Use the link to my webspace, for the details, for the time being:
I decided to build an electric vehicle from off-the-shelf components, using existing technology. The goal was to define auto transportation, down to the basic motor vehicle errand: One passenger plus a sizeable payload, to and from destinations of up to 5-10 miles away, rapidly, all at an affordable price.
And electric mobility scooters, unlike most electric automobiles, seemed to already be on the right track -they just needed to run faster. And, after checking the mobility scooters on the market, the HCF-305 seemed uniquely suited for the project. It actually ran so fast that it got the manufacturer in trouble and the medical mobility vendors quickly unloaded their HCF-305 inventories. And I knew that this vehicle would be perfect for the task.
I began to modify the HCF-305, by first installing an ultralight aircraft seat and harness for comfort, stability, and protection, and then building up the body around it.
This homemade vehicle is classified as a "Light Electric Vehicle": A new breed of efficient, lean-and-mean machines that weigh little more than the passenger(s). The Light Electric Vehicle is powered transportation distilled to its essence.
The issue with most electric vehicles these days is that they often weigh in at 2,500 pounds or more. And such a vehicle has the daunting obstacle of simply transporting itself, which is, at best, a losing battle.
Another uncomfortable truth is that full size electric vehicles put a strain on the local electric power grid: Most communities do not have the electric power infrastructure, specifically, neighborhood power lines and transformers, to properly charge more than one or two full size electric vehicles per neighborhood.
Now, I have 3,000 miles (360 charge cycles) logged on this vehicle. Everywhere I drive this odd duck people approach me, wanting to buy one. I politely tell them that I would starve if I made these things for a living.
This project is not unlike my radio control model aircraft: It's a true labor of love -that requires a considerable amount of research and tinkering to keep everything running smoothly. But the casual bystander only sees a cute, reliable vehicle that quickly and effortlessly runs errands all over town. And it would be a quite a stretch to assume that this vehicle is anywhere near ready for the mass market.
Like many members in my local Electric Automobile Association, I see my electric vehicle as a toy and a joy, and certainly not yet a viable substitute for an internal combustion engine vehicle.
But we try.
Step 1: Unorthodox Treatment for High Rate Sealed Lead Acid Batteries:
Four - 12Volt, 21Amp PowerSonic PSH-12180NB-FR batteries, producing a 24 Volt, 42 Amp battery pack.
But, upon receiving the delivery of the batteries, I promptly pried off the sealed plastic panel, which covers the six soft rubber valve caps to the cells, and added almost 1-1/2 fluid ounces (44.4 milliliters) of standard battery electrolyte solution (an over-the-counter product of 35% sulfuric acid and 65% water) to each cell, for a total of 9 fluid ounces (266 milliliters) per battery. The electrolyte level just needs to cover the lead plates, and no more. Standard lead acid batteries require topping off with an electrolyte level of almost 1/2" over the lead plates, but your sla agm batteries are far better off with less.
To inject the electrolyte into the cells, I prefer to use a small, el-cheapo battery electrolyte bulb tester, with the colored plastic balls removed. The pointed tip of the bulb tester is inserted into the small cell opening, and the electrolyte is quickly squirted into the cell so that the solution doesn't have a chance to flood onto the outside-top of the battery. The battery cell is then inspected with a small led flashlight, to see if the lead plates are just covered by the electrolyte, but no more. A darkened room, or shed, is best for this. A thin, plastic drinking straw (chemically inert) comes in handy, in case a bubble in the cell hole is blocking your view, to poke it and pop the bubble.
Breaking open and "topping off" a perfectly good set of new batteries and voiding the warranty may sound shocking and radical to most people. But, after thoroughly reading up on the subject, I came to the conclusion that my judgement is correct -and the advice of the battery specialists is either wrong or non-existent. You see, sealed acid batteries are, by their very nature, "starved electrolyte", due to the simple fact that the fiberglass mats between the lead plates are only 95% saturated, in order to make them spill proof. As such, water depletion of the "sealed" system is a constant concern. Performance can only take a back seat when a battery is designed this way.
