Ultimate Charger I

1992-1996

The Ultimate Charger is designed to completely maintain the electrical capacity of 8 nicad systems simultaneously. The primary application of this charger is Radio Control systems.

A typical R/C system consists of a transmitter with 8 1.2 volt 500 mah batteries in series for a nominal rating of 9.6 volts at 500 mah, and a receiver with 4 1.2 volt 500 mah batteries in series for a nominal rating of 4.8 volts at 500 mah. Most modelers do not have just one R/C system; they have many systems.

Many serious modelers, especially those with large expensive models are replacing the original batteries in the receiver and sometimes the transmitter with more powerful batteries. Another trend is to have a single transmitter operate many flight systems (but not simultaneously, of course.) A growing awareness of the electrical idiosyncracies of a nicad battery pack has resulted in cycling chargers, trickling chargers, and Expanded Scale Voltmeters. Many have looked in vain for a universal answer to these situations.

The Ultimate Charger was designed to fit all of these needs in a single unit. It can maintain the charge on the various combinations of transmitters and receivers. It can charge nicad packs from 270 mah to 2200 mah capacity. It can discharge, charge, and trickle charge the battery packs. It can automatically cycle (Discharge-Recharge-....); Discharge, Charge, and Trickle; or Charge and Trickle the 8 packs, each with a different operation and rating, simultaneously. The Ultimate Charger constantly checks the packs and gives a warning when it detects a shorted cell. The system senses that the battery pack has been removed for use, and switches back to fully charge the battery when the battery pack is reconnected. The precise voltage and capacity of each of the 8 packs is displayed on a 16 character LCD. The Ultimate Charger is functionally very complex, but simple to operate.

Nicad battery chargers come in several different types. They all provide a flow of current through the battery pack for a period of time. When the battery pack is used, this current flow reverses, and the electrical energy stored during charge now flows outward to power an external circuit.

Batteries, like everything else in life, are not perfect devices. Up to 40% of the charging current is lost in heat, compared with the amount of electrical power derived from the battery. Charging the battery puts an electrical strain on the nicad, and different types of nicads are better suited to withstand this electrical strain. Almost all nicads are able to withstand a charging current equal to 1/10 the mah rating on the battery. For example, a 500 mah battery can be charged at 50 ma. Because of inefficiencies, the battery pack has to be charged for 16 hours (50ma x 16hrs x about 60% efficiency = 500 mah) if fully discharged. Of course, a more efficient battery may take somewhat less time, but this is difficult to predetermine.

The "500 mah" rating is also important to understand. Many think that this means you could draw 500 ma for 1 hour, or 250 ma for 2 hours, or 100 ma for 5 hours, etc. Unfortunately, life isn't quite that simple. The battery capacity rating is non linear, with lower current applications receiving more total energy than high current applications. A classic example of misinformation is the mah rating produced by a cycle charger. Most other cycle chargers discharge a 500 mah battery pack at 300 ma and measure the time from fully charged to an average of <1.1 volts per cell. 300 ma x the time in hours = mah rating, right? Wrong.

The manufacturer discharges at 100 ma which produces a considerably higher mah rating. When your pack under 300 ma cycling discharge shows 400 mah, it does not indicate a bad pack. If it showed 500 mah, your only conclusion would be that you have a superior pack! The major value of the mah reading is to keep track of whether the pack is approaching the end of its service life. Nicads can not be charged and discharged forever. Most are rated at about 500 charge/discharge cycles, under good conditions. Few modelers operate under ideal conditions. The batteries cook inside a model in Summer, and freeze at the field in the Winter. This does not make the battery pack a "happy camper". Modelers also use their factory supplied wall charger to recharge, generally leaving the batteries to continually charge. Or, they may take them off charge during the Winter, storing the model in a cold garage.

But the battery has its revenge - death at an inopportune moment. Two major failure modes exist. It loses its capacity to store the charge, no matter how long it is left on charge, or one or more of the cells in the pack shorts out internally.

