X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 24 Jun 2013 13:24:53 -0400 Message-ID: X-Original-Return-Path: Received: from mail-bk0-f42.google.com ([209.85.214.42] verified) by logan.com (CommuniGate Pro SMTP 6.0.5) with ESMTPS id 6346615 for lml@lancaironline.net; Mon, 24 Jun 2013 12:41:49 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.214.42; envelope-from=bakercdb@gmail.com Received: by mail-bk0-f42.google.com with SMTP id jk13so4311177bkc.1 for ; Mon, 24 Jun 2013 09:41:12 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.204.229.208 with SMTP id jj16mr3576785bkb.65.1372092071723; Mon, 24 Jun 2013 09:41:11 -0700 (PDT) Received: by 10.205.142.134 with HTTP; Mon, 24 Jun 2013 09:41:11 -0700 (PDT) In-Reply-To: References: X-Original-Date: Mon, 24 Jun 2013 17:41:11 +0100 X-Original-Message-ID: Subject: Re: [LML] Re: Odyssey Batteries From: "bakercdb ." X-Original-To: Lancair Mailing List Content-Type: multipart/alternative; boundary=485b395e7d9189037104dfe9144c --485b395e7d9189037104dfe9144c Content-Type: text/plain; charset=ISO-8859-1 Below from the Archives is what makes sense to me and what I follow. I also do this following test at each annual (although I use 45 minutes min)- >>a word about battery capacity tests. These are required periodically to assure that an aircraft battery is airworthy which, as defined by the FAA, means the battery must last at least 30 minutes in an emergency avionics configuration with the charging system inoperative<< Maybe Brent would be kind enough to comment if his opinion has changed or if he doesn't feel this is applicable to the Odyssey design. (I have Two Odysseys PC625 (12V) in my IO550 Legacy with the ST5 SkyTec starter (the ST3 is too small for a 10/1 12V).) Regards, Clark Baker Legacy 175hrs tt >>>The energy capacity of a battery decays with time and use. If you wait until you notice that your battery performance is marginal it will likely be the time you need it most. It is better to replace on "time" as a maintenance item than on "performance" as a repair item. Depending on service, temperature swings, and flight hours, replacing your battery every two to three years would be a good plan.<<< Mailing List lml@lancaironline.net Archived Message #30181[image: previous message] [image: next message] back to list From:Brent Regan Sender: Subject:Batteries and MaintenanceDate:Mon, 30 May 2005 00:22:04 -0400To: lml@lancaironline.net[image: Message Header] [image: Undecoded Message]Repair ...Fixin' what's broke Maintenance ....Fixin' what aint broke...yet. When you discharge a Lead-Acid battery the lead oxide on the positive plate and the lead on the negative plate combine with the sulfuric acid in the electrolyte to produce lead oxide on both plates, water and free electrons (a lot of them). When a battery is fully discharged the positive and negative plates are chemically identical (lead sulfate) and the battery can then, theoretically, be charged in with the opposite polarity. Lead, lead sulfate and lead oxide all have different densities so that during the charge and discharge cycles the plates are expanding and contracting slightly. One of the limiting factors in battery life is mechanical fatigue of the plates. Over time they disintegrate and , in wet cells, fall to the bottom and short the cell. Batteries designed for starting engines have a low cell resistance and a high peak current capacity. Batteries designed to provide standby power are optimized for maximum power density and are referred to as "Deep Cycle" type, as they are designed to be discharged until their cell voltage falls to a fraction of the initial voltage. A typical (in this case) battery is composed of cells. Each cell produces a nominal 2.0 volts so several cells are connected in series to produce the needed voltage. Because they are manufactured at the same time, these cells are nearly identical in performance, which is a good thing because if one cell fails the battery fails. A battery only has the capacity of the weakest cell. Because both charging and discharging produce heat and the cells are stacked side by side, the middle cells run a little hotter than the cells on the end and therefore end up having slightly different performance. This difference is small and insignificant MOST of the time. The time it becomes significant is when the battery is completely discharged. During a complete discharge, one cell reaches exhaustion first but it is still part of the circuit so the other cells are still trying to push electrons through it. What happens when you push electrons through a battery rather than it doing the pushing? It charges, but it charges in the reverse polarity (remember the plates of a discharged battery are chemically identical). This "cell reversal" is very damaging because a large portion of the remaining charge in the stronger cells is dumped in to to weakest cell. The mechanical stresses on a "reversed" cell are very high due to the density changes mentioned above. To make matters worse the internal cell resistance increases as the battery discharges so the batteries ability to accept a charge current also decreases. This is why the charging current on a completely dead battery starts out low then climbs rapidly and then falls slowly as the battery charges. Battery life is frequently specified in charge discharge cycles and a cycle is usually specified as a percentage of capacity (e.g. 80%). Using only a portion of the capacity will extend the life and using ALL the capacity will shorten the life. Running the battery all the way out to cell reversal will GREATLY shorten the life. How much is that? I can't say. But it would be a good idea to replace the badly abused battery at the next annual or major service. The energy capacity of a battery decays with time and use. If you wait until you notice that your battery performance is marginal it will likely be the time you need it most. It is better to replace on "time" as a maintenance item than on "performance" as a repair item. Depending on service, temperature swings, and flight hours, replacing your battery every two to three years would be a good plan. Regards Brent Regan --485b395e7d9189037104dfe9144c Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Below from the Archives is what= makes sense to me and what I follow. =A0I also do this following test at e= ach annual (although I use 45 minutes min)-