Another benefit of flooding a sealed lead acid battery is to provide an inherent ability to dissipate heat. That is, typical flooded deep cycle batteries may normally become warm to the touch, either from heavy use, or from quick charging, but if a sealed lead acid battery ever becomes hot (or even warm) to the touch, the internal lead/glass mat cells, more than likely, have dried up and burned out, due to the complete inability of the empty spaces in the cells to dissipate intense heat away from the lead plates. Another symptom of a sealed lead acid battery that is burned out (aka: thermal runaway) is that it also vents off a sick vinegar smell.
And if the new high-rate sealed lead acid batteries were truly reliable, then why haven't the golf cart manufacturers installed them, making their vehicles lighter and more responsive? I feel that those relatively expensive, compact, and high-performance sealed lead acid batteries must be flooded (electrolyte added), to enjoy their maximum potential.
The electrolyte added, the six soft rubber cell caps were replaced onto the battery cells, and any spilled electrolyte from the top of the battery cleaned up with a paper towel. I then punctured each of the six soft rubber cell caps, in the middle, with a standard push pin, to eliminate the internal vacuum that happens as the batteries cool back down to ambient temperature, causing the electrolyte in the glass mats to deplete to less than 95% saturation (*** Warning: At one time, with an earlier battery pack, I placed the battery cell caps on a wooden board and punctured each one, in the middle, with a heated, red-hot straightened end of a paper clip, for even better ventilation of the cells, but the possibility of an electrical spark causing a battery explosion is greatly increased by the larger diameter vent holes and I no longer do it this way). The now-flooded batteries, simply, do not have to be completely "sealed". The plastic cover was then fitted back into place, over the cell caps, and taped shut, lengthwise, leaving the ends uncovered, to allow for venting of the battery.
Working with battery electrolyte solution does require certain precautions (some say it's dangerous -but so is using a table saw, or driving a car):
- Only use standard battery electrolyte solution (an over-the-counter product of 35% sulfuric acid and 65% water). Never use pure sulfuric acid. It is extremely dangerous, as well as ineffective. And "topping off" with water will only weaken your sla/agm batteries, as they are not at all like typical flooded batteries.
- Make sure that there is someone nearby, within shouting distance, just in case electrolyte gets in the eyes, to help flush your eyes with water, or better yet, special emergency eye-flush solution. Or, if heavy electrolyte contact, a trip to the emergency room of a local hospital (but still do a first aid flush, as time is critical).
- Wear eye protection and wear old, worn out clothes. Small droplets of electrolyte have the insidious habit of producing large holes in your favorite yard work clothes, appearing a week or two after exposure. Cellulose products are surprisingly vulnerable to electrolyte solution (blue jeans, canvas shirt, wooden floors).
- Snug fitting latex (or nitrile) gloves should be worn. I only wear them sometimes. But any case, afterwards, hands should be scrubbed down with baking soda, and face, hands, and arms washed with soap and water.
The four - 12Volt, 21Amp PowerSonic PSH-12180NB-FR batteries were then wired, in pairs, in series, and then parallel wired, to produce a 24 Volt, 42 Amp battery pack.
But further reading on the subject indicates that the batteries may function better if first wired parallel, as 2 - 12 Volt groups, and then wired in series, to produce a 24 Volt battery pack. The reason for this is that a weak battery will not degrade the over-all battery pack as much, in this type of arrangement.
A 7/8" thick pad of Insulite, a closed-cell foam, resistant to battery electrolyte solution, was positioned under the battery pack to absorb road shock, as the shock absorbers on the vehicle were adjusted to maximum stiffness, to create a more efficient ride and maximize the range of the vehicle.
These high rate PowerSonic batteries were actually developed for emergency power backup systems, for computer networks, etc.. Although tried and proven in electric wheel chairs that cruise at 3-4mph, these batteries have not been extensively tested on higher performance powered vehicles. But they are formulated for high-drain usage -without damage. Also, being agm (absorbed glass mat) batteries, they have a strong tolerance of the shock and vibrations of an electric vehicle environment.
