# Float charge 12v car battery?

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news18
Guest

Sun Jun 24, 2018 11:45 am

On Sun, 24 Jun 2018 19:35:53 +1200, ~misfit~ wrote:

Quote:
I have a solar car battery float charge thing about the size of a car
sun visor I got from Jaycar a few years back (I don't shop there any
more) but with that thing plugged into the cigarette lighter for a
couple of weeks the battery actually got flatter! (In the car I have
the cigarette lighter is always connected regardless of key position.)

I don't suppose you could give me a link to the Oatley thing? I'm in
NZ so shipping would probably be prohibitive but I'm curious. I've cut
the regulator off the Jaycar panel and just the panel outputs 24v in
sunlight. I'm not sure how many (milli)amps it will deliver though,

You've posted the OCV(open circuit voltage),
What is the SCC(short circuit current)?

I don't know my meter only goes up to 10A and the fuses aren't cheap.

Which is what I get out of a 120watt full solar panel, so it would have
to be incredible if something the size of a car visor got anywhere near
it. Stick some "resistance" in the circuit at first.

John_H
Guest

Sun Jun 24, 2018 11:45 pm

~misfit~ wrote:
Quote:
Once upon a time on usenet news18 wrote:

You've posted the OCV(open circuit voltage),
What is the SCC(short circuit current)?

I don't know my meter only goes up to 10A and the fuses aren't cheap.

You don't need to measure the current. Load the panel with a wire
wound resistor (22 ohm ought do) and measure the voltage when it's
facing the sun. Ohm's Law being the clue.

Don't hang about too long as the resistor is likely to get very hot.

Power (which is what you really need to know) = V^2/R.

--
John H

~misfit~
Guest

Mon Jun 25, 2018 7:45 am

Once upon a time on usenet news18 wrote:
Quote:
On Sun, 24 Jun 2018 19:35:53 +1200, ~misfit~ wrote:

I have a solar car battery float charge thing about the size of a
car sun visor I got from Jaycar a few years back (I don't shop
there any more) but with that thing plugged into the cigarette
lighter for a couple of weeks the battery actually got flatter!
(In the car I have the cigarette lighter is always connected
regardless of key position.)

I don't suppose you could give me a link to the Oatley thing? I'm
in NZ so shipping would probably be prohibitive but I'm curious.
I've cut the regulator off the Jaycar panel and just the panel
outputs 24v in sunlight. I'm not sure how many (milli)amps it will
deliver though,

You've posted the OCV(open circuit voltage),
What is the SCC(short circuit current)?

I don't know my meter only goes up to 10A and the fuses aren't cheap.

Which is what I get out of a 120watt full solar panel, so it would
have to be incredible if something the size of a car visor got
anywhere near it. Stick some "resistance" in the circuit at first.

Yeah I mis-read, checking the newsgroup quickly. I thought he meant SCC of
the battery!
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)

~misfit~
Guest

Mon Jun 25, 2018 7:45 am

Once upon a time on usenet John_H wrote:
Quote:
~misfit~ wrote:
Once upon a time on usenet news18 wrote:

You've posted the OCV(open circuit voltage),
What is the SCC(short circuit current)?

I don't know my meter only goes up to 10A and the fuses aren't cheap.

You don't need to measure the current. Load the panel with a wire
wound resistor (22 ohm ought do) and measure the voltage when it's
facing the sun. Ohm's Law being the clue.

Don't hang about too long as the resistor is likely to get very hot.

Power (which is what you really need to know) = V^2/R.

Thanks. I mis-read when checking the newsgroup quickly. I thought you meant
SCC of the battery! I'll check the solar panel when I get a chance. It's
'stored' so might take some finding.
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)

~misfit~
Guest

Tue Jun 26, 2018 5:45 am

Once upon a time on usenet ~misfit~ wrote:
Quote:
Once upon a time on usenet John_H wrote:
~misfit~ wrote:
Once upon a time on usenet news18 wrote:

You've posted the OCV(open circuit voltage),
What is the SCC(short circuit current)?

I don't know my meter only goes up to 10A and the fuses aren't
cheap.

You don't need to measure the current. Load the panel with a wire
wound resistor (22 ohm ought do) and measure the voltage when it's
facing the sun. Ohm's Law being the clue.

Don't hang about too long as the resistor is likely to get very hot.

Power (which is what you really need to know) = V^2/R.

Thanks. I mis-read when checking the newsgroup quickly. I thought you
meant SCC of the battery! I'll check the solar panel when I get a
chance. It's 'stored' so might take some finding.

Also we've not had any really sunny days here for a while.
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)

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