Deep cycle batteries

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I once had an electric outboard motor for a canoe, and was told that it
needed a deep-cycle battery, that was designed to be fully discharged and
then re-charged. In this it differed from a car battery, which is meant to
be kept near full charge all the time. I can see the logic in this.
My Wildview motion-sensing camera, which  runs off four C-cells can also be
powered by an external 12Volt battery, which can be had from the U.S. at
enormous expense.
I occurs to me that I could use a motorcycle battery or perhaps a battery
from a powered golf-buggy. It seems to me that the Wildview is used in such
a way that a deep-cycle battery would be more appropriate than a motorcycle
battery. Is this the case, and if so, is a golf-buggy battery a deep-cycle
battery?
Or, is there a better option? The camera is left out in the bush for a day
or two at a time.



Re: Deep cycle batteries

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  Regarding "standard" and "deep cycle" versions of batteries, the battery
technologies are basically the same, they just fiddle with the chemical and
physical makeup a bit to ensure it will stand up to deep cycle abuse better.
  And you pay a premium for this.

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  Hmm, I imagine it's just deep cycle lead-acid of some specific size, or
within some specific connector that "mandates" purchase at great expense from
the manufacturer in question.
  In other words, it's ripe for options.

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  Yes and no.  They are wet type lead-acid batteries, and while that doesn't
stop them from working of course, the risk of spillage during transport and
handling will lean you towards some flavour of non-spillable battery instead.

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  Maybe.  However, if you're salvaging a battery from a buggy, the fact that
you CAN salvage the battery probably means it's done it's life already.

  Though if the buggy battery is free, I'm quite sure you can't complain about
battery life.

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  You have a number of options:

  Lead acid (sealed or otherwise, deep cycle or otherwise) might not be the
"best" battery technology choice for the job, but it certainly is the
cheapest. In the shorter term anyway.  Remember, you have to factor in the
cost of the charger too!

  NiCad has a decent enough charge storage life and is reasonably cheap.  But
contains cadumium which is damaging to the environment.  If you care about
that. (If they keep selling them, it means people keep buying them).

  NiMh is not as good as NiCds as far as battery life storage life goes, but
it makes up for it in capacity per volume.  And costs a bit more than NiCd.

  LiIon has a terrible charge shelf life, but again, it more than makes up for
it with obscene storage per unit volume.  It's also so expensive that it'll
make your wallet run for cover.
  LiIon also doesn't cater for Joe-Average either as far as "a black box that
puts out 12v" goes.  Great for DIY engineers who eat this stuff for breakfast,
(because you have to design the charger yourself as well) but little available
off the shelf.

--
Linux Registered User # 302622
<http://counter.li.org

Re: Deep cycle batteries

"John Tserkezis"

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**  Not generally true.

Plus apparently identical NiCd cells are in fact horribly variable in their
self discharge rate and change over time and with usage. If ever a NiCd cell
is significantly heated by over charging, its self discharge rate goes
through the roof.

The above two facts account almost entirely for the mysterious but
non-excitant  "memory effect " so often complained of with NiCds.


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** Bollocks.

 It is by far the best of the three.

 Some makers claim NO self discharge at all.



.....   Phil






Re: Deep cycle batteries

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  I figured since we were painting everything with a big brush...

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  I presumed we would only use better quality batteries.  I am aware of some
real garbage that gets sent out with equipment that makes things not-worthwhile.

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  Yes, all a case of Bah Humbug.  Media over-blow-out.  Reproducing memory
effect is almost impossible within the domestic market.  Quite happy to blame
sub-standard batteries on that though.

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  No idea where I read that.  I was obviously sleeping.

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  Seen mention of that, though I would take that with a grain of salt on what
they actually mean.

--
Linux Registered User # 302622
<http://counter.li.org

Re: Deep cycle batteries

"John Tserkezis"

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**  Shame you dipped your brush in a bucket of diarrhoea.


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**  My remarks apply to all NiCds -  even the best ones like Sanyo.



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** They mean that there is actually a gradual loss of max capacity over
several years,  instead of self-discharge, ie internal current leakage.

The difference is easy enough to tell.

 If you are not totally stupid.



......   Phil






Re: Deep cycle batteries
On Sat, 21 Feb 2009 12:42:01 +1100, John Tserkezis
(snip)

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(snip rest)

John, you are waaaay off track if you actually believe that.

Back during the evaluation of a commercial Li-Ion charger I designed back in
(crikey!) 2003 I did some cyclic charge/discharge working on packs comprising
18650 size cells.  They are still sitting on the workshop shelf where they
finsished up charged to 4v20/cell on 23 Feb 2003.

I routinely check them about once a year, in case they drop below the 3v0
protection module cutoff.

Just checked - all cells still around 3v85.