The caution here is that the HCF-305 is unique in that the OEM electronic controller allows the 600 watt motor to run the vehicle at 14 mph. This is a world of difference, from running, say, a 600 watt motor in a vehicle that will max out at 4 mph. In short, a set of sla batteries that have successfully run a wheel chair for years can quickly burn out when connected to a high performance electronic controller (as in the HCF-305) that runs a vehicle at 14 mph.
The original OEM battery pack (2 - 24V 20A batteries) for the HCF-305, at 24 Volts / 40 Ampere-hours capacity, is just not durable enough to power the vehicle at a 14mph cruising speed. It should have been designed with a 24 Volts / 70 Ampere-hours capacity sealed lead acid/absorbed glass mat battery pack + a 24 Volt / 70 Amp electronic controller, for this type of load. The OEM battery pack was designed to cruise at about 8mph, with , maybe, occasional 14mph speeds for racing against other mobility scooters out of the stoplight.
But this limitation can be worked around. Read on.
And another warning: Don't be tempted to build a custom 24 Volt battery pack that exceeds 40-42 amps. Doing so will quickly burn out the electronic controller. And substituting a higher capacity electronic controller will create a loss of many of the special functions that are unique to the HCF-305's performance and convenience. In short, a high performance, off-brand electronic controller will simply run the motor -and nothing else.
Measuring the same height, the same length, and half the width of the standard issue HCF-305 batteries, the pack of four PowerSonic replacement batteries fit snugly into the HCF-305 battery compartment. Be sure to fashion a means to tightly secure each and every battery into position. The HCF-305 has minimal sized shock absorbers and any bumping and movement of the batteries WILL cause the battery cables to come untightened and loose. And the amperage running in the battery cables is strong enough to melt steel.
Although the new batteries arrived pre-charged, it is imperative that the modified "topped off" set of batteries were given a full, overnight charge, using the standard HCF-305 charger. After charging, each battery will test at 13.5-14 Volts -yet another advantage of adding standard electrolyte to the sla batteries, adding extra "pep" to the performance, without overloading the HCF-305 electronic controller.
It makes no sense to enhance the battery pack performance on the HCF-305, if full power is restricted from reaching the electronic controller, and the motor. Specifically, the OEM 12AWG wiring harness needs to be replaced with a custom, more robust 10AWG automotive wiring harness.
The problem with the OEM 12AWG wiring is that it is really not adequate for fast discharge characteristics of running the HCF-305 at full cruising speed. The OEM 600 watt motor is also wired with the same 12AWG wiring, indicating that the motor manufacturer probably never intended that their motor be run that hard.
Also, the cross-section of the OEM 12AWG wire has no less than 65 fine copper wires, that are extremely vulnerable to trace amounts of battery electrolyte wicking deep into the wiring (acid wicked in and damaged 10-1/2" / 27cm of wire on my HCF-305!). Whereas standard 10AWG automotive wiring is much heavier, capable of handling 60% more current and, more importantly, the cross-section a typical 10AWG automotive wire has about 19 coarse copper wires that are far less likely to absorb battery electrolyte, and if that happens, is somewhat less susceptable to acid corrosion eating through the wiring, blocking the high flow of current.
Once fabricated, the lugged contacts, on the new red and black 10AWG battery pack cables, need to be carefully "tinned" with an electrical rosin core solder, to make the battery wiring more efficient. The battery pack cables have battery contacts that are originally crimped on, which can sometimes restrict large amounts of current to freely pass through, causing a "hot spot". Lead-based solder, with a much lower melting point (374 degrees Fahrenheit) than lead-free solder (430 degrees Fahrenheit) will freely melt into the copper braids of the wiring, with a 75 watt soldering gun, for a clean, heavy flow of DC current. Lead-free solder will probably require a butane pencil torch, to overcome the heat-sink nature of the heavy copper wire and quickly melt the solder well into the connector and wire.
But, if you choose to add electrolyte to your sla batteries (and you should), "tinning" is a required step. The reason is that there will always be trace amounts of electrolyte that somehow make it outside of the battery (from riding the vehicle over rough surfaces, etc.), and make contact with the battery terminals and battery connections. And once on the connections, an even miniscule amount of electrolyte can quickly wick into the braided copper wiring, to do its mischief and impede in the proper flow of DC current. "Tinning", while not preventing this corrosion, will effectively ensure a clean, heavy flow of DC current through the wiring at all times.
