Deep cycle batteries

[KR]

On Feb 21, 10:35 am, "L.A.T." <to...@sci.net.au> wrote:

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.

If its going to be left out in the bush for 48 hours, It would be
worth considering the temperature extremes that it will be subjected
to day and night also. If this is going to be a problem, a small esky
might help.

 

[L.A.T.]

snip

What's the battery life with the existing C cells?

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


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.


Another question:

The battery charger I use is from Jaycar, charges four batteries at a time,
and has LEDs to show when the cells are charging and when they are charged.
It also has a sort of bar-graph to show the state of charge.
If I wait until the LEDs and the bar-graph show that the C-cells are fully
charged, and then disconnect the charger, wait a minute or two and
re-connect the charger, it tells me that all the cells are half-charged and
takes about an hour to show full charge again. And again if I do the same
thing immediately.
Is this a faulty charger, dud batteries, or just the way things are?
In other words, are the cells fully charged the first time, or are they more
charged the second or third time? Or are they never more than half-charged?
They sure don't last very long whatever I do.

 

[rebel]

On Sat, 21 Feb 2009 22:14:36 +1100, Sylvia Else <sylvia@not.at.this.address>
wrote:

rebel wrote:
On Sat, 21 Feb 2009 12:42:01 +1100, John Tserkezis
jt@techniciansyndrome.org.invalid> wrote:
(snip)

LiIon has a terrible charge shelf life

(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.

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.

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.

 

[Sylvia Else]

rebel wrote:

On Sat, 21 Feb 2009 22:14:36 +1100, Sylvia Else <sylvia@not.at.this.address
wrote:

rebel wrote:
On Sat, 21 Feb 2009 12:42:01 +1100, John Tserkezis
jt@techniciansyndrome.org.invalid> wrote:
(snip)

LiIon has a terrible charge shelf life
(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.
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.

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.

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.

 

[Gordon W]

"L.A.T." <tonyt@sci.net.au> wrote in message
news:8k%nl.22598$cu.2381@news-server.bigpond.net.au...

snip


What's the battery life with the existing C cells?

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


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.


Another question:
The battery charger I use is from Jaycar, charges four batteries at a time,
and has LEDs to show when the cells are charging and when they are charged.
It also has a sort of bar-graph to show the state of charge.
If I wait until the LEDs and the bar-graph show that the C-cells are fully
charged, and then disconnect the charger, wait a minute or two and
re-connect the charger, it tells me that all the cells are half-charged and
takes about an hour to show full charge again. And again if I do the same
thing immediately.
Is this a faulty charger, dud batteries, or just the way things are?
In other words, are the cells fully charged the first time, or are they more
charged the second or third time? Or are they never more than half-charged?
They sure don't last very long whatever I do.


I have a charger that does 1, 2 or 4 batteries. It stops charging when there is

a sudden change in charge current. That could be when one of the 4 batteries
reaches full charge. I had the same problem as you and now have better results
charging one battery at a time.

HTH
Gordon

 

[terryc]

On Sat, 21 Feb 2009 00:35:56 +0000, L.A.T. wrote:

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.

I strongly doubt that you could fully discharge them, if you wanted to get
maximum life(cycles) from the. The Bill Harden(?) FAQ on lead acid
batteries that is floating around the et recommends 50% max or
shallower.

I also doubt that any modern battery (could be fully discharged either due
to risk of cell reversal.

To cut to the chase, you can get deep-discharge 6v lead acid batteries as
these are how you safely build up to bigger Amphour reserves without
needing to hire a forklift or crane to move them..

If this requirement is a regular one, then a proper DD is probably the way
to go, complete with proper recharger. If it is occassional requirement,
then a motorcycle battery may be more economical.

It really is a question of how much power is drawn out of the battery over
this period.

You of course can get lighter batteries, but you pay the price. Capacity
wise, SLA were no cheaper than DD lead-acid in the 12V range. might be
different in the 6V, then there is NimH, or LiPoly if you pockets are
deep or needs low.

 

[terryc]

On Sat, 21 Feb 2009 02:38:11 +0000, L.A.T. wrote:

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

Which capacity one are they?

aps if there is only one. I was looking a NiMH AA replacement and wondering
which of the almost dozen different capacities would be safe with my
recharger.

Sounds like one of their high capacity 6V SLA and matching charger would
probably suit you,

 

[terryc]

On Sat, 21 Feb 2009 06:14:28 -0800, KR wrote:

If its going to be left out in the bush for 48 hours, It would be
worth considering the temperature extremes that it will be subjected
to day and night also. If this is going to be a problem, a small esky
might help.

Err, IME, exkies only work if there is something inside them as a cold
sink. Poly brocolli boxes from the vege shop would be cheaper and
better insulation.

 

[John Tserkezis]

Gordon W wrote:

I have a charger that does 1, 2 or 4 batteries. It stops charging when there is
a sudden change in charge current. That could be when one of the 4 batteries
reaches full charge. I had the same problem as you and now have better results
charging one battery at a time.

Note chargers go both ways, and could do what your charger does and place
two batteries in series, and charges them as a set. Others have an individual
charger circuit for each battery.
--
Linux Registered User # 302622
<http://counter.li.org>

 

[TonyS]

Max Harding vk3jin wrote:
[snip]

what state are you in?if in victoria go to Truscots in croydon they have
deep cycle ex medical industry batteries.very cheap

Does anyone know a similar shop in Perth?

Tony

 

In article <M%Hnl.22345$cu.20518@news-server.bigpond.net.au>,
tonyt@sci.net.au says...

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.

Go to the RSPCA and get a pitbull to watch the crop.