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  Your KMD-150, Skyforce IIIC or Tracker IIIC Internal Memory Battery is Dead



You Need to try to source the battery with the wires at the end.


So, your KMD-150 or Skyforce IIIC or Tracker IIIC internal battery is Tango Uniform and are getting the failed battery message and the unit does not remember where it was when it was last shut down?


Did the avionics shop quote you $250 or more to change it?


Well I hate to break this to you but that battery is under $10! These units are circa 1999/2000 and my battery lasted 9 years. Many of these units still in use will be requiring this memory battery replacement right about now.


Here's the info on how to find a source for the battery and change it out.


Order your Battery HERE for the CSOB price of $1.95 or try The Battery Store P/N LS14500C AX or try BatterySpace and you'll have to solder wires on the ends. is another potential source @ $4.75 HERE


You will want the battery with the "Axial" connections, these are the wires pre-soldered onto the ends of the battery (see battery pic above and below). This is usually -AX in the part number. You may remove a battery marked 3.7 volts. My experience is that the 3.6 volt battery works just fine.



Skyforce Battery Spec Sheet HERE


Here are the guidelines (posted by Tom B. at Piper Owners Forum) to do micro-surgery on your Skyforce unit to get at the battery. KMD150 is different (see Beech owner pirep below) but not much more complicated:


Disclaimer: this operation is best performed by someone with electronics expertise or at least that is comfortable with electrical disassembly and pencil soldering. The battery is soldered directly to the printed circuit board (PCB) and there are no provisions to isolate / disable the battery while removing the old and soldering the new. If the battery is installed backwards, the leads inadvertently touch an adjacent component, static electricity, etc… your GPS will instantly become nothing more than an expensive desktop paperweight.


Changing the battery itself is not difficult, you just have to be aware, be comfortable using a pencil-type soldering iron and make sure you do it right. If you are the least bit squeamish, don’t chance damaging a great GPS. Buy the battery and take everything to the local electronics shop or return it to the factory.

1. Place the GPS face-down on a thick piece of foam (to prevent damaging the front panel toggle switch).

2. Remove the hex-head screws retaining the rear panel assembly.

3. Slowly separate the rear panel from the main chassis. This is a little difficult because the interconnections (stake-pin connectors) between the PCBs have a lot of retention force. Move one corner, then the other, etc and the connectors will separate without bending the leads on the gold stake-pin connectors.

4. After separating the rear panel assembly from the main chassis assembly, disconnect the coax connection between the GPS receiver PCB (mounted on the main chassis) and the rear panel assembly. Set the main chassis assembly aside.

5. Carefully remove the PCB from the rear panel assembly. The battery is located on the opposite side of this PCB.

6. Using an indelible pen, mark the + / - battery orientation on the PCB. This is to aid you to install the new battery with the correct polarity. The battery terminals are clearly marked with a + and – on the GPS.

7. Now it’s time to remove the old battery. If you sourced a new battery WITHOUT the axial wires cut the old battery leads as close to the body of the battery as possible, leaving the battery leads attached to the PCB. You will use these leads to reattach the new battery later on unless you got the battery with the wires already soldered. If you got the battery WITH the axial wires on the end, simply unsolder the old battery wires from the PCB and pull up (using needle nose or some other such tool) on the wire when the solder becomes liquid. Carefully clip the excess wire below the PCB after you have them soldered.

8. Now it’s time to install the new battery. Carefully orient the new battery correctly and carefully lay it onto the PCB. Notes: Install the battery backwards and its goodbye GPS. Let the battery leads touch an adjacent component and its goodbye GPS. Get the idea?

9. Solder the – lead first, then the + lead. Don’t loiter, solder the lead and remove the soldering iron. Too much heat will damage the battery, unsolder the lead to the PCB and subject the circuitry to unnecessary static discharges.

10. Repeat steps 5 – 1 in reverse order, being careful to fully seat the GPS antenna connection and CORRECTLY align the interconnections (stake pin connectors) when mating the rear panel assembly to the chassis assembly.



Here are pics of the KMD-150 that my buddy did surgery on to remove his TU battery. It's not rocket science, just careful disassembly and a steady hand with a soldering pencil.



Here is a narrative contributed by fellow Beech Lister and K35 Bonanza owner for the KMD150 battery replacement:


Well as luck would have it, the system battery on my KMD150 Display died. Each time you would activate the unit there would be a pesky reminder that stored data would be lost. Nothing serious because I've never taken advantage of any type of available storage, if it actually does exist.