Initially, I simply cut off the OEM wiring connectors and replaced them with heavy duty 12-10 AWG ring terminals, for a #8-#10 stud, crimped onto the battery pack cables and "tinned" with liberal amount of solder. And then applied and worked in liberal amounts of special battery terminal grease, which also has special inhibitors to neutralize battery electrolyte.
The battery terminals and wiring connectors must be clean at all times. The powdery deposits that sometimes form on the terminals are result of battery acid corrosion. The battery pack can usually be charged through corroded contacts. But the high rate of battery discharge, required for driving the vehicle, will create "hot spots" where corrosion is present, greatly diminishing performance of the vehicle.
To remove corrosion from the battery terminals, I've found that a good spray of "Windex" window cleaner (substitute brands don't work as well), with its alkaline composition, quickly dissolves most corrosion and also wicks into the wiring harness to further dissolve any hidden corrosion. Saturating an old toothbrush with Windex works well in removing acid corrosion from the more stubborn areas.
"CRC" brand Battery Cleaner with Acid Indicator is also a quick and excellent aerosol product that has a thorough foaming action, with a yellow colored foam that turns pink, upon contact with acid. A second application, in the pink areas, leaves a thoroughly clean set of battery terminals and connectors. The instructions on the can recommend flushing with water, but I simply wipe clean with a paper towel, leaving some foam residue to neutralize any acid that might reappear.
If this doesn't completely remove all corrosion, take a small brass bristle brush (the size of a tooth brush) and carefully remove the remainder of the corrosion from the battery terminals and connectors. Any stubborn areas can be removed with a small, sharp knife. Medium-coarse steel (soap-free) can also be used ensure a solid electrical connection. Wipe dry and allow everything to air dry completely. To prevent corrosive deposits from forming again, coat the terminals and wiring connectors with a liberal application of dielectric grease -or even better: A silicone dielectric terminal grease.
The new battery pack also needs to be gradually "broken in". That is, run your HCF-305 no more that 2 miles on the first test run. Then completely recharge the battery pack. Run your HCF-305 no more than 4 miles on the second run, and recharge. 7 miles on the third run, 9 miles on the fourth run, 11 miles on the fifth run, and 14 miles on the sixth run. Your battery pack is now ready for hard use.
The HCF-305 should now have a maximum range of 15.5 miles on a smooth surface in open country, or 9.5 miles in neighborhood stop-and-go traffic, at 15 miles per hour.
The first test run on the HCF-305, the vehicle was driven at full speed, for about 8-1/2 miles (but don't do what I did -see above), before the heat sensor in the motor caused the circuit breaker button to fully extend out, turning off the power to the vehicle. Following the instructions of the HCF-305 Operator's Manual, the vehicle (actually, the motor) was allowed to cool off for about 20 minutes, before the circuit breaker button was pushed back into the flush (reset) position, and the HCF-305 was turned on and driven home, about a mile away, with power to spare.
Before the second test run, a digital speedometer/odometer was installed to provide greater accuracy. A digital odometer is especially useful when operating a Light Electric Vehicle, as it provides a clear, precise display of the remaining mileage on your vehicle.
* Here are the results with the PowerSonic battery pack (on a smooth, paved surface, and with the modified bicycle trailer in tow):
Maximum speed: 15mph (24.2kph)
* Maximum Range (on a smooth surface, in open country):
15.5miles (24.9 kilometers) @ 15mph (24.2kph)
31 miles (49.9 kilometers) @ 9.2mph (14.8kph)
46.5 miles (74.8 kilometers) @ 4.6mph (7.4kph)
* Maximum Range (in neighborhood stop-and-go traffic):
10 miles (15.3 kilometers) @ 15mph (24.2kph)
20.5 miles (30.6 kilometers) @ 9.2mph (14.8kph)
31 miles (45.9 kilometers) @ 4.6mph (7.4kph)
* It's important to note here that the above are MAXIMUM ranges. That is, I ran my electric vehicle, at full cruising speed, until the electronic controller shut it down, and then carefully noted the miles. This is not recommended, if you want your battery pack to enjoy a satisfactory lifespan. Doing so (driving your vehicle hard, until it just crawls back home) is commonly known as "batterycide".
