Well, your 2000 only has a 10 amp push coming from the 12V dc plug if I
remember right. Your onboard charger is probably about the same! Most
boats only have between 10 and 15 amp chargers because you'd expect to
use it at shore and never need too much more at a time. The times that
you are not aboard lets the charger catch up with your needs.

I don't think either of those ways will do you right. What you probably
need to do is get a big charger but DO NOT GET A CAR CHARGER! Car
chargers will fry your frig and a few other electronics that you might
have plugged in.

Your other choice is a high power alt. If you do that you should get
one of those things that goes between your battery and alt. I forget
the name off hand but it is a big condenser type thing that tames the
power so you don't have lots of static all over your radio and other
sensitive gear.

Or you could just touch your tong between the posts:-)

------ no I am joking DON'T do that

I didn't think about bad batteries because my mind was thinking typical
power hog.

You can sort of fix crystallized batteries by over charging them to
16.8 volts and then beading off the excess charge. That melts most of
the crystallization that happens. There is also some acid that you can
buy to add to your cells that prolongs the life of batteries but I a
big believer in changing batteries about every 2 years. Call it cost of
ownership and live with it because it is better and safer for not that
much money.

"Da Kine" wrote in
oups.com:

You can sort of fix crystallized batteries by over charging them to
16.8 volts and then beading off the excess charge. That melts most of
the crystallization that happens. There is also some acid that you can
buy to add to your cells that prolongs the life of batteries but I a
big believer in changing batteries about every 2 years. Call it cost of
ownership and live with it because it is better and safer for not that
much money.



All a disaster waiting to happen. Adding acid to electrolyte to
"rejuvenate" dead cells is SUICIDE! The lead was eaten away from the
plates and crystallized into the bottom of the battery, in the space
provided for it. You come along and add acid, eating holes in already
weakened plates, possibly creating a shorting hazard so the battery
explodes. You have to see a boat whos battery has exploded to realize
what damage that does. Please don't add acid to a dead cell, please?

Going to sea with crap batteries is stupid! Batteries are cheap unless
you suck up to some idiotic gauze batteries for $600 by some slick
salesman in boat shoes. Golf cart batteries are throwaway consumables at
$89 a pop. Use them. They work great for years, and when something
doesn't start to look right, TOSS THEM to the battery recycler pile and
BUY NEW ONES from a BATTERY SHOP, not a boat store!

I like your idea of the 2-year swap, but cheap golf cart batteries will
last much longer if one takes care of them properly....

When you zap a battery with 16.8V at really high current, the good cells
boil like hell, possibly warping a plate and causing an explosion. NEVER
do this crazy crap! You are NOT going to "save" a dead cell...its acid
is used up, its plates are eaten away, its full of lead sulphate
crystals...buy a NEW ONE.

" Adding acid to electrolyte to "rejuvenate" dead cells is SUICIDE!"
The bottle of stuff is sold in most auto stores. It's not my idea. I've
used it before and it works. The lead is not the problem. Its sulfur
crystals formed from gassing and when you add water, the sulfuric acid
gets a little weaker as some of the sulfide stays crystallized.
Shorting just lowers the voltage you can get but it doesn't blow up
batteries as far as I have ever seen. Hydrogen is given off and that
might but crystals don't.

Now as for your view on buying new batteries, I'm right with you. I
buy Wal-mart batteries and they last me 2 years before I dump them.
Even if they are working pretty well, I like really good and easy to
charge batteries. For what I put into my boat, an average of $180 to
$200 a year is nothing.

I've been told by owners that the 6 volt batteries are the best but I
have never liked the idea of losing one and really losing 2. Maybe next
time I will give them a try.

As for the 16.8 volt thing, the majority of high end chargers all offer
that. It can't be that bad can it? I'm still into just buying new ones
but I know people that zap theirs and they say it works for them.

Da Kine wrote:
[snip]
I've been told by owners that the 6 volt batteries are the best but I
have never liked the idea of losing one and really losing 2. Maybe next
time I will give them a try.

As for the 16.8 volt thing, the majority of high end chargers all offer
that. It can't be that bad can it? I'm still into just buying new ones
but I know people that zap theirs and they say it works for them.

hi da kine,

the 6 volts are "better" because of plate thickness and material used
to make the plates, and they are sometimes easier to service, and they
can have tougher boxes so they are harder to puncture, but that's about
it. plate thickness is the biggest thing, with thicker plates being
able to handle a lot more use. i don't replace mine like you do, i
just "over-charge" them sometimes and watch the water levels. it's
really not much use to get heavier better made batteries if you don't
gas them sometimes because they'll get crap on the plates just as fast
as a walmart marine battery and quit holding a charge after enough
cycles. the heavier plates are most useful to people who aren't afraid
to gas them on occasion like you are supposed to.

Do not buy the ones with the little floating balls or with an
arrow pointer made of plastic. They're worthless. A hydrometer looks
like a glass turkey baster with a floating glass vial with lead shot in
the bottom of it and a little paper scale on top. Make SURE you get a
hydrometer with a THERMOMETER in it. The electrolyte specific gravity is
very dependent on temperature, which renders the little plastic testers
useless. [ . . . ]

Hmm. There's a lot of voo-doo (emphasis on doo) floating around about
wet cell batteries, so I'll just parrot what the Trojan master
distributer in this region had to say last time I chatted with them.

