Batteries 2/2

About my Battery Choice 

Beforehand: all the information below represents my personal opinion, built after research over the content I consider a good and reliable information source 

So, here I'm going to compare some energy carriers (batteries and Gasoline) in terms of specific energy (watts per mass - or weight if you prefer, in kg) and energy density (watts per volume, e.g. litre). If space and weight are a problem, you want a carrier with high specific energy and energy density.

So, about the alternatives: 

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Gasoline (Petrol)

Total potential (*1)

Specific energy: 12 889 Wh/Kg

Energy density: 9 500 Wh/L

 

*1 = Average engine efficiency: Car engines = only 20% - 35%

Specific energy * 30% efficiency = 3 866 Wh/Kg

Energy Density * 30% efficiency - 2 850 Wh/L

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Lead-acid battery (regular car batteries)

Specific energy: 35-40 Wh/kg

Energy density: 80-90 Wh/L

Life expectancy: < 350 cycles

Pros - High power capability, can discharge a lot of energy in very short bursts

Cons - very heavy (like, really heavy!) and bulky!

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Lithium Iron Phosphate (LiFePO4)

Specific energy: 200Wh/kg

Energy density: 325 Wh/L

Life expectancy: 2 000 to 12 000 cycles (depending on the unit)

Cost: 3 to 24 Wh/U$

Pros: reasonable price for the lifespan of the battery. Many companies can build one for you, matching the space you have available, so, easy to fit in void spaces in your car or truck.

Cons: Bully. Less bulky than lead-acid space, but still very bulky! you will need 8.7 times the space of your gas tank for the same range

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Lithium-ion

Specific energy: 180 (+/- 40) Wh/Kg

Energy density: 500 (+/- 250) Wh/L

Cost:

Life expectancy: 400 to 1000 cycles

Pros: higher energy density and possibly specific energy, depending on the kind of li-ion cell you bought. 

Cons: li-ion has a relatively low lifespan. Tesla is known to, software-wise, avoid full recharge/discharge of their cars to decrease battery degradation and increase lifespan. Also way more complex to set up.

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In a nutshell:

LiFePO4 is the best choice by far if space is not a problem. Why? 1/5 of the weight of the lead-acid batteries and 10 to 40 times the lifespan. Way higher lifespan compared to Li-ion batteries as well. Depending on your setup, you may need to sacrifice some of the cycling capability (e.g. 12 000) for higher performance. Still, there will probably remain a lot of cycles.

However, my choice is:

I do have space constraints. Motorcycles don't have that much space available. So the higher energy density of the Li-ion may be a game-changer for me.