Harbor Freight sells a battery tester that draws a HUGE current out of the battery and gives a reading on the result. I can't comment on how accurate it is but it should provide pretty good clues about the health of a battery.
Bob,
He suggests that cranking ability is a poor indication of a battery's capacity. In other words, energy capacity as would be required to drive your critical systems if your alternator failed at night or IMC should not be confused with short term power generation required to crank an engine. You may lose lots of capacity without a noticeable drop in cranking ability.
In his book and online he talks about ways to measure capacity. In simple terms, it boils down to applying a constant known load (like a load bank or just a light bulb) and measuring voltage over time (or simply measuring the time until the voltage has fallen below a preset voltage). See http://www.aeroelectric.com/articles/battest.pdf for more info.
- Kyrilian
Angier wrote:I installed two Odyssey PC545 batteries during the build in May 2008.First flight was back in February and about a month ago I thought I sensed a little less cranking power on startup.On start on the last flight, the prop would not pass through the compression stroke so I waited a bit, hit the starter again and even through there was a bit of hesitation, motor started normally. So my uneducated guess is that these batteries are tired and have lost a lot of there cranking power. They have always been maintained on an Odyssey Battery Minder and with a check on a battery tester, they're still in the green. Anyway, two new PC545 will be installed today.Everybody else having good experience with their Odyssey batteries?Angier,Five years is pretty good service life for batteries, but generally, the Odesseys should do better, especially since you've kept them in good condition/lightly used. I have two independent electrical systems on my IV-P, using two PC 680s each. I replaced the pair of batteries I bought in 2006 last year, and was planning to replace the 2008 batteries at this condition inspection. Both sets still crank the airplane well, but this is one area where I'm "second guessing," so I could use some factual information as well. For example, is there a valid test for power available, etc.One other note. These batteries require a higher charging voltage than "regular" batteries. Be sure your regulator is adjusted to the specs called for in the Odessey literature. Can send same if needed, but also available on-line.Bob--For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html
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