- Joined
- Oct 31, 1996
- Posts
- 1,790
- Type aircraft owned
- Carbon Cub FX-3
- Base airport
- KFCI
- Ratings
- COMM, IFR, MEL, SEL
I'm calling this Project Cactus. Ever feel like you have that professor in college that there is no way you're ever going to graduate? Well, I missed graduation and now I'm in summer session, well, hoping to graduate in the fall now. So here goes version 3 of my thesis, my backup ignition upgrade. Version 1 is the default install with the PowerSonic 1221S which I don't trust. Version 2 is this thread of my attempt of using an EarthX ETX-104. And now version 3 is submitted for hopefully my final thesis.
There were two issues with version 2 that are of high concern, one of which was not often discussed but I was aware of it. The first problem is not being able to control the charge current and exceeding the circuit as designed. I've blown my 10A fuse on two occasions now, the risk is there. The second problem is that a LiFePO4 battery is not supposed to be charged below 32F or "lithium plating" can form which damages the battery. EarthX has workarounds they promote as obviously this situation does not help their business model. I have an ETX-900 for my starter battery, it is now wrapped in a heating pad and I have a cockpit heater should I need it. Having your starter battery and the ignition backup battery of the same chemistry with the same vulnerability is added risk. This includes non heated TCW IBBS batteries which are LiFePO4.
So this leaves us with AGM and I've heard enough times of PowerSonic degradation or failures, however, how I'm handling this v3 install would solve the PowerSonic problem I have which is charging it with a charger when not in flight. My aircraft has the USB port and 12V "cigarette" receptacle under the panel, right side. I have an additional 12V receptacle at the seat base aft side for the passenger to use, who will never use it, and my passenger sheds. Additionally, I charge my ETX-900 through a pigtail and not these 12V receptacles which have a 5A current limit on them via the 5A blade fuse under the seat. Some may not even realize that circuit is blown, so pay attention to whether your USB ports work or not as that is your indication. With that said, my plan is to run power from the ignition backup battery to the 12V receptacle under the panel which now gives me a path to charge the ignition backup battery. This solves my concerns of this battery never reaching 100%, float charge, etc. and keeping it healthy and maintained like most do with their starter batteries keeping it on a charger when not in flight.
I researched small batteries and found the Duracell 5.1 AH AGM which I posted in the other thread, here is a link to it if needed. It fits in the space we have just fine, I designed a mount for it modifying my design for the ETX-104 mount, it was a 20 hour print and I sturdied it up, printed it solid (100% infill) and it works great. I picked up the battery at my local Batteries Plus store and it was interesting seeing the batteries available on the shelf. The 3AH version was tempting but why not just go for the 5 AH and give myself ample time if needed. It's approximately 2 lbs heavier than the PowerSonic so that will feel significant. If you're worried about the 2lbs you can find ways of getting that back with the occupant of the front seat. Cut out the Culver's, Ben & Jerry's, etc. and you have 3 more AH's to work with now
Here are a few pictures of the two batteries I compared in the store (3 AH and my 5.1 AH) and you can see I have a Y connection to both pos and neg where I'll run a connection to the 12V receptacle tomorrow. I'll use my NOCO genius to maintain the ignition backup battery while my Optimate will continue to maintain the starter battery. I decided to add a velcro strap around the battery just to help stabilize it, even though it's velcro'd into the mount, I don't want it knocking on the carbon fiber interior panel which is a tight spacing. Back side is a non issue.
I hereby submit my thesis:
There were two issues with version 2 that are of high concern, one of which was not often discussed but I was aware of it. The first problem is not being able to control the charge current and exceeding the circuit as designed. I've blown my 10A fuse on two occasions now, the risk is there. The second problem is that a LiFePO4 battery is not supposed to be charged below 32F or "lithium plating" can form which damages the battery. EarthX has workarounds they promote as obviously this situation does not help their business model. I have an ETX-900 for my starter battery, it is now wrapped in a heating pad and I have a cockpit heater should I need it. Having your starter battery and the ignition backup battery of the same chemistry with the same vulnerability is added risk. This includes non heated TCW IBBS batteries which are LiFePO4.
So this leaves us with AGM and I've heard enough times of PowerSonic degradation or failures, however, how I'm handling this v3 install would solve the PowerSonic problem I have which is charging it with a charger when not in flight. My aircraft has the USB port and 12V "cigarette" receptacle under the panel, right side. I have an additional 12V receptacle at the seat base aft side for the passenger to use, who will never use it, and my passenger sheds. Additionally, I charge my ETX-900 through a pigtail and not these 12V receptacles which have a 5A current limit on them via the 5A blade fuse under the seat. Some may not even realize that circuit is blown, so pay attention to whether your USB ports work or not as that is your indication. With that said, my plan is to run power from the ignition backup battery to the 12V receptacle under the panel which now gives me a path to charge the ignition backup battery. This solves my concerns of this battery never reaching 100%, float charge, etc. and keeping it healthy and maintained like most do with their starter batteries keeping it on a charger when not in flight.
I researched small batteries and found the Duracell 5.1 AH AGM which I posted in the other thread, here is a link to it if needed. It fits in the space we have just fine, I designed a mount for it modifying my design for the ETX-104 mount, it was a 20 hour print and I sturdied it up, printed it solid (100% infill) and it works great. I picked up the battery at my local Batteries Plus store and it was interesting seeing the batteries available on the shelf. The 3AH version was tempting but why not just go for the 5 AH and give myself ample time if needed. It's approximately 2 lbs heavier than the PowerSonic so that will feel significant. If you're worried about the 2lbs you can find ways of getting that back with the occupant of the front seat. Cut out the Culver's, Ben & Jerry's, etc. and you have 3 more AH's to work with now
Here are a few pictures of the two batteries I compared in the store (3 AH and my 5.1 AH) and you can see I have a Y connection to both pos and neg where I'll run a connection to the 12V receptacle tomorrow. I'll use my NOCO genius to maintain the ignition backup battery while my Optimate will continue to maintain the starter battery. I decided to add a velcro strap around the battery just to help stabilize it, even though it's velcro'd into the mount, I don't want it knocking on the carbon fiber interior panel which is a tight spacing. Back side is a non issue.
I hereby submit my thesis:
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