* Running the above mileages, per charge, your battery pack will last about 1,000 miles / 120 charge cycles. But simply running your vehicle at 2/3 the above mileages, maximum (but still cruising at 15mph), will double the lifespan of the battery pack, to 2,000 miles / 240 charge cycles, which I've found to be a better trade-off.
* It's also important to note that the average annual temperature of where I live and drive my electric vehicle is 58.6 degrees Fahrenheit (= 14.8 degrees Centigrade). If your average annual temperature is higher, then expect your battery pack to have a somewhat shorter lifespan. If your average annual temperature is lower, then expect your battery pack to have a somewhat longer lifespan.
The above mileage is at an ambient operating temperature of 70 degrees Fahrenheit. Driving in cold weather can reduce range, and driving in warm weather can increase range as follows:
100 degrees Fahrenheit: 128% range With dual LED headlights on: 115% range
90 degrees Fahrenheit: 119% range With dual LED headlights on: 107% range
80 degrees Fahrenheit: 109% range With dual LED headlights on: 98% range
70 degrees Fahrenheit: 100% range With dual LED headlights on: 90% range
60 degrees Fahrenheit: 87% range With dual LED headlights on: 78% range
50 degrees Fahrenheit: 74% range With dual LED headlights on: 67% range
40 degrees Fahrenheit: 61% range With dual LED headlights on: 55% range
30 degrees Fahrenheit: 47% range With dual LED headlights on: 42% range
* Increase above ranges 75% if PowerCheq electronic balancing modules are installed in the battery pack (see PowerCheq page in this Instructable).
One possible complication, though, is the HCF-305 motor overload sensor. While this valuable feature will prevent the motor from overheating and burning out, the sensor-activated circuit breaker, after about 4-1/4 miles of hard riding (at 15 mph) will kick in at the darndest times, such as when speeding through a busy intersection, etc.. At full speed (15 mph), the heat sensor, inside the aluminum end plate of the motor, signals the electronic controller, which makes the decision to shut down the power, at 126 degrees Fahrenheit, causing the HCF-305 to come to a complete stop. A short wait, of a few minutes, is all it takes for the motor to cool off, and the vehicle's circuit breaker can be reset.
Or, a better option: Accelerate to full cruising speed, then back off on the throttle until there is a noticeable drop in speed, then increase the throttle ever so slightly back to full cruising speed. You'll cruise like a pro. And, more importantly, you'll be able to cruise at a sustained cruising speed of about 15 mph, and the electronic controller will now allow the motor to operate at up to temperatures of 145-150 degrees Fahrenheit, without overheating the motor.
The replacement PowerSonic battery pack requires a full 8 hours to charge, before the amber charging led turns green. But a full overnight charge (12-14 hours) is highly recommended. After a full charge, each 12 Volt battery will test at 13.5-14 Volts.
Note that sealed lead acid batteries have a slightly different electrolyte, which influences the terminal voltage. If you have installed a set of PowerSonic batteries -and chosen not to break them open and add electrolyte, a full charge voltage should read about 12.8 to 14 Volts.
ALWAYS recharge your lead acid battery pack after a good run (4-1/2 to 7-1/2 miles, or more). Failure to do so can cause deterioration of the lead plates.
Also, like Ni-Cad batteries, I've read that lead acid batteries can also develop a memory. This means that after a short test run around the block, for example, the battery pack should not be recharged before storing the vehicle away. Recharging the battery pack, as such, may adversely affect the next cycle, reducing the range. I don't really worry myself with this possibility, but posted it as a precaution.
So far, the results from the new battery pack have been dramatic. Costing about $ 260.00 American dollars, which included shipping (but the price is going up in 2009), I feel that these batteries will provide a compact, yet powerful and reliable high-rate discharge system to power the HCF-305's 600 watt motor.
