TWL: Battery Equalizing
I have heard and read about equalizing batteries but I don't know how to do
it. Can someone give me instructions about equalizing
batteries? Basically I guess I need to know what voltage to bring them up
to and for how long. I would also like to know exactly what it does.
Thanks for the info.
Greybeard
40' Marine Trader '77 "Sea Dreamer"
Portland Oregon.
Greybeard wrote:
I have heard and read about equalizing batteries but I don't know how to do
it. Can someone give me instructions about equalizing
batteries? Basically I guess I need to know what voltage to bring them up
to and for how long. I would also like to know exactly what it does.
Thanks for the info.
Greybeard
40' Marine Trader '77 "Sea Dreamer"
Portland Oregon.
I too, would be very interested in learning more about this process.
Thanks,
Dick
--
Capt Dick Schroder
43' Gulfstar trawler
"Panhandler"
docked Jeffersonville IN
812-246-4822
I know the theory and have done it, so I can help you out. I was interested
in the experiences on the list and posted a request to the list a short
while back, asking for people to tell me their equalizing regime and got
very little back. I suspect that most people do not do it at all, even if
they know about it. You should see my post and a few answers in the
archives.
The theory is simple. In time, batteries sulphate; to over simplify, all
the acid does not go back into the liquid, forming a hard deposit on the
plates. This generally happens unevenly from cell to cell. The result is
you get less and less capacity out of your batteries. In extreme cases, the
batteries won't "take a charge". The sulphate can be removed by controlled
over-charging. Some people advocate doing it every month, some every year
and in the army, we only did it when the SG of the battery varied from cell
to cell enough so that it was noticeable (there is a recommended difference,
but I don't recall what it was and we did not pay it much heed anyway).
To do it, you apply a charge voltage with a heavy-duty charger (anything
over 20 or 30 amps) of about 15.5 volts (assuming the usual 12-Volt system)
to the battery for seven or eight hours, or until the charge current drops
back to a low level (say about 10 amps). Some of the newer chargers have a
switch to do this all automatically. In the army, we used to start the
process then forget about the darned things and amazingly we never ruined a
battery as far as I know; I bet we shortened the life of a few though!
Some things to watch out for:
This only applies to flooded batteries, not to AGM or gels. You can destroy
anything but a flooded battery by equalizing. So, if you have a mixed
system you will have to isolate the non-flooded batteries before equalizing.
The batteries should be ideally of the same make and type. So, if you have
a mixture you have to equalize them individually.
You have to watch the battery temperature. They will get quite warm, but if
they get hot to the touch you can cause plate buckling or other problems.
The batteries will gas vigorously. Some people advocate removing the caps
so that a plugged vent hole will not cause a rupture. I don't do that but I
do check the vent holes from time to time to be sure they are clear.
If you have those fancy caps (Hydro caps?) that have a bit of platinum in
them to reduce the loss of electrolyte, you should probably remove them, as
I think that the innards cannot withstand pure battery acid and it could
bubble up there.
Before starting, you should top up all the cells to the split ring with
distilled water. After equalizing, you should do it again.
If you do it as preventive maintenance, I'd suggest about four times per
year. As restorative maintenance, do it when the difference in SG from cell
to cell in the same battery is noticeably different.
That's about all I know. No doubt the big battery manufacturers have a more
complete description on their sites; you should have a look. I just typed
this up from the top of my head and do not guarantee that it is accurate (my
advice is worth what you paid for it!).
Good luck and watch for acid burns! Also watch out that you do not short
out your battery with a wrench or jewellery when doing this. Contrary to
conventional wisdom, 12-Volts can hurt you, given enough current flow!
Finally, a shorted battery can overheat and explode.
Maurice
AKAMA
Singapore
-----Original Message (snipped)-----
I have heard and read about equalizing batteries but I don't know how to do
it. Can someone give me instructions about equalizing batteries? Basically
I guess I need to know what voltage to bring them up to and for how long. I
would also like to know exactly what it does.
Maurice Nunas wrote:
I know the theory and have done it, so I can help you out.
Maurice,
I understand the theory too. I also read about it on... I think it was
Surrette's web site. It's something I would like to do periodically to
my batteries. The thing I'm not clear on is... will I have to buy a
heavy-duty portable automotive-type charger and shlep it down the dock?
I don't think I can get my on-board charger to stay in a full charge
mode until I say 'enough.' It just automatically does its 3-stage thing.
Mel Knott
Sandpiper
West Indian 36
Annapolis, Md
nunas@pacific.net.sg writes:
In time, batteries sulphate; to over simplify, all
the acid does not go back into the liquid, forming a hard deposit on
the
plates. This generally happens unevenly from cell to cell. The
result is
you get less and less capacity out of your batteries. In extreme
cases, the
batteries won't "take a charge". The sulphate can be removed by
controlled
over-charging.
I just would like to thank you for a well-written simple set of
instructions that even my old salt-clogged brain can understand. I
have printed your post and shall glue it somewhere near where my
batteries "live". Thanks again - George of Scaramouche
To do it, you apply a charge voltage with a heavy-duty charger (anything
over 20 or 30 amps) of about 15.5 volts (assuming the usual 12-Volt
system)
to the battery for seven or eight hours, or until the charge current drops
back to a low level (say about 10 amps). Some of the newer chargers have
a
switch to do this all automatically. In the army, we used to start the
process then forget about the darned things and amazingly we never ruined
a
battery as far as I know; I bet we shortened the life of a few though!
