Ultimate Mini Charger

1997-1998

The Ultimate Mini Charger was designed as a low cost way to maintain the electrical capacity of 8 nicad systems simultaneously. The primary application of this charger was 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. Some PCM systems use slightly larger batteries. 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 idiosyncrasies 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 most of these needs in a single low cost unit. It can maintain the charge on the various combinations of transmitters and receivers. It can charge 9.6 v @ 600 mah transmitters, 4.8v @ 600 mah, 4.8v @ 1200 mah, or 6.0v @ 1200 receivers, and 1.2 v nistarters. It can Charge and Trickle the 8 packs, each with a different operation and rating, simultaneously. The Ultimate Mini Charger constantly checks the packs and gives a warning if you try to use a nicad pack with a shorted or weak cell(s). The system senses that the battery pack has been removed for use, and switches back to fully charge the batteries when the battery pack is reconnected. An audible beeper provides user feedback when nicads packs are connected and disconnected. A special external data connector is provided so that optional software and an external cable can be used to send the battery data to the parallel port on an IBM or Clone PC. 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 600 mah battery can be charged at 60 ma. Because of inefficiencies, the battery pack has to be charged for 16 hours @ 60ma x 16hrs x about 60% efficiency =600 mah) if fully discharged. Of course, a more efficient battery may take somewhat less time, but this is difficult to predetermine.

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. The Ultimate Mini Charger does not have cycling capability, as it does not have a readout, but a simple discharger can be built for about $2 worth of Radio Shack parts. Plans for building this discharger are included later in these directions.

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

Preparing the Ultimate Mini Charger

1. Plug the wall transformer into a 117v 60 Hz socket. The wall transformer will then output 14 volts AC to rectifier and regulator circuitry inside the charger.

2. The charger should identify itself, sending out 5 long beeps, then go through the channels, finding them all OPEN. The charger will give a single long beep for each channel with a battery pack attached.

3. Unplug the wall transformer.

4. Orient the charger so that the dipswitch is facing away from you..

5. You will notice that the dipswitch has 8 switches are numbered 1-8, from left to right.

6. The dipswitches operate in pairs. 1&2 control channels 1&2, 3&4 control channels 3&4, 5&6 control channels 5&6, and 7&8 control channels 7&8.

7. Each dipswitch pair has 4 states: Both OFF, 1st ON & 2nd OFF, 1st OFF & 2nd ON, and both ON.

8. Both OFF (down) = 4.8v @ 600 mah receiver pack

9. 1st ON (up) and 2nd OFF (down) = 4.8v @ 1200 mah receiver pack.

10. 1st OFF (down) and 2nd ON (up) = 6.0v @ 1200 mah receiver pack.

11. Both ON (up) = 9.6v @ 600 mah transmitter pack.

12 . 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.

13. Example: I have a Pattern airplane with a 4.8v @ 1200 mah receiver pack, a 20% Ultimate Biplane with a 600 mah receiver pack, a 600 mah spare receiver pack, a JR 388 PCM transmitter for the Pattern airplane, a JR 347 PCM transmitter for the 20% Ultimate, and 2 Nistarters. This translates to an Ultimate Mini Charger requirement of 2 9.6v @ 600mah transmitters, 2 4.8v @ 1200mah receivers (only one used), and 2 4.8v @ 600mah receivers, the last two channels used for the Nistarters by setting them for 6.0v @ 1200 mah which produce the maximum charge rate into the nistarters

The 2 transmitter charge cables are connected to channels 1 & 2. I push dipswitches 1 & 2 up to ON. The spare battery charging cable is connected to channel 3, and channel 4 charging cable is connected to the 20% Ultimate. Since these are 4.8v @ 600mah, I push the dipswitches 3 & 4 down (OFF). The channel 5 charging cable goes to the 4.8v @ 1200mah pack in the Pattern airplane, and channel 6 is unused presently, but could be connected to a spare 1200mah pack. Dipswitch 5 is pushed up (ON) and dipswitch 6 pushed down (OFF) programs the microcomputer to 4.8v @ 1200mah 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 6.0v @ 1200mah receiver channel. Dipswitch 7 is pushed down (OFF) and dipswitch 8 is pushed up (ON). After all this, the dipswitch settings come out to all up (ON) except for dipswitches 3,4,6,& 7 which are down (OFF). After setting the switches, but before connecting anything, I plug in the wall transformer. If a computer is attached to the external data connector, it will verify the channel settings.