Another factor to consider in the life & times of a nicad is called "memory". When a nicad pack repetitively is partially used then recharged, its capacity diminishes. An example of this might be an airplane always flown 2 flights on evening outings might go dead on the 4th flight when taken out all day Sunday, even though the batteries should be fine for 8 flights. Considerable controversy surrounds this whole area, but to be on the safe side, the battery pack is occasionally fully discharged then recharged to "lie to the battery" about what it should be supplying. Newer batteries claim to be free of memory effects, but ....

Cycling repeatedly will obviously use up the 500 cycle life of the nicad, so an occasional use is appropriate, but continual use is ill advised. An ESV or Planesaver will provide a good margin of safety to avoid memory effect problems, and an occasionally cycled battery provides a rating history that should be kept for preventative maintenance.

Instead of complete repetitive cycling, a preferred technique is occasionally discharging, charging, and trickle charging which lies to the pack, telling it that you have big expectations of it!

The Ultimate Charger was designed as a lifetime device. It is very conservatively rated. It was designed for worst case - all channels charging 1200 mah to 2200 mah packs for 16 hours. In actual operation, most of the time the channels are on Trickle, which lightly loads the charger.

The discharge current of the Ultimate Charger is set to 160 ma. This results in a longer cycle time than competitive cycle chargers, but the mah rating will be closer to the factory rating. Discharging a 500 mah pack will take about 3 hours, and a 1200 mah pack will take about 7 hours. The discharging function is performed on a single channel at a time to limit the thermal loading on the charger, as well as not stressing the Discharging IC. When more than 1 battery pack is being cycled, a queue is formed for the discharge function.

Preparing the Ultimate Charger

.The power transformer's connector pins are arranged in a square. Notice that the connector has a plastic holder barb on one side. This barb should face upwards (towards the switch side). The needed two 16 volts AC pins are located next to the barb. Plug the transformer's connector into the charger with the barb upwards in between the black teeth of the charger's PCB mounted plug. Plug the transformer into a 117v 60 Hz socket.

. The charger should identify itself, display the factory settings, then go through the channels, finding them all OPEN.

. Unplug the wall transformer.

. Orient the charger so that the channel switches end is towards you, and the switches are facing down.

. You will notice a 10 pole dipswitch inside a rectangular hole in the bottom pan of the charger. Note that the individual switches are numbered 1-10, from bottom to top. A white dot is located near switch 1.

. Switches 9 & 10 are used to determine the number of transmitters (9.6v) being charged, and the default number of receiver packs (4.8v) being charged.

. Determine how many transmitters to charge. You may select 0, 2, 4, or 8.

. Plug the charger back in. The channel ID should match your selection.

. The dipswitches are only read at Power On, so if you change the switches, you must momentarily unplug the transformer to force the microcomputer to reread the dipswitch settings.

. The other dipswitches are used to set the currents on the various channels.

The channels are paired 1&2, 3&4, 5&6, and 7&8. The dipswitches are likewise numerically paired, and result in 4 different possible combinations of on-off for

. The transmitter channels just have 2 options, 9.6v 500mah and 9.6v 1000mah. The 9.6v 500mah setup has both switches pushed down on the right, and the 9.6v 1000mah setup has both switches pushed down on the left. The other 2 possibilities will default to 500mah. All of the transmitters I have seen come with 500mah batteries. However, you may now consider replacing the 500mah cells with 800, 1000, or 1200mah cells to have longer flight time, especially if you are using the higher drain PCM radios. Mr. Nicad (608) 643-3194, B & P (817) 662-5587, as well as other nicad suppliers, have a line of nicads the same size as the 500mah originals, but with 1000mah capacity. Charge an 800mah transmitter pack at the 500mah setting, and a 1000 and 1200mah transmitter pack at the 1000mah setting.

. Each receiver channel set has 4 options. All channel sets will produce 4.8v 500mah if the corresponding dipswitch set is pushed down on the right, and 4.8v 1200mah if both are down on the left. The other 2 positions are differently defined so that the greatest flexibility in charging voltages and currents can be accommodated.

