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Pulse Technology
What's it all about?



Pulse Technology. What does it do?

Pulse technology, as applied to batteries, can do two very important things. It allows rapid charging and battery conditioning. Pulse charging, with the right charger, can bring your lead-acid batteries from 0 to 80% in 15 minutes, from 0 to 100% in around 45 minutes. NiCd and NimH batteries can be charged more quickly.  Pulses condition your batteries by breaking down the sulfation on the plates, the number one cause of premature battery failure. Your batteries last much longer, even when they're sitting idle for months.


How do rapid pulse chargers work?

There are two types of rapid pulse chargers.  All of them use a sequence of charge pulses separated by a shorter period when the charge pulse is turned off. The time between pulses allows the battery's capacitive reactance to partially discharge, thus lowering the impedance of the battery. The lower impedance allows the next charge pulse to go in much more efficiently, avoiding excessive heat build-up and over-voltage gassing.  In order to more completely and quickly discharge the capacitive reactance of the battery, the better rapid pulse chargers also use short discharge pulses after each charge pulse. Discharge pulses also help to condition the plates of the battery. Rapid pulse chargers without discharge pulses work well for "opportunity" charging.  Here the batteries are rapidly charged up to about 80% of their capacity. The batteries charged this way need to be brought up to 100% every few cycles with a slow charge. The incorporation of discharge pulses into the rapid charging process has many advantages. The discharge pulse more quickly discharges the capacitive reactance of the battery. This allows a shorter rest period between pulses, thus a more rapid charge. The short rise-time, strong discharge pulses also condition the battery by causing the sulfation crystals on the plates to break down more easily and release their ions back into the electrolyte. The discharge pulses also allow much more rapid charging from 80% to 100% of capacity, around 30 minutes for lead-acid batteries.


Will it make my battery explode?

Only if you buy your charger somewhere else! Seriously, the commercialization of pulse charging technology has not been without incident. The early charge control processes worked well in the laboratory, but were not robust enough to be successful in the real world. Sometimes they would not completely charge the battery.  Sometimes they would over-charge.  Rhino-Charge has developed a very robust charge control process that will take your batteries to a full charge, without over-charging, and then maintain them there indefinitely.


I've heard of CC charging, CV charging, Taper charging, Trickle charging, and Float charging.  What do Rhino-Charge chargers do?

The Rhino-Charge process starts at a low charge current.  The discharge pulses help to reduce the battery impedance. The current then increases as the battery can accept a higher charge rate.  The processor monitors the battery's condition and adjusts the charge and discharge pulses for the optimal charge.  As the charge process nears completion, the charge current is tapered down in steps until a full charge is reached.  A couple of minutes after the charge ends, the charger enters a maintenance mode with pulses that keep your battery charged and conditioned indefinitely.  Yes, you can leave your charger plugged up to your battery for months without gassing or drying out your battery.


How do I pick the right charger?

1.    The first step is to determine how many amp-hours you need to return to your battery during a typical charge.  For example, your golf cart may have six 6-volt 105 Amp-Hour batteries in series.  Your course may normally use about 40% of the capacity of the batteries.  You would need to replace 42 amp-hours.

2.    The second step is to decide the charge time you need and what state of charge you want at completion.  By this we mean, is this a situation for opportunity charging up to 80%, or do you need a full charge on the batteries.  In the case of the golf cart batteries using 42 amp-hours, either charge process will work.  With opportunity charging, the batteries could be operated between 40% and 80% state-of-charge during the day, and then fully charged at night.  The amount of time required for the charge is estimated with the following formulas.

For Opportunity Charging up to 80% Capacity:
Charge Time (h) = (Amp-Hours to be replaced) / (Charger Output in Amps)  + 0.1 hour

  For a Full Charge to 100%:
Charge Time (h) = (Amp-Hours to be replaced) / (Charger Output in Amps)  + 0.5 hour
     
In the golf cart example, a two hour total charge time to 100% would require a 28 Amp charger output, while a half-hour charge time to 80% would require a charger output of 105 Amps.
       
3.    You may now select a pulse charger with a current output suited to meet your charge time needs.  There are some restrictions based upon the battery / charger combination.  There is very little advantage in having a charger output more than four times the battery's amp-hour capacity.  In our golf cart example, there would be little charge time advantage in any charger output capability above 420 Amps.