A battery change is about $250.00 and King would probably have to send it to England where there is only one fellow working all repairs on the Skyforce and KMD150's. Been there, done that, 7 weeks and $600.00 for I don't know what once. I figured if one monkey can do it, this monkey can do it better and a lot cheaper. Using info obtained from, I decided to go for it. Read and reread the Piper owner's narrative about how he replaced it in his Skyforce and how difficult it was and not for the faint of heart. He stated that he was an engineer so he had the capability to do it. This put me over the edge because for a short while I worked for Conrail and was able to drive a locomotive. Not far, but drive it I did so I figured I could try this. If I screwed it up I could sneak up to Kevin's, pinch his and get a new database card to boot. Life is good being a Democrat (or it will be soon!).


Okay, on to it! I realized that the Skyforce and KMD150 are really and truly two different animals but they were both British and hey, I do work on my Jag so here we go. After sliding the radio out and placing it on the bench I gave it the once over and scanned how I could crack this safe.


Started by removing the top panel. Two stainless Allen head screws around back. Next I popped off the bottom, similar securing devices. Now you can see a few boards, some ribbon cables (which IMHO would be the weak point - remember that Jaguar?) and some plugs. Next comes the screen overlay (4 countersunk Phillips head screws) with the controls which I place in an antistatic bag but do not disconnect the ribbon, so it's still attached. Next, the screen unit which gets the same treatment. The screen is held onto the side chassis with 4 countersunk Phillips head screws and onto a bottom brace with 1 regular Phillips head screw. Side chassis are still attached. Now, since the entire viewing end is swinging in the breeze, I really need to be careful. Somewhere along the way I needed to remove a guide pin, held on by an Allen head screw from inside the box.


Now I can see the battery. Yup, it's the same 3.6 volt Lithium battery that you see on the CSOB site. About $4.00 and $10.00 shipping. At this point I do not know how much juice it's still carrying, so I'm a bit apprehensive about maneuvering about it with metal tools. Lots of mini circuitry that could be damaged without you even knowing it. In order to retrieve the battery, the first overlay board needs to be removed. Easier said than done because there's a 9 pin plug hardwired in and screwed to the board. I elected to only loosen the board up and move it out of the way, which was okay. I removed the Phillips head screws (4) that held the board to the standoffs. Due to the lack of any reasonable amount of room to work, I just clipped the battery wires AT the battery, negative first, then positive and removed the battery. After that I just unsoldered the wires from the board. All the screws were placed into a container as they were removed and of course, the radio was on a rubber mat. Incidentally, the battery measured .99v. Date stamp was 05/99.


At this point it was time to get a battery. This is something that I highly recommend you have before you start the job, I didn't. By using the CSOB guidelines, (this has been corrected to specify AXIAL) I first wound up with the wrong battery configuration. You don't want "tabs" connected, you want it configured as AXIAL, which means there is a solid wire on each end. "Tabs" come through as flat pieces of metal that are solderable. If I didn't remove the wire stubs from the board, I may have been able to solder them to the tabs but that would really be Mickey-Mouse, something you would expect from an overpriced avionics shop. So after two weeks of saying I'll never do this again, I get back to the bench and start the reassembly, shaking my head all the way.


I start by cleaning out the holes in the board using a solder remover. I tested the holes with the wire and had to open one up a bit with a tiny circuit board bit. Next I cut the positive + side wire on the battery to size and tried it. After a bit more trimming, I slid on some wrap and shrunk it down, just like the part that was removed. Soldering was straight forward, I used a battery powered iron that I've had good luck with on boards. Positive first just in case it came into contact with another past of the circuitry, then negative.


Let it cool and gave it the yank test. All was good!


Now to reassemble. Every screw had a white substance on it that I figured was a chemical thread lock. Used a tiny bit of Locktite on all, so I hope my guess was a good one. Back to the advice that you need to have a battery before you start and make this a one sitting job. If you can't, digital pictures and a log are a must to know which comes/goes first, the chicken or the egg. Mine sat for two weeks before I got back to it. In two weeks I can easily forget how high my tab is with Kevin O.,  so I had a bit of a struggle which section to start with. After removing panels a few times to route those lousy ribbons, it was back together and in the aircraft.


Turned it on and viola! it worked. We'll see how it fares as again, I don't trust the ribbons.



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