Let's see  - about 30% in 9 years, or 0.3% per month, and that's with the minute
but measurable parasitic load of the pack protection module.  Beats the hell out
of lead-acid or any Nickel chemistry I've seen.

Re: Deep cycle batteries

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  I know, I'm sure I replied to Phil's first post, but it seems lost
somewhere. (where do all those bits go?)

  I had read, seen or heard (can't remember for the life of me) a bazillion
years ago that LiIons were not that great on the self-discharge area.  And
never having to work on them, I never bothered to actually check that.
:-\
--
Linux Registered User # 302622
<http://counter.li.org

Re: Deep cycle batteries
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    I can tell you that the Li-Ion batteries in Tomtom GPS receivers go
flat after about a week of just sitting around, switched off.

    Conversely digital camera Li-Ion batteries I've had experience with
seem to hold their charge for many weeks when they're out of the camera.


Re: Deep cycle batteries

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  I'm pretty sure it uses a bit of power to keep up a clock, and empheris data
and perhaps other crap like l^Huser setup and such.  Though this is not
exactly a high energy application, so a week does seem a bit short.  Bad
design dare I say it? Have I mentioned I'm not fond of TomTomTom?

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  Yep, depends heavily on design as far as I've seen, some devices keep an lcd
display on all the time, and still last quite a significant time (some months
for my slr camera), and other things that barely keep up a clock can't seem to
last a week or two.

--
Linux Registered User # 302622
<http://counter.li.org

Re: Deep cycle batteries
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     I have to correct myself ... the Tomtoms use a Lithium Polymer not
Li-Ion battery.
     According to the Wiki entry at
http://en.wikipedia.org/wiki/Lithium-polymer , this battery type has a
self discharge rate of 5%/month so apparently something's using
significant current when it's nominally turned off.


Re: Deep cycle batteries

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  My embedded GPS module uses 2 AA batteries for empheris data upkeep.  I
can't remember the current draw details (long time ago), but I do remember it
was a tossup between shelf life of the alkaline batteries and enough current
draw to battery depletion.
  Basically, I knew that once I put them in, they weren't coming out.

  Adding a clock to the mix really can't be too much worse, and perhaps some
more sram for general user data storage (additional points, stored routes,
tracks etc).

  On the other side, I've seen some car clocks that are quite rude with their
power consumption.  Three lines, ground, +12v, and another +12v to actually
light up the display, thus allowing a low power mode when otherwise off.
  The "low" power mode took several tens of milliamps.  I don't care who says
what, that's just not on.

  If it isn't in the microamp range, they've done something very, very wrong.
--
Linux Registered User # 302622
<http://counter.li.org

Re: Deep cycle batteries

"Bob Parker"
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**    Irrelevant    -  cos  the battery is NOT switched off.



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**   Very scientific evidence   -  not.




.... ..    Phil



Re: Deep cycle batteries
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    In a bad mood tonight Phil?



Re: Deep cycle batteries

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Ahem!  Mental maths failure!  Would you believe 30% in SIX years, or 0.5% per
month.

Re: Deep cycle batteries
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This article

http://en.wikipedia.org/wiki/Lithium_Ion

cites concerns that Lithium Ion batteries lose capacity with age, even
if they're not being repeatedly discharged and recharged.

In the context of cell with a low self-discharge I'd have to wonder how
that reduction of capacity would show up in the EMF.

Sylvia.

Re: Deep cycle batteries

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I haven't tested "aged" cells, but the normal range of OCV is between 3v0 at low
voltage cutoff and 4v2 for fully charged and that remains the same as it is the
charger characteristic.  I'd expect the normal curve of cell OCV vs SOC to be
pretty much the same regardless of loss of capacity.

Re: Deep cycle batteries
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I was thinking that the loss of capacity would be masking the self
discharge, something along the lines of if the battery has 50% self
discharged, but also lost 50% of its capacity, then its EMF would be
unchanged.

On reflection, I don't think it could work that way.

Sylvia.

Re: Deep cycle batteries
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What's the battery life with the existing C cells?
Alkaine D cells would offer improved capacity. You could make up a pack that
connected to the 12V battery connector (mindful of the operational voltage
range on that connector of course).

Dave.



Re: Deep cycle batteries

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Less than 48 hours. They are Jaycar NiMH at about thirteen dollars a throw.
They charge in about six hours.


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Re: Deep cycle batteries
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In that case a 12V pack of Alkaline D cells might give you very roughly,
about 8 times that life, say 16 days.
If you only used it say that many days a year, a non-rechargable solution
like Alkaine may be better. Also other factors like charging can be annoying
if you forget for instance.
Also, you don't know how efficient (or ineffecient) the internal converter
is, it needs to drop the external 12V to whatever is required by the
internal circuitry. That will have an impact on whatever solution you
choose.

Dave.



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