Don't use the glass vial hydrometers, a broken glass (full of sulphuric
acid!) hazard on boats. Get a *good* plastic hydrometer, the disc
pointer type (the only type Trojan master distributers sell).

The S.G. of the electrolyte is *slightly* dependent on temperature, in
the typical boat environment (60 to 90 degree F. range), not
compensating for temperature would result in an error of +-0.008 or so.
You'd have tough time reading that on your hydrometer. Much bigger
error results using the above quoted measurement procedure, instead,
fill and drain the hydrometer 2 to 4 times before pulling out a sample,
or you'll get a false reading due to stratification of the electrolyte
in the battery. Tap the hydrometer to knock off any bubbles on the
pointer. Orient the tester vertically.

This nonsense of charging the batteries at 100A for 20 minutes is just nonsense. [ . . . ]

That would be a 30ah charge; about right for a motorcycle battery,
indeed nonsense. Good batteries can accept 20% of their rated capacity
when in a deeply discharged state(50%); a 500ah bank can be charged at
a 100 amp rate with minimal loss of service life. They can be charged
at much higher rates (40%) if a shorter service life is acceptable.
Charge rates must be dropped rapidly as the battery nears full charge,
of course. Temperatures should not exceed 120 degrees F., and probably
will just rise slightly at a 20% charge rate. Indeed, slow charge
rates are beneficial concerning service life, but time is money; it'll
take 3 hours or so to charge a 50% discharged 500ah bank starting with
a 20% charge rate, conversely, at a 20 amp rate it'll take 15 hours.

Modern wetcells don't use water unless something is perking them with overcharging.

If your batteries aren't using some water, you are undercharging them.
More batteries are damaged due to sulphation from undercharging than
from overcharging. Mild gassing (boiling is a misnomer) is a healthy
part of the charging process; it aids in mixing the electrolyte, and is
an indicator that the batteries are becoming fully charged at the end
of the charge cycle, when charge rates should be 1-5% of the capacity
of the bank. Periodically, or when the S.G. of the cells differ
significantly, an equalization charge should be performed, with
significant gassing.

If the charger brings the cells up above 1.280, check the charger voltage at full charge because it's overcharging the cells.

??? The absolute value of a fully charged battery is determined by
the battery chemistry when manufactured. After a dozen or so cycles on
a new bank, fully charge the bank, top off the batteries and write down
the S.G. value. That's the number for *your* batteries, and cannot
be exceeded by overcharging, unless you add or spill acid from the
battery (acid, not water). Might be 1.300 for batteries manufactured
for the tropics, might be 1.260 for batteries sold in Fairbanks,
Alaska.

Use only DISTILLED water to top them up to just above the plates.

Top your batteries up to the measurement rim in the vent holes,
significantly above the plates. A portion of the plates which uncover
for a significant period of time are permanently damaged and will never
again contribute to the battery's capacity. The extra electrolyte is
there to guarantee the plates are immersed when water loss from normal
gassing occurs, and the batteries are not level on a moving platform, a
sailboat on one tack for a few days, for example.

I suspect you may have a "dead cell", one whos acid has been converted to lead sulphate crystals that have precipitated out of solution into the space for them at the bottom of the cell.

There are many reasons for a "dead cell", one of which is lead sulfate
crystals falling off the plates to the cell bottom, ultimately shorting
the bottom of the plates. Precipitation is not involved. Other
processes can result in an open cell, a short between plates, etc. If
you have a dead cell, you're screwed, time to buy a new battery.

Please recall I'm only the messenger; the message is from the Trojan
guy, who deals with thousands of commercial customers who work the hell
out of their batteries, and have sharp pencils concerning charge rates
and service life. In essence, he says maintain water levels, charge
them vigorously at least periodically, and try to hold the discharge
depth to 50% in normal service.

More straight info available at:
http://www.trojanbattery.com/Tech-Su...intenance.aspx

"Mark" wrote in news:1142325016.130679.130510
@j33g2000cwa.googlegroups.com:

Please recall I'm only the messenger; the message is from the Trojan
guy, who deals with thousands of commercial customers who work the hell
out of their batteries, and have sharp pencils concerning charge rates
and service life. In essence, he says maintain water levels, charge
them vigorously at least periodically, and try to hold the discharge
depth to 50% in normal service.

More straight info available at:
http://www.trojanbattery.com/Tech-Su...intenance.aspx



Remember that advise about NOT using the seller's surveyor report to buy
the boat?...(c;

Battery salesmen are certainly not concerned with lengthening battery
life, no more than GM is concerned with engine longevity telling me to
put 5W-30 in a Chevy V-8 in South Carolina or Evinrude telling me 100:1
TC-W3 won't wear out a 2-stroke engine any faster than 25:1 premixed gas.

About the proper temperature-compensated hydrometer.....I'm not going to
be measuring battery gravity in 10' swells, 90 miles offshore. I'm going
to measure it docked at the marina. I'm also not going to leave
electrolyte in the hydrometer after I'm done, so I won't have to worry
about breaking it and flooding the bilge with acid, either. I took two
little broom clips, designed to hold the broom on the wall in the pantry,
and mounted them to the back side of the battery box, to hold the glass
hydrometer in perfect safety when it's stored....not rolling around under
the engine banging against the shaft. It hasn't broken it and flooded
the bilge, yet....(c;