Roger Lee Posted February 19, 2011 Report Share Posted February 19, 2011 Hi All, One of our electrical engineer members came up with this and if he wants to step forward for the credit he can. Have you a low voltage output around of 13.1V - 13.3V from the Rotax Ducati regulator on a Dynon or analog gauge? Well for starters the Dynon seems to read .3V - .4V low. I tested a couple of Dynon's with a multi-meter at the battery and each Dynon was that much low. The analog gauges seem to read much closer. I need to call Dynon and ask why. (Tomorrow) Our battery never gets to a full charge as it needs 13.9V - 14.2V. When I turn on my landing light my voltage drops to 11.8V on my Dynon at low rpms whether at idle or coming in for landing, plus the light is not near as bright. There is a fix, but you technically need an LOA from FD. Here is a picture below. You use a 1 amp 200V diode which is available at any electronics store if you read 13.1V - 13.2V at the battery while it is running. The number for the diode is 1N4001 thru 1N4007. If you only need a .4V increase then a 1N5817 SCHOTTKY 1 amp 20V (http://www.allelectronics.com/make-a-store/category/205/Diodes/1.html). Do not use any other brand as when I tested the others they were off by . 3V -.4V too high. This 1N5817 seems to be good for most Ducati regulators in a CT. The band on one end will face up. It goes between the Regulator Rectifier "R" slot and the "Charge" slot. There is a small white wire already between these two slots and this is what you are replacing and then that small wire needs to be clipped in half. This will raise your output charging voltage .4 volts with the 1N5817. When I tried this mod it went from 13.5V to 14.0V at the battery while running. When I turn on my running lights and all other electrical (other than the landing light) the voltage drops .1V - .2V. When I turn on the landing light it drops to 13.2V, but at least it doesn't drop to 11.7V any more. We all know our type battery requires 13.9V - 14.2V to charge fully and that's one reason for the right type of charger in the hanger. When you have a battery that only gets charged 60% - 70% (13.2V) things don't work as well. Lately my flaps were running slow and once in a while blinked for a few seconds. Now they are quick and crisp again. My plane starts up much faster and easier with a fully charged battery. You have 2 options for a connection. Solder the diode in place or use something like a Molex connector crimped on each end of the diode (better option). Use a wire tie to secure this diode or jumper wire in place to help protect against any vibration. What is the down side? None that I can find. If it were me I would use the crimp method on the diode and make up another 2.5" plain wire jumper with Molex connector on each end. I would most definitely put some heat shrink over the diode wire so it isn't bare and touch something. If you need to go back to stock all you would have to do is unplug the diode and plug the jumper wire in place. Keep the little jumper in your tool kit. I'll try to take a picture of the jumper wire and post it here this weekend. This is not an approved mod yet so if you do this you would need an FD LOA. Rotax Voltage output increase1.pdf Link to comment Share on other sites More sharing options...
Runtoeat Posted February 19, 2011 Report Share Posted February 19, 2011 Roger, this is a neat way to raise charge voltage to required levels. I'd like to see a before and after picture of the finished setup. Not sure about "clipping" the white wire? Guess I'll take a look at the regulator wiring on my CT to see what is being proposed. No changes will be made unless FD provides the "OK". Link to comment Share on other sites More sharing options...
ozairangel Posted February 19, 2011 Report Share Posted February 19, 2011 Wonderfull info, thankyou. I have been concerned why the Dynon amp charge rate runs continually between plus and minus all the time. from -5 to +3, +4, -2, -4, 5, +4, +5, +5, -3, -2, etc. Always having issues with flat batteries,Especially when undertaking short flights then not flying for a couple of weeks. Any help with further detail on this mod would be appreciated. thanks to all concerned.By the way indicated Dynon voltage in cruise is 13.2 Link to comment Share on other sites More sharing options...
Roger Lee Posted February 19, 2011 Author Report Share Posted February 19, 2011 Hi Oz, Amps will always fluctuate a little, but it should help. Hi Dick, The smaller gauge white wire that goes from that 3rd from the bottom "R" terminal up to the top where it says charge (same place the diode goes) must be clipped or it just shorts the diode and nothing will change. That's why I would use connectors over soldering because you could use a small 2.5" jumper wire with connectors to join it back up. Link to comment Share on other sites More sharing options...
