I have (2) 8D lead acid batteries that I just tried to equalize using
my ProSine inverter/charger. Based upon a battery temp of 70F and the
documentation supplied by the manufacturer I specified a maximum
equalization voltage of 15.5V and a maximum charging rate of 22A (5%
of 440 AH capacity). Upon starting the equalization the charging
voltage rose to 14.7V at 22A. It stayed there for about 5 hours and
then the charging voltage dropped to 14V at 22A. The battery temp
rose from 73F to 75F during the period. After 2 hours at 14V I
aborted the equalization. Upon switching back to normal charging mode
batteries started charing at 27A at 14.3V and have been at that charge
rate for about 1/2 of an hour.

Any ideas as to what's going on? I expected to see the voltage rise
during the equalization and not drop. I certainly didn't expect to
see the batteries charge at the 27A following the aborted
equalization.

-- Geoff

GeoffSchultz wrote:
I have (2) 8D lead acid batteries that I just tried to equalize using
my ProSine inverter/charger. Based upon a battery temp of 70F and the
documentation supplied by the manufacturer I specified a maximum
equalization voltage of 15.5V and a maximum charging rate of 22A (5%
of 440 AH capacity). Upon starting the equalization the charging
voltage rose to 14.7V at 22A. It stayed there for about 5 hours and
then the charging voltage dropped to 14V at 22A. The battery temp
rose from 73F to 75F during the period. After 2 hours at 14V I
aborted the equalization. Upon switching back to normal charging mode
batteries started charing at 27A at 14.3V and have been at that charge
rate for about 1/2 of an hour.

Any ideas as to what's going on? I expected to see the voltage rise
during the equalization and not drop. I certainly didn't expect to
see the batteries charge at the 27A following the aborted
equalization.

-- Geoff

Batteries should be fully charged BEFORE starting equalization. Fully
charge the batteries then test with a hygrometer to see if equalization
is needed
krj

On Feb 24, 5:35 pm, krj wrote:

Batteries should be fully charged BEFORE starting equalization. Fully
charge the batteries then test with a hygrometer to see if equalization
is needed
krj

The batteries were fully charged. Unfortunately these are sealed lead
acid and can't be tested with a hygrometer. The batteries are 1.5
years old and have never been equalized and have gone through 2
cruising seasons.

-- Geoff

"GeoffSchultz" wrote in message
ups.com...
On Feb 24, 5:35 pm, krj wrote:

Batteries should be fully charged BEFORE starting equalization. Fully
charge the batteries then test with a hygrometer to see if equalization
is needed
krj

The batteries were fully charged. Unfortunately these are sealed lead
acid and can't be tested with a hygrometer. The batteries are 1.5
years old and have never been equalized and have gone through 2
cruising seasons.

-- Geoff


I'm guessing that you had at least one sulfated cell that broke-free during
your aborted equalization, and that now the charger is able to bring the
whole battery up to full charge. I'd watch the temperature, but let it do
it's thing unless it starts to boil.

On 24 Feb 2007 14:45:32 -0800, "GeoffSchultz"
wrote:

The batteries were fully charged. Unfortunately these are sealed lead
acid and can't be tested with a hygrometer.

I'm opposed to the use of sealed batteries for deep cycle house banks
for exactly that reason. How do you know that your batteries are not
half dry? I'd be almost willing to bet on it.

On Feb 24, 7:19 pm, Wayne.B wrote:
On 24 Feb 2007 14:45:32 -0800, "GeoffSchultz"

wrote:
The batteries were fully charged. Unfortunately these are sealed lead
acid and can't be tested with a hygrometer.

I'm opposed to the use of sealed batteries for deep cycle house banks
for exactly that reason. How do you know that your batteries are not
half dry? I'd be almost willing to bet on it.

Clearly I don't know. The problem is that my battery boxes are under
the sole and have no venting. I wanted AGMs, but the only thing
available in Guatemala was lead acid. Based upon conversations that I
had with highly respected boat builders and a relative who designs
batteries for a living, they suggested the use of a sealed battery to
avoid the build-up of hydrogen in this space. As is usual, boats are
a series of compromises. I took the advice of people who have far
more expertise than I do in this field.

Anyhow, this is what I have and I'm trying to figure out what's going
on. I suspect that there's a short in a cell.

-- Geoff

GeoffSchultz wrote:
On Feb 24, 7:19 pm, Wayne.B wrote:
On 24 Feb 2007 14:45:32 -0800, "GeoffSchultz"

wrote:
The batteries were fully charged. Unfortunately these are sealed lead
acid and can't be tested with a hygrometer.
I'm opposed to the use of sealed batteries for deep cycle house banks
for exactly that reason. How do you know that your batteries are not
half dry? I'd be almost willing to bet on it.

Clearly I don't know. The problem is that my battery boxes are under
the sole and have no venting. I wanted AGMs, but the only thing
available in Guatemala was lead acid. Based upon conversations that I
had with highly respected boat builders and a relative who designs
batteries for a living, they suggested the use of a sealed battery to
avoid the build-up of hydrogen in this space. As is usual, boats are
a series of compromises. I took the advice of people who have far
more expertise than I do in this field.

Anyhow, this is what I have and I'm trying to figure out what's going
on. I suspect that there's a short in a cell.

-- Geoff

AGM's are lead-acid also. They just have a glass mat that is 95%
saturated with acid vs a "flooded" cell
krj

On 24 Feb 2007 16:49:58 -0800, "GeoffSchultz"
wrote:

Clearly I don't know. The problem is that my battery boxes are under
the sole and have no venting. I wanted AGMs, but the only thing
available in Guatemala was lead acid.

The best bet for deep cycle batteries with difficult access are the
Rolls or Surettes with the recombinant caps, also known as HydroCaps.

Supposedly the cell caps contain a catalyst which turns escaping
hydrogen back into water if my understanding is correct.

http://www.rollsbattery.com/

If nothing else, they have a great warranty.

The best bet for deep cycle batteries with difficult access are the
Rolls or Surettes with the recombinant caps, also known as HydroCaps.

Clearly you haven't tried to buy batteries in Guatemala...

-- Geoff

On 24 Feb 2007 14:45:32 -0800, "GeoffSchultz"
wrote:

On Feb 24, 5:35 pm, krj wrote:

Batteries should be fully charged BEFORE starting equalization. Fully
charge the batteries then test with a hygrometer to see if equalization
is needed
krj

The batteries were fully charged. Unfortunately these are sealed lead
acid and can't be tested with a hygrometer. The batteries are 1.5
years old and have never been equalized and have gone through 2
cruising seasons.

-- Geoff

I believe that it is widely recommended that maintenance-free
batteries MUST NOT be equalized, as equalization DOES boil off some
water, which can not be readily replaced in a sealed battery.

The equalization instructions for my Xantrex charger say :

"An equalization charge should be performed /only/ on vented, flooded
(non-sealed or "wet") batteries. It should be performed only if
recommended by the battery manufacturer and only as often as
specified."

(I will admit that some "maintenance-free" batteries are actually
"maintenance-resistant" - a determined user can remove the caps, to
check and replenish fluid levels.)

--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
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