Battery storage?

We put a fresh battery in our plane for the winter starting season even
though the old one was in good shape. On advice from several sources, I put
the old one on a Sears trickle charger as a spare. The charger claims to
sense the battery condition and be suitable for long term connections.

I checked the battery after a couple months and there was electrolyte all
over the top and running down the sides and onto the shelf.

Is the battery toast? Are these maintenance trickle chargers inappropriate
for long term connection?


--
Roger Long

I don't know about "toast", but I've got a theory...and am fleshing it out in a
3-part Kitplanes series right now...

With a fresh battery, a "trickle charger" that puts a small amount of current
into the battery and then "tricles down" as the battery voltage gets up to a
point does just fine.

However, as the battery ages and the internal resistance goes up, it requires a
higher and higher voltage from the trickle charger to bring itself up to what it
senses as "full charge". (I could snide comment about human males working the
same way, but I will refrain {;-) ) This higher voltage actually
overcharges the battery and forces the electrolyte out the spigots. (The mental
image fairly blushes...)

I'm working right now on a "cyclic" type of charger where the charger puts out a
full slug of current up to a precisely limited voltage (13.6 to be exact) and
then completely shuts itself off and lets the battery self-discharge itself down
to some much lower voltage (12.6 to be exact) and then repeats the cycle. The
folks at Concorde turned me on to this trick and they claim it is the ONLY way
to keep a recombinant gas battery happy. Seems to me it is the way to go with
flooded plate as well.

April, May, June 2004 Kitplanes columns.


Jim




"Roger Long" om
shared these priceless pearls of wisdom:


-
-Is the battery toast? Are these maintenance trickle chargers inappropriate
-for long term connection?

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

On Sun, 11 Jan 2004 08:53:40 -0800, Jim Weir wrote:


I don't know about "toast", but I've got a theory...and am fleshing it out in a
3-part Kitplanes series right now...

With a fresh battery, a "trickle charger" that puts a small amount of current
into the battery and then "tricles down" as the battery voltage gets up to a
point does just fine.

However, as the battery ages and the internal resistance goes up, it requires a
higher and higher voltage from the trickle charger to bring itself up to what it
senses as "full charge". (I could snide comment about human males working the
same way, but I will refrain {;-) ) This higher voltage actually
overcharges the battery and forces the electrolyte out the spigots. (The mental
image fairly blushes...)

I'm working right now on a "cyclic" type of charger where the charger puts out a
full slug of current up to a precisely limited voltage (13.6 to be exact) and
then completely shuts itself off and lets the battery self-discharge itself down
to some much lower voltage (12.6 to be exact) and then repeats the cycle. The
folks at Concorde turned me on to this trick and they claim it is the ONLY way
to keep a recombinant gas battery happy. Seems to me it is the way to go with
flooded plate as well.

April, May, June 2004 Kitplanes columns.


Jim


I'd be hesitant in applying what Concorde says about the recombinant gas
batteries to other types of batteries, or even other manufacturers.

Living off the grid, and relying on FLA (flooded lead acid) batteries, I
have had a lot of experience in maintaining them. For the FLA batteries,
the manufacturers generally publish a recommended "float" voltage. So what
you need is a voltage limited charger.

For example, for my particular batteries, the recommended float voltage
(which is what you would use to keep a fully charged battery fully charged)
would be 2.20-2.23 volts per cell, or 13.2-13.4V for a nominal 12V battery.

A higher voltage would be used for charging (14.2-14.7V in my case).

At 13.2-13.4V, my batteries would not be overcharging, and the electrolyte
would not be leaking out.

And the numbers that apply to AGM or gas recombinant batteries are not the
same as what one would use for FLA batteries.

So for most FLA batteries, there should be no need to let them
self-discharge. But rather maintain them at the lowest voltage that will
maintain a full state of charge.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

Respectfully disagree. You take an OLD 25/35 ah aircraft battery and float it
at 13.4 for a week or so and it will burp acid. New ones will not, old ones
will. Been there, done that.

Your huge batteries may have a better thermal characteristic than these little
loaves of bread, so it may not be a problem for you.

Jim



Ron Rosenfeld
shared these priceless pearls of wisdom:


-
-Living off the grid, and relying on FLA (flooded lead acid) batteries, I
-have had a lot of experience in maintaining them. For the FLA batteries,
-the manufacturers generally publish a recommended "float" voltage. So what
-you need is a voltage limited charger.
-
-For example, for my particular batteries, the recommended float voltage
-(which is what you would use to keep a fully charged battery fully charged)
-would be 2.20-2.23 volts per cell, or 13.2-13.4V for a nominal 12V battery.
-
-A higher voltage would be used for charging (14.2-14.7V in my case).
-
-At 13.2-13.4V, my batteries would not be overcharging, and the electrolyte
-would not be leaking out.

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

Yep, and I'm working on laying out the PC board as we speak.

Jim


Stu Gotts
shared these priceless pearls of wisdom:


-April, May, June 2004 Kitplanes columns.
-
-So you'll have the plans in these three issues?

