1. What are we talking about in this video?
2. Why are we changing our current battery system to lithium.
3. What did we do to determine we required lithiums.
4. What are the problems that we faced in the past three years.
5. How do we think lithiums will improve our system.
6. why we feel it is necessary to change our current electrical system on narrowboat Dunworkin.
Disclaimer- All the information and considerations in this video are purely from our own experience and information gathering.
Our experience will not necessarily apply to any other installations as other people’s circumstances may differ, however this could be used as a general guide.
We have not been sponsored by Victron or any other company to make this video.
We have now had the boat for more than 3 years. Our current system consists of 5 12volt sealed lead acid batteries totalling 710ah. A 3000w inverter which provides 230 volts,
We also have 4.4 Kva generator, a dedicated leisure 110a alternator connected to the engine and 6 x 100ah solar panels.
Over the last 3 years we have used all of these systems extensively.
Pat is going to give you some background information of his experience of electrical systems.
My career before becoming a engineering manager, was as a electrical controls engineer working for Honeywell controls systems in UK for around 15Years.
My job consisted of working on large commercial buildings, maintaining the building controls infrastructure or BMS building management system, The BMS is a computer controlled electrical system which controls all aspects of heating, cooling, electrical, inputs and outputs and many other functions within the building, One of my primary roles was to make sure that the buildings computer suite which contained multiple service systems were supported by a cooling system and a UPS, uninterrupted power supply, this was made up of hundreds of lead acid batteries.
This has mean’t Pat has approached the difficulties we faced with our current system in the same way as he would a project at work, by evaluating and quantifying what is needed to give us the best options for winter cruising.
All of my calculations and results have been defined around the British Standard 17th Edition Electrical Installation Regulations.
( But I am not a Marine electrical engineer )
We installed test equipment to first determine what was happening with our current system and why we were not getting sufficient power for our means.
We installed 6 battery shunts, 1 for each battery with a relay isolating each battery connected to a control panel which collected data from all of the battery’s and sent them to a cloud Victron remote monitoring system, Known as VRM.
This was set up in November 2020 while on the Llangollen canal. As a result we have data for the past 6 months.
The results of this have been quite enlightening
The first graph shows our solar yield from December 2020 to May 2021. As you can see the solar collected over this period during the winter months is extremely low but picks up as the year progresses into Spring.
The next graph shows the battery voltages over the same period.
On average our lowest voltage was 11.4 and the highest 13.2. Also notice the areas highlighted which were as a result of being plugged into Shore power for a period.
This is when our batteries would have had the chance to be fully charged and in Float.
The conclusion from this graph is that during this period we were only using the engine alternator to charge the batteries and as you can see this comes nowhere near the float condition required to keep the batteries in good health.
The next graph shows the load consumption on the batteries in Amps.
as you can see there are some peaks and troughs but on average our consumption over that period is relatively consistent.
We want to continuously cruise throughout the year.
To look after and get the best out of a lead acid, Agm, gel or lead carbon system we would need to go into a marina to hook up over the winter period as our data has shown us in this country we don’t get enough winter sunshine to run on solar.
And our engine alternator will not provide the correct voltage rise to sufficiently maintain the battery health.
A lead acid system has a 3 stage charging process.
When charging lead acid,AGM, Gel or lead carbon batteries, the first stage is Bulk, this is when the battery is of low resistance and accepts the charge quickly as the name suggests.
2nd stage is Absorbtion, when the batteries are almost full, this stage conditions the battery.
3rd stage is Float which is just a trickle charge to maintain the battery at a full stage of charge.
From the Bulk state to reach Float can take a considerable amount of time which has a cost implication.
As you can see from the 2nd graph showing the voltages, running the engine to charge the batteries via the alternator, which is only 50% efficient means the batteries never reach Float stage, which is considered fully charged.
This is why we purchased a generator with the aim to charge the batteries more efficiently on 230v
Running a generator is more efficient and float can be achieved however due to the 3 stage charging strategy the generator would start off at running at high revs and as the batteries become fuller the generator would reduce its speed running at a much lower speed. This resulted in the injector becoming clogged and sooted up leading to the generator choking up.
In the summer however, we use our solar panels to charge the batteries, which also has a 3 stage controller, and providing we have long enough sun spells we can charge the batteries to the float condition.
Another consideration for battery technologies are that regardless of whether they are lead acid, AGM, Gel, lead carbon or lithium they all will degrade over time but will degrade faster if the temperature in the area they are stored are above or below certain values.
The fourth graph shows over the same period our engine bay temperatures this is measured from the top of the batteries and therefore is a good indication as to what temperatures the batteries are working under.
Lead acid battery chemistrys do not perform very well in cold conditions. Their output voltage and current drops dramatically when the The temperature is too cold. The chemistry cycle within the battery slows down and therefore will not yield as much output performance as at normal operating temperatures. Adversely in high temperatures the batteries will over produce and Sulphation will harden and thereby reducing the life expectancy dramatically.
This is why large companies spend tens of thousands of pounds protecting their batteries by making sure that they remain at the correct temperature.
So lets talk about some cost implications. For the same period we kept a record of our fuel costs. Last winter we mainly used the generator to charge the batteries on days that we did not travel. During this winter, which of course we travelled very little we used our engine mainly to charge our lead acid system. Our overall average cost was significantly higher for this year.
In addition this meant that our running hours increased significantly and our service costs have also gone up.
Battery manufacturers will talk about cycles and give you a value of 300 to 1000 cycles for a lead acid battery and 5000 cycles for a lithium battery
So what is a battery cycle it is one charge and one discharge that is a cycle so every time a battery is charged and discharged it counts as one cycle even if the battery has only been discharged by 30% and recharged that is classed as one cycle
But of course all this is dependent upon the temperature in the conditions that they have been stored in and are used in and how they are charged and how long they are discharged all of these things will be a factor in its cycle life
The ideal situation is to control all that goes in and all that comes out of the batteries keep them in the correct temperature and treat them the best you can this will give you the longest life out of any battery
For current to flow through any battery a voltage is required. For a 12 volt system this is typically 12.5 to 13 volts, however as the temperature rises falls the voltage can be affected. Equally when the battery is being used and the current is flowing from the battery to the load, a lead acid battery will have a discharge sag meaning that the voltage will drop from say 12.5 to 12 or even lower.
This battery sag creates a problem for some electrical appliances which require a 12 V supply and therefore may they may not work efficiently
So why Lithium’s?
One characteristic which makes lithium batteries better for us, is that the charging cycle is not required and the batteries will charge much faster. Lithium can accept a higher current input into the batteries, meaning we can charge them at a higher rate and at a faster time.
Using the generator will be the most efficient way to charge the batteries in the winter when there is little solar.
This will mean that our generator will need to work harder and will be put under more load, thereby reducing the possibility of choking up.