4.     Make sure you have the electrical power available.  You can estimate the maximum power that the charger will require with the following formula:

Power in Watts = Battery Voltage x Charger Output in Amps x 1. 2

Using the golf cart example for the two hour charge, 36 x 28 x 1.2 = 1209.6 Watts would be required    from the utility line.  For the half-hour charge, 36 x 105 x 1.2 = 4,536 Watts.  A 1.2 kW charger or higher would be needed for the two hour charge, and 4.5 kW charger for a half-hour charge.  For chargers over 2 kW, you will want to have 240 VAC service.  If the charger uses over about 5 kW, you will want to have 3-phase service, 240 VAC or 480 VAC.


What about the maximum charge current on my battery's label?

There is a maximum charge rate that a battery will accept.  When the charge current exceeds this rate, two things can happen.  First, overheating may occur because heat is being generated proportional to the battery impedance and the square of the charge current.  Second, a "surface charge" effect may inhibit the battery from reaching its full capacity.  This means that the outside of the plates becomes completely charged, but the deeper portions of the plate were left discharged.  The charged layer creates an electrochemical barrier that impedes the flow of ions from the electrolyte to these uncharged portions of the plate.  To regain access to these uncharged regions, the battery must be discharged enough to remove this barrier layer.  The maximum current label on the battery is set with these constraints in mind for a DC charge process, not pulsing.  A pulse charger keeps the battery impedance low by allowing the capacitive reactance to discharge between pulses, keeping the overheating problem under control.  The discharge pulse used in Rhino-Charge chargers not only keeps the battery impedance low, but serves to pull ions away from the surface of the plates.  This breaks down the barrier to those inner portions of the plate, allowing the battery to reach full capacity at very high charge rates.  Without charge pulses, the maximum charge rate than can be attained without sacrificing full capacity is somewhere between 0.4 C and 2 C, where C is the Amp-Hour capacity rating of the battery.  Using properly managed discharge pulses in conjunction with the charge pulses, Rhino-Charge chargers have been able to reach charge rates of 10C in lead-acid batteries without loss of capacity.  The total charge time from 0% to 100% capacity was about 30 minutes with a battery temperature rise under 10 degrees Celsius.


What if I don't need a rapid-charge?

Okay, there are situations where an overnight charge is fast enough.  However, you will still benefit from the maintenance/conditioning capabilities of either a charger or conditioner from Rhino-Charge.  Our chargers have built-in pulse conditioning and maintenance.  If you have a good conventional charger, you can choose from the PulseTech conditioners we offer.  There is the PowerPulse conditioner, the Solargizer solar powered conditioner/charger, and the World Charger.  The World Charger is not a rapid charger, but a conventional charger with the PulseTech conditioning pulses included.


How does a pulse battery conditioner work?

Electrical pulses hit the battery with a fast rise-time pulse that makes the battery resonate electrically, like ringing a bell.  In this higher energy state, some of the sulfation crystals will break down.  Their ions are released back into the electrolyte.  This keeps the battery capacity up and cranking power high.  Like most inventions, this discovery was an accident.  Wilford Burkett noticed this ringing effect with one the earliest pulse chargers.  He didn't know why it worked, but he controlled his discharge pulses to take advantage of it.  Later, the same conditioning effect was noticed during system testing at NASA's Stennis test facility.  This discovery led to the patents for positive pulse conditioners held by PulseTech.  This technology is enjoying widespread success in the military, where vehicles and aircraft sit idle for long times, but must be ready to go at a moment's notice.


How do I know the condition of my batteries?

Voltage is a crude estimate.  Specific gravity is a crude estimate for a flooded cell battery.  The true measurement is from a controlled load test over time.  However, the test itself degrades the life of the battery somewhat.  The best measurement is with a battery impedance analyzer.  We offer different types for starting batteries and for motive or stand-by batteries.


What are these outrageous claims about recovering dead batteries?

When a battery has been poorly maintained or been allowed to sit uncharged for too long, the sulfation of the plates becomes so bad that it will not accept a charge from a conventional charger.  The pulse chargers and conditioners from Rhino-Charge will recover most of these batteries to serviceable condition.  (They will not recover shorted or opened cells.)  Two or three charge/discharge cycles on one of our chargers will normally bring these sulfated batteries back into service.


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