. Channels 1&2, receiver, have the 4 choices, in order, of 4.8v 500mah, 4.8v 270mah, 4.8v 800mah, or 4.8v 1200mah.

. Channels 3&4, receiver, have the 4 choices, in order, of 4.8v 500mah, 6.0v 1000mah, 4.8v 270mah, or 4.8v 1200mah.

. Channels 5&6, receiver, have the 4 choices, in order, of 4.8v 500mah, 4.8v 2200mah, 4.8v 800mah, or 4.8v 1200mah.

. Channels 7&8, receiver, have the 4 choices, in order, of 4.8v 500mah, 6.0v 1000mah, 4.8v 800mah, or 4.8v 1200mah.

. The order of the switch settings is the same as the 4 transmitter count settings above. While this may seem a bit confusing, you will learn the code very quickly, since all you need to do is to make your best guess at the settings then momentarily connect the wall transformer. The Ultimate Charger LCD will check your switch settings and tell you what it finds to verify your settings.

. Example: I have a 30% Ultimate Biplane with a 2200 mah receiver pack, a 20% Ultimate Biplane with a 500 mah receiver pack, a 500 mah spare receiver pack, a JR Century 7 PCM transmitter for the 30% Ultimate, a JR 347 PCM transmitter for the 20% Ultimate, and 2 Nistarters. This translates to 2 500mah transmitters, 2 2200mah receivers (only one used), and 4 500mah receivers, the last two receiver channels being used for the Nistarters.

I push dipswitch 9 down on the left and dipsw 10 down on the right. This sets the Ultimate Charger to 2 transmitters and 6 receivers. The 2 transmitter charge cables are connected to channels 1 & 2. The spare battery charging cable is connected to channel 3, and channel 4 charging cable is connected to the 20% Ultimate. Since these are 500mah, I push dipswitches 3&4 down on the right. The channel 5 charging cable goes to the 2200mah pack in the 30% Ultimate, and channel 6 is unused presently, but could be connected to a spare 2200mah pack, if I had one. Dipswitch 5 is pushed down on the left and dipswitch 6 is lpushed down on the right to program the microcomputer to 2200mah for these two channels. The two Nistarters are connected to cables from channels 7&8. A 1.2v Nistarter will receive 150ma charge current when connected to a 4.8v 500mah receiver channel. Dipswitches 7&8 are pushed down on the right. After all this, the dipswitch settings come out to all right except for #5 (makes 2200mah) and #9 (makes 2 transmitter channels), which are pushed down on the left. After setting the switches, but before connecting anything, I plug in the wall transformer, and verify that the channel capacities are correct. Channels 7&8 will read 500 mah receiver, but this is ok.

. Once you have the correct switch settings, then the next task is to make the charging cables. Many possibilities exist. The first consideration is the connector needed to mate with your transmitter, airplane, or Nistarter. Your friendly hobby shop generally carries spare connectors that will go to your plane at the usual exorbitant markup. The transmitter connector for JR and many Futabas can be obtained at your friendly neighborhood Radio Shack store as "Coax barrel type DC power plugs" catalog #274-1567 through #274-1574 for a pair. Take your transmitter along to match the correct one. Ignore the stupid comments you'll get.

Another possibility is to cut the connectors off your wall charger that comes with the radio. I like to keep this charger intact, myself. The Nistarter cable can be made from a mini phone plug (R.S. #274-286 or #274-287) or an audio cable (R.S. #42-2420) with a bored out 6-32 large (5/16") nut soldered to the barrel. Or, you can cut the cord off your Nistarter wall transformer. Next consideration is that you may want to have long cords from the Ultimate Charger to the airplanes, transmitters, and Nistarters. I splice R.S. speaker wire (R.S. #278-1385) to the charging cords. Cover the splice with heat shrink tubing (Ace or R.S.) and shrink tight with a heat gun. Since my transmitters and Nistarters are kept on a shelf with the Ultimate Charger, I make the transmitter and Nistarter cables about 3 feet long. The airplanes are hung on racks on the garage wall, so the airplane cables are about 6-10 feet long.