14. Charlie down the street has 4 transmitters and 4 airplanes, all with the original 500 mah battery packs. He connects the 4 transmitters to Channels 1-4 and the 4 airplanes to Channels 5-8. Dipswitches 1-4 are up for 9.6v @ 600 mah each, and dipswitches 5-8 are down for 4.8v 600 mah each. The charge is 100 mah high, but the nicad batteries will easily handle the higher charge rate.

15. Once you have determined 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.

16. 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. My airplanes are hung on racks on the garage wall, so the airplane cables are about 6-10 feet long.

Cal Orr at Custom Electronics (Box 123 Higginsville, Mo. 64037 (816)-584-6284) has some universal receiver battery connectors definitely worth considering. The connector part is called "CEU" and will plug into Futaba, JR, and Airtronics battery connectors. A matching universal airplane fuselage Mount is called "CCM". Using this system, a given receiver channel connector can plug into an airplane with a Futaba, JR or Airtronics radio inside.

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

If you look carefully at the area below the square white 50 ohm power resistors, 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 -.

18. 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.

19. 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.

20. Recheck your work several times before connecting the attached cables to the battery packs.

Case for the Charger

The Ultimate Mini Charger was designed as a very low cost option for the R/C hobbyist. A Custom silkscreened and painted metal case was provided for the original full featured Ultimate Charger, but added $25 to the cost. You can save a considerable amount of money by using a generic plastic or metal case. Radio Shack has a plastic box that is 7 1/2" x 4 1/4" x 2 1/4" (#270-224) for $3.49 that will fit nicely. A similar box (#270-232) for $3.69 with an aluminum cover can also be used. Jameco (1-800-831-4242) has a very nice die cast metal box of similar dimensions (#11973) for $8.95.

The Ultimate Mini Charger MUST NOT TOUCH the plastic case, since many of them get quite hot and could melt the plastic.

The Ultimate Mini Charger PCB is mounted to the bottom of the case, with the Ultimate Mini Charger spaced to just clear the top of the case. Use four 2" long 4-40 screws and 12 4-40 nuts. Use the four 1/8" corner holes of the charger's PCB or the white dots of the decal as guides. The holes are 2.7" apart vertically and 5.7" apart horizontally.

Put the 4 screws through the holes and fasten with 4 of the 4-40 nuts. Then put another 4 of the 4-40 nuts about 1 1/2" up the 4 screws. Place the PCB on the 4 screws on top of the 4 nuts. Final adjust the four nuts under the PCB so that the top of the data connector just clears the bottom of the case's top.

Later, the last four 4-40 nuts will be used on top of the PCB to hold it securely to the case. Remove the PCB. Put a dots of instant glue on the nuts & screws to hold them in place.

Cut slots for the power cable and the charger cables. If you want to attach an external computer to the data jack, drill a 3/4" hole to provide clearance for the 5 pin DIN female connector. Drill a 13/64 " (3/16 + ream) hole in the top of the case for the LED Power Indicator.

A color decal is provided for the top of the charger. Trim the decal to size. Use a hand paper punch or x-acto knife to cut out the hole for the LED. Remove the waxed paper backing from the color decal. Put the top on the case with the LED protruding through the hole. Put the decal hole over the LED and align the decal with the case edges. Press the decal evenly down on the case top. Remove the top from the case bottom and drill a 1/2" hole through the top where the large black dot is on the decal. Smooth out any paper burrs. Cut out and smooth the rectangular hole for the dipswitch access if desired. The dipswitch is rarely used, so you may wish to just take the top off when you need to change the settings.

Drill several 1/4" holes in the case bottom for ventilation. The charger can get very hot.

Mount the PCB in the case and tighten the four 4-40 nuts on top of the PCB.

Initial Operation

Plug in the Ultimate Charger. The Charger will identify itself with 5 long beeps.

Assuming that you have nothing connected yet, the microprocessor should find every channel OPEN. A computer attached to the external data connector, will show the dipswitch settings of all 8 channels, then show all 8 channels with # OPEN ! where # is the channel number with nothing connected.

Plug in a battery pack to any channel. The Ultimate Mini Charger should make a single long beep. A computer attached to the external data connector, will show the battery connected as # XX.Xv 0hrs C ,where # is the channel number, XX.X is the battery voltage read, and C indicates that the Ultimate Mini 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 normal operation goes like this. Plug in your airplanes, or boats, and transmitters. When you are ready to fly or float, unplug the charging cord. The Ultimate Mini Charger will check its memory for the most recent state of the battery before it was unplugged.

If the battery was on Trickle charge, and was OK, the charger will make a single short beep.

If the battery was on Full charge, and was OK, the charger will make a single long beep.

