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Battery Care & Coddling
Our Thanks to a Contributing club member, Dean Child

Battery Care & Coddling:

I figure most folks, like me, have several different types of batteries they use. For me, when I’m at the field I don’t think about it much, but either the day before going flying or when I get home from the field I always have to try to remember what I did the last time with respect to my on-board NiCd or NiMH receiver batteries or my removable NiMH and LiPo batteries. The chart below, though concise, is by no means “the bible”, or otherwise… it’s just what I do and is basically a compilation of various sources of information. I printed the chart (below) and have it sitting next to my charger for quick reference.

BATTERY CARE & CODDLING:

Discharge: NiCd: >0.90 V/cell
NiMh: >0.90 V/cell
LiPo: >2.8 V/cell

Charge: NiCd: 0.5 - 1.0C @ <131 oF
NiMh: 0.5 - 1.0C @ <131 oF
LiPo: 0.5 - 1.0C @ <115 oF <4.20 V/cell

Charge Threshold: NiCd: 0.5 - 1.0C @ <131 oF 10 - 15 mV/cell
NiMh: 0.5 - 1.0C @ <131 oF 5 mV/cell
LiPo: 0.5 - 1.0C @ <115 oF <4.20 V/cell

Storage: NiCd: Fully DISCHARGE at low rate (e.g., 0.1C) to 0.90 V/cell, store at 40 - 80 oF
NiMH: Charge FULLY, then discharge to 50% capacity, store at 40 - 80 oF
LiPo: Charge FULLY, then discharge to 50% capacity, store at 40 - 80 oF

If the above chart is confusing, consider this:

NiCd Batteries: Don’t discharge them below 0.90 volts per cell and when you charge them, charge them at a rate less than 1C, with a cut-off threshold of 10 – 15 millivolts per cell, and for best longevity don’t let them get hotter than about 130oF (140oF MAX.) when charging. When you store them, and to minimize “memory” effect, discharge them at a very slow rate (overnight, if possible) to no less than 0.90 volts per cell. Store them in an airtight container, if possible, in the refrigerator. Do not freeze. Note: All of my NiCd’s are permanently installed in planes, so they get stored at whatever Mother Nature throws at them.

NiMH: Don’t discharge them below 0.90 volts per cell. When you charge them, charge them at a rate less than 1C, with a cut-off threshold of 5 millivolts per cell, and for best longevity don’t let them get hotter than about 130oF (140oF MAX.) when charging. When you store them, charge completely and then discharge to about 50% of amperage capacity. Store them in an airtight container, if possible, in the refrigerator. Do not freeze and re-check every 4 - 6 months.

LiPo: Don’t discharge them below 2.80 volts per cell. When you charge them, charge them at a rate less than 1C, and for best longevity don’t let them get hotter than about 115oF when charging. When you store them, charge completely to no greater than 4.2 volts per cell and then discharge to about 50% of amperage capacity. Store them in an airtight container, if possible, in the refrigerator. Do not freeze and re-check every 4 - 6 months.

All: I always try to let my batteries warm up to room temperature before charging and, with NiCd only, I try to “cycle” them a couple of times the day before use. I don’t cycle my NiMH’s or my LiPo’s, but I’m also not trying to get every last bit of performance out of them… I just want them to last along time since they cost so much. For LiPo’s “balancing” is key, though. Larry Porter gave me the idea of balancing my LiPo’s basically any time I touch them. If your LiPo’s don’t have the balancing connector, then don’t worry about it… just consider purchasing the type that can be balanced on the next go-around. I balance them prior to charging, during charging, after charging, prior to use, and after use (when I remember). The point? Balance, balance, balance!!! This process effectively equilibrates the individual cells in the pack and helps them not only perform better, but last longer as well.

All of the above is for when I’m not flying. When at the field I charge at rates dependent upon my needs, but I try not to exceed the 1C mark and I like 0.5C when time permits.

Good Flying,

Dean Child

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