Originally Posted by davedindubai
Hi CNB, I have a feeling you may well have all the power requirements on board in a spreadsheet somewhere?
If you do, would you share? I do love a spreadsheet.
Hi, sorry, I do not have a spreadsheet (yet).
I have done a different approach when re-fitting the electric
system without using excel for the sizing.
We searched for a used catamaran
of this size for liveaboard
and to start our journey, I did not know what to expect from the electric
system at this time.
What I did - was to think about, what I would like to have on board, assuming no vessel will have the perfect set up what I want to have.
So I just evaluated upfront how much I would have to cough up after buying
a used cat to make it perfect - and what energy I would need to make the electric galley
happen and how I would produce and store this energy. Regarding renewable energy usage, We have a RV for years that I had re-fit with solar
and AGM batteries
and I am pretty aware how they behave and how long they last, also was investigating for years LiFeYPO4 batteries
and installations in that area.
So to make it short, the plan to use the largest available cells and the 5000W inverter charger
along with the induction hob and the convection oven
was in my mind already long before when visiting boat
shows and searching for boats.
Then we found our boat
and it was over-equipped for my taste, it has factory installed ONAN generator
and 4 A/C units, also washing
machine and 2kVA MassSine Mastervolt inverter
plus the Dessalator 100DUO, that is a 12V and 220V water
maker, also a solar installation
450Wp with a poor PWM regulator
over the davits
. I did not want the A/C and the generator
, but kept them in place, the GEL batteries was half past dead and digging deeper I found the system inappropriate. I also had to remove the battery
monitorMastervolt MasterShunt, it was way too weak for the task, and had to replace it by a Victron BMV 712 with 1000A.
The boat stays on the dry for the winter after the survey
1000km away from home, so I could not test, measure and evaluate the system during this time, but I could buy and test the parts
I wanted to install - what I did.
My main goal was first to get rid of the old GEL batteries, 2 of the four were damaged - one had a cell short cut and was boiling, the other one has a high resistance cell, meaning it does not hold the voltage, it was just dead, also the start AGM battery
was deep discharged and does not come back to life.
So first step was to remove the crap and fit the LFP with the balancer and solenoids to have a running 12V system again for the fridges and freezers to live a board and refit
the boat (bottom job with copper coat, replace the propane
by the electric galley
, install the solar arc
and the new controller, change the 220V installation
with the new inverter. You can find the details and changes in my thread related to the LFP / galley.
To do this I digged up the wiring
plans and checked out the circuitry and found much better ways to wire up and use the system.
Originally there are 2 separate 220V circuits ending on the switch panel, one for the shore power
for the boat (outlets, washing
machine, microwave, charger
heater) and one for the A/C. The generator connects with 2 fuses
to the switchboard and joins both when in use. The Inverter has relays that gives shore power
priority hidden somewhere near the chart table.
My new setup is different. The generator output goes straight to the Victron Quattro inverter and then is distributed either directly to the house 220V installation, the relays are removed. The output also goes where the former output of the generator was to the A/C system to the switch panel. Now I can use the inverter to run the AC and the house, the generator can pass through the inverter to run both too, I can separate the A/C from the house by the switch panel and also can run AC on shore power either through the house line and power assist by the Victron Quattro, or by a separate shore line as original designed.
On the other hand the shore power panel for the shore line can now switch between the old inverter as Input and Shore power - that allows to team up both inverters to 7kVA using the power assist if needed.
The switch panel and all fuses
remain, I have added some for the second Inverter and for the new galley appliances
, that have isolated separate 220V wiring
After finishing up the installation I had the first time the chance to really measure what on board uses how much power and what can run in parallel for how long without overwhelming the system. The checkpoints are:
- the REC-BMS - it measures and displays SOC, Ah, in and out, cell voltages, cell temperature, cell resistance, BMS temperature and battery voltage.
- the Victron BMV712 - it measures the Amps in and out, the Wattage, the Ah SOC and the system voltage. it is a little redundant but easy to read and it sends the data over BT to smart devices, and it has a programmable relay, that is very handy for my circuitry.
- the Victron Quattro has a USB MK2 interface, where you can configure it, and also measure all 220V and 12V currents, voltages and frequencies on the inputs and outputs there - using a computer - this helps to really find out what this devices use and how much power it draws on the 12V side to run them.
- The Victron SmartSolar MPPT
150/100 controller - it has its own retractable display and also sends all data via BT to smart devices, it measures incoming voltage and current
on the solar, outgoing voltage, current
and power and also accumulates Ah / Wh daily plus the times of bulk, absorption and float by day for 30 days.
This is how I've got the figures, but I have not did any estimations or spreadsheets upfront for planning or sizing. I was sure, my system will provide the power needed at any time simply by the assumption, that the factory installed system has done it before (with the factory optional upgraded system = 480Ah GEL usable 240Ah) and having now 4 times the capacity and 10 times the current and not needing the A/C at all. My main concerns were more the navigation
systems and board electric for winches autopilot
etc., fridges and freezers, water maker and the galley. I had an idea what it takes to re-charge such a battery and sized the appropriate solar array for the task given the available space aft.
It was during the spring sometimes quite chilly and I also used the dyson heater
when living on board and re-fitting. During this time I also disconnected the shore power and used only solar, battery and inverter for everything for weeks, including the power tools I used for the re-fit - just to see how much power I possibly can produce and use off-grid.
Then we set sails
for 5 weeks and never used a plug
nor the generator a single
time, staying in anchorages
, making our own water, and using anything including A/C - as described.
During sailing I do have daily checked and logged the SOC and looked at the solar figures, also measured consumption
of devices for curiosity, but have not done any spread sheet out of it, each day was different, we cope with good and bad weather
periods and the system was ding just fine as expected. I have also not advised the admiral to be cautious with power and water consumption
at all when she was cooking
or washing during our trip, except to turn off the inverter when not in use. I wanted a realistic load profile.
This was the shake-down trial for the system and I am very confident, it will serve us well for the journey ahead.