X-Junk-Score: 0 [] X-Cloudmark-Score: 0 [] X-Cloudmark-Analysis: v=2.3 cv=cpHlbGwi c=1 sm=1 tr=0 a=CjJ+5yp3x2JyNzL18rYx+A==:117 a=x7bEGLp0ZPQA:10 a=A-0mRrAPPO4A:10 a=3JhidrIBZZsA:10 a=pGLkceISAAAA:8 a=Ia-xEzejAAAA:8 a=_6GpL_ENAAAA:8 a=Pudi3VGAX0lG4kbZMHEA:9 a=QEXdDO2ut3YA:10 a=oufKT8-UiSVrhEDsXzgA:9 a=D0rAYnoQkZXe24Ac:21 a=Urk15JJjZg1Xo0ryW_k8:22 From: "Charlie England ceengland7@gmail.com" Received: from mail-pf1-f180.google.com ([209.85.210.180] verified) by logan.com (CommuniGate Pro SMTP 6.2.10) with ESMTPS id 12098327 for flyrotary@lancaironline.net; Sun, 13 Jan 2019 10:24:30 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.210.180; envelope-from=ceengland7@gmail.com Received: by mail-pf1-f180.google.com with SMTP id r136so9174342pfc.6 for ; Sun, 13 Jan 2019 07:24:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=wZ2F01DvlEzl5ujNpB0RaAKkPczr4TDZGZd5FDToZkI=; b=AA0N7+8DUlWmvKyaJ/2xGKZf9d8v9riPye8u3nuevukfYGiEDrUY1rNip4ZUOqxgH/ 2g0JFRiwQJFYPJp8ft/PHcAriPPdnazgO6gCL2UdfUd9I6dDdBnGcpKgrY22C7HFcD4n ZgPbkzPNc9jZMEGQVLPtGSGQ8M74VHmWo04YwRpTU8wiYFn9s2wV5jLeKDM7Aq7QJDvf gG4yW1RkMoMboMc3BNuQFP1UHl7GsGFukkoyIOYt74vaJW/nLlXQgRx/3nOFzUS5PpFR RZ0+HK/zsKwwllYurZQUDXJ6CGKz7uChdP2aNXCTyEnDcoIInc3sPFfCiXgwcM9+azYN kHyw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=wZ2F01DvlEzl5ujNpB0RaAKkPczr4TDZGZd5FDToZkI=; b=DWJedHXCKf5rOXw6MvahVR3nrGvE7avnK4l8dQj2LRVhbdwReSyraaX6sqzl2aSFs5 rddsnLVIWdrdJVIa2ThNPv7UttIIEIKRsBzwuKgtLCl9ph9IuUyRBzckSaz59fYax4NX XrbfKvnCQBeXP0AYViExjRbpIew3AZooOm5mHGIXRB3FQKt/yOyVB9VQrgY/2RpmxxHq bxuPTeXOjM3UP5NH3UKwHBeXJnYwSR+0DocYYDfGdyGN5s6FADsjuWA+0CshBCW4BUxn z32zUH7RlU3JZDitXHX12lpVtoWTresSIjIZjRWL4lvc4/2KR/8q6sd7R3k9gyYUcybh UOOg== X-Gm-Message-State: AJcUukfUgyhs6m0VsCm+4FN6pXzZQ/XrpEDX7dyaSnKABOJCV8fi86tR oytOxkI8nBJ66rgVWD/HK7mvJGAqQlR0JvfbaeYQbw== X-Google-Smtp-Source: ALg8bN5Cu1q5YlJCEDPddS46EaOZ2V36myYfr79ElWlHCzPtsnmd5z2ypthpZ3jhWl8R8qq3kItYRArNFbJbyY6XKh0= X-Received: by 2002:a63:c141:: with SMTP id p1mr19959925pgi.424.1547393051582; Sun, 13 Jan 2019 07:24:11 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: Date: Sun, 13 Jan 2019 09:23:04 -0600 Message-ID: Subject: Re: [FlyRotary] CofA To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary="0000000000002ae440057f58850d" --0000000000002ae440057f58850d Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable 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 circu= it > > I understood that a shorted cell was very low risk in AGM=E2=80=99s if no= t > 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 Virus-free. www.avast.com <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> --0000000000002ae440057f58850d Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


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 G= lasair 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 equivalen= t) 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:
=C2=A0 =C2=A0 =C2=A0 =C2=A0 Open circuit cell - Alternator and second batte= ry do the job (No indication that one battery has failed)
=C2=A0 =C2=A0 =C2=A0 =C2=A0 Short Circuit cell - Battery voltage drops and = overcharges ??
4. Alternator failure modes:
=C2=A0 =C2=A0 =C2=A0 =C2=A0 Open Circuit - Low current and Low voltage alar= m with 30min electrical reserve capacity
=C2=A0 =C2=A0 =C2=A0 =C2=A0 Short Circuit - Charge circuit fuse blows then = same as open circuit

I understood that a shorted cell was very low risk in AGM=E2=80=99s 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 h= omebuilts, especially running automotive style injection. FWIW, 55-60 amp a= lternators are available for very little money (at least here in the USA) a= nd 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 le= ast likely things to have a catastrophic failure. Alternators, not so much,= though modern ones are pretty tough. You left out one failure mode: overvo= ltage due to regulator failure. That is the one that presents the biggest r= isk, because it can take out everything electrical in the a/c. There are si= mple protections for it, which result in the same plan B as your other fail= ure modes: get on the ground within 30 minutes. Some have tested battery li= fe in VFR a/c using Tracy's engine controller & minimal airframe el= ectrical loads, & saw around 35-40 minutes life with a PC-680 size SLA = battery.

More later; time for breakfast.

Charlie

3D"" Virus-free. www.avast.com
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