. Remove the 4 6-32 screws holding the front panel to the bottom pan.

. Carefully lift the front panel from around the protruding switches.

. Attaching the cables to the Ultimate Charger must be carefully done!

If you look carefully at the area below the switches (or underneath the top cover's grommets), you will notice the numbers 1 to 8 along with a - and a + sign on either side of a number. All of the - leads are connected to a common ground bus, and the + leads head up towards the charging and discharging current limiting resistors. If proper polarity is not observed serious damage to the charger and the transmitter or receiver could occur. However, the problem is easily avoided if a simple procedure is followed. Futaba and most other manufacturers use the standard color coding system of black is - and red is +, just like on your car battery. But not JR! They had to get it screwed up! JR receivers and servos have red as + and brown as -. Then to really do it up in style, they made the transmitter jack and color code totally reversed, with black + and red -.

. I find that the best way to get it right is to make up the cable, and plug in the cable to the transmitter, airplane (boat or car), or Nistarter. Then take a voltmeter and measure the voltage at the charger end of the cable, noting the polarity. The suggested speaker cable is color or insert coded, so note the color or insert coding of the - lead of the cable. Solder this lead to the - side of the channel's cable pads. Now again measure the voltage by connecting the voltmeter - lead to the common ground bus of the charger's printed circuit board, and the dangling + lead of the cable to the + lead of the voltmeter. Proper voltage polarity should be detected. Then unplug the cable from the battery pack and solder on the + lead of the charging cable. Do this for all 8 channels.

. Example: My Ultimate Charger system described above has 2 JR transmitter cables soldered to channels 1 & 2. I connect the RED lead to the - side of ch #1 and the BLACK lead to the + side of ch #1. The second JR transmitter cable is soldered just like the first, with the RED lead to the - side of ch #2 and the BLACK lead to the + side of ch #2. The receiver pack cables have the BROWN lead to the - side of ch #3 or #4 or #5 and the RED lead to the + side of #3 or #4 or #5. The Nistarter leads consist of two halves of a Radio Shack shielded cable with the outer shield soldered to the - side of #7 or #8 and the inner conductor to the + side of #7 or #8.

. Very important also! Put the cable through the grommet of the appropriate channel and tie a strain relief knot in the wire about 2" from the inner ends of each cable before soldering!

. Final evidence of proper connections is when the charger reads out the correct voltage when connected to each channel. However recheck your work several times before connecting the attached cables to the battery packs.

. Carefully replace the front panel and fasten with the 4 6-32 screws.

Initial Operation

All the switches and leads can look very complicated, but normal operation is really quite simple. The row of 8 channel switches have a switch dedicated to each channel. The channels are labeled 1-8 from left to right. Each channel switch is independent from is neighbors.

Each channel switch has 3 positions. If the switch handle is down (towards the channel's leads coming through the grommet), the switch is in the Charge-T (Charge-Trickle or CT) position. If the switch handle is up (towards the display), the switch is in the Cycle position. The third position is a detent between the other two positions, called the DCT (Discharge-Charge-Trickle) position.

Normally, all 10 switches should be down. The "SCAN" switch and the "FORCE-T" switch will be discussed later.

Plug in the Ultimate Charger. The Charger will identify itself, and the channel ratings will be scanned. If the ratings are incorrect, unplug the charger, and go back to the previous section on dipswitch setting.

Assuming that you have nothing connected yet, every channel should read # OPEN ! Plug in a battery pack to any channel. When the display finally shows this channel again, the # OPEN ! is gone, and the display will show # XX.Xv 0hrs C (where XX.X is the battery voltage read). The C indicates that the Ultimate Charger is now charging the battery. The elapsed hours on charge are displayed for 16 hours. After 16 hours the display will change to # XX.Xv 0hrs T, meaning that the charge has been reduced to a Trickle charge. The elapsed time on Trickle is now displayed, showing from 0-9999 hrs (about 14 months). If you disconnect the battery pack at any time, the charging current is restored and the timer is reset. # OPEN ! will be displayed. Reconnect the battery and the charging process starts over again.

