When we bought the Waponi Woo she had 800 AH of AGM batteries. This means that we had 400AH of actual energy to use while off shore.
While 400AH sounds like quite a bit the the average household in the WA state uses around 1041 KWH of energy per month (35 KWH/day, 289 AH/Day) Coverting KWH to AH is :[Kwh = AH * V / 1000], assume 120VAC. Per <https://www.electricchoice.com/blog/electricity-on-average-do-homes/>
The batteries were also approaching 10 years of use. Most AGMs, when treated well can last 7+ years with declining energy storage. Around July of last year we had to run our small generator to get enough power into the batteries to get one engine started. We would then run that engine long enough to get the second engine started. I would usually do this in a serepticious manner as to not let the inlaws know how bad the power systems were! “I am just warming up the genset/engine etc..!”
Waponi Woo also lacked any AC power when we left the dock outside of a small inverter under the navigation station in the salon. (Translation: Under the wall of radios in the living room). This tiny inverter was not even up to the task of charging a laptop. India would howl that her electronics were ‘dead’ when we left for a sail.
With some windfall from Caroline’s business we decided to upgrade our power systems to something more complete. My goal was to be able to unplug from the dock and not have to reboot anything or even realize we were away from the dock.
- Batteries. We were going lithium. Caroline and I manage a few remote radio sites in WA state. We use AGM batteries at these sites. AGM batteries have 2 advantages and a heap of disadvantages. The two advantages are no acid leaks and cheaper cost. Some of the disadvantages are being unable to use 1/2 of the capacity you purchased without doing some damage to the chemistry, the requirement that you top them off and float the batteries as often as possible, the lack of cycles available over their lifespan and their weight.
- Inverter/Charger. We wanted an inverter that would handle EVERYTHING AC at the same time on the boat. I wanted to be able to unplug from shore and just keep on going. Bonus: The inverter should also be a battery charger. One less component.
- Solar. I talk about my inlaws pretty often so most of you know they live off-grid via solar and hydro. Caroline and I love this lifestyle and I know she wants to emulate it somehow. We wanted solar. Caroline hates the generator as does everyone around us. To be honest it is not very loud but something about silent power from the sky attracts us.
- Monitoring. We wanted to monitor the system in an easy to grasp method. I am a geek that likes to monitor things. Caroline likes to know what is happening without having to ask me to explain what is happening. Simple diagrams and graphs help these things.
I did quite a bit of research and aways went back to the Technomadia site. Chris Dunphy & Cherie Ve Ard have been geeks on the road for some time now. I occasionally binge-read their blog and have watched them move from a very small trailer being towed by a diesel jeep to a refurbished bus with all the proper power systems. Chris and Cherie; I never paid a subscription fee and I am sorry. Hopefully people reading this entry drive traffic to your site.
With all of this research and much Caroline convincing we finally decided on what we were going to do.
We went with a 500Ah LiFeMnPO4 lithium battery bank from Starlight Solar. The battery bank is more of a battery system than a bank. LiFeMnPO4 batteries need some monitoring to make sure individual cells don’t exceed the safe specifications of the chemicals within. To this end, each cell of the batteries has a monitoring board on top of it. This board tracks the charge of the cell and the temperature. Should anything go bad these boards tell the battery management computer (BMS) to shut down any incoming or outgoing energy from the battery bank.
We received the batteries via ground freight and I was able to install them a few weeks after receipt. During installation I removed the old AGMs and the boat lifted out of the water about 2 inches. Waponi Woo looked like a 1960’s Hotwheels car with big tires in the back and small ones in the front. I was going to carry the batteries up the dock to the truck for recycling right then but then I saw that the tide was a -6 or something. I had a soda and waited for the moon to do the heavy lifting.
The new 500AH pack also takes up less than 1/2 of the space of the 800AH AGM bank. I now have space for a watermaker on the port side of the boat.
The BMS requires that all incoming and outgoing power be on a dedicated busbar. The f-ing-french boat I own has random cables attached to random locations on the 4 batteries on the port side and 4 batteries on the starboard side. All of this wiring had to be drug to the starboard side of the boat and combined into a single busbar.
We went with a Victron Energy Multiplus 12/3000/120-50 Inverter/Charger 120V This thing allows us to run everything on board via AC as well as charge the battery.
One of the best features of this device is the ability to dial down the AC input. Are you at a good marina with a solid 30A power supply? Great, allow 30A of input. Are you at a bad marina with only 15A of power on a 30A plug and you keep tripping the breaker? Then dial it down to 15A. The dialing feature also allows for us to use our 2KW Honda generator without blowing it out with a demand for higher amperage.
Another cool thing this inverter/charger does is draw from battery during peak loads. If you kick on an AC motor or something that requires more power than your generator of bad AC connection allows then the inverter draws from both the battery and the shore power. It will do this for a LONG time as we discovered while at anchor one night.
We waited until we got to LaPaz for solar. We wanted to place an arch between the two hulls of Waponi Woo to support the panels and the best price and artistry with a welder was in La Paz. Even with a hefty discount in the US, solar panels were cheaper in Mexico. We now have three 265W Kyocera panels sitting on top of our arch. These panels feed into a Victron MPPT 150V / 70A charge controller
A strong note: I was a fan of higher voltages and lower amperages going into the solar charge controller from the panels. I changed this configuration over to parallel using a midnight solar combiner box. This has improved the input of my panels significantly!
Caroline is a romantic about wind and wind power. After 1.5 seasons of having a low battery in the morning we decided to bite the bullet and get something that would take the edge off during the dark nights. After much excel work to get the most Watts/Dollar we went with a Rutland 1200 Wind Charger. I am disappointed that I could not easily add it’s power input to our monitor below. We did get the remote display so we can watch what power is being put into the system and turn the device off if things get crazy.
We chose to use some more expensive gear in order to safely monitor it in a user friendly way. To this end we have a 2 graphical displays in the living room. The first is the Victron BMV-700 Battery Monitor This small dial simply gives us state of charge information and AH usage stats in real time. The display can be confusing as it is so simple. Think of it as a fuel gauge with some extra options. This device also translates data from its sensors to a second, more colorful monitor, the Victron Color Control.
The Color Controller allows us to change Amperage draw settings and see with moving dots how much power each part of the boat is using and charging with. Super easy to understand.
The Color Controller also uploads data every 15 minutes to a public site so we can see historical usage. When we are off-line it stores the data until it can forward it.
All of this text demands pictures. Here is a simple schematic showing the various pieces and how they go together. Pink is control wires to let the alternators talk to each other. Green is DC power. Blue is control cabling and Red is AC power.
I also have another diagram showing pictures of each of the devices here:
The solar panels were hooked up about 3 days ago. We are now into our second day of being unplugged at the dock simulating what it is like out at sea. We are doing ‘ok’ even with some cloudy days. I am looking into more solar. MOAR SOLAR!
I’ll have some other geek posts coming up as I have time. I know people want to know all about communications and how we do it.