Re: [PSUBS-MAILIST] What do Hydro-caps do?

["Marsee Skidmore" <heyred@email.msn.com>]

Very informative. Thank-you. - Joe

----- Original Message -----
From: D. Blake <dblake@bright.net>
To: <personal_submersibles@psubs.org>
Sent: Saturday, March 04, 2000 11:27 AM
Subject: Re: [PSUBS-MAILIST] What do Hydro-caps do?


> Check out this file I found at http://www.independent-power.com/  It seems
> to explain what you are asking.
> Big Dave
>
> Independent Power & Light
> Deep Cycle Lead Acid Storage Batteries
>
> The Equalization Charge and More
> An equalize charge is often defined as a controlled overcharge. I prefer
to
> think of it as a true 100% full charge of your battery bank. Since
finishing
> the
> last ten percent of a full charge takes a disproportionally long amount of
> time
> and is less efficient in energy use (especially so when charging with a
> generator). We do not recommend attempting to complete a full charge every
> time
> you charge. If your renewable energy charging resource (pv, micro-hydro,
or
> wind) accomplishes this regularly then that is great (as long as you have
a
> good
> charge controller in your system that will prevent excessive
overcharging).
> The equalize charge should be accomplished at least once per month to
ensure
> that the individual cells within the batteries are fully charged, equal to
> one
> another, and that the electrolyte is stirred up by the gassing of the
cells.
> You
> may have to do an equalize charge with your generator (when there is not
> enough
> natural power to accomplish battery equalization with your renewable
source
> alone). Depending on how unequal your battery cells are the equalization
> charge
> may take an additional two hours after a good amp hour meter considers
your
> batteries fully charged. If the weather has been very cloudy (with pv
> systems),
> or you have been using more power than usual, and you have neglected to
> perform
> the equalization charge once per month then the length of time to equalize
> your
> cells could take from several hours to a few days.
> After the equalization charge is finished check the cells to see if you
need
> to
> add distilled water. Never add distilled water unless the batteries are
> fully
> charged because the electrolyte level increases as the voltage increases.
> Since
> during battery gassing the cells lose water and not sulfuric acid never
add
> battery acid to your cells. The electrolyte will become too acidic and eat
> your
> battery plates.
> If your battery, bank consists of separate 2 volt cells (such as the
> Surrette
> Solar series) you are in luck. This type of a battery bank generally lasts
> much
> longer than battery banks of 6, or 12 volt batteries because the plates
are
> much
> thicker and the cells hold more electrolyte. Tests and real life
experiences
> have shown these 2 volt cells to be capable of 2,750 deep cycles compared
to
> 700
> for the typical 6, or 12 volt deep cycle battery. You also enjoy the
> benefits of
> maintaining far less cells for your bank; typically a total of 6 cells for
a
> twelve volt bank and 12 cells for a 24 volts for up to 1,400 amp hours of
> storage. Compare this with maintaining 36 cells in a battery bank of
twelve
> 6
> volt golf batteries series-paralleled for 1,320 amp hours at 12 volts. And
> you
> get the additional benefit of having to add distilled water less often
> because
> the 2 volt cells have a larger reservoir for electrolyte above the plates.
> You
> also can check each cells voltage with a hand held digital voltmeter and
> compare
> readings of all the cells of the bank so that you can tell how equal all
the
> cells are. Cells voltages should all be within .05 volts, for batteries at
> rest
> (no charging or discharging happening) for example the highest reading may
> be
> 2.15 volts and the lowest reading may be 2.10 volts. If your cells vary by
> more
> than this than you should charge your batteries until all cells fall
within
> .05
> volts.
> If your bank consists of 6 volt or 12 volt batteries that do not allow you
> to
> take voltage readings of each individual 2 volt cell then checking each
cell
> with a battery hydrometer is the only way to be absolutely sure that your
> batteries are equalized. Each cell is fully charged at, about, 1.270
points
> sg
> (specific gravity) on a temperature compensated battery hydrometer. This
> reading
> may actually vary slightly due to manufacturers different specs for
various
> battery types. Some batteries may be fully charged at 1.260 sg. Equalized
> cells
> will all be fully charged, and all within .010 points sg of each other.
> Unequal cells, as measured by specific gravity with a battery hydrometer
are
> a
> normal fact of life with deep cycle batteries. Over several
charge/discharge
> cycles the individual 2 volt cells (3 per each 6 volt battery) drift apart
> in
> voltage and the only way to bring them all back to an equal state of
charge
> is
> to overcharge the entire battery bank until the cells lowest in charge
catch
> up
> with the other cells. Cells that are in a low state of charge will begin
to
> sulfate, that is the lead sulfate on the plates stays there because it is
> not
> driven off during a complete recharging of that cell. The longer the
sulfate
> stays on the battery plate the more crystalized and hard it becomes making
> it
> more difficult to get it off the plates and back in the electrolyte
> solution.
> Sulfation on the plates means less plate area for the electrochemical
> process to
> take place which results in reduced storage capacity. This can happen
within
> a
> few weeks and become a problem. I have seen good battery banks become
> reduced to
> the point where they stored half of their normal power after just 6 weeks
> without a good equalization charge. This low capacity problem was
corrected
> with
> a seriously long equalization charge.
> Tests have shown that use of a battery DeSulfator, a sweeping pulse device
> that
> uses a very small amount of your battery bank's power to send a variable
> frequency, variable voltage boost, will dissolve lead sulfate crystals
back
> into
> the battery's electrolyte solution. These devices are a great insurance
> policy
> against plate sulfation but they do not let you totally avoid the
> equalization
> charge. The DeSulfator will shorten the time necessary to equalize but you
> still
> need to make sure that the electrolyte gets sufficiently stirred up so it
> does
> not become stratified and eat away the lower portions of the battery
plates
> thus
> destroying your valuable batteries.
> The severity of your batteries sulfation condition and the charge rate of
> your
> PV array and, or, your engine generator powered battery charger (may be
> combined
> in your inverter) will determine the actual length of time the
equalization
> charge takes. A reasonable charge rate for efficient equalization charging
> is
> between C/10 to C/20. The charge rate is simply your battery bank capacity
> in
> amp hours divided by your charging current. For example: With a battery
bank
> capacity of 1,000 amp hrs and a PV array charging current of 30 amps your
> rate
> is stated as C/33. Add in your generator driven battery charger along with
> the
> PV charging and your charge rate could drop to C/11 (if the battery
charger
> was
> actually putting out 60 amps).
> During a good long charge the batteries will eventually gas rapidly. This
is
> necessary as it stirs up and redistributes the heavier sulfuric acid
> (battery
> electrolyte is 65% water and 35% sulfuric acid) so that it will not settle
> on
> the bottom of the cells. Safely vent these gases outdoors (see my battery
> box
> and auto vent fan descriptions in the Mid-Size System design).
> Actual battery storage capacily usually stated in amp hours, depends on
> temperature. The colder the batteries the less storage capacity available.
> At 50
> degrees F storage capacity is reduced by about 15%. At 32 degrees F
storage
> capacity is reduced by about 30%. Also the voltage necessary to charge
> batteries
> increases as they become colder. With the Trace Engineering line of PV
> charge
> controllers and inverter/Chargers we have available an optional
temperature
> sensing unit which automatically compensates for this condition by
allowing
> progressively higher charging voltages as the batteries become colder.
> However
> it can not make the batteries recover their full storage capacity, only a
> temperature of 78 degrees F can do that. A couple of more points about
> temperature and lead acid batteries. A battery at a 20% state of charge
will
> freeze (and most likely become ruined) at about 18 degrees F. Cold
batteries
> are
> also less efficient in their transfer of energy. But don't get too carried
> away
> keeping your batteries warm because too warm is not good either. Above 80
> degrees F shortens the life of the batteries and also increases their self
> discharge rate. 78 degrees is perfect, I manage to keep my batteries
between
> 60
> to 65 degrees F and I'm happy with that. We have many battery banks
> operating
> fine at 40 to 50 degrees F also. You just have to compensate for the
reduced
> amp
> hour storage capacity by buying more amp hours of battery than you would
for
> a
> 65 degree battery temperature.
> These batteries are rated for cyclic use of up to 80% of capacity. That is
> you
> can drain the batteries down to 20% state of charge without harming them
as
> long
> as they are completely recharged soon thereafter. Lead acid batteries will
> last
> longer if they are cycled less deeply. By using only 10% to 60% of
capacity
> before recharging your battery bank will give you good service for many
> years. I
> have seen, twice now, in my fourteen years of working with these batteries
a
> cell that would not take a charge no matter what I did. In both cases the
> problem showed up soon after installation of the system with a check of
> specific
> gravity (two good cells in battery read 1.270 bad cell 1.050).
Manufacturing
> defects do happen and they show up very early on. So check with the
> hydrometer
> for bad cells. If they cannot be equalized as I have described (and the
cell
> goes dead), and you are doing everything else you should be doing as to
the
> proper charging of the batteries then I will replace the battery that the
> bad
> cell is in. This offer is good for one year after purchase with Trojan
> batteries. Surrette batteries carry a longer warranty.
> Rotate your batteries? Yes! If you really want to get the most out of your
> battery investment then by all means rotate. Years of experience have
shown
> that
> the cells at the ends of the battery bank (the main positive cable comes
out
> of
> one end and the negative out of the opposite end) usually fail before the
> other
> batteries in the bank. We (manufacturers, engineers, practitioners) do not
> exactly agree on the cause of why this happens but that is not too
> important. To
> rotate the individual cells, or batteries, simply disconnect them and move
> them
> to the middle of the bank once per year. This is also a good time to check
> tightness of all your connections in the battery bank and through to the
> disconnect, inverter, and ac load center. If you are also seeing a
> performance
> drop on your charging sources, or poor performance on your loads check
> tightness
> of all applicable connections. It is paramount that all connections be of
> low
> resistance and of high mechanical integrity, especially in a low voltage
> system.
>
> If you can not, or do not want to perform annual system maintenance
yourself
> then hire an experienced professional (such as myself - Independent Power
&
> Light) to help you get the best performance and longest life out of your
> system.
> If you are simply using an accurate voltmeter, along with occasional
checks
> with
> your hydrometer, this chart should be helpful in determining your
batteries
> state of charge.
> Charge LevelSpecific GravityVoltage 2V nVoltage 6V nVoltage 12V
>             nVoltage 24V n
>             100.00%1.2702.136.3812.7525.50
>             75.00%1.2242.086.2412.4824.96
>             50.00%1.1702.026.0612.1224.24
>             20.00%1.0971.945.8211.6423.28
>             0.00%1.0451.895.6711.3422.68
>
> n stands for nominal voltage
> They are also only accurate for batteries at rest. Meaning that the
voltage
> is
> not lowered by a load, or elevated by a charging source. You have the most
> accuracy after a half hour of rest time.
> I recommend The Tri-Metric meter for users who want more information from
a
> meter. This meter uses a remote current measuring shunt and an on board
> microprocessor to calculate ampere flow in and out of your batteries. It
> also
> measures and tracks battery voltage. It displays voltage, net current
> (amps),
> and battery % full.
> It also tracks and can display amp hours discharged, days ago since last
> "full"
> (not equalized) charge, lifetime amp hours discharged, minimum battery
> volts,
> and maximum battery volts. In addition it can also be set up to remind you
> when
> it is time to equalize charge. I use this meter myself and like it a lot!
> I sell this meter for $160, plus $30 for the necessary shunt.
>
> End
>
> -----Original Message-----
> From: Marsee Skidmore <heyred@email.msn.com>
> To: personal_submersibles@psubs.org <personal_submersibles@psubs.org>
> Date: Saturday, March 04, 2000 1:41 PM
> Subject: Re: [PSUBS-MAILIST] What do Hydro-caps do?
>
>
> >Tell us more about periodic controlled overcharge. How much and how
> often? -
> >Joe
> >
> >----- Original Message -----
> >From: David Buchner <buchner@wcta.net>
> >To: <personal_submersibles@psubs.org>
> >Sent: Friday, March 03, 2000 8:29 AM
> >Subject: Re: [PSUBS-MAILIST] What do Hydro-caps do?
> >
> >> However if you don't give the batteries a regular controlled
overcharge,
> >they won't last as long either -- and they cost way more!
> >>
> >> --
> >> David
> >> Osage MN USA
> >> buchner@wcta.net - http://customer.wcta.net/buchner
> >>
>
>
>