I strongly advise the list members to disregard the above advice.
If your charger has an equalize switch, look up the instructions and follow
exactly.
If it does not, do not "shlep a heavy duty automotive etc...". Get a charger
that does have equalize and instal it permanently.
Check with your battery manufacturer to get their recommendations.
My personal regime is once every two months or so in winter, once a month
when the boat is being used actively.
Even if the charger has an automatic shut off for equalize, (and many do
not), the best plan is to follow the battery manufacturer regime rather than
just letting it time out.
Not long ago I boarded a 50 Cheoy Lee at a brokers. About 16 GC batteries
had been installed behind the lower helm. Someone had left the boat with the
equalize on and no timeout. Don't ask.
Richard
Richard,
Gee I can't argue with your suggestion that one should buy a charger that is
purpose built to do the job; there is absolutely no doubt that this is the
best choice and I should have said so. Indeed, that's what I now use.
I thought your admonition was a bit black and white though. I mentioned
that if the equalization were done too long the battery life would be
compromised; I guess I should have also said that if left long enough they
would be ruined. Not that many years ago, what I described was exactly how
we did it. Until these new fangled chargers and inverter/chargers came
along, the most sophisticated automatic set-up I ever saw had a simple
clockwork timer on a charger.
Note to Mel,
If you are going to buy anything, buy an automatic; heck, even if you
already have a charger that will equalize with manual settings you are
better off with an automatic one. With a little intelligence and watching
for overheating you can do it manually though. You can also navigate your
boat without a computer, GPS and an autopilot...<grin>...
Maurice
AKAMA
Singapore
-----Original Message-----
From: owner-trawler-world-list@samurai.com
[mailto:owner-trawler-world-list@samurai.com]On Behalf Of Richard
Sent: Monday, March 20, 2000 1:45 PM
To: nunas@pacific.net.sg; Greybeard; Trawler World List
Subject: TWL: Re: RE: Battery Equalizing
To do it, you apply a charge voltage with a heavy-duty charger (anything
over 20 or 30 amps) of about 15.5 volts (assuming the usual 12-Volt
system)
to the battery for seven or eight hours, or until the charge current drops
back to a low level (say about 10 amps). Some of the newer chargers have
a
switch to do this all automatically. In the army, we used to start the
process then forget about the darned things and amazingly we never ruined
a
battery as far as I know; I bet we shortened the life of a few though!
I strongly advise the list members to disregard the above advice.
If your charger has an equalize switch, look up the instructions and follow
exactly.
If it does not, do not "shlep a heavy duty automotive etc...". Get a charger
that does have equalize and instal it permanently.
Check with your battery manufacturer to get their recommendations.
My personal regime is once every two months or so in winter, once a month
when the boat is being used actively.
Even if the charger has an automatic shut off for equalize, (and many do
not), the best plan is to follow the battery manufacturer regime rather than
just letting it time out.
Not long ago I boarded a 50 Cheoy Lee at a brokers. About 16 GC batteries
had been installed behind the lower helm. Someone had left the boat with the
equalize on and no timeout. Don't ask.
Richard
on 3/19/00 6:26 PM, Maurice Nunas at nunas@pacific.net.sg wrote:
nip...
asking for people to tell me their equalizing regime and got
very little back.
...snip
Hi All,
Better late than never...our Camano came with Trojan Batteries (3 - G27 in 2
banks) and a Statpower TrueCharge 20+ multi-stage battery charger (includes
a separate equalization setting).
Here is what the Trojan battery literature says,
"When do I need to perform an equalization charge?
Equalizing should be performed when a battery is first purchased (called a
freshening charge) and on a regular basis as needed. How often this might
occur with your battery will vary depending on your application...For
example, it is time to equalize if the measured specific gravity values are
below manufacturer's recommended values after charging (recommended value
for Trojan Deep Cycle batteries is 1.277 plus/minus .007). Equalizing is
also required if the specific gravity value of any individual cell varies 30
points or more {I guess they mean .030} Reduced performance can also be an
indicator that equalizing is necessary. Equalization should also be
performed when individual battery voltages in a battery pack range greater
than 0.15 volts for 6 volt batteries or 0.30 for 12 volt batteries. A good
rule of thumb is to perform equalize charging once every 10 cycles."
The TrueCharge literature provides the following,
(When the eqalization button is pushed) "the TrueCharge first completes a
regular charge cycle to establish a charge state reference point. The
Truecharge then charges at 5A raising the battery voltage to maximum 15.5V.
The operator is then to test the battery cells specific gravity every hour,
and take the charger out of equalize mode when the cells are no longer
equalizing. If the operator does not...TrueCharge will exit equalize and go
into float after 6 hours."
There are several salient points associated with this:
- Turn-off or disconnect all loads on the battery during equalization.
Remember, the voltage during equalization is 15.5V. - Only equalize fully charged batteries.
- Check the specific gravity every hour.
- Water batteries after equalization is complete.
As an aside, we found this helpful product called "Wet Check Electrolyte
Level Checker" which is a piece of cardboard die-cut into six perforated
'fingers' that you use to measure the liquid level in the batteries.
(Although we can get to the batteries easily, we can't look directly down
the fill hole). Yes, you could make them yourself. We got them from
Sail200.com (800) 877-4797.
As to all the above, consult your boat physician for your specific
condition, mileage may vary, etc.
--
HNick&Sherri&SmallWonder (Camano Troll)
HYY, Galesville, MD