battery experts

[motion30]

Due to a failed charger I have sulfatled batteries. I bought a power source specifically to equalize my batteries I've searched the internet finding the best information on the Trojan battery Site
So i understand the voltage should be 15.5. but I cannot find the appropriate amps to use for equalizing . can I do all 5 batteries at one time, will that affect the Amp setting ? I have 5 8d. Flooded cell batteries

[twinboat]

The amps not inportant, they will be whatever it takes to get to your target voltage. As the battery charges, the amps that the batteries will accept, will drop off.

5, 8ds will take a large charger or a long time, just to get to float. You may be better off spliting them up.

Sent from my VS840 4G using Cruisers Sailing Forum mobile app

[motion30]

The unit i purchased for equalizing has settings for both volts and amps

[sailorboy1]

it probably allows you to limit the amps, but really the battery will only accept the amps that it will at a given state of charge and voltage

the batteries probably will take 1% or less of the amp-hour rating at full charge, so if you have to set it set it at max of 1%

[btrayfors]

Yep, as has been said on this Board a dozen times or more:

So long as you control the voltage, the battery itself will determine how many amps flow into it.

It really doesn't matter if you have a battery charger capable of putting out 1,000 amps, if you control the voltage to, say, 15.5 volts, the battery will determine how many amps will flow.

It's just Ohm's Law: E=IR or Voltage(E) = Current (I) X Resistance (R)

The battery is the Resistance (R). At any given state-of-charge (SOC), it has a certain value of resistance.

To state Ohm's Law another way: Current (amps) = Volts / Resistance (of the battery)

In this equation, since Resistance (the battery) is fixed for any SOC, the ONLY way to increase the current flow (amps) is to raise the voltage.

But wait: you're holding it constant at 15.5 volts for equalizing.

Ergo, the amperage flow CANNOT change unless the resistance changes.

And, at the given SOC of the battery (fully charged) the resistance can only GO UP slightly, thereby DECREASING the amperage flow.

It's a simple relationship, really. I continue to wonder why so many folks don't seem to get it.

Maybe they skipped 7th grade Algebra? Never heard of Ohm's Law?

Bill

[motion30]

Originally Posted by btrayfors

Yep, as has been said on this Board a dozen times or more:

So long as you control the voltage, the battery itself will determine how many amps flow into it.

It really doesn't matter if you have a battery charger capable of putting out 1,000 amps, if you control the voltage to, say, 15.5 volts, the battery will determine how many amps will flow.

It's just Ohm's Law: E=IR or Voltage(E) = Current (I) X Resistance (R)

The battery is the Resistance (R). At any given state-of-charge (SOC), it has a certain value of resistance.

To state Ohm's Law another way: Current (amps) = Volts / Resistance (of the battery)

In this equation, since Resistance (the battery) is fixed for any SOC, the ONLY way to increase the current flow (amps) is to raise the voltage.

But wait: you're holding it constant at 15.5 volts for equalizing.

Ergo, the amperage flow CANNOT change unless the resistance changes.

And, at the given SOC of the battery (fully charged) the resistance can only GO UP slightly, thereby DECREASING the amperage flow.

It's a simple relationship, really. I continue to wonder why so many folks don't seem to get it.

Maybe they skipped 7th grade Algebra? Never heard of Ohm's Law?

Bill

7th grade algebra was my favorite class...i took it 3 years. I did finally pass but by then i was old enough for the draft. So off i went. I would probably remember more if not for the brain injury. Actually thanks you did answer my question

[Stu Jackson]

Another way to say it is this:

Don't equalize your bank unless it is already full.

Once full it will take little current regardless of what the voltage is.

Equalizing voltage is usually around 15 to 15.5.

[btrayfors]

Originally Posted by Stu Jackson

Another way to say it is this:

Don't equalize your bank unless it is already full.

Once full it will take little current regardless of what the voltage is.

Equalizing voltage is usually around 15 to 15.5.

Not quite, Stu. If the voltage is too high, the battery will take too much current and boil over and possibly do some serious damage to the battery.

I know you know this.

Don't exceed the recommended voltages when equalizing.

And, don't equalize unless you are there to monitor the process, including voltage and battery temp.

Bill

[Panope]

Originally Posted by btrayfors

.,...............It's a simple relationship, really. I continue to wonder why so many folks don't seem to get it.

Maybe they skipped 7th grade Algebra? Never heard of Ohm's Law?

Bill

For those having trouble with a mathematical understanding of electricity, the analogy of pumped water into a pressure vessel can make it very easy grasp.

Voltage is analogous to water pressure (psi). Amperage is analogous to volume (gallons). The battery is analogous to a pressure tank (the kind with some sort of compressible air chamber or bladder).

If the pressure tank is empty (battery at zero charge), and water is introduced at high pressure (high voltage), then the tank will fill very rapidly at high gallons per minute (amperage).

