Click the below link to order replacement tire(s). Listed as Part Number: 154-11, the price was $9.99 + $ 8.00 shipping.  Note:  I ordered 3 tires = $ 29.97 + $ 24.00 shipping.

"Qing Da" is the actual brand name, of Chinese manufacture, seems to be made of vulcanized rubber. It's significant that they inflate to 50p.s.i. (versus 30p.s.i. for the OEM HCF-305 knobby tires). But go ahead and top them off at 60p.s.i., and enjoy the best possible rolling performance for 12-1/2" diameter tires. 

Be sure to always have a spare belt on hand, as local suppliers do not stock the unusual 20mm Optibelt Omega belt width.

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 wrong. 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 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.

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, I replaced the six soft rubber cell caps, and then took a standard push pin and punctured each cap, in the middle, 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. Also, flooded batteries, simply, do not have to be sealed.

Sealed lead acid batteries produce hydrogen gas (and also oxygen, via electrolysis), internally, which bleeds through the one-way, valve caps, and prevents outside air from entering into the battery. Oxygen, especially, will damage the thin lead plates of a typical, compact sealed lead acid battery, so they were designed to best operate in an internal atmosphere of hydrogen gas. Completely covering the lead plates and fiberglass mats with electrolyte solution also prevents direct contact with air. Once this is done, the battery will only need to be occasionally "topped off" with distilled water, for regular maintenance.

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 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 this step is not absolutely required, as physical checks of the battery pack wiring, even during heavy use, has never found the wiring warm to the touch, even though the wiring still seems light for the task.

But, if you choose to add electrolyte to your sla batteries, "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 pack, remove the wiring connectors from the battery terminals, and remove the batteries from the vehicle. Clean the deposits off by wetting down an old toothbrush and sprinkling it with baking soda, straight from the box, and scrubbing the terminals and connectors. Dipping a toothbrush in Coca-Cola also works well in removing acid corrosion. 

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 14 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: 14mph (22.5kph)

Maximum Range (on a smooth surface, in open country):

                           15.5miles  (24.9 kilometers) @ 14mph (22.5kph)

                           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):

                           11 miles (15.3 kilometers) @ 14mph (22.5kph)

                           20.5 miles (30.6 kilometers) @ 9.2mph (14.8kph)

                           31 miles (45.9 kilometers) @ 4.6mph (7.4kph)

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 headlight on: 115% range

           90 degrees Fahrenheit: 119% range      With headlight on: 107% range

           80 degrees Fahrenheit: 109% range      With headlight on: 98% range

           70 degrees Fahrenheit: 100% range      With headlight on: 90% range

           60 degrees Fahrenheit:  87% range      With headlight on: 78% range

           50 degrees Fahrenheit:  74% range      With headlight on: 67% range

           40 degrees Fahrenheit:  61% range      With headlight on: 55% range

           30 degrees Fahrenheit:  47% range      With headlight on: 42% range

But the Power-Sonic still provides twice the range from a charge, and an 11% increase in cruising speed, over the standard issue HCF-305 battery pack. After the second test run, the batteries were opened and the electrolyte level inspected. There was no noticeable loss of fluid in the cells.

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 13.7 mph) will kick in at the darndest times, such as when speeding through a busy intersection, etc.. At full speed (13.7mph), 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, another option, the circuit breaker can also be immediately reset and driving resumed on the HCF-305, as long as the cruising speed is no more than 12mph. Although the motor still has a temperature of 126 degrees Fahrenheit, the controller will allow the HCF-305 to continue to operate because it will no longer predict a rapid rise in temperature, that could cause a motor burnout. Preliminary testing indicates that a sustained cruising speed of about 12 mph  -and recent testing at 13 mph, the electronic controller will allow the motor to operate at up to temperatures of 145-150 degrees Fahrenheit, without overheating the motor. But, in normal use, this will probably not be a factor, since most errands will be a series of short trips, at the convenience of full speed, giving the HCF-305 adequate time to cool down before the next run. But this trait could prove to be undesirable for those who are contemplating using the HCF-305 as a short range commuting vehicle, recharging it at work. I'm working on a design of radial aluminum cooling fins for the motor, with a under-the-carriage ram-air duct, that should keep the motor running cooler, allowing maximum cruising speed for greater distances. Stay posted.

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 2008), 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.

I've given up on restoring the damaged, original issue WP20-2E batteries. They, simply, can't be rejuvenated.

The PowerSonic batteries, and the unorthodox electrolyte treatment, have, so far, logged over 1,400miles (about 140 charge/discharge cycles) of hard use, running the vehicle at maximum cruising speed.

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 (don't use distilled water). The batteries in the battery pack were also occasionally rotated, from front to rear, to distribute wear (if any) evenly on the batteries. I have also presented my findings to the local Electric Auto Association members, of flooding sealed lead acid batteries. Some of the members have the capability to bench test a single PowerSonic battery: Break it open and add electrolyte to the cells and not only duplicate my results, but also run the battery through a rapid series of charge/high-discharge cycles to determine if the concept will work over the long haul, and forsee complications. My only hesitation is that I didn't have a solid two year track record (or 2,000 miles), on my modified PowerSonic battery pack, which was my original goal. Sealed lead acid battery packs, when driven at full speed discharge rates, have lasted somewhere between 1,000 to 2,000 miles (100 to 200 charge-discharge cycles) on other light electric vehicles, which is somewhat useful as a comparison.

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. 

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.

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.