X-Junk-Score: 0 [] X-Cloudmark-Score: 0 [] X-Cloudmark-Analysis: v=2.3 cv=cpHlbGwi c=1 sm=1 tr=0 a=T3HAWIOdjWoca81rNQcl3g==:117 a=pFtCNgx41Vb+AYeSCkeOFA==:17 a=x7bEGLp0ZPQA:10 a=A-0mRrAPPO4A:10 a=3JhidrIBZZsA:10 a=r77TgQKjGQsHNAKrUKIA:9 a=pGLkceISAAAA:8 a=Ia-xEzejAAAA:8 a=DPcQqcAIAAAA:8 a=_6GpL_ENAAAA:8 a=YJzM2N8FqAOnHUQjpG4A:9 a=QEXdDO2ut3YA:10 a=nyTWUAQCpSsA:10 a=7Qvf_UgvWh4A:10 a=4PR2P7QzAAAA:8 a=HGlI-rBn9Sfl24expsAA:9 a=kWACj7Vbxswf3B58:21 a=_W_S_7VecoQA:10 a=Urk15JJjZg1Xo0ryW_k8:22 a=8T8z6dguDQsxr2U_3ga_:22 a=4dqwQCo7Po2mVW515mGf:22 From: "Charlie England ceengland7@gmail.com" Received: from mail-yw1-f46.google.com ([209.85.161.46] verified) by logan.com (CommuniGate Pro SMTP 6.2.10) with ESMTPS id 12098483 for flyrotary@lancaironline.net; Sun, 13 Jan 2019 11:37:16 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.161.46; envelope-from=ceengland7@gmail.com Received: by mail-yw1-f46.google.com with SMTP id t13so7731476ywe.13 for ; Sun, 13 Jan 2019 08:37:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-language; bh=nw6dWdn6rDpyNvROn/ApZXWuPR4SDoW5bNov/jkxJOI=; b=Ekuc1IaXq5dSvVTjF+j4v9+48kEWg/bd5VdafYqL1gZTE4VjH7tIIyKtapAiX7yFtm Le293brT1cTodCuiAU03VOHFQE4Qx8Haqc1tSOX9QTPcykvTnm8KHWm7fqFP7EaxY7+6 S5M+BSsY1+FKZ34TnQD93H44WtTZU/NFmMAQzSFqvMjeoH+WbbTMaYT+0v0pqRnVS0Xj 15I7F7OU+FcWhZT/npwionukN1qyGTgIkujfh7e4b4WjPFkkT1E+SQ8EhCBykckcMpmd i43rLjombVpJtM8WKqZc0fM3SyxVqX8QxQtjWPcx9tTuv09pREGq0z3hK0cY9/9eKUS7 6+8Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language; bh=nw6dWdn6rDpyNvROn/ApZXWuPR4SDoW5bNov/jkxJOI=; b=k3rHpQ/yNyFTbk08jMhwcXq1kQtqbWB723Vk5quDpmEh0/RshanwXH0IPKmUTpkQo6 5TB971Qn2SqDAM+1SgxBu4fwqbysbXBWDbKvrdO/fwcJxDErkZlxJlpbDo3p+jQ+xaIa KtlIqFLDNulpT/e4132WdOsROMynhJfdK8Fin2twkLzucK7LJV6akVxiQa+zhsrc9JFH xxxvP9GkT2cMbPfOXd37AGhHVocXIHBe1y1jpt9fkhnLphxwk4FiATa4XoMqxaLMElBg Kn74rpSs4eiMgDzdPBlG9x96ZfcZOwvHC893hpUB/GO3Cl31Xkhc/jFnxr+mbPvDYake w2jg== X-Gm-Message-State: AJcUukeqcSESlEdveSJfUBeDD1tjKKvjmxehWPgpyb2MbND3zOs1cafB Kl83WwIqJLoWSm+jpgRGCETbBDra X-Google-Smtp-Source: ALg8bN6q+6FEbMCQOVbpDquiNyEtq0iO42W3Qk41jadZXhR+IhrcESuXbMWMXIUWPhj34fdYno9VGg== X-Received: by 2002:a0d:ea81:: with SMTP id t123mr21311170ywe.496.1547397418356; Sun, 13 Jan 2019 08:36:58 -0800 (PST) Return-Path: Received: from [192.168.10.217] (mobile-166-170-58-101.mycingular.net. [166.170.58.101]) by smtp.googlemail.com with ESMTPSA id g138sm29837626ywb.64.2019.01.13.08.36.56 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 13 Jan 2019 08:36:57 -0800 (PST) Subject: Re: [FlyRotary] Re: CofA To: Rotary motors in aircraft References: Message-ID: <50a68e1c-7915-84e9-ab83-a92ba2833b0a@gmail.com> Date: Sun, 13 Jan 2019 10:39:53 -0600 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/alternative; boundary="------------6AA80E361079AE0F5B9B4347" Content-Language: en-US X-Antivirus: Avast (VPS 190112-6, 01/12/2019), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. --------------6AA80E361079AE0F5B9B4347 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit On 1/13/2019 9:23 AM, Charlie England ceengland7@gmail.com wrote: > > > On Sun, Jan 13, 2019 at 9:00 AM Stephen Izett stephen.izett@gmail.com > > wrote: > > Hi there people > > We are in the process of getting the Certificate of Airworthiness > for our Glasair powered by Renesis 4 port. > > Our AP is questioning the electrical system and wondering if we > should have redundant supplies in case of electrical system failure. > Can any of you make comments on risk or preferred systems. > > Our setup has one automotive 40amp alternator and two HC20 (PC680 > equivalent) paralleled (two batteries are used due to physical > location) and mounted in tail for W&B and to keep cool. > > My planning was: > 1. Keep battery cool > 2. Replace every two years > 3. Battery Failure modes: >         Open circuit cell - Alternator and second battery do the > job (No indication that one battery has failed) >         Short Circuit cell - Battery voltage drops and overcharges ?? > 4. Alternator failure modes: >         Open Circuit - Low current and Low voltage alarm with > 30min electrical reserve capacity >         Short Circuit - Charge circuit fuse blows then same as > open circuit > > I understood that a shorted cell was very low risk in AGM’s if not > overheated. > I thought creating redundancy may introduce other failure modes. > > Appreciate any feedback. > Steve > > Hi Steve, > > Are you signed up for the Matronics Aeroelectric List, and do you have > a copy of the Aeroelectric Connection book? If not, then stop, do not > pass go, and do both. Those issues are pretty well hashed out there. > > Now to specifics. Have you done a load analysis for your plane? If > not, you might be a bit surprised at how much current can get sucked > up by modern homebuilts, especially running automotive style > injection. FWIW, 55-60 amp alternators are available for very little > money (at least here in the USA) and likely will weigh no more than > your 40A model. The higher output models will be running a lot farther > from their max output (think heat). > > Failure modes: I'd agree that properly maintained, the battery is one > of the least likely things to have a catastrophic failure. > Alternators, not so much, though modern ones are pretty tough. You > left out one failure mode: overvoltage due to regulator failure. That > is the one that presents the biggest risk, because it can take out > everything electrical in the a/c. There are simple protections for it, > which result in the same plan B as your other failure modes: get on > the ground within 30 minutes. Some have tested battery life in VFR a/c > using Tracy's engine controller & minimal airframe electrical loads, & > saw around 35-40 minutes life with a PC-680 size SLA battery. > > More later; time for breakfast. > > Charlie > Ok, refueled. The 'simple protections' mentioned earlier are an overvoltage detection module that monitors bus voltage and if it gets too high, has the power to shut down the alternator. B&C Specialty used to sell a little 'crowbar' module that did this job. It's fairly simple to fabricate your own, or you can buy something 'off the shelf' that can work in a similar manner. ex: https://www.tomtop.com/p-e1021.html Here in the USA, inspectors have accepted single alt, single battery, but most don't even question it; it's 'experimental'. But if you accept the premise that odds of multiple failures in a single flight *extremely* unlikely, and battery failures are almost always 'graceful' (meaning gradual and detectable), then the battery becomes the backup for the alternator. It's our job to decide how long we need that backup to last in operation, and to do our due diligence in maintaining the battery in good condition. That does mean doing capacity testing, because battery power and battery capacity are not the same thing. A very unhealthy battery can start an engine, but might have very reduced capacity to keep the electronics alive for the expected time. In my mind,  the biggest risk is the battery's variable capacity as it ages. I chose to add a 2nd identical alternator (~10 lb weight penalty), and my wiring architecture has my engine functions on one bus and the rest of the plane on a separate bus. Either bus can feed the other if there's a power feed issue to a bus (bad switch or contactor), and the engine will continue to run if the master must be turned off ('smoke in the cockpit' scenario). Charlie --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus --------------6AA80E361079AE0F5B9B4347 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 8bit
On 1/13/2019 9:23 AM, Charlie England ceengland7@gmail.com wrote:


