Advanced Batteries for Electric Bikes and Scooters
By Ed Benjamin
Most of the light electric vehicle product currently on the market uses lead acid batteries. And most consumers express dissatisfaction with the batteries.
Not enough range, too much weight, too few cycles and too long recharge times is the normal complaints.
Of course, consumers also ask for low prices.
This writer has observed that when consumers shop for light electric vehicles they often focus on price; good bikes and scooters represent a substantial cost. This focus, and early feedback to the retailer and eventually to the manufacturer causes product developments focus on low price.
However, when consumers use the product, especially when it is used every day, their focus changes to battery recharge time and cycles they get from the battery. The comments on weight of the vehicle and the actual range from each charge also increase.
This leads to the thought that the market is going to move toward light electric vehicles with more advanced batteries.
In today's market, the realistic options are Ni-Cad, NiMH, and Li-Ion. Of these, NiMH offers the best balance of performance, weight and cost.
NiMH is coming down in price. The high margin business that NiMH makers have enjoyed supplying the cell phone and laptop business is going away; these products are now using Lithium Ion batteries. This forces NiMH makers to seek larger battery sizes, and to sell their product for a lower price.
Additionally, Chinese NiMH makers are pushing the price down. And the Japanese, rather than let the business go away, are stepping up to the challenge and competing. Good news for the light electric vehicle customer.
A lead acid cell will last, in general terms, 200-300 cycles. (One charge / discharge is one cycle.) If incorrectly charged, or poor quality, or stored incorrectly, the cycle life may be much shorter.
NiMH will last 500 -- 1000 cycles. And they have a longer shelf life. They can be damaged by poor storage conditions, and incorrect charging can damage them.
Since NiMH stores more energy per Kg., it is possible to either build a lighter vehicle with the same range, or a vehicle of the same weight with a longer range.
Charging and storage are separate issues; too complex to tackle in this article.
This author's prediction is that almost every viable electric vehicle will be offered with a NiMH battery, or with a NiMH option within two years.
Good news for NiMH makers.
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