Runtoeat Posted February 20, 2011 Report Share Posted February 20, 2011 Thanks for the note Roger. I'll have to look into a "test" jumper for the diode and see how it works! Link to comment Share on other sites More sharing options...
westcoastoz Posted February 20, 2011 Report Share Posted February 20, 2011 OZ...your observations of the amp charge rate mirrors mine and I have also had some concerns about it. My indicated voltage in cruise is also 13.2V My CT is almost 5 years old but I still have the original battery. I put the longevity down to having always had the battery connected to a float charger when not in use. Not sure if you have AC power available to your hangar, but it might be worth considering a 'float charger' to avoid problems. Regards, Dave Link to comment Share on other sites More sharing options...
chanik Posted February 21, 2011 Report Share Posted February 21, 2011 Properly charged, these AGM batteries should last 10+ years so you can indeed credit the longevity to your charger. 13.2V is way too low and will result in their premature demise. It is a shame the regulator does such a poor job, but I think the snag will be Rotax, not FD. FD just goes along with whatever Rotax says. Really it would have to be Rotax approving the mod to their charging setup in order to get the right voltage out and I suspect they will be hard to sway. Link to comment Share on other sites More sharing options...
Roger Lee Posted February 21, 2011 Author Report Share Posted February 21, 2011 Rotax approval is not quite true. Rotax sends their engines out without wiring. It is up to the other Mfg or individual to wire it. These batteries more than others need to be at full charge. My electrical system is happier all the way around and the flaps seem to work better at 14.1V. Link to comment Share on other sites More sharing options...
chanik Posted February 21, 2011 Report Share Posted February 21, 2011 Well, I would love it if FD would approve it. It also means no low voltage alarms with landing light and the battery would have hours of reserve if the generator went out, instead of less than 1/2hr. Link to comment Share on other sites More sharing options...
Roger Lee Posted February 22, 2011 Author Report Share Posted February 22, 2011 Hi All, After some research I have changed a few things in the original post. Please read that again. There have been some changes. Link to comment Share on other sites More sharing options...
westcoastoz Posted February 22, 2011 Report Share Posted February 22, 2011 Roger...for some reason, parts of the text in your original post has been corrupted. Is anybody else seeing this or is it my computer? Dave Link to comment Share on other sites More sharing options...
Jacques Posted February 22, 2011 Report Share Posted February 22, 2011 Roger...for some reason, parts of the text in your original post has been corrupted. Is anybody else seeing this or is it my computer? Dave same for me here....very hard to r`<e ? a =d Link to comment Share on other sites More sharing options...
westcoastoz Posted February 22, 2011 Report Share Posted February 22, 2011 Thanks Roger....all good now. Link to comment Share on other sites More sharing options...
Runtoeat Posted February 27, 2011 Report Share Posted February 27, 2011 Some questions regarding the regulator and diode. My local electronic supply store sold me a NTE585 Schottky Barrier Diode which cross references to the 1N5817 Schottky recommended here in the Forum. I'm wondering if the NTE585 will work same as the 1N5817 that was recommended? I am note sure what specs are important to achieve the desired small voltage increase? The NTE585 literature indicates "reverse" voltage of .6 volt @ 1 amp and .9 volt at 3 amps. Are we looking for .4 volt? Second question: While looking at the regulator and the wiring, the white wire that we're discussing virtually fell out of he hardshell connector when I moved this. The blade connectors at both ends of this wire (at the "R" and the "Charge" terminals) were pulled away and just barely touching the regulator blade terminals. I had noticed this same concern while working on my friend's CTLS a while ago. The blade connectors will loose their mechanical "stop" and are no longer securely held in the hardshell after a few disconnects and re-connects of the hardshell from the regulator. I'm considering some way to "lock" the individual connectors in the hardshell so they remain connected to the regulator. Is there any suggestions from one of the forum members? Without a positive lock into the hardshell, these tend to eventually pull away as my charge wire did. Link to comment Share on other sites More sharing options...
jaak Posted February 27, 2011 Report Share Posted February 27, 2011 Some questions regarding the regulator and diode. My local electronic supply store sold me a NTE585 Schottky Barrier Diode which cross references to the 1N5817 Schottky recommended here in the Forum. I'm wondering if the NTE585 will work same as the 1N5817 that was recommended? I am note sure what specs are important to achieve the desired small voltage increase? The NTE585 literature indicates "reverse" voltage of .6 volt @ 1 amp and .9 volt at 3 amps. Are we looking for .4 volt? I looked on the NTE cross reference and NTE585 is listed as a replacement for 1N5817. The spec you are looking for is forward voltage (also called forward voltage drop, the symbol is VF). Actual forward voltage will depend on current and temperature (the datasheets usually have a graph). The NTE585 datasheet I found only lists the maximum forward voltage, not the typical forward voltage. For a 1N5817 it is typically just over 0.4 volts. So with an NTE585 it will be a maximum of 0.6 volts (at 1 amp). Link to comment Share on other sites More sharing options...