My HCF-305 is now being run on as many errands around town as possible, to find out how tough these improvised batteries really are. Occasional checks of the battery electrolyte levels required only a light "topping-off" of one cell, of one battery only, with electrolyte (with these batteries, don't ever use distilled water for topping off). The batteries in the battery pack were also occasionally rotated, from front to rear, to distribute wear (if any) evenly on the batteries.
I've been asked: How does one know when the electric vehicle battery pack has reached the end of its lifespan? The answer is that the performance of the vehicle simply, and quickly, degrades to half the range, after a year or two of service. Lead acid battery packs, in electric vehicles, are usually replaced when the capacity drops to 80% (80% capacity = 1/2 the range of a new battery pack) or less. To fully understand the usefulness of an old battery that is now at 80% capacity: Mark out the "21 Amp Hour" rating on the outside of the battery and write in "16 Amp Hour" and treat the battery accordingly. But my "discarded" 12VDC sealed lead acid batteries (but flooded) are more than welcome, joining up with the old battery pack of my wind generator -or sun tracking solar panel, where they will continue to enjoy years of satisfactory service.
The purist may choose to charge their custom battery pack, using four 12 Volt chargers, one for each battery, to ensure a "balanced battery pack". But this is unnecessary with the HCF-305, since the batteries were ordered from the supplier, specified as a matched set. Also, the HCF-305 electronic controller never allows the battery pack to discharge below 40 percent, so a possible weak battery in the pack becomes less of an issue. And periodic rotation (done every time the battery electrolyte level is checked) of the battery arrangement in the pack tends to balance out possible system stress on any one battery. The four 12 Volt battery pack arrangement is also defined a "low voltage traction pack", which is not as maintenance-critical as the newer, higher voltage, multiple battery packs in the newer electric cars on the market. A "balanced battery pack" is essential for a lithium-polymer powered radio controlled model airplane, but not for a pack of four lead acid batteries, carefully protected by the HCF-305 electronic controller.
But I am building a lightweight 12 Volt fast charger, which will be permanently mounted on the vehicle, to take advantage of the locally proposed electric vehicle infrastructure, to double the operating range of the vehicle. And it will require four 12 Volt chargers, in order to carefully control the fast-charge process.
The new battery pack will soon be wired with a fuse, on each battery, so that a short-circuited battery won't destroy the entire pack. The OEM battery pack wiring harness, oddly, is not fused. Also, the series-parallel arrangement pushes the limits of what an amateur should really attempt on these sort of projects, so stay posted for specific wiring details, complete with photos.
Powering your HCF-305 / Light Electric Vehicle with other types of batteries:
The HCF-305 comes equipped with small, compact sla-agm (sealed lead acid - absorbed glass mat) deep cycle batteries. The problem is that, while deep cycle, the standard issue WP20-24E batteries are not designed as "High-Rate" batteries, in that they are not designed to survive the heavy discharge demands of a 600 watt motor.
But with the new breed of high-rate sealed lead acid batteries, there's really no better class of battery for the task. Sealed lead acid batteries first appeared in the 1970's, and have slowly improved and evolved into today's SLA's, which have twice the capacity, for their size, than those of the 1970's and 80's. SLA/AGM's are now a better choice than lithium-ion batteries. Even if not used, an electric vehicle, equipped with sla-agm batteries, will lose only about 8% of its battery charge, per month. And even that tapers off to only about 20%-30%, total, over a 6 month period. But breaking open and flooding the battery pack with electrolyte will cause the batteries to behave like typical flooded lead acid batteries, and battery pack will self-discharge almost 1% per day.
Traditional flooded lead acid - deep cycle golf cart batteries are just too large and cumbersome.
Traditional flooded lead acid automotive batteries are not designed to survive the deep cycle applications required by electric powered vehicles. Using standard automotive batteries, in the HCF-305, will do permanent damage with each cycle, destroying them after about 25 run/charge cycles.
