You use them in your flashlights, your remotes, your car or truck needs one too ! And E-bikes would not exist without them.. Just like bicycles, Light or Heavy, Inexpensive or Expensive, batteries come in many different flavors .
Batteries...... The fuel of the Electric world !
Terms, Slang, Lingo ! ( Read this if you are not familiar with things like " Ah " or " wh/km " . or " C-Rate " , i'll keep it simple.. I promise.. and if you have any questions don't be shy E-mail Me ! )
SLA - Sealed Lead Acid
Nicd - Nickel Cadmium
Nimh - Nickel Metal Hydride
Li - Lithium ( Lithium Ion and Lithium Polymer )
SLA - Sealed Lead Acid:
These batteries usually look like this ( picture of sla , vrla , flooded acid ) and are the heaviest of the them all, a good solution for the budget E-biker, are trouble free, tough, and they get the job done. Depending on how you treat them, expect between 200( average ) and 500 ( rare ) recharge cycles before you have to replace them, you MUST.. and i repeat this as it's very important YOU MUST RECHARGE THEM RIGHT AWAY anytime you use them.. never let them sit for hours on end ( or even worse.. days !! ) un-charged.. you must keep them fully charged at all times to expect a lot of life from them otherwise they will die pre-maturely and not get you very far.
Each battery is usually 12v each, are cube shaped, and can be connected together to become 12, 24, 36, 48, 60 or even 72v.
Depending on how far you need to go, you need to have enough capacity to go the distance, expect to have either 7 ah ( ah = Amp/Hour ) for short trips , or 12 ah for longer trips.
Charge time - 2 to 8 hrs depending on charger and how deeply they were discharged.
Do you have a cordless drill ? If you do, chances are it's powered with Nicad batteries. Lighter than SLA and smaller in size, Nicad batteries are the next step up and a very attractive option for many reasons.. They can be left partially charged without any negative impact , unlike SLA. Will go between 500 and 1000 recharge cycles before retirement.
These are usually shaped like your typical D or F sized battery ( AA's in your walkman.. C's in your tickle me Elmo. D's in your Mag-Light flashlight.. for example, and Yes.. F is an actually size !!!) and are connected together to make battery packs of different voltages.. they are 1.2v each. so 30 batteries together make a 36v pack !
You will want at least 8 ah of capacity for good measure, less than this is possible, but tends to be too great a stress for long life ( Look up " C-Rate " in the terms section to find out why )
Charge time - 1 to 3 hrs depending on charger used, and the size of the pack, usually 2 hrs from fully discharged !
Similar to Nicad in many respects, slightly lighter for the same capacity, but smaller in size. Better for the environment, but will not provide as many recharge cycles as Nicad. ( Confused yet ? )
Expect 300 to 600 cycles depending on how you treat them. Can be left partially or fully charged, they do not suffer the " Memory Effect " , and also come in D or F size, and are 1.2v each.
Costs more than Nicad, but is better for the environment, 2/3 the size of Nicad makes it a good candidate when you don't have a lot of room to spare ( 72v ! )
Lithium ! :
The holey grail of E-bikes, expensive.. light weight.. compact. Expensive.
If you want the Ultimate, Lithium is the key, not for everyone, but if you are serious about long range, high-performance, Light-weight, ( Off-Road ! ) etc ! It can be done !..
Lithium-Polymer and Lithium-Ion are made in various shapes and sizes..
Typically Li-Ion is what you find in a laptop computer, slightly taller than a AA battery, they are 3v each instead of 1v like Nimh and Nicad. And Li-Po is what you find in your cell phone, comes in a rectangular shape of many different sizes.
In small size, Lithium cells are not very dangerous, but for powering an E-bike a much larger pack is required.. Your cell phone may have 1000 mah 3.9v.. An E-bike will have 10,000mah at 36v !!! ( Think fire cracker vs stick of Dynomite ! )
This means you have a number of batteries connected together to form a larger pack.. Recharging a Lithium pack requires special care. Safety Circuitry that monitors maximum and minimum voltage.. and balance of every cell is a must. ( This is called a BMS )
Only in the last year or so have I been able to find sources for Lithium Polymer packs that I would be comfortable strapping to my bike safely. This is the cutting edge of technology and holds great promise, but please play safe ! Do your research.. ask questions.. before you buy !
For a whole lot of information about lithium options, read up on my Projects Page