If the battery was on Trickle or Full charge, and the voltage was a bit low, indicating a partial charge, the charger will make a short beep and 2 long beeps (W for WEAK in telegraph code) - The pack is <1.4v/cell.

If the battery was on Trickle or Full charge, and had a shorted cell, the charger will make 5 sets of 3 short beeps (S for SHORT in telegraph code) - The pack is <1.1v / cell.

Make sure that the battery pack that you want to use is not shorted (5 sets of 3 short beeps). Your airplane will either not run at all, or will crash about half way through the first flight.

Be very cautious with a battery pack diagnosed as "weak". The pack may be partially charged, need cycling, of just tired and ready for replacement.

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.

Force Trickle

Suppose you went to the field to fly your fully charged airplane, but it was raining. You didn't even take your airplane out of the car. When you got back home, and put the airplane on the Ultimate Mini Charger, the charger will try to charge the battery for 16 hours. It is already fully charged; you want it to keep it charged by continuing the Trickle charge that it was on before you left.

The Ultimate Mini Charger has a feature just for you. It is called Force-Trickle. A channel can be put into Trickle mode by a simple sequence of plugging, unplugging and plugging.

1. Connect the charging plug from the Ultimate Mini Charger to the airplane (or transmitter) You should get a single long beep.

2. Within 20 seconds, unplug and replug the airplane (or transmitter. A single short beep verifies that this channel has been forced immediately into Trickle Charge mode.

3. If you did not get the verifying short beep unplug the airplane (or transmitter) wait about a minute, and try again.

4. If you are using paralleled channels for higher current capacity, you will get a second long beep after the short beep. Unplugging and replugging again will Force Trickle the second channel. If you don't do the second unplug and replug, you will have the first channel on Trickle and the second on Full Charge, resulting in an effective current somewhere between Trickle Charge and full Charge, not what you had in mind.

Cycling Your Batteries

Many amusing articles have appeared in various R/C magazines by so called experts claiming cycling isn't necessary, doesn't work, must be always used, etc. Pick your own opinion. It does keeps my batteries at a higher voltage level, resulting in more flights. I cycle my batteries about every 3-6 months. Cycling consists of taking the batteries down to 1.1v /cell (8.8 volts for transmitters, 4.4 volts for 4.8 volt receiver packs or 5.5 volts for 6.0 volt receiver packs). Taking the voltage to 0 risks a cell reversal, a definite no-no. 1.1 volts / cell is just fine. Then fully charge the pack on the Ultimate Mini Charger for 16 hours or so. Then discharge. Then fully charge. Then discharge. Then fully charge. That's why they call it cycling the batteries. The Ultimate Mini Charger handles the charging part just fine. The trick is discharging to precisely 1.1 volt / cell. It is easier than you think. The simple circuit above uses about $3 worth of Radio Shack parts, and will do the trick just fine, even if it is a manual operation to put the batteries on the discharger, then the charger, then the discharger.... You could also take your batteries to someone that has the original Ultimate Charger and have it all done automatically.

A very simple automatic discharger can be built with about $3.30 worth of Radio Shack parts. A simple 1.5 v motor (#273-223) and a pack of diodes (#276-1653) can be assembled to discharge the nicad pack at about a 180 mah rate. When first connected, the motor will run fast. A 2" x 1/4" square "prop" will show the motor running. The diode string acts like a zener diode that will stop the flow of current if you are not around or watching when the nicad pack is discharged to 1.1v/cell. This prevents damaging the pack by reversing a cell when the voltage goes too low. 5 diodes in series works for 4.8v packs, 7 diodes in series for 6.0v packs, and 11 diodes in series works for 9.6v transmitters. Since there are 25 diodes in the package, get 2 motors & build one for a friend!

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 Mini 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 Mini Charger does not have an external reset switch, so just momentarily unplug the charger if you don't get the beeps that should occur when battery packs are connected or disconnected. A failsafe battery systems (mentioned on the next page) solves power failure problems.

The microcontroller may fail to reset properly if battery packs are still connected. Temporarily disconnect all batteries, momentarily unplug the charger (and failsafe batteries if 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. You may also use a set of three deep cycle 6 volt car batteries with separate trickle chargers, connected directly to the FAILSAFE pads on the PCB mentioned below in this document.

Some people, like me, use batteries that provide different levels of capacity than 500 mah or 1200 mah. In general, pick a charger current setting closest to the pack. However, some large 1/4 & 1/3 scale airplanes use batteries with capacities of 1700 mah or 2200 mah capacity. The Ultimate Mini Charger can charge these bigger batteries by simply paralleling channels. I use 4.8 volt @ 1700 mah packs on my large airplanes. I simply connect the charging cable to two channels, say channel 3 set for 4.8 volts @ 600 mah, and channel 5 set for 4.8 volts @ 1200 mah. The 2 channels add their respective charging capacity, and the result is 4.8 volts @ 1800 mah.