Deep cycle "marine" lead acid batteries (both flooded and absorbed gass mat) are not suitable for powering electric vehicles. Marine batteries have an internal design that is somewhere between that of a deep cycle golf cart lead acid battery and a traditional flooded lead acid automotive battery. The problem is that the initial performance will seem spectacularly successful -until the battery pack finally dies after about 50 run/charge cycles. But, one real advantage of using marine batteries, is that the harbor masters, in many marinas, will freely give you their surplus used marine batteries. The batteries will work, but are just tired, and not up to full capacity. Not a bad deal for someone on the cheap.
Sealed lead acid - gel batteries are now making their way into electric powered "fun" vehicles. Sealed lead acid absorbed glass mat batteries are sometimes mislabeled "gelcells" -which they're not, but creates to the confusion. But, like most compact sla-agm batteries, compact gel batteries cannot survive the rigors of 500 watt and 1,000 watt motors. And, more importantly, having an electrolyte in a gel state, they cannot be tampered with and effectively serviced by the handyman. Sla - gel batteries are, essentially, disposable batteries.
And don't be tempted to install a pair (or a four-pack) of readily available Fisher-Price Power Wheels 12 Volt, 9.5Ah batteries (wired in series) -or a pair Peg Perego 12 Volt, 12Ah batteries. Although a reliable, long-running power source for childrens' toy cars, these types were designed to handle only dual 20watt motors, geared down to run at 3 or 4 mph. Running these through a 600watt HCF-305 motor will quickly destroy them.
Nickel metal-hydride battery packs (made of multiple 1.2 Volt cells) are still too problematic for mobility scooter applications. So are nickel-cadmiums. And an electric vehicle, equipped with NiMH, or Ni-Cad batteries, if not used, will lose almost 10% of its battery charge, per day!
Lithium-ion batteries are sometimes used in cost-is-no object projects, to appear high-tech and gain instant credibility. But in fact, the only "advantage" is that it would cost about an extra $ 1,000 American dollars to outfit your HCF-305 with a set of lithium-ion batteries, and they would still be the same size, same weight, and same 40 Amp capacity. But one little-known characteristic of Lithium-Ion batteries is that they just can't tolerate a fast discharge rate -especially the demands generated by an electric vehicle.
Also, the OEM electronic controller on the HCF-305 would need to be replaced with a custom unit, since the lithium-ion battery pack voltage drops dramatically during normal discharge, and the OEM electronic controller, sensing a low voltage, would shut down the vehicle prematurely, with less range than the standard lead acid battery pack would produce.
The same applies to the new lithium-polymer batteries -except that they do handle fast discharge rates quite well.
Fuel cell batteries, while promising, are too fragile, too expensive, and still under development for light electric vehicle applications. And even, if and when, they are developed and marketed, there is, at present, no infrastructure for readily fueling electric vehicles.
LiFePO4 (Lithium Iron Phosphate) battery technology just may change forever the light electric vehicle industry. The technology is here, but at a cost of about ten times the cost of an equivalent set of SLA batteries.
The development of truly new batteries for electric powered vehicles has been painfully slow and stubborn, with no real break-throughs in sight. False hopes have been generated by the fabulously successful lithium-polymer batteries, now used in many high-performance radio-controlled model race cars and model aircraft. But the transition of lithium-polymer power into electric powered vehicles has just not been cost-effective. And, quite frankly, not even effective.
So it appears that compact sealed lead acid absorbed glass mat batteries, with after-market electrolyte added, are the best bet for powering the HCF-305. With a 1:4 weight ratio (battery pack : total vehicle), this is what the good electric car of the future should be.
I've been tempted to re-fit my HCF-305 with two, switchable, 42 Amp Lithium-Iron battery packs (one main + one reserve), to double the range -without increasing the weight, or overloading the electronic controller. But, quite frankly, am not willing to spend my time, driving my vehicle more than one hour, while doing local errands.
A more provocative -and fun, idea is investing the extra cash in a 24 Volt, 450 Watt wind generator and 110W solar panel combo, a $ 1,500.00 package that also includes tower hardware and an electronic charging panel. http://www.home.earthlink.net/~hcf-305userforum