What's special about the EarthX Battery for Aviation (ETX-680C)? I think everyone knows about all the issues with Lithium batteries and fires, which has a lot of people afraid of Lithium batteries, even though everyone is carrying one in their pocket installed in their phones. So what's different about the EarthX Aviation battery? First off, all Lithium batteries provide a very high energy release, so can provide a lot of amperage all at once from a very small, light weight package. However, there are a number of Chemical processes to make a Lithium battery. Lithium-ion Polymer batteries (LiPo) are the ones that are famous for catastrophic failure under either heat or impact with spectacular fires. The EarthX batteries are a Lithium Iron Phosphate (LiFePO4) composition, so are not prone to burning upon break down. So instant and catastrophic fire is not a concern with them. Most of the Lithium batteries being sold for automotive use are Lithium-Iron (LiFePO4) batteries. A 12V Lithium battery only has 4 cells that provide 3.3 volts per cell. That is significantly different from a wet cell battery. It is critically important for the cells in any Lithium battery to both discharge and charge in sync with each other and always stay balanced. It is also critically important that the cells not be allowed to fully discharge or overcharge as that will damage the cells. So the EarthX batteries have a Battery Management System (BMS) built into each battery. The Battery Management System (BMS) ensures that the cells discharge and charge at exactly the same rate and keeps the cells balanced during recharge. The Battery management system will also disconnect the cells from the system if the battery voltage drops below something like 9 volts or over 15.5 volts to protect the cells from excessive discharge or a runaway charge. I've left the master switch on after working on some avionics and discharged mine. The BMS simply disconnects the cells and leaves everything dead. You apply 12V to the battery for 5 seconds, and the BMS will reconnect the cells and it is ready to go again. Additionally, the BMS adds protection to disconnect in the case of a dead short.
But the BMS also adds a failure point to the battery. So, EarthX added a redundant Battery Management System to their Aviation batteries. In addition to the second BMS, they also have installed a LED on the top of the battery and a small wire leading from the battery. The LED will start flashing if there is an issue with either the battery or the primary battery management system, and the secondary battery management system will take over. The wire can be connected to either an LED on your panel, or to an EFIS as an input for notification of a battery management issue (I have done neither). If you ever see a BMS issue such as a primary BMS failure, EarthX will replace the battery. The EarthX Batteries are designed for an 8 year life span. I had not planned to use an EarthX battery in my KR. Since the day it was new I have used a very standard 12V motorcycle battery that was rated at 175 cold cranking amps, mounted in front of the firewall, and have always got a 7 - 8 year life out of these wet cell batteries. The Odyssey battery didn't exist when I was building my KR, and I would have switched to it, except that it was too tall to fit in the battery box I had built for the old wet cell batteries. However, after installing the higher compression pistons in my engine, I kept destroying the clutch in the Niagara starter drive on the old Delco pull starter. At $320 a pop, I decided it was time to upgrade starters. I found a guy that was removing the B&C starter and Plane Power Alternator from a C-85 that was going onto his Cub, so bought the whole charging/starting system. After installing the B&C starter, I rolled the plane out to start and the engine spun over like it was idling. Only problem was that it wouldn't start. It's a long story, but what I found was that the highly efficient B&C starter was so efficient that it was pulling the battery voltage down low enough that the Emags (which require battery voltage for starting) would not fire. My only choice at this point in time was to buy a battery with more cranking amps. I really didn't want to install a larger battery as I didn't have room and really didn't want to add more weight to the plane. That left a Lithium battery as the only viable choice. So, I studied the Lithium batteries and talked to some people that had them. I found the EarthX battery to be the most reasonable choice for my application. (YB-16 motorcycle battery = 175 CCA for starting, Odyssey PC680 = 170 CCA, EarthX ETX680C = 320 CCA) I had to add a bolster under the battery and padding around it to use the same space I had for the old wet cell battery. I also provided a cooling air line to it, although it shouldn't need it. With replacing the alternator and starter, I removed 10# from in front of the firewall. With the installation of the EarthX battery, I removed another 10#, to make for a 20# weight loss for the plane. I am coming up on 4 years into the expected 8 year life of the battery. So far, I have been quite happy with it. However, these batteries are not cheap at $370 per unit. One caveat to using a Lithium type battery. These batteries can deliver a ton of power all at once. But they also want all that power back at once as well. What that means is that your charging system will charge full bore after starting until the battery is back to 100% charge, then will quickly drop back to normal. Typically, my battery is topped off again before I even make it to the end of he runway for run up. But if you have a low battery, it's going to charge full bore for a bit, so you want to make sure all your alternator wiring is up to snuff. There is nothing wrong with using the Odyssey battery. That's what I have in my SuperCub Clone and have been pleased with the performance. However, if I were to switch that plane to duel Emags, I would also need to switch to the lighter, more powerful battery for it as well. -Jeff Scott Arkansas Ozarks > Sent: Monday, January 13, 2020 at 5:47 AM > From: "n357cj via KRnet" <krnet@list.krnet.org> > To: KRnet <krnet@list.krnet.org> > Cc: n357cj <n35...@ptd.net> > Subject: Re: KR> Odyssey PC680 > > > Jeff/All, > I did get a new battery but stayed with the conventional that I had for > now. I did talk to the battery guys and they told me that the company that I > am using as well as some others have the lithium in matching sizes to what > they produce for the conventional batteries. SO to do a bit more homework I > am wondering about Jeff's statement below about configuring to aviation use. > What specifically are the things that need to be in the battery to make it > safe for flight? > I remember a couple or maybe a few years ago someone had posted a pretty > long description of the things that are wrong with the lithium's which just > made it seem like they were not ready for our use yet, but technology has a > way of getting things worked out. If I remember correctly the charging system > was also part of the issues to configure correctly for the lithium's.? > Thanks, > Joe Horton, N357CJ > > ----- Original Message ---- > > Subject: Re: KR> Odyssey PC680 > > Thanks again Jeff, > I am going to look into this battery. > Joe Horton > ----- Original Message ----- > > Cc: "Jeff Scott" <jscott.pla...@gmx.com> > EarthX has done a good job of configuring this battery specifically for > aviation use. > > -Jeff Scott > Arkansas Ozarks > > > _ > > _______________________________________________ > 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 > _______________________________________________ Search the KRnet Archives at https://www.mail-archive.com/krnet@list.krnet.org/. 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