The white area above each channel is provided so that you can write the name of the transmitter, airplane, boat, etc. assigned to this channel with a water based transparency pen such as Vis a Vis by Sanford. Wipe off with a damp cloth, then 409 spray cleaner or equivalent, to change labels.

The normal operation goes like this. Plug in your airplanes, or boats, and transmitters. When your are ready to fly or float, check the channel display. Make sure that the battery pack that you want to use is not shorted (Blinking S). Unplug and have fun. When you return, plug them back in. They will be ready to use again tomorrow, or next month, or next year.

Not only is this system carefree, it also gives an indication, by reading the Trickle hours, of how long it has been since each unit was used. Occasionally switch a channel to the DCT (center) position. Now when you return from the outing, this channel will be Discharged first, then Charged and Trickle charged. This will avoid "memory buildup". It will put a bit more wear on your packs, so that is why I recommend it as "occasionally".

You may want to cycle your pack. In this case, turn the channel switch handle up. The channel will Discharge, read mah and Recharge for 16 hours, Discharge, read mah and Recharge for 16 hours,..... until the switch is taken off Cycle. The first mah rating may not be calibrated, as the Discharge could occur before the pack was fully charged. Subsequent cycles should be calibrated. The readings should be logged so that weak packs can be replaced before they cause problems. The Discharge rate is fixed at 160 ma. The Discharge continues until the shutoff voltage of 8.7 volts, 5.4 volts, or 4.3 volts is reached.

When finished with cycling after a few cycles (averaging about a cycle a day), turn the channel switch from Cycle to CT to resume normal operation. The pack will be charged and ready the next day, or sooner, depending on where the battery was in the Recharge portion of the cycle.

Operational Theory

@ Power On:

Switch on Charge-Trickle:

. Channel is set to Charge, Timer in hours is Reset

* . Display shows channel #, Voltage, Elapsed time in 0-15 Hours and C (or blinking S if a shorted cell is detected)

. After 16 hours, channel is set to Trickle, charge constant is reduced to 1/4, Timer in hours is reset.

. Display shows Channel #, Voltage, Elapsed time in 0-9999 hours and T (or blinking S)

. If battery not connected at any time, Channel reset to Charge, full charge constant is restored, and Timer in hours is reset.

.Display shows Channel # and OPEN !

. Switch on Discharge-Charge-Trickle:

. Channel is set to Charge, full charge constant is restored, & Timer in hours is Reset.

** . Display shows Channel #, Voltage, Elapsed time in 0-15 hrs, & C (S).

. After 16 hours, charge current set to 1/4, set to Trickle mode, and timer in hours is reset and entered into discharge Q.

. Display shows Channel #, Voltage, Elapsed time in 0-9999 hours, and T (Blinking S).

. When selected for Discharge from Q, Discharge bit is set, set to Discharge mode, and elapsed time in minutes is reset.

. Display then shows Channel #, Voltage, elapsed time in minutes, & D.

. When voltage drops to 8.7v, 4.3v, or 1v (<1.1v/cell), discharge ends and set to Charge mode, discharge bit cleared, elapsed time in hours set, & removed from Q.

. Display then shows Channel #, Voltage, elapsed time in 0-15 hours, and C (Blinking S).

. After 16 hours, Channel is set to Trickle, the charge constant is set to 1/4, and timer in hours is reset.

. Display shows channel #, Voltage, elapsed time in 0-9999 hours and T (or a blinking S).

. If Battery is or becomes unconnected, channel set to Charge, full charge constant is restored, and elapsed timer in hours reset.

. Display shows Channel # and OPEN !

Switch on Cycle:

. Channel is set to Charge, Timer in hours is reset, and channel placed in discharge Q.

*** . Display shows Channel #, Voltage, Elapsed time in 0-15 hours, and C (or blinking S).

. After 16 hours, If not selected for Discharge yet, charge constant is reduced to 1/4, timer in hours is reset, a the channel is put in trickle mode (note that Cycle has a t, not at T.)

. Display then shows channel #, 000mah, elapsed time in 0-9999hrs, and t (or a blinking S if shorted).