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

Do this test to determine if your charger is designed to be left
on indefinately:

1. Connect and leave the charger on for 24hours.
2. Using a digital voltmeter (known to be better than
0.5% accuracy) measure the battery voltage under charge.
Touch the meter probes directly to the lead posts.

If the battery voltage under charge exceeds 13.80V, then the
charger should not be left connected more than 24 hours per month...

If the voltage is more than 13.00V but less than 13.60V, then it
is ok to leave the charger on indefinately.

If the voltage is between 13.6 and 13.8, then it depends on
some other parameters, like temperature. However, the charger
should not be left on indefinately...

As I have previously written, the best solution is often
a time clock and a 2A constant-current charger. This allows
you to "charge" the battery for about 8-10 hours at times
you control. I would do it about once month if the battery
is below 80 deg F, and once every two weeks if the
battery is at more than 80 deg F

see: http://makeashorterlink.com/?I66613A07

MikeM
Skylane '1MM
Pacer '00Z

Roger Long wrote:

We put a fresh battery in our plane for the winter starting season even
though the old one was in good shape. On advice from several sources, I put
the old one on a Sears trickle charger as a spare. The charger claims to
sense the battery condition and be suitable for long term connections.

I checked the battery after a couple months and there was electrolyte all
over the top and running down the sides and onto the shelf.

Is the battery toast? Are these maintenance trickle chargers inappropriate
for long term connection?


--
Roger Long

Jim Weir wrote:

Respectfully disagree. You take an OLD 25/35 ah aircraft battery and float it
at 13.4 for a week or so and it will burp acid. New ones will not, old ones
will. Been there, done that.

Respectfully disagree with your respectful disagreement...

If the voltage is 13.6V, then with caps off you get little specks of
acid splattered around.

If the voltage is 13.5V, then no splatter...

The splatter is caused by charging hard enough to evolve gas. As the gas
bubbles rise to the surface, they pop, causing the splatter, just like
a carbonated drink. At 13.5V, no bubbles, therefore no splatter...

MikeM

On Mon, 12 Jan 2004 09:05:49 -0800, Jim Weir wrote:

Respectfully disagree. You take an OLD 25/35 ah aircraft battery and float it
at 13.4 for a week or so and it will burp acid. New ones will not, old ones
will. Been there, done that.

What are you disagreeing with?

As I pointed out in my message, the float voltage for a particular battery
will vary from one manufacturer to another. I was careful to state that
the numbers were for *my* batteries, but proper float voltage should be
obtainable from the various manufacturers.

And if the battery is old, it probably is partially sulfated and, if so,
should be equalized at a low current before putting it on float.

If you can't obtain the proper float voltage from the manufacturer, it can
be determined empirically by looking for bubbles in the electrolyte after
it's been charging for a while.

But the concept that Concorde says works for their gas recombinant
batteries, of repeated discharges and recharges, is not one that should be
generalized to all batteries. A steady float will likely be better for a
FLA battery.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

On Sun, 11 Jan 2004 19:52:33 -0600, Stu Gotts
wrote:

On Sun, 11 Jan 2004 08:53:40 -0800, Jim Weir wrote:

I'm working right now on a "cyclic" type of charger where the charger puts out a
full slug of current up to a precisely limited voltage (13.6 to be exact) and
then completely shuts itself off and lets the battery self-discharge itself down
to some much lower voltage (12.6 to be exact) and then repeats the cycle. The
folks at Concorde turned me on to this trick and they claim it is the ONLY way
to keep a recombinant gas battery happy. Seems to me it is the way to go with
flooded plate as well.

April, May, June 2004 Kitplanes columns.

So you'll have the plans in these three issues?

Speaking of sulfated batteries, I've had really good
luck with these high frequency pulse chargers and have
been able to "revive" several batteries I thought were
ruined.

http://www.pulsetech.com

There are several subsequent patents on this technique and
various implementations, but an earlry one, if not the orginal
one, was patent #5,491,399, Gregory et al.

I found a Pulsetech model at a local Batterys Plus retail store.
They have both transformer and solar panel powered versions.

Works great for long term maintenance of the battery.




"Ron Rosenfeld" wrote in message
...
On Mon, 12 Jan 2004 09:05:49 -0800, Jim Weir wrote:

Respectfully disagree. You take an OLD 25/35 ah aircraft battery and
float it
at 13.4 for a week or so and it will burp acid. New ones will not, old
ones
will. Been there, done that.

What are you disagreeing with?

As I pointed out in my message, the float voltage for a particular battery
will vary from one manufacturer to another. I was careful to state that
the numbers were for *my* batteries, but proper float voltage should be
obtainable from the various manufacturers.

And if the battery is old, it probably is partially sulfated and, if so,
should be equalized at a low current before putting it on float.

If you can't obtain the proper float voltage from the manufacturer, it can
be determined empirically by looking for bubbles in the electrolyte after
it's been charging for a while.

But the concept that Concorde says works for their gas recombinant
batteries, of repeated discharges and recharges, is not one that should be
generalized to all batteries. A steady float will likely be better for a
FLA battery.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)