Currently we are working on a direct system of solar charging the lithium ion battery on the bicycle to remove some of the energy losses in our current system and the need for an extra storage battery. We have been working on getting a direct charging system going from a panel to the battery to either be mounted on the bike itself or to be used as a "solar charging station" at set locations. One of the main problems is that the best battery voltage for electric bikes is generally 36V and this is nearly exclusively used for electric bikes, not many other items that we know of come in this voltage and solar regulators in this voltage suited to lithium ion batteries are difficult to come by. Even though we've found some after lots of searching, we have not found these to be applicable and fully functional for direct charging of our lithium ion batteries. So far we've destoryed a few batteries, been ripped of a number of times from overseas suppliers and had batteries that only charge partially. However, we have finally figured out a functional system and this is in test phase. Once this is achieved we will start working on making the bicycle hydrogen powered. Just for interest, what we've tried and the problems we've encountered to date with developing a direct charging system are these:

Attempt: Use a 48V panel (100W) to directly charge the 36V lithium ion battery used on our bikes.

Result: Open circuit voltage of panel was too high (81.1V) and fried the battery - luckily this didn't lead to an explosion but it has serious potential to be quite dangerous so please don't try this.

Attempt: Use a 48V panel (100W) through a 36V solar regulator and connect this to the 36V lithium ion battery.

Result: The voltage outupt from the regulator would switch between ~ 48, 36, 22 and do this repeatedly. The batteries would charge up to a degree but the the regulator wasn't ideal as they wouldn't become fully charged and eventually a charge burst would blow the fuse (10amp) on the line to the battery - indicating that they are being charged too quickly with this regulator. We have some new regulators that are doing better now but are still being tested. Off the shelf regulators from a variety of Chinese distributors promising to do what I want don't seem to work as well as intended. Having tested over 5 different models I've only found a couple to be moderately affective. The voltage typically plays around a lot or is not in the range we need for direct charging (~42.5V).

Attempt: Use a 12V panel, connect this to an inverter (12V DC to 240V AC), connect this to the battery charger.

Result: Inconsistant power supply, too many steps in the line, didn't work.

Attempt: Put 3x 12V panels and 12V regulators in series and connect this straight to the battery.

Result: Complicated system, batteries only reached partial charge.

Attempt: Have panels made with a voltage output of 42V (this is what the chargers put out and what voltage the 36V lithium ion batteries generally reach at full charge.

Result: Chinese company took all our money and never delivered anything.

Attempt: As above.

Result: Semi-successful! Panels came with an open circuit voltage of approximately 52V. Closed circuit seems to be closer to 38V but depends on the wattage of the panel (we are trying from 10W - 80W). It is semi-successful. The battery certainly charges to a degree but it is not ideal to have an un-regulated solar charging system. However, it does work but care has to be taken not to overcharge the battery by leaving in the sun for days on end with no use - though it is partically protected by the BMS and the inability of a lower voltage to charge a higher voltage once the battery voltage exceeds that of the panel output. Also, we are still in the process of determining to what capacity the panel is charging the battery - it seems to be a little higher than 3/4 full charge. Currently we are semit-happy with this direct charge system using small panels (about 10-20W) but we are working on getting a regulated system to protect against overcharge and have a voltage and current output more suited to our batteries.

Attempt: Use 48V electric bike batteries and get commercial 48V regulators to match 100W 48V panels.

Result: The first attempts resulted in failure of the battery to charge with cheap regulators. However, when increasing the quality of the regulator we've now found some that work very well. These have been running for about 6 months now so it appears that it is possible to directly charge through this means. Even though the batteries are not being pulse charged through this system, and so are likely not meeting their full capacity, they are charging to a sufficiently high degree and very little difference in range is found if charging using solar or the regular charger. It saves a lot of trouble if you use a 48V ebike battery than a 36V ebike battery. This method of charging can be seen here at about 4 minutes into the video.

Current Attempts: Get 48V panels and find regulators that can be used to reliably charge the 36V lithium iron phosphate batteries we employ with our electric bicycles.

Result: So far no commercial regulator seems to be available that actually works. However, through this business I've been fortunate to meet many electrically able people and Brett from Balmain has been kind, able and active enough to design a custom made regulator to suit 100W 48V panels I've ordered. The panels have an open circuit voltage of approximately 80V and a closed circuit voltage of approximately 70V. The regulator can work with this voltage and current to put a steady output of approximately 42.5V into the battery. The system fully charges our 36V 10Ah lithium ion batteries in approximately 4-5 hours from dead flat and so far hasn't damaged them. It has also been tested with a variety of 36V lithium ion batteries with different capacities successfully. It has now been setup for longer testing at the University of Western Australia and hopefully will encourage further development of such systems. It was set up on the 20th October 2010 and I've been using this system solely for re-charging purposes daily with no issue. Please click the link below to see some pictures of it: