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08-19-2019, 03:34 PM
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Join Date: Nov 2015
Location: Osage, IA
Posts: 142
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Electronic Ignition: Two alternators or two batteries
Looking for electrical power and backup for electronic ignition and I am asking for the pros and cons of a two battery system with one alternator or a two alternator system with one battery. Thoughts?
Dave
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08-19-2019, 03:42 PM
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Join Date: Mar 2017
Location: Birmingham, Alabama
Posts: 1,643
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Which electronic ignition?
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RV-14A #140376
N196 (Flying)
2019 Bronze Lindy
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08-19-2019, 04:09 PM
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Join Date: Oct 2007
Location: Sacramento, CA
Posts: 3,351
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Based on my personal choice and safety assurance;
Two alternator, one main alternator that runs/supports the whole ship's power and one that is built-in to the EI and works a self generating EI.
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Mehrdad
N825SM RV7A - IO360M1B - SOLD
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08-19-2019, 04:11 PM
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Join Date: Aug 2010
Location: Brookshire, TX
Posts: 1,036
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I'm planning on an SDS CPI2 ignition. My intent is to have two alternators, as well as the integrated backup battery solution offered with the CPI2. I'm leaning towards the two-alternator system because, to me, it offers fewer concerns in the case of a primary alternator failure. That is, rather than needing to worry about battery capacity, I can effectively fly indefinitely. If I have both alternators fail, then the backup battery will give me enough juice to get on the ground.
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Philip
-8 fuselage in progress (remember when I thought the wing kit had a lot of parts? HAHAHAHAHA)
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08-19-2019, 04:25 PM
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Join Date: Jun 2005
Location: Cedar Park, TX
Posts: 3,156
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I wonder how many of us have actually used that second alternator that we haul around 100% of the time. I have. It allowed us to continue a week long trip without a care in the world until we got home. ONCE. We're all different, and I've gone back and forth, but I think that one use, saving our vacation enjoyment, was worth it to haul around the ballast for the last 12yrs. Hmm, or was it. A personal choice that the math can't always support.
I've also failed both at the same time in a distant foreign country across a big body of water... (which we won't talk about).
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Scott Card
CQ Headset by Card Machine Works
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08-19-2019, 04:33 PM
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Join Date: Jan 2005
Location: SC
Posts: 12,887
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Install two P-mags and you will not have to ask because you won't need either.
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Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
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08-19-2019, 04:49 PM
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Join Date: Sep 2007
Location: BC
Posts: 1,674
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Quote:
Originally Posted by Davea320
Looking for electrical power and backup for electronic ignition and I am asking for the pros and cons of a two battery system with one alternator or a two alternator system with one battery. Thoughts?
Dave
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It’s good to define what each is best suited for. You need at least one of each, but for a third supply of electrons, which form of supply should it be?
A) Batteries are a short term reservoir of electrical power with decreasing capacity over time, capable of high loads for a short period of time, and topped up by the alternator.
B) Alternators are a constant supply of electrical energy good for supplying some/all constant loads and recharging the battery (reservoir).
Choosing one or the other involves considering failure modes of components and of the electrical system in general.
I have 2 Pmags (they self generate electrical power) one lithium battery, one main alternator, one smaller standby alternator. That makes 4 alternators total and one battery, which is easily changed during routine maintenance. To each their own but these are my choices.
Bevan
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O-360-A1F6 (parallel valve) 180HP
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Located in western Canada
Last edited by Bevan : 08-19-2019 at 04:51 PM.
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08-19-2019, 04:55 PM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Do those alternators work well with the battery disconnected?
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Dan Horton
RV-8 SS
Barrett IO-390
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08-19-2019, 05:45 PM
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Join Date: Dec 2012
Location: chattanooga,tn
Posts: 231
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One battery, one alternator, one electronic ignition, and one engine. A man?s man.
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Tracy Willingham
RV-8
Powered Paraglider 
Pitts S2B- sold
Chattanooga, Tn
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08-19-2019, 06:03 PM
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Join Date: Nov 2015
Location: Osage, IA
Posts: 142
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Thanks for all the quick replies. Leaning towards two alternators and one battery.
Dave
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RV7 QB started 1/17
Working on FWF
2020 dues sent
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