As the pressure in the tank rises and nears the pressure of the inlet water supply, (fully charged battery) the flow of water (amps) slows and eventually stops even though the inlet pressure (voltage) remains high.

Steve

[FlyingCloud1937]

What all yall battery experts forgot is, the state of the battery.

Typically for FLA's I recommend about, amps=4% of total amp hr @ 20 hr rate.

Never EQ a bat that is not fully charged.

EQ at 15-15.5 temp dependent, all ways make sure the bat temp is at least 70-75F to start, never let the bat exceed 125F, during EQ.

Check the SPG every hour, as well as the temp. As soon as the "Monitor Cell" quits rsising, or reaches 120F, stop the charger EQ.

If you are trying to revive a dysfunctional battery, it's probably a waste of time.

If you are trying to bring a healthy bat/bat bank into balance then, by all means EQ.

You can not save or extend the life of a dead/murdered battery/bank. PERIOD...

A fully charged FLA, will have a resting voltage of 12.7 volts at 77F+/-.

The EQ amps that will flow into a battery (at a fully charged resting voltage of 12.7, 77F) will on average =/or exceed about 4% of the 20 hr rate of the nominal bank, When charged at 15.5 volts.

An EQ is an intentional overcharge rate of nominal, it is not a fix all.

Lloyd

[FlyingCloud1937]

In a perfect battery, yes/maybe. There are no perfect batteries, just like there are no Perfect Transformers!

Two cells in series, that one has higher resistance, will allow the same amps to flow to the same.

The heat has to be dissipated somewhere.

The high resistance calls for the same amps, and will degrade the healthy cell.

Lloyd

Originally Posted by Panope

For those having trouble with a mathematical understanding of electricity, the analogy of pumped water into a pressure vessel can make it very easy grasp.

Voltage is analogous to water pressure (psi). Amperage is analogous to volume (gallons). The battery is analogous to a pressure tank (the kind with some sort of compressible air chamber or bladder).

If the pressure tank is empty (battery at zero charge), and water is introduced at high pressure (high voltage), then the tank will fill very rapidly at high gallons per minute (amperage).

As the pressure in the tank rises and nears the pressure of the inlet water supply, (fully charged battery) the flow of water (amps) slows and eventually stops even though the inlet pressure (voltage) remains high.

Steve

[FlyingCloud1937]

Since this site won't allow me to edit.

substitute.... 4% of the nominal amp hr.

for,

(4% of total amp hr @ 20 hr rate.)

Lloyd

Originally Posted by FlyingCloud1937

What all yall battery experts forgot is, the state of the battery.

Typically for FLA's I recommend about, amps=4% of total amp hr @ 20 hr rate.

Never EQ a bat that is not fully charged.

EQ at 15-15.5 temp dependent, all ways make sure the bat temp is at least 70-75F to start, never let the bat exceed 125F, during EQ.

Check the SPG every hour, as well as the temp. As soon as the "Monitor Cell" quits rsising, or reaches 120F, stop the charger EQ.

If you are trying to revive a dysfunctional battery, it's probably a waste of time.

If you are trying to bring a healthy bat/bat bank into balance then, by all means EQ.

You can not save or extend the life of a dead/murdered battery/bank. PERIOD...

A fully charged FLA, will have a resting voltage of 12.7 volts at 77F+/-.

The EQ amps that will flow into a battery (at a fully charged resting voltage of 12.7, 77F) will on average =/or exceed about 4% of the 20 hr rate of the nominal bank, When charged at 15.5 volts.

An EQ is an intentional overcharge rate of nominal, it is not a fix all.

Lloyd

[Maine Sail]

+1 on everything Bill and Lloyd have said, and I will add this.

If you have an adjustable power supply, dial the current down until the battery can attain & maintain the desired EQ voltage.

Why? As I am sure Lloyd and Bill can attest that occasionally non-healthy batteries can sometimes short or fail internally during equalization. If this happens, and you have a large current source, the battery can really heat up and it can potentially become a bad situation. I have had this happen in my shop....

If the charge source is current limited you will create less heat in the event the battery goes from being a 12V battery to a 10V battery. This is also why I will not EQ batteries wired in parallel or as banks......

You have nothing to lose by limiting the current to only what is necessary to attain your desired EQ voltage and it creates a safer situation. Motion30 I believe stated has an adjustable power supply so I would suggest only enough current to get to the desired voltage.

[btrayfors]

+1 MaineSail

Bill

[Panope]

Originally Posted by FlyingCloud1937

In a perfect battery, yes/maybe. There are no perfect batteries, just like there are no Perfect Transformers!

Two cells in series, that one has higher resistance, will allow the same amps to flow to the same.

The heat has to be dissipated somewhere.

The high resistance calls for the same amps, and will degrade the healthy cell.

Lloyd

Lloyd: Sorry for the oversimplification with my above water analogy.

Ok, let's assume the pressure tank has a small leak allowing water to continuously escape, eventually sinking the boat!

Steve