostly) just keep the current going "forward", so to speak,
into the battery.
(or go up one step to a diode bridge...)
In any event, thse will be outputting a sinusidal wave form,
just at 13V instead of 120. However, that means that part
of the time it'll be at 18 or so volts, other times it'll
be under 12 and dropping to zero...
Knowledge may be power, but communications is the key
OK - I'll eat some crow. You can even leave the feathers on.
I did some real world testing on a couple of chargers I have sitting
around that work. One of them has a center tapped secondary with 2
plate rectifiers. It is an old non-automatic charger with 6 and 12
volt, 2, 15 and 100 amp boost positions.
With it not connected to anything it reads 10.2 volts on my high
impedence digital voltmeter. If I put any ac load on it, including a
capacitor, it jumps to 14.6 volts and on the capacitor (7800ufd 75
volt electrolytic) it behaves the same as on a fully charged batteery,
cycling between 12.2 and 14.6 volts.
On my bridge rectified charger it is 14.6 open circuit, and on my
automatic it is zero volts until connected to a voltage source either battery or charged capacitor (artly or fully - reading over
about 5.5 volts) it outputs the voltage required to force a charge
into the battery.
The dumb chager limits itself to about 14.4 volts and the smart ones
shut down at 14.6, then come back on, alternating between 12.2 (or
whatever the battery voltage is) and 14.6 (in other words, not
charging, then charging at full voltage/little or no current)
SO - a center tapped transformer with 2 plate rectifies (I believe
they are metal oxide - not selenium, but not silicon)- it IS possible
for a working battery charger to put out less than expected voltage
into an open circuit. Interestingly there is a resistor between the
common and one stud on the plate rectifier, which might have something
to do with the unexpected voltage.
In the case ofmine - significantly below nominal battery voltage.
I think I was wrong about this. I assumed it worked, but I just
looked for and found the Freecycle ad, for 20 months ago, and it says
"This is an AC powered battery charger for charging vehicle or boat
batteries. I measured 12V DC on it but you will need to clean up the
clamps a bit."
"BUT", like the first part wasn't a problem. I jumped to the
conclusion that meant it was good. Usually, if something fails it
has less than 12 volts, but today I measured my 1 amp charger that I
got 50 (50) years ago and it has over 16 volts with no load.
This bad one will light the scooter's tail light, or its brake light,
but I dont' think it will charge the battery. Measured voltage with
a Kelvin meter, and it was 0.1v lower, and you know that's a good
brand because Kelvin was a great man. Discovered warm weather, iirc.
They still sell this, Century 87102C Battery Charger, $74 including
shipping at Amazon, Lowes, and HD, but only $58.50 inc. shipping at
the manufacturer's site, but it's not smart at all. The smart ones
are pretty darn expensive.
I remember the guy. He had a messy house, loads of stuff to get rid
of, so he could move, I think, but nothing else I wanted.
Sorry for stirring up the tussle between two of you. Glad you made
I'll try to fix it soon.
On Mon, 30 Nov 2015 01:19:29 -0600, firstname.lastname@example.org wrote:
Maybe you're right. If it doesn't, I found the email from Freecycle
where it was offered, and even though it's 20 months later, I'm going
to write the guy and ask him if it worked. Maybe he'll remember. I'm
grateful for a free charger either way, and I'll tell him that. One
advantage of email, if he was moving, his email should stay the same.
OTOH, the email providers give a lot more trouble than my house does.
Verizon jus announced if you dont' read your mail for 6 months,
they'll throw it away and close your account, even if seems if you're
paying your monthly bill to Verizon.
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