---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 08/23/12: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:50 AM - Re:Adding an electrical system (Speedy11@aol.com) 2. 08:12 AM - Re: Re:Adding an electrical system (Robert L. Nuckolls, III) 3. 08:56 AM - Re: Low Voltage Disconnect needed (rparigor@suffolk.lib.ny.us) 4. 11:38 PM - OT: analog VOM worth battery cost. (rayj) ________________________________ Message 1 _____________________________________ Time: 07:50:12 AM PST US From: Speedy11@aol.com Subject: AeroElectric-List: Re:Adding an electrical system Bob, Your points are all well taken. But, the customer wants a complete electrical system installed including some type of charging system. I suggested to him that the demand on the battery will be nominal for the short 1 hours flights he plans in the airplane. There will be no long distance flights. I suggested a battery only electrical system and charging the battery between flights. But, he insists on a system with charging capability. So, the only option is to install an external wind generator for recharging. Do I need a voltage regulator for this setup? As mentioned, the airplane will be flown only occasionally and only locally. It will be in a flying museum in Chile. We will install a charging point for the battery so it can be maintained to full charge between flights. I am considering the RG-35 battery only because it was used in a previous 337-approved PT-22 installation so reapproval will be much easier by using the same battery. >From my experience, a single PC-680 battery will just barely turn over my IO-390. I have two in the plane and have to connect both to get good rotation of the engine. The PT-22 has a radial (not sure yet which one) and I'm not sure that the PC-680 will have enough juice to spin it well. Since we are installing a starter on the engine, we can afford some weight in the aft fuselage (behind seat) for the battery weight. I'm planning to use #2 wire from the battery forward. The power demands from the Becker radio and transponder are minimal. Your numbers are for the VHF radio. Standby" reception mode 70 mA Reception mode 500 mA Transmission mode 2.5 A The transponder requires only Standby - 0.3A Transmit - 1.1A So, the inflight demand on the battery will be zero when the wind generator is producing 5A. I agree that the RG-35AXC is a monster. It is very heavy which translates into extra weight for the stronger battery mount required. What do you think of using an Aerovoltz lithium battery? It has about 550CCA and shelf life is excellent (10% loss over one year). Otherwise, I will lean toward the PC-680 - or maybe a pair of them. The main concern overall for this installation is that the cranking power must be sufficient to start the engine. All other demands on the system are achievable. More thoughts? Stan Sutterfield In a message dated 8/23/2012 3:01:37 A.M. Eastern Daylight Time, aeroelectric-list@matronics.com writes: I am adding an electrical system to a PT-22 per a customer's request. It will consist of an overhauled Eclipse Y-150 starter, a RG battery, starter switch and contactor, a switched bus to power a Becker radio and transponder, a wind driven generator, and associated wiring. Does anyone have experience with adding electrical to a PT-22? Any gotchas? I can't find any generator or alternator that is approved for the PT engine, that's the reason for the wind generator. It will only produce about 5 amps, so it will barely power the transponder and slowly recharge the battery and allow occasional radio transmission. Since I'm doing a form 337 for the change, I should be able to use any battery. So, we're considering a PC-680 or a lithium ion battery such as the Aerovoltz. Otherwise, we'll us a RG-35AXC. What are your design goals for the installation and how do you envision it will be used operationally? Will this airplane be used for cross-country flight? Is it parked in a location serviced by AC mains power? Keep in mind that cranking an engine from the typical battery takes only 5% or so of that battery's capacity. Transponders take typically 2 amps to operate when generating lots of replies. If I recall correctly, the Becker was designed for battery only ops in gliders. It's power demans are: Standby" reception mode =A3 70 mA Reception mode =A3 500 mA Transmission mode =A3 2.5 A Energy demands for this instance are trivial. Further, it has a low voltage warning built in set to trigger at 10.5 volts. http://tinyurl.com/9upvqxg An RG-35 is a beast of a battery . . . 30+ pounds as I recall. B&C did some cranking tests on the SMALLER cousin to the PC-680 and found that it would do a 10-blade crank of a high compression engine (aerobatic aircraft), 5 times in a row (with about a minute cool down between events). The PC-680 should do better yet. How about NO generator, a PC-680 as the only battery and a Battery Minder plugged in while the airplane is parked? Li-FePOH batteries are low risk because you're not going to charge it at a high rate while airborne . . . and it can be recharged at a benign rate while hangared. But take care also that you do not heavily discharge it between flights as they're more sensitive to deep cycle damage than their SVLA cousins. Bob . . . ________________________________ Message 2 _____________________________________ Time: 08:12:08 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re:Adding an electrical system > >More thoughts? Sounds like you have a plan. 5A applied to an RG35 probably doesn't represent much of an OV risk. But it would be easy to add crowbar protection right on the b-lead breaker. Bob . . . ________________________________ Message 3 _____________________________________ Time: 08:56:04 AM PST US Subject: Re: AeroElectric-List: Low Voltage Disconnect needed From: rparigor@suffolk.lib.ny.us Hi Bob Thx. for the info. Ron P. > Here's both all solid state and a relay version > of what I think you asked for. I'd go with the > MosFet version. FETs are quite rugged these days. > > http://tinyurl.com/9lc72qs ________________________________ Message 4 _____________________________________ Time: 11:38:48 PM PST US From: rayj Subject: AeroElectric-List: OT: analog VOM worth battery cost. Greetings, I have a Triplet 630-NA VOM. I'm wondering if it is a good enough quality VOM to justify putting $15 worth of batteries into. Opinions please. do not archive -- Raymond Julian Kettle River, MN. 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