**** . When finally selected from Q, set to Discharge mode, discharge select bit is set, and elapsed time in minutes is reset.

. Display shows channel #, voltage, elapsed time in 0-9999 min & D.

. When voltage drops to 8.7v, 4.3v, or 1v (<1.1v/cell), discharge ends.

Set to Recharge mode, clear discharge bit, and reset elapsed time in hours.

. Display shows channel #, mah rating, Elapsed time in 0-15 hrs, & R (blinking S if shorted)

. After 16 hours, Channel is placed in discharge Q, charge constant is reduced to 1/4, timer in hours is reset, and the channel is put in Trickle mode.

. Display shows channel #, mah rating, elapsed time in 0-9999 hrs, & t (blinking S if shorted).

. When again selected for discharge, set to Discharge point, restore charging constant, and return to Discharge loop (****).

. Whenever battery not connected, set channel to Charge, place in Q, and reset timer to hours.

. Display then shows Channel #, and OPEN!

@ Switching from Charge-Trickle to Cycle:

. Channel is set to Charge, restore charging constant, timer in hours is set, and channel is placed in discharge Q. Go to ***.

@ Switching from Charge-Trickle to Discharge-Charge-Trickle:

. Channel is set to Charge, restore charging constant, timer in hours is set, and channel is placed in discharge Q. Go to **.

@ Switching from Discharge-Charge-Trickle to Cycle:

. Channel is set to Charge, restore charging constant, timer in hours

is set, and channel is placed in discharge Q. Go to ***.

@ Switching from Discharge-Charge-Trickle to Charge-Trickle:

. Channel is set to Charge, charging restored, timer in hours is set, channel removed from Q, and discharge bit is cleared. Go to *.

@ Switching from Cycle to Charge-Trickle:

. Channel is set to Charge, restore charging constant, timer in hours is set, channel removed from Q, and discharge bit is cleared.

Go to *.

@ Switching from Cycle to Discharge-Charge-Trickle:

. Channel is set to Charge mode if running in Recharge mode. Go to **.

SCAN

The Ultimate Charger is programmed to either scan all channels sequentially, or to continuously display a user selected single channel.

When the Ultimate Charger is first turned on, the title appears, then the 8 channel ratings are displayed. Next the word "ALL" appears on the display. This means that the charger will be sequentially displaying ALL 8 channels, pausing about 2 seconds after each so that the user can read what is happening. While it would be nice to display all 8 at one time, this would require an 8 line x 16 characters (128 characters) LCD and would add about $100 to the cost of the charger.

Several people said that they would like a single channel continuously displayed at certain times. If you press upwards and hold the switch marked "SCAN", the display will step through the channels giving the channel rating. Press the SCAN switch downwards when the desired channel number appears. This channel will now continuously display until the charger is powered down, or the SCAN switch is again pressed upward. If you want to return to the default ALL SCAN, just hold the SCAN switch upward until "ALL" appears and press downward.

FORCE-T = Force Trickle

The switch labelled "FORCE-T" is used to force a channel to go immediately into Trickle mode instead of first charging for 16 hours. If you want to do a Force-Trickle, perform the following operation.

FORCE-TRICKLE

. The Channel to be forced to Trickle must be displaying "C" on the LCD.

. When the LCD is displaying the desired channel #, flip "FORCE-T" switch upwards (on).

. When the display either steps to the next channel #, or changes the "C" mode to "T" (depending on whether the LCD is on SCAN ALL or continuously displaying a single channel), flip the "FORCE-T" switch downwards (off).

. The Force-Trickle operation will not occur if the channel is switched to Cycle (D or R), already on Trickle (T), or is showing a shorted battery (blinking S).

. Verify that you did the Force-T to the intended channel and no other.

. If you Force-T the wrong channel, momentarily disconnect the pack to force C.

