FREQUENTLY ASKED QUESTIONS 


Why electric motors?

The traditional Antares have mid-mounted diesel engines under the sole plates of the galley and master cabin, perfect for weight distribution and driving shaft driven props. The trade-off is noise levels while under way, residual block heat after motoring, maintenance and smells dealing with diesel/oil in the living spaces.

The Fischer Panda permanent magnet, fluid cooled electric motors and controllers are tiny, there is no gearbox, they are ideal for direct shaft props, have zero maintenance, no smells, no residual heat, and simple engineering. The electric motors have proved flawless, but should a time comes to replace them, they could be carried out under one arm. Electric motors are totally silent, you only hear prop wash while motoring allowing exploration in total silence without disturbing either the crew or wildlife. When the batteries need to be recharged, the generator runs in the starboard bow compartment, you hardly hear it running at the helm or in the living quarters.


How often do you use the motors?

Cat Ion is primarily a sail boat, not a power catamaran. She has cruised thousands of miles, it is usually quicker and always cheaper to sail. While sailing, the power reserves in the Lithium batteries (LiPO4) allow us to use navigation equipment and autohelms for extended passages without the need to recharge the batteries as would traditionally be done by running diesel motors and intervals during the night or day.


How many amps are used to run the engines?

We typically motor cruise in balance with the generator output drawing 100A on each motor, 20A for navigation and autohelm, to cruise at 5-6 knots. With new batteries under similar conditions, you can motor for @ 1 hour before recharging. 


Why Lithionics Lithium batteries?

Lithium batteries provide excellent power density, ideal for a catamaran looking to keep weight down while providing large battery capacity. They are safe, can be recharged quickly and routinely discharged >20% SOC.

The Battery Management System (BMS) and State of Charge (SOC) monitoring are crucial to safe application of Lithium batteries. We liked Lithionics design for cell monitoring reporting to the system BMS, with automatic protection in the event of charging issues or battery faults.

We found Lithionics a capable supplier, helpful, great support, providing solid technology at reasonable prices. From our early experience we also wanted to be able to manage individual battery cells, should that need arise. Cat Ion uses 4# x 12VDC batteries in series to make 48VDC battery banks. Lithionics provide an external Bulgin connector on each 12V battery that allows you to monitor cells, connect external LED cell monitors or charge individual cells, if required. We wanted to automate the start/stop charging cycle of the Fischer Panda generator, Lithionics created the controls required.


How long will Lithium batteries last?

Battery technology is always improving and our understand of their characteristics improves with experience. Cat Ion was built using Lithium Polymer batteries which have been upgraded to Lithium Iron Phosphate (LiPO4) batteries. All batteries degrade over time and with use, and perhaps abuse. We are finding 7 years to be a reasonable expectation of their practical working life.


Can you rebuild Lithium batteries?

The battery hardware and supporting electronic system are unlikely to wear out and could be reused. The cells within the battery could be replaced by a capable person. On Cat Ion there are 4# CALB 180Ah cells in each 12V battery which are widely available for @ $225 per cell.


How do you store Lithium batteries?

Best practise is to store LiPO4 batteries at 50-60% SOC with one charge and discharge cycle every 6 months and stored at the recommended storage specifications noted below.

Storage temp & humidity range:

< 1 Month: -4~95°F (-20~35°C), 45~75%RH

< 3 Months: 14~86°F (-10~30°C), 45~75%RH

Recommended storage: 59~95°F (15~35°C),45%RH~75%RH


Why Propane and not Electric appliances?

It would be a viable option to use electric hobs and ovens, Cat Ion uses a 5KW x 120VAC inverter. Aboard we have a combination microwave oven and the Antares supplied LPG 3 ring gas hob and oven/grill. We prefer using LPG for the Magma BBQ. There are two 20lb gas cylinders, each one lasts around 3 months.  


Why use a large Generator?

We need the 13KW output to maintain continuous motor cruising on electric motors. The diesel driven DC 48V generator is very weight and fuel efficient. We can refill LiPO4 fast, they take very high current, empty banks recharge in < 1 hour and then while at anchor, we have 2-3 days of quiet, running all mains appliances off a 5KW battery inverter.


Is fuel drawn from both tanks?

The generator draws diesel fuel from the starboard tank. Fuel can be moved between either fuel tanks for use, balance or polishing. 


What if the Fischer Panda Generator fails?

Cat Ion carries a backup portable Honda EU 2000i generator that can run the battery chargers. Its a 2KW generator aimed to backstop charging while sailing or at anchor. These Honda generator are designed to be paired with a 2nd portable Honda generator if you wanted to increase output.


How much solar panel is aboard?

4 x 50W BP solar panels produce 200W of power directly charging the Lithium batteries. We are content with this level of recharging, other Antares owners with smaller battery capacity have added solar panels between the bimini hard top and davits. In this area, we added a mesh sun screen to extend protected cockpit area while maintaining a clear view of the main sail for trimming.