On Sun, Jan 13, 2019 at 9:00 AM Stephen Izett stephen.izett@gmail.com <flyrotary@lancaironline.net> wrote:
Hi there people

We are in the process of getting the Certificate of Airworthiness for our Glasair powered by Renesis 4 port.

Our AP is questioning the electrical system and wondering if we should have redundant supplies in case of electrical system failure.
Can any of you make comments on risk or preferred systems.

Our setup has one automotive 40amp alternator and two HC20 (PC680 equivalent) paralleled (two batteries are used due to physical location) and mounted in tail for W&B and to keep cool.

My planning was:
1. Keep battery cool
2. Replace every two years
3. Battery Failure modes:
        Open circuit cell - Alternator and second battery do the job (No indication that one battery has failed)
        Short Circuit cell - Battery voltage drops and overcharges ??
4. Alternator failure modes:
        Open Circuit - Low current and Low voltage alarm with 30min electrical reserve capacity
        Short Circuit - Charge circuit fuse blows then same as open circuit

I understood that a shorted cell was very low risk in AGM’s if not overheated.
I thought creating redundancy may introduce other failure modes.

Appreciate any feedback.
Steve

Hi Steve,

Are you signed up for the Matronics Aeroelectric List, and do you have a copy of the Aeroelectric Connection book? If not, then stop, do not pass go, and do both. Those issues are pretty well hashed out there.

Now to specifics. Have you done a load analysis for your plane? If not, you might be a bit surprised at how much current can get sucked up by modern homebuilts, especially running automotive style injection. FWIW, 55-60 amp alternators are available for very little money (at least here in the USA) and likely will weigh no more than your 40A model. The higher output models will be running a lot farther from their max output (think heat).

Failure modes: I'd agree that properly maintained, the battery is one of the least likely things to have a catastrophic failure. Alternators, not so much, though modern ones are pretty tough. You left out one failure mode: overvoltage due to regulator failure. That is the one that presents the biggest risk, because it can take out everything electrical in the a/c. There are simple protections for it, which result in the same plan B as your other failure modes: get on the ground within 30 minutes. Some have tested battery life in VFR a/c using Tracy's engine controller & minimal airframe electrical loads, & saw around 35-40 minutes life with a PC-680 size SLA battery.

More later; time for breakfast.

Charlie

Ok, refueled.

The 'simple protections' mentioned earlier are an overvoltage detection module that monitors bus voltage and if it gets too high, has the power to shut down the alternator. B&C Specialty used to sell a little 'crowbar' module that did this job. It's fairly simple to fabricate your own, or you can buy something 'off the shelf' that can work in a similar manner. ex:
https://www.tomtop.com/p-e1021.html

Here in the USA, inspectors have accepted single alt, single battery, but most don't even question it; it's 'experimental'. But if you accept the premise that odds of multiple failures in a single flight *extremely* unlikely, and battery failures are almost always 'graceful' (meaning gradual and detectable), then the battery becomes the backup for the alternator. It's our job to decide how long we need that backup to last in operation, and to do our due diligence in maintaining the battery in good condition. That does mean doing capacity testing, because battery power and battery capacity are not the same thing. A very unhealthy battery can start an engine, but might have very reduced capacity to keep the electronics alive for the expected time. In my mind,  the biggest risk is the battery's variable capacity as it ages.

I chose to add a 2nd identical alternator (~10 lb weight penalty), and my wiring architecture has my engine functions on one bus and the rest of the plane on a separate bus. Either bus can feed the other if there's a power feed issue to a bus (bad switch or contactor), and the engine will continue to run if the master must be turned off ('smoke in the cockpit' scenario).

Charlie

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