The Murphy Builders Site

Does anyone have any experience with earthX batteries. They are lithium but their weight to power ratio is crazy.
I was looking at the 35C http://earthxmotorsports.com/product-ca ... -aircraft/

Interested in opinions.

No experience. However, if you look at the specs provided, they are pretty thin on information. There is no indication of the internal resistance of the battery (hence what fault current it will produce and what you might have to interrupt), how it is protected from the same problems that Boeing encountered and so on (do they really know something Boeing doesn't?). I have had a look at the only lithium battery eligible for installation in certified aircraft and would not install it in my aircraft - period. Essentially the same deficiencies. How they got it certified is totally a mystery.

So far, all I have seen in the way of this type of battery for aircraft is marketing. Read the reviews by Bob Nuckolls in either Kitplanes or SportAviation earlier this year. These will come eventually, but they aren't here yet, so unless you are an electrical engineer and able to put the risks in context with adequate protection provisions, this should not fly. The benefits over Odyssey weight wise are pretty small for a rebel so lacking reliability data, safety information, protection information, long service history, and low cost, it seems like it might not be a winner unless you really want to experiment.

There are excellent threads on Lithium Ion Phosphate batteries in Vans Air Force Forum. Quite a few are using them, especially the Earth-X. It's difficult to compare apples to apples since they are a different animal than the Odyssey. There are many different types of Lithium batteries out there, the Lithium Ion Phosphate battery is substantially different than the battery Boeing used in the Dreamliner, or what Elon Musk uses in the Tesla, or what you find in your laptop etc. Search VAF and plan on spending a day or two reading.
Best,
Jerry Folkerts

The earth x batts are lithium iron, not ion. Don't know what the diff is...maybe just an R. My neighbor just bought one for his maule. It is seriously lighter than my odyessy 680. like, I wouldn't not mind if he dropped it on my foot lighter. Cw

Quite timely... here's a Mandatory Service Bulletin that just came out from Rotax tonight.

I found out the hard way what that third wire on the cordless drill battery chargers are for, when mine died and I just slapped a 18V x 500ma power supply to my battery pack. Forgot about it in the shop and when I came out the next morning it had got so hot and boiling that it jumped off the table (thank God steel !) and onto the floor. The expelled gas still filled the shop and was unbearable.

..... Rotax MSB

Lithium batteries are fundamentally different than lead-acid batteries. If overheated or overcharged, Li-Ion cells are prone to accelerated cell degradation and can catch fire or even explode. The lithium cells inside the battery need electronics to monitor and balance the voltage & charge level of the individual cells.

Some older types of lithium batteries require an external balancing charger, which you have to plug in periodically to “top off” and balance the cells. These kinds of batteries are NOT approved.

The more modern lithium batteries have a built-inmicroprocessor Battery Management System (BMS) that continuously monitors the charge level of each cell and balances the charge when needed, protecting the cells from overcharge or over-discharge. Some can also provide short circuit protection, and excessive cranking protection.

Typically, the individual cells in a battery have somewhat different capacities and may be at different levels of state of charge (SOC). Without balancing, the cell of smallest capacity is a "weak point", it can be easily overcharged or over-discharged while cells with higher capacity undergo only partial cycle. For the higher capacity cells to undergo full charge/discharge cycle of the largest amplitude, balancer should “protect” the weaker cells; so that in a balanced battery, the cell with the largest capacity can be filled without overcharging any other (i. e. weaker, smaller) cell, and it can be emptied without over-discharging any other cell. Battery balancing is done by transferring energy from or to individual cells, until the SOC of the cell with the lowest capacity is equal to the battery's SOC.

A full battery management system (BMS) might include active balancing as well as temperature monitoring, charging, and other features to maximize the life of the battery pack.

Bottom line: if you use a lithium battery in your aircraft, make sure it includes a built-in Battery Management System. (For a technical deep dive into BMS principles, refer to this article at Electropaedia )

Just got back into town and catching up on emails
Looks like a guy might want to wait a while until there is a little more history in airplanes.

The Van's forum is the perfect example of everyone having a different point of view.

Thanks for the responses.