Smaller systems like those that use one or two AA batteries usually are better suited to different battery types with higher energy densities like “alkaline” batteries or “nickel metal hydride” batteries. Those types are more expensive, but they pack more energy into a smaller, lighter package so they make more sense for running things like small flashlights or cameras. Larger battery operated systems like those used to store energy from a big wind turbine or solar panel to run the electrical system of a whole house, or the battery systems of boats or RV’s are usually made with lead acid batteries, but often not the permanently sealed type.
The lead acid batteries used on large systems are often called “deep cycle” batteries, and have access ports for the user to perform basic checks and maintenance like adding more liquid from time to time. This type of large lead acid battery, though very powerful, would not be ideal for use on an electric bike or kit since the liquid could possibly spill and the weight of these systems is often in excess of 100 lbs.
Though lead acid battery technology is one of the oldest around, this is not a bad thing. The technology has been proven and tested over many decades and production methods have been specialized to produce high quality, low cost types of lead acid batteries for thousands of different niche applications. Other battery types may be more ‘high performance’ in terms of weight or energy density, but lead acid batteries are a time-tested, proven, and reliable option for applications like electric cars and electric bikes.
This type of chemistry has a high energy density like the LiCoO2, but the nickel and manganese elements in the cells make them more stable and therefore safer and easier to produce. Lithium NCM batteries must still be monitored by a battery management system (BMS) during operation to protect the cells from over charging, over discharging, short circuit situations, and over current situations, but can safely be built into bigger sizes with internal BMS circuit boards. These Lithium Nickel-Cobalt-Manganese batteries are safe, stable, and powerful, and are used in electric wheel chairs, bikes, and the Hill Topper electric bike conversion kit
Different types and sizes of lithium battery will have more or less ability to store a certain amount of power, and it’s important to understand some basic terms used to describe this issue. A battery is basically like a gas tank for an electric motor. In terms of shopping for a battery, to power your electric bike hub motor you’ll be considering things like overall price, weight, and how much power your “gas tank” can hold, so it’s good to have a basic vocabulary to accurately compare different batteries. “Amps” describe how big a flow of electricity a battery can put out, for example. So one good way to compare batteries is by asking, “if these two batteries were putting out the same size flow of electricity, which one would run out first?” It’s like comparing two bath tubs that are draining. You could ask, “if these two bath tubs had exactly the same size of drain hole, which tub would empty out first? The basic answer in this case is simply, “the tub with the least amount of water stored up in it to begin with will be empty first.” If the drain hole on each tub could let water through it at a rate of, say, 8 gallons per hour, and one tub starts with 8 gallons and the other starts with 12 gallons, the first tub will drain in 1.0 hours while the other will drain in 1.5 hours. If these tubs were batteries we would expect the “1.5 hour” battery to be a little more expensive, and maybe a little bit bigger or heavier as it could do work for a longer time. If you shopped around and compared prices and specifications and found one of these “1.5 hour” batteries with the same price or maybe a higher price but the same or even smaller size or weight as the “1.0 hour” battery, you could then easily tell if it was a good deal.
To understand how far a battery will drive your electric bike compared to another one, it’s good to speak in terms of “flow per hour.” You can ask, “ok, if these two batteries have electricity flowing out of them at a rate, or ‘flow size’ of 8 amps, how many hours will each of them do that until they are drained?” If one of the batteries could have electricity flow out of it at a rate of 8 amps for one hour before it was empty, we would call this an “8 Amp/hour” or “8Ah” battery. If another battery could last for an hour and a half while being drained at that rate, we’d say it was an “8.5Ah” battery.
One more thing you may consider when buying a battery for an electric bike or conversion kit is when you may want to replace it. No battery lasts forever, however, most rechargeable batteries will be able to be recharged many hundreds of times before they begin to wear out. For example, The Ukko Big Lithium (nickel-cobalt-manganese) battery can be fully discharged and recharged 500 times before its performance drops to below 80% of what it was originally. The standard lead acid battery pack in Ukko’s standard Hill Topper kit is rated at 400 cycles. The two biggest factors to consider here are probably the total number of rated recharge cycles, and the overall price of a new battery. Under normal usage (say two full battery cycles per week) any Ukko battery pack will give you years of good service and performance. The price of a given type of battery may affect your decision at some point in the future when you want to purchase an additional battery pack to increase your range or replace your original pack altogether. The cost of a standard lead acid battery pack is generally much lower than a lithium pack This is due to the higher production cost of the more complex chemistry and management circuitry in the lithium battery.Ukko offers a variety of options for new battery packs and lithium upgrades for kits with standard packs so that you can always have the battery features you want.
So, as you shop around and research the electric bike conversion kit market, keep in mind the chemistry type of the batteries you are comparing, make sure you have some clear comparison criteria in your mind regarding how much power a given battery will hold given it’s size, weight, and price, and check out our additional battery pack and lithium upgrade options at http://www.electric-bike-kit.com/ if you’re pondering what your future battery pack purchase options will be.
Also, if you haven’t already, please show your support of electric transportation by becoming a Facebook fan of the Hill Topper, because each individual making conscious decisions about energy consumption is the best option we have for creating a sustainable society without sacrificing our standards. You can also post your thoughts and comments on our Blog.