After hearing of other successful installs, I decided to replace our 1200AH golf cart battery pack with Lithium Ion batteries.
Since Lithium battery packs are capable of 80% discharge, by my calculation an 800 Amp hour pack was the equivalent of my lead acid system. We plan to never discharge more than 640 amps.
My system consists of two 400ah packs with 4 cells each of CALB (Chinese Aviation Lithium Battery) cells which I purchased directly from CALB USA. We had one defective cell about six months after installation and this redundancy proved itself at this time, as we were able to operate completely normally but with half the capacity. The defective cell was covered under warranty.
I fabricated a housing for each pack out of Aluminum Plate with pieces of steel all thread holding the plates together. The bottom is a piece of boat board with grooves in the underside to slip over the all thread. The all thread is covered with pieces of black irrigation tubing to keep the all thread from abrading the cell cases. A bracket is fitted over two pieces of the all thread to mount the regulators. This thin piece of sheet metal helps to dissipate heat from the regulators which can get very warm when they are dissipating current to bypass a fully charged cell. A small fan is also mounted that is thermostatically activated when the regulators get warm.
A clear acrylic cover was fabricated to prevent accidental shorting of this very high amperage system. As a Navy Electrician, I saw a man blow the head off a crescent wrench shorting out a larger diesel starting system. This system has greater discharge capability.
Each pack has an isolation switch, which allows you to disconnect the pack from the system or bypass the disconnect relay in the event you are willing to risk the pack for navigational concerns.
Components of the Manzanita Micro System are connected in a buss formed with standard telephone cable.
The Manzanita components are:
The regulator board mark 3x4SMT:
The regulator board has voltage taps for each cell of the “battery”. Temperature sensors are also available. I have not installed these because the pack does not fluctuate in temperature at all when charging. With our system we rarely charge at more than 200 amps and this pack will absorb 800Amps/hour. The board has a telephone jack that allows it to connect to other components of the Manzanita system. The regulator is programmed through the display. The interface is pretty clunky but once you’ve done it, you will never be back.
The Robb II Regulator relay output board:
This Black box, it’s aluminum actually, plugs into the telephone buss system and provides a low current set of normally open or closed contacts that will actuate in the event of high or low voltage. These contacts are used to trigger a high current relay opening the battery circuit in the event of High or Low Voltage.
Rudman Buss Display:
A pair of monitors, one for each pack independently, is also connected to the buss. This product is discontinued. Theoretically one display can monitor both packs, but I was unable to make that work, so I have one display for each pack. There is also a USB Dongle available which allow you to monitor the pack with a computer. Per the owner, Rich Rudman, these monitors are replaced with a system that uses a cheap Android pad as a Monitor. In my last conversation with Rich, I think I finally understood that one monitor could be used by renumbering the cells, 1-4 for the first pack and 5-8 for the second pack. Since I want each regulator to turn off one pack only, I have two independent BMS systems so that only the failed battery is disconnected.
In addition I used 2 Gigavac GXL14 high current latching relays to open the battery circuit in case of High or low voltage state… These guys are expensive $400 each give or take. And on first reading of the ROBB manual you might think you need two, one for the high voltage state and one for the low voltage state. Making 4 if you have two packs. Luckily, if you access the regulator board, you can set up the high voltage ROBB contact to act for both high and low voltage states.
The connections for the 400 amp CALB cells are very large. I had difficulty finding a termination that would fit over the bolt and provide a solid High current connection at this high torque connection. I made my own termination by soldering the voltage sensor wires to pieces of copper ground strap. I then punched a hole of the size necessary for the battery bolt. If you use this method you should be certain that your copper connector is small enough that it cannot short to an adjacent post….. (Don’t ask how I know this). During the assembly each connection was cleaned with fine sandpaper and then immediately coated with antioxidant grease. Oxidation or poor connections will adversely affect the regulator operation. It is also a good idea to complete all connections to the pack before plugging in the voltage sensor plug as the Regulator board is very sensitive to voltage surges.
Before final assembly, each pack was balanced. The cells were connected in parallel with a digital power supply. I used a BK Precision 1688B set at the individual cell charge voltage of 3.4 volts. Interestingly, the pack took the max current for about 40 hours and then quickly tapered to nothing over the course of an hour or so.
My system works great although I haven’t seen any failure modes. The battery temperature is always at ambient. The batteries charge at full current with a short taper at the end perhaps one hour. On the gen set, I don’t usually complete the cycle. Another great feature is that it took about 500 lbs. out of my cabin. The waterline raised about an inch in the bow…
Manzanita Micro is closely managed by Rich Rudman, an early innovator in Electric Vehicle performance components. His interest is in extracting as many watts as possible from a smaller pack. To meet this need, his system provides a high level of adjustability and monitoring.
From a boaters perspective, however, it is needlessly complex. As a boater, I want a big pack charging and discharging at less than 1C to provide a long time between charges. I also want redundancy, so 2 packs, to allow me to isolate a bad pack. Trouble tends to come in batches so I want a safety for a dark night in a crowded foggy channel, like the time my radar stopped in the mouth of San Francisco bay with heavy traffic and fog.
I have encouraged Rich to develop a boat-specific product. To me this is a single card/box with the following features:
- Thermal sensor
- Voltage sensor
- Normally open contact to disconnect the pack from the buss via a latching relay
- An appropriate contact to shut down a charger
- USB or wireless output to a computer
- Conformal coated
- A piece of software
- Should be able to recognize multiple regulators say up to four.
- The software should allow the user to set voltage limits for the specific cell type in use.
- Settable alarms would be good.
Rich believes this market is too small for the investment required. I paid about 6000 dollars for my 800 AH Lithium pack with all the bits and pieces. The current West Marine catalog shows a 12v 180 AH Mastervolt pack at about $5000 and a 360ah at $9000. I would think there is a little room for profit in that mix. If you are interested, I think Rich would entertain an investor.
Michael Cope is a fellow Catana owner. He used components from EV Power. Doing it again I might consider this method simply because the Manazanita system is more “geeky” than necessary for boats. With that said Manzanita Micro gave me excellent support, delivered components quickly and were a pleasure to deal with. Rich is a fountain of knowledge regarding Lithium power. I had originally planned to follow in Mike’s footsteps, but in 2014, when I called EV Power to order, the owner (These seem to be small companies) told me he was switching to a surface mounted design and had no inventory, and no product availability date.
That is my experience to date. It is not a recommendation, in that you should proceed at your own risk, but hopefully my experience can help others with their process. I would certainly do it again.
Catana 471 #28