Similarly, some glider and pylon racers use 4.8 volt @ 270 mah packs. In this case take the channels that will be connected to these small packs, and change the square white 50 ohm 3 watt resistor powering this channel to 100 ohms 1 watt (2 Radio Shack 271-009 47 ohm 1/2w in series), thereby cutting the Charging and Trickle current in half.

Certain transmitters (such as Futaba and some JRs and Airtronics) have a forward biased diode between the charging jack and their 9.6 volt battery. This results in an inability to externally draw current or voltage readings or discharge the pack, which makes cycling impossible. The Ultimate Mini Charger will give a false indication of OPEN (no beeps) due to the diode preventing any reverse flow of current out the charging jack. The solution is to eliminate the diode. Then you can cycle the transmitter, which will give it extra life.

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.

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. All leads are bypassed, and the microcontroller runs at a lowered clock frequency. Using a metal case should completely solve an problem. I live in a TV fringe area, and there is no interference coming from the Ultimate Mini Charger, even without any case. Should you experience TVI, reorienting the charger leads or TV antenna will undoubtably solve the problem.

Some people may want to watch the current pulses going to the battery. I don't know why, but if so, expect about channel mah rating/10 ma on Charge, and channel mah rating/60 ma on Trickle, all average pulse currents. A 200 ma to 300 ma DC meter is ideal. The current levels were set assuming 1/2 the packs were on charge, and 1/2 the packs were on trickle. The current will be a bit lower when most are on charge, and higher with most on trickle or open.

FailSafe Operation

Like most digital clocks and computers, if the power goes off at your house, the system stops. Ultimate Mini Chargers have been tested with a fail safe system which consists of three 6 volt sealed lead batteries in series across the 18 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.

The pins on either side of the power lead are presently connected to the to the 18 volt charge bus to facilitate upgrading to a failsafe charger system.

Take the cover off the charger, and orient the charger so that the power lead is towards yourself. The hole on the left of the power lead, nearest the large 40 pin microcontroller IC, is connected to the - or ground side of the charge bus. The next 2 holes hold the power leads which provide the 14 volts AC from the power transformer. The hole on the right, nearest the large 1" diameter filter condenser is connected to the +18 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 leads out of #14 wire and connect them between the - and + terminal 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 + 18 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 charger 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.

or

The Ultimate Mini Charger has 2 additional power diodes on the circuit board. These bring the voltage from the battery pack attached to Channels 1 and 2 over towards the flat IC which is the main voltage regulator for the microcontroller and A/D IC. Just to the right of the voltage regulator, you will see a small straight line labeled jumper. You'll never guess what goes here. ....... You guessed. If you solder a small wire between the 2 pads on either side of the line, a transmitter connected the channels 1 or 2 (or both) will provide backup power for a short time to avoid problems during those annoying power glitches during a storm. The transmitters will only power the charger for an hour or so, but this is far more than usually required. There are problems, though.

The charger has no way of knowing that this happened, and if the transmitters are on Trickle, the charge utilized may not be replaced. Another problem is that a long outage could totally drain your transmitter batteries, not very good on the batteries. So if you do use this very convenient backup system, be sure to unplug and replug your transmitters on channels 1 & 2 to fully recharge if your household clocks are showing a significant power outage occurred. The first system with the separate lead batteries is much preferable, but the price is certainly right on this second system.

Troubleshooting

One channel does not beep though apparently connected. - Airplane (boat) or transmitter on/off switch left on or is broken. Charging connector not seated or reversed. Broken lead. Futaba transmitter with the diode still in the circuit. Reversed polarity.

Beeps missing. - Mostly likely you had a momentary power outage, and you don't have a battery backup to prevent the microcontroller from losing its mind. Simply disconnect all batteries, unplug the Ultimate Mini Charger's wall transformer, and replug the wall transformer. If you get the 5 long beeps, you are back in business and can reconnect all batteries.

Battery voltage off on all channels. - The potentiometer, just to the right of the beeper, sets the A/D converter IC's calibration. Connect a PC so that you can get the voltage for each channel on the display. Put a calibrated voltmeter across the battery pack's outside terminals, or as near as you can get. Very slightly turn the potentiometer. The PC updates its readings only once every several seconds, so you must wait to see results. Counterclockwise increases voltage reading.

Repairs no longer being done.

Dr. Robert Suding SAI

27107 Richmond Hill Rd.

Conifer, Colo. 80433