Considerations

Since this is a computerized device, several unique actions can happen. Most computers step through a carefully designed set of instructions called a program. If anything unexpectedly disturbs this flow, the computer may become confused. The most frequent disturbance is a power line glitch caused by a lightening strike or power company problem. Another cause can be a very strong RF field or electrostatic discharge. The Ultimate Charger is designed to be insensitive to these problems, but should this happen, the computer must be reset so that it finds itself. The Ultimate Charger does not have an external reset switch, so just momentarily unplug the charger if you see the LCD staying static with strange characters on the LCD. A failsafe battery system (mentioned on the next page) solves power failure problems.

The microcontroller may fail to reset properly if a transmitter pack (9.6 volts) is connected. Temporarily disconnect the transmitter(s), momentarily unplug the charger (and failsafe batteries is attached), then reconnect .

Some customers indicated that the Ultimate Charger was going to be mounted in a trailer with their airplanes. Remember that the charging, etc. stops when the electricity to the charger transformer stops. Avoid the problem by supplying power to the Ultimate Charger through a 25 watt or greater DC to AC inverter running on a dedicated deep cycle 12 volt battery.

Some transmitters (such as Futaba) have a forward biased diode between the charging jack and their 9.6 volt battery. This results in an inability to externally discharge the pack. Three options exist. 1. Don't Cycle or DCT this transmitter. 2. Disconnect the battery internally and Cycle it directly. 3. Bridge a shorting wire across the diode. Unless you know what you are doing, don't try #3. This diode could also interfere with charging. If so, find someone to help you with #3.

Older 10.8 volt (9 cell) transmitters can be charged on a 9.6 volt channel setting, but the charging current will be slightly lower. Discharging will be a problem, however, since the charger will try to Discharge to 8.7 volts instead of 9.8 volts. The discharging current will be a little higher. If you really want to Cycle, then do it this way. Put on Cycle and watch the voltage reading on the LCD. When the Discharging voltage reaches 9.8 volts on the LCD (about 3 hours on a 500 mah pack), note the elapsed time in minutes. Multiplying the time by 3 will give you the approximate mah rating. Then switch the channel to Charge-T.

Some people are concerned about voltage drops in long charging cords. Relax. If you use the suggested speaker wire for extensions, you will have no problem. The battery is measured at charging and discharging pulse off time, so the voltage measured at the charger would still be accurate if 500' of thin wire were to be used.

Nistarter discharging is a problem, due to a need for a 15 ohm resistor for programming short circuit protection of the batteries. The result is a very low Discharge current of about 25 ma. This will eventually discharge the Nistarter, but, the mah rating will be wrong. The reading actually overflows the mah counter, so the displayed mah is meaningless. Record the elapsed time on Discharge, which will be about 4000 minutes (66 hrs).

TV Interference is always possible from all digital type circuits. The Ultimate Charger is designed for no RF problems either from it or to it. The case is metal, all leads are bypassed, and the microcontroller runs at a lowered clock frequency. I live in a TV fringe area, and there is no interference coming from the Ultimate Charger. Should you experience TVI, reorient the charger leads or TV antenna.

Some people may want to watch the current pulses going to the battery. I don't know why, but if so, expect about 160 ma on Discharge, battery mah rating/10 ma on Charge, and battery mah rating/40 on Trickle, all average pulse currents. Meter polarity will be reversed when Discharging. A 200 ma to 300 ma each side of center DC meter is ideal. Your little pocket VOM will work too, but a DPDT polarity reversing switch will be needed.

The Ultimate Charger has many tricks, that just happened, which you may want to take advantage of. You may wish to find out how many mah's are left in your pack after flying or floating. Make sure all other channels are on the Charge-T (down) switch setting. Then put the desired channel on Cycle. Connect the battery pack. This will immediately pass the Discharge "pin" to this channel. When Recharge displays the mah rating, this was the remaining energy, since you never allowed any charge to occur between use and Discharge. Switch this channel back to the desired mode after reading the rating.

If you are on the Charge phase of DCT and wished that you could see what happened during the Discharge phase, momentarily switching to Cycle will display the mah calculated as a function of the end of Discharge.

