---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 02/14/15: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:14 AM - Re: LiFePo Battery (user9253) 2. 08:32 AM - Re: Raise internal reg. Alternator voltage (Tim Olson) 3. 10:21 AM - Re: Question about monitoring output in two alternator configura (user9253) 4. 09:02 PM - Re: 12v vs 14v System? (mmayfield) ________________________________ Message 1 _____________________________________ Time: 07:14:45 AM PST US Subject: AeroElectric-List: Re: LiFePo Battery From: "user9253" A RV-6A builder replaced a PC-680 with a 2.7lb Shorai LFX18L1-BS12 LiFePo battery a year ago and yesterday posted that there have been no problems during the past year. Read the thread here: http://www.vansairforce.com/community/showthread.php?t=108103 Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=438347#438347 ________________________________ Message 2 _____________________________________ Time: 08:32:03 AM PST US From: Tim Olson Subject: Re: AeroElectric-List: Raise internal reg. Alternator voltage Hi Rene', That is a good idea, and one I've come across before. I haven't really explored watching the difference between switch on and switch off for a long time, so I'll have to do that on my next flight and see how much change it is. I seem to remember it being .1V or so is all. The switch positions are definitely important. The alternator field is connected to the MAIN bus. But, in normal flight operation, the MAIN bus and E-Bus are directly connected with no diode voltage drops in the path. Now there is a little more complexity in the switching than that, because I do have a schottky diode path to the e-bus (and aux batt) when the switch is on to the e-BUS. So my aux batt will always be charged via schottky. But the actual BUS the avionics are on would only read that lowered voltage when the e-bus switch is turned on. It's harder to follow without a diagram because there is a bit more to the system for brownout prevention and such, but the important part is that in the position the switches are all in for standard ops, the main bus and "critical systems bus" as I call it, are actually at the same voltage potential. I actually feed that bus via 2 diodes from both the MAIN bus and "Avionics" bus, which allows for switching the e-bus feed without losing any power to that bus. So the e-bus switch is always on during engine start but then is turned off for normal operation, which keeps the bus tied directly to the MAIN bus. It is not an exact copy of any z-diagram, but incorporates many features plus some brownout protection. I did think of the idea that Bob provided about putting a 1N540x diode in line with the alternator feed. The worry I had about doing that was that perhaps this extension of the internal circuitry would have some unintended consequence. I couldn't think of any, but just wondered if I may be missing something. It's probably worth a shot some day when it bugs me enough to dig into it. I think before I do that though, I should get a good independent volt meter in the plane during a flight and actually test what that reads for main bus voltage. It could be that the EIS has error, or by testing directly the various BUS voltages I find what the real differences are. For today, I was just putting the question out as a sounding board to see if anyone else ever noticed the same thing and what ideas everyone had. I'm not too worried about actually fixing it, because I don't really consider it "broken". But I am building my 2nd plane which is going to be largely identical to the first, and thought it a good time to start thinking of this topic. I'll probably go schottky diode again on that plane too, just to keep the drop low where there is a drop. Tim On 2/13/2015 1:55 PM, Rene wrote: > > Tim, depending on if you have an e-bus. > > I see the same thing on my GRT EIS. It is on my e-bus. If I look at > the power bus, then it is 14.2. Just recently I added a GRT Sport > (long story) as my backup and it is NOT on my ebus and it showed 14.2 > all the way to Vegas and back this week (first real flight with it). > I never tried to measure my power bus before and my other EFIS is on > the e-bus. I had the same concern as you until this week. > > One way to check, is to turn on your e-bus and see what happens. > When I did, my EIS and EFIS (SPORT) voltage reading was the same. > Only 500 hours...not a 1000 like you....and I finally figured it > out. > > I did not think the diode was supposed to drop the voltage that > much.....but it sure appears to. My normal full power voltage > reading on the EIS is 13.9 or sometimes 14.0. > > Rene' 801-721-6080 > > -----Original Message----- From: > owner-aeroelectric-list-server@matronics.com > [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of > Tim Olson Sent: Friday, February 13, 2015 10:08 AM To: > aeroelectric-list@matronics.com Subject: AeroElectric-List: Raise > internal reg. Alternator voltage > > > I've got an oddball question that I've been pondering for a while. > > I have an older Plane Power 70A internal regulated alternator. The > output voltage is always 13.9V at least as detected by my engine > monitor > > Since it's internally regulated, and has it's own overvoltage module, > and ties to the bus through I think a 5A breaker, I'm not sure what I > would be able to do to raise the output voltage. They told me that > the regulator is fixed and non-adjustable, so on the alternator end > I'm sure there's not much I could do. > > Now I've flown with it for almost 1,100 hours now and it's never been > an issue, but I do use an Odyssey battery as my primary and some AGM > batteries in my aux bus. So I think ideally I'd raise the voltage up > to something just slightly higher if I wanted to optimize my battery > charge state. > > Is there any simple way of tricking the alternator into thinking the > bus voltage is slightly lower than it is so that it raises the output > slightly? I envision some way to drop voltage on the sense line so > that it jacks it up another .5V or so. > > Just wondering what kinds of ideas anyone has, or if maybe anyone > else has done it and knows what would work. > > Tim > > ________________________________ Message 3 _____________________________________ Time: 10:21:00 AM PST US Subject: AeroElectric-List: Re: Question about monitoring output in two alternator configura From: "user9253" I have a great idea (sometimes they turn out to be not so great). :-) If only a single shunt is installed, put it in the standby alternator output circuit where it will be most useful. When the main alternator fails, that is when monitoring the current can help the pilot choose which loads to turn on or off. Of course if the electrical system includes an E-Bus, then the loads that are most important have been predetermined. During normal operations, if it is desired to know what the current is, the main alternator can be shut off and current from the standby alternator can be observed. Doing that could be part of a pre-flight check to be sure that the standby alternator is working. Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=438355#438355 ________________________________ Message 4 _____________________________________ Time: 09:02:35 PM PST US Subject: AeroElectric-List: Re: 12v vs 14v System? From: "mmayfield" It's probably too much to ask for standard terms to be applied to electrical systems after all these decades. [Wink] 12V. 14V. Tom"ay"ta. Tom"ah"ta. The batteries are nominally "12 volt". The charging systems for said battery will operate nominally at "14 volt". As mentioned above, your charging device needs to output a higher voltage to the bus than the battery is putting out, in order to actually charge the battery. Your equipment will take 12-14V no matter which of those figures is on the label. -------- Mike Read this topic online here: http://forums.matronics.com/viewtopic.php?p=438359#438359 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.