AIRNERGY 14.4V 30.5Ah NMC Battery

In gliding avionics applications the current and power are relatively small compared to batteries for e-bikes or handtools. Our goal is to get the highest capacity. A Japanese manufacturer of NMC-cells, SANYO, produces a cell with 12-13Wh per cell. Furthermore the variations between cells are very small. When these cells are combined with a high-quality Battery Management System (BMS), the normal cycle life of 500-800 is raised to over 1500 cycles, which nearly equals the longevity of LFP (2000 cycles).

The result is the 14.4V NMC battery of 30.5Ah in a common size “fat” battery housing. The battery has a minimum guaranteed energy content of 439Wh or 30.5Ah. Compared to LFP the new NMC battery has more than double the energy, and about four times the energy of lead-acid.

Remember when LiFePO4 was the new “wow”? LiNiMnCoO2 is the next “WOW”!

We use Japanese SANYO NCR18650GA cells. It’s not a secret. We’d like to shout it to the world: we use quality cells! No unbranded dodgy cells which only last a few cycles…

We buy them straight from the European distributor, which results in brand-new, fresh batteries which we test and spot-weld ourselves. Another supplier uses LG MJ1 cells, which are a bit older, but pretty good as well. Testing and prototyping showed that our selected SANYO batteries were slightly better, although at a higher cost for us.

We use a high quality custom made BMS rated to 40A, branded with AIRNERGY. We partnered up with a Hong Kong based company to build a BMS system which is just perfect for us; no compromises. This results in a safe and efficient battery with many safety features like a cell-temperature sensor, (conservative) over-discharge protection (11.2V), over-charge protection and internal balancing of the individual cells which results in a long lifespan.

Yes, we spotweld and test our own AIRNERGY batteries since 2014. Back in the day it started off with specialized, custom made high capacity NiMH and LiFePO4 tail-batteries for ASG29’s, Ventus 3’s, etc, and have built hundreds of batteries since… We use 100% nickel strips, and in some places double thickness to bring the resistance and power losses down to a minimum. Our batteries are safely insulated with flame/heat resistant Kapton tapes, and are protected from vibrations where needed.

If not in use for periods longer than 2 months, discharge to 40% / 14.0V and store at a cool temperature.
Charge with a suitable 16.8V Li-Ion charger only. Do not short-circuit, disassemble, puncture or incinerate.
No fuse inside. Warranty void if opened. For warranty and service contact info@MillenAir.eu.

Is 16.8V not too high?

Most modern avionics can handle input voltages well above the battery’s maximum voltage of 16.8V. Special caution must be used with certain older avionics as these sometimes have voltage limits between 15 and 16V. A diode can be installed in the power supply line of the specific device, which would result in a voltage drop of about 0.8V (up to 1.0V under load). This will ensure the input voltage will remain below the manufacturers’ specified limit. It’s not advised to install a diode in the battery’s main supply line, as all instruments would be affected by this, which may not be necessary. The diode’s maximum rated current must be equal or higher than the fuse/circuit breaker. Find suitable, ready to install diodes here: up to 3A, up to 6A.

Alternatively a DC-DC step down converter could be used, but we don’t recommend this as RF interference (noise on the radio) could be experienced.