Mah ratings are rather meaningless if a partial Charge or Recharge (same thing) takes place. Yet you may be doing a study on the effects of partial charges, so have at it by forcing a Discharge after XX hours or Charge. Put all channels to Charge-T except this channel to Cycle. After the battery is Discharged and at the desired time into Recharge, disconnect the battery for a couple of seconds. This will force Discharge. When Recharge redisplays, that mah reading is what you wanted.

FailSafe or Field Charger Operation

Like most digital clocks and computers, if the power goes off at your house, the system stops. Several Ultimate chargers have been tested with a fail safe system which consists of three 6 volt sealed lead batteries in series across the 20 volt charge bus. As long as the power lines are hot, these batteries are charged or trickle charged, as well as powering the rest of the charger circuitry. However, when power fails the 18 volts from the lead batteries will provide power for several hours until the power lines are restored. The lead batteries tried were rated at between 1 AMP to 3 AMP . In fact several people now use the Ultimate Charger as a field charger by connecting three 6 volt 3 amp batteries in series across the charge bus. The resultant system will keep charging 2 channels for about 10 hours or more.

The pins on either side of the connector are presently connected to the to the 20 volt charge bus to facilitate this upgrading to a failsafe or field charger system. The failsafe system can be added for less than $50 worth of parts.

Take the cover off the charger, and orient the charger so that the power connector is at the top, away from you. The hole on the left of the power connector, nearest the LCD, is connected to the - or ground side of the charge bus. The next 2 holes hold the pins which provide the 16 volts AC from the power transformer as mentioned on the 3rd page of this documentation. The hole on the right, nearest the Force-Trickle switch is connected to the +20 volt charge bus. Do not connect the batteries directly to the two charge bus holes. Use a polarized connector so that the voltage can be removed to reset the Ultimate Charger for changing dipswitch settings, etc.

Epoxy the 3 lead batteries together. Make 2 jumper lead out of #14 wire and connect them between the - and + termainal of adjacent batteries. Measure the resultant battery pack and verify that 18 volts is available between the 2 outside terminals. Disconnect all power and nicads. Solder on the polarized connector to the two empty holes. Solder the - side of the leads to the - side of the series battery pack. Temporarily leave the + lead disconnected. Now power up the charger. Verify that the + 20 volts is at the unconnected lead, and + 18 volts is at the unconnected battery terminal. The reason for these precautions is that a reversed polarity from the battery to the chargeer will totally destroy the Ultimate Charger's circuitry.

Unplug the polarized connector and solder the + lead from the connector to the + terminal on the battery pack. Plug in the polarized connectors and you are done. You can test how long the system will stay powered by fully charging the batteries for a day or so, and then monitoring the voltage across the battery under load until the voltage drops to about 14 volts.

Troubleshooting

Display not centered - The display is attached to the case side by silicon that may have come detached.

Display Blank - Check power. Reset by momentarily unplugging.

LCD shows wierd characters - You electrostatically zapped Charger. Reset.

Display not scanning - Normal, you hit the scan switch. Otherwise, Reset.

Display hard to read - A small potentiometer between the "SCAN" switch and the LCD sets the viewing angle. 1/8 turn will usually correct.

Battery voltage off on all channels. - The other potentiometer, just above the channel switches, sets the A/D converter IC's calibration. Activate the charger's SCAN switch so that a single channel is displayed. Put a calibrated voltmeter across the battery pack's outside terminals, or as near as you can get. Very slightly turn the potentiometer. The A/D reads once every 2 seconds, so you must wait to see results. Clockwise increases voltage.

Battery voltage off on one channel. - Bad battery pack. Transmitter diode problem. Connector problem including reversed plug to JR receiver charging jack will read the remote control cord voltage (that one got me!). Resistor divider problem in the 16 resistors by the dipswitch.

One channel shows OPEN though apparently connected. - Airplane (boat) or transmitter on/off switch left on or is broken. Charging connector not seated or reversed. Broken lead. Reversed polarity ( Oh No!)

Repairs are no longer being done.

Dr. Robert Suding SAI

27107 Richmond Hill Rd.

Conifer, Colo. 80433