Roger Lee Posted February 27, 2011 Author Report Share Posted February 27, 2011 Hi guys, We tried a replacement for the 11N5817 Schottky and the voltage output was too high. If you do use a replacement then you must run your plane and check the voltage at the battery to double check it. As I understand it with my limited electronics knowledge some diodes are a little different make up from another. JAAK is right though that you are looking for the forward output voltage. I tested our replacement diodes with a meter and it did measure too much forward voltage out. The Schottky diode will hold it to .4V output. You can order the 1N5817 Schottky diode from Allied Electronics (link in post above) for about .30 cents each. Link to comment Share on other sites More sharing options...
chanik Posted February 27, 2011 Report Share Posted February 27, 2011 The 585 is fine as it is really a 1N5817. NTE just remarks it; they don't make parts. At the 10mA it needs for control, the Vf will be ~0.4V http://www.allelectronics.com/make-a-store/item/1N5817/SCHOTTKY-RECTIFIER-1A-20-VOLT//1.html It's also here, pretty affordably. While you're at it, you can get some fresh crimps: http://www.allelectronics.com/make-a-store/category/196/Crimp-Terminals/1.html Link to comment Share on other sites More sharing options...
Roger Lee Posted February 27, 2011 Author Report Share Posted February 27, 2011 Hi Kurt, I ordered my diodes from Allied including a lot of Molex connectors and pins. After our chat and my experience with the generic brand diode I figured I better stay with Schottky. Link to comment Share on other sites More sharing options...
chanik Posted February 27, 2011 Report Share Posted February 27, 2011 It's better, but NTE is what radioshack would have. The Allelectronics stuff is name brand. What is the part number or size for the molex spade connectors? Link to comment Share on other sites More sharing options...
Runtoeat Posted February 27, 2011 Report Share Posted February 27, 2011 Kurt, thanks for the good info. I was going to order from the link you supplied but figured I'd try my local electronic shop first. They usually stock name brand, hard to find parts that one cannot get at Radio Shack. I'm surprised that I got the NTE diode from them but you indicated it's OK so I'll try it. Not sure what charge I'm getting during engine running. I've looked at the voltage meter too many times to count but can't recall if it reads "low or mid 13's" for voltage? I'm so used to automotive related things that I think I've been seeing "low 13's" for voltage and thinking "good to go". If low 13's, might need to get the 1N4001 to achieve proper charge voltage. Link to comment Share on other sites More sharing options...
chanik Posted February 27, 2011 Report Share Posted February 27, 2011 The other thing Roger pointed out with his plane and I noticed myself is that the Dynon seems to read low about 0.4V compared to a good DMM on the battery terminals. That's bad firmware on their part. My plane reads 12.9V on the EFIS which means 13.3V on the battery which is still too low. Roger said some planes he's looked at seem to run 13.5 really. My guess is that the Ducati is only accurate to +-0.2V so some people would need just the Schottkey and others would want the PIN diode, 1N4001. You should figure out the offset with the engine off and a multimeter and then fly the plane, noting the charging voltage. Then aim for 13.9 to 14.2 for your target voltage Link to comment Share on other sites More sharing options...
Runtoeat Posted February 28, 2011 Report Share Posted February 28, 2011 Kurt, interesting about Dynon reading low. Can the Dynon display "settings" be reconfigured to show correct voltage as indicated by a DMM on the battery? I have steam gages. Good idea to determine offset first with DMM on the battery. I'm just going to try to get voltage in the "hi" 13's, due to your comment about the +/- .2 volt variance, and call it a day. My battery never seems low, even after long X country trips. Really don't have a high current draw during flight so this is probably why no worries with present charge rate? I note that my CTek 3300 charger momentarily goes "yellow" then immediately goes "green" indicating no charge required when attached after each flight, no matter the length of time in the air. Seem to always have strong and fast cranking when starting the engine, even in the coldest weather. Link to comment Share on other sites More sharing options...
Roger Lee Posted February 28, 2011 Author Report Share Posted February 28, 2011 Hi Dick, The Dynon can not be reconfigured for voltage. The best places to test your output voltage is at the shunt and the battery. These will give you a good idea if the voltage you are reading is accurate. Link to comment Share on other sites More sharing options...
ozairangel Posted February 28, 2011 Report Share Posted February 28, 2011 Roger, And other helpfull electrical people, QUESTION...I have only been able to get hold of a Schottky retifier No n5819, which is 1A 40V instead of the 1n5817 which is 1A 20V. Is this going to do the same job? Have been told that the amperage rating refers to the maximum current capacity, but unsure if this will affect the job in hand. Rgds David Link to comment Share on other sites More sharing options...
ozairangel Posted February 28, 2011 Report Share Posted February 28, 2011 Amazing the things you find out!. Today I am informed that Schottky is not a brand but the name of the guy who first invented this type of diode Link to comment Share on other sites More sharing options...
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