>>= a word about battery capacity tests. These are required periodically to ass= ure that an aircraft battery is airworthy which, as defined =A0by the FAA, = means the battery must last at least 30 minutes in an emergency avionics co= nfiguration with the charging system inoperative<<=A0=A0=A0

Maybe Brent would be kin= d enough to comment if his opinion has changed or if he doesn't feel th= is is applicable to the Odyssey design.

(I have Two Odyssey= s PC625 (12V) in my IO550 Legacy with the ST5 SkyTec starter (the ST3 is to= o small for a 10/1 12V).)

Regards,
Clark Baker
Legacy 175hrs tt


>>>The en= ergy capacity of a battery decays with time and use. If you wait until you = notice that your battery performance is marginal it will likely be the time= you need it most. It is better to replace on "time" as a mainten= ance item than on "performance" as a repair item. Depending on se= rvice, temperature swings, and flight hours, replacing your battery every t= wo to three years would be a good plan.<<<


Mailing List lml@lancaironline.net= Archived Message #30181 3D"previous=A03D"next=A0back to list

From:Br= ent Regan <brent@regandesigns.= com>
Send= er: <marv@lancaironline.net>
Subj= ect: Batteries an= d Maintenance
Date= : Mon, 30 May = 2005 00:22:04 -0400
To:<= /td> lml@lancaironline.net


= 3D"Undecode=
Repair ...Fixin' what's broke
Maintenance .= ...Fixin' what aint broke...yet.

When you discharge a Lead-Acid = battery the lead oxide on the positive plate and the lead on the negative p= late combine with the sulfuric acid in the electrolyte to produce lead oxid= e on both plates, water and free electrons (a lot of them). When a battery = is fully discharged the positive and negative plates are chemically identic= al (lead sulfate) and the battery can then, theoretically, be charged in wi= th the opposite polarity.=A0=A0

Lead, lead sulfate and lead oxide all have different densities so that = during the charge and discharge cycles the plates are expanding and contrac= ting slightly. One of the limiting factors in battery life is mechanical fa= tigue of the plates. Over time they disintegrate and , in wet cells, fall t= o the bottom and short the cell.

Batteries designed for starting engines have a low cell resistance and = a high peak current capacity. Batteries designed to provide standby power a= re optimized for maximum power density and are referred to as "Deep Cy= cle" type, as they are designed to be discharged until their cell volt= age falls to a fraction of the initial voltage.

A typical (in this case) battery is composed of cells. Each cell produc= es a nominal 2.0 volts so several cells are connected in series to produce = the needed voltage. Because they are manufactured at the same time, these c= ells are nearly identical in performance, which is a good thing because if = one cell fails the battery fails. A battery only has the capacity of the we= akest cell. Because both charging and discharging produce heat and the cell= s are stacked side by side, the middle cells run a little hotter than the c= ells on the end and therefore end up having slightly different performance.= This difference is small and insignificant MOST of the time. The time it b= ecomes significant is when the battery is completely discharged.=A0 During = a complete discharge, one cell reaches exhaustion first but it is still par= t of the circuit so the other cells are still trying to push electrons thro= ugh it. What happens when you push electrons through a battery rather than = it doing the pushing? It charges, but it charges in the reverse polarity (r= emember the plates of a discharged battery are chemically identical). This = "cell reversal" is very damaging because a large portion of the r= emaining charge in the stronger cells is dumped in to to weakest cell. The = mechanical stresses on a "reversed" cell are very high due to the= density changes mentioned above. To make matters worse the internal cell r= esistance increases=A0 as the battery discharges so the batteries ability t= o accept a charge current also decreases. This is why the charging current = on a completely dead battery starts out low=A0 then climbs rapidly and then= falls slowly as the battery charges.=A0

Battery life is frequently specified in charge discharge cycles and a c= ycle is usually specified as a percentage of capacity (e.g. 80%). Using onl= y a portion of the capacity will extend the life and using ALL the capacity= will shorten the life. Running the battery all the way out to cell reversa= l will GREATLY shorten the life. How much is that? I can't say. But it = would be a good idea to replace the badly abused battery at the next annual= or major service.=A0

The energy capacity of a battery decays with time and use. If you wait = until you notice that your battery performance is marginal it will likely b= e the time you need it most. It is better to replace on "time" as= a maintenance item than on "performance" as a repair item. Depen= ding on service, temperature swings, and flight hours, replacing your batte= ry every two to three years would be a good plan.

Regards
Brent Regan

<= /div>
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