Hi All,
Regarding aircraft batteries, I’ve recently (two years ago) moved to “inexpensive" motorcycle lithium iron - and so far love them. They cost a little more than the lead acid, but I like the trade off. Longevity - I’ve been through five Odyssey PC680’s. I really liked the old Odyssey PC680’s, though with limited flying (100hr/yr) they would be dead in 2 years. With only two years experience, I can’t speak to lithium’s longevity, but all the literature says they last close to 6-10x lead acid. Additionally, lithium batteries self discharge much slower than lead acid - so your airplane will probably still start with lithium after your three week hiatus. Safety - Lithium Iron are safer than the common lithium ion battery. Lithium phosphate cells are incombustible in the event of mishandling during charge or discharge, they are more stable under overcharge or short circuit conditions and they can withstand high temperatures without decomposing. When abuse does occur, the phosphate based cathode material will not burn and is not prone to thermal runaway. Phosphate chemistry also offers a longer cycle life. Weight - They are so light they almost seem fake, but even the smallest ones punch out enough juice to start a lycoming 4 banger engine at least once. They weight factor is what sold me. The Odyssey weighs 15.4 lbs, and the lithium battery I’m using weighs 4 lbs! So while getting a lithium battery isn’t the best place to reduce the weight of your airplane, it is certainly the easiest. Capacity - While the littlest LiFePO4 batteries will probably start your engine, they may not have the capacity run everything for very long if your charge system goes down. Unlike lead/acid, the lithium batteries should judged on amp hour capacity rather than CCA. The $120 Odyssey PC680 has close to a 20 amp/hour capacity, while the $150 lithium battery I use only has only an 8 amp hour capacity. So you get way more amp hours / dollar with lead acid. But, usually, capacity is not the aspect of battery performance you experience/notice. What you notice daily with your battery is how much “juice” you have for cranking the engine (commonly measured as CCA) - and lithium batteries excel here. The Odyssey PC680 is rated at 230 CCA while the 8 amp hour lithium I use is rated at 480 CCA. Even more striking, the other aspect of battery performance we ofter deal with is coming back to the plane after a month only to find a dead battery due to a problem know as battery self discharge. Lithium batteries have a much much lower self discharge rate, and will likely start your engine even after a year. If you’ve read this critically, you’ll realize that the lithium excels were it is not critical - on the ground. However, lithium batteries falls behind where it is critical - in the air. If you lose your alternator, you will likely have far less time before complete electrical failure. Of course having an entire back up battery is still only half the weight of the lead acid. Priorities and compromises - Deciding on which battery is best for you depends on your priorities. Cost, amp hours, weight, CCA, self discharge, and “newfangled” are all issues you should consider. I went with the lithium and have been very happy so far. But I haven’t lost an alternator yet - and I have twice in my flying experience. Owen _______________________________________________ Search the KRnet Archives at https://www.mail-archive.com/krnet@list.krnet.org/. Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options. To UNsubscribe from KRnet, send a message to krnet-le...@list.krnet.org
