Lithium batteries

by Dudley Johnston in General Tech Discussion 13 years ago

Does anyone have any info about using lithium batteries in an aircraft? The argument is good about performance, longevity, etc. but what about safety and other concerns?

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Re: Lithium batteries

by Lary Carlston » 13 years ago

Lary Carlston

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I have a Shorai 18ah LiFePo4 (Lithiun, iron, phosphate) - starting a 912s on a Rans S-7 in Minnesota. Installation is two months old and saved over 10 pounds. It stays cool and really spins the engine over. It has not been through winter yet, but I think it is the greatest thing since peanut butter.

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Re: Lithium batteries

by Roger Lee » 13 years ago

Roger Lee

125 5.12k 4.53k

Hi Dudley,

Lithium batteries are used in many things that have to do with aircraft and are just fine for your use in the cockpit. As a 30 yr. firefighter and HazMat Tech too many people are blowing the lithium battery issue out of proportion.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: Lithium batteries

by Ted Norris » 13 years ago

Ted Norris

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I don't know that I would use a lithum battery, they require a special chargeing sequence that a normal chargeing system can't supply, read below and then do what you think is right:

Charging procedure

Stage 1: Apply charging current until the voltage limit per cell is reached.[61]

Stage 2: Apply maximum voltage per cell limit until the current declines below 3% of rated charge current.[61][unreliable source?]

Stage 3: Periodically apply a top-off charge about once per 500 hours.[61][unreliable source?]

The charge time is about three to five hours, depending on the charger used. Generally, cell phone batteries can be charged at 1C and laptop-types at 0.8C, where C is the current that would discharge the battery in one hour. Charging is usually stopped when the current goes below 0.03C but it can be left indefinitely depending on desired charging time. Some fast chargers skip stage 2 and claim the battery is ready at 70% charge.[61][unreliable source?]

Top-off charging is recommended when voltage goes below 4.05 V/cell.[61][unreliable source?]

Typically, lithium-ion cells are charged with 4.2 Â± 0.05 V/cell, except for military long-life cells where 3.92 V is used for extending battery life. Most protection circuits cut off if either 4.3 V or 90 Â°C is reached. If the voltage drops below 2.50 V per cell, the battery protection circuit may also render it unchargeable with regular charging equipment. Most battery protection circuits stop at 2.7â€“3.0 V per cell.[61][unreliable source?]

For safety reasons it is recommended the battery be kept at the manufacturer's stated voltage and current ratings during both charge and discharge cycles.

[edit] Battery charging procedure

The charging procedures for single Li-ion cells, and complete Li-ion batteries, are slightly different.
A single Li-ion cell is charged in 2 stages:[62]
1.CC
2.CV
A Li-ion battery (a set of Li-ion cells in series) is charged in 3 stages:[63][64]
1.CC
2.Balance (not required once a battery is balanced)
3.CV

Stage 1: CC: Apply charging current to the battery, until the voltage limit per cell is reached.

Stage 2: Balance: Reduce the charging current (or cycle the charging on and off to reduce the average current) while the State Of Charge of individual cells is balanced by a balancing circuit, until the battery is balanced.

Stage 3: CV: Apply a voltage equal to the maximum cell voltage times the number of cells in series to the battery, as the current gradually declines asymptotically towards 0, until the current is below a set threshold

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Re: Lithium batteries

by Lary Carlston » 13 years ago

Lary Carlston

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All I know about batteres I learned from the battery rep, so... The Shorai brand battery is Lithiun/Iron/Phosfate, not Lithium Ion like laptop batteries. The biggest practical difference between Li"Iron"and Li"Ion" is LiFePo4 does not get hot and in fact needs to be warmed by some discharge for cold weather use.

Yes, Li"Iron" does require "different" charging proceedures. However, they were designed for motorcycles with the same primative charging system as the Rotax 912. Also they cannot be topped with a charger with a "desulfateing cycle" such as automatic chargers or most trickle chargaes. Shorai does sell a special charger, but a standard Battery Tender brand charger is approved. I use one and it works great.

I still had concerns about heat, so I mounted my battery close to my feet and monitor it in flight. It stays cool as a cucumber. At 2 1/4 pounds it is so light I mounted it with heavy duty ty-raps. There is no liquid inside, so all position mounting is possible. A battery box will follow when I am done with W/B issues on my airplane.

I think $175 is a bargin to dump 10 pounds.

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Re: Lithium batteries

by Ted Norris » 13 years ago

Ted Norris

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Your right Larry, I didn't realize that it was the Shorai battery that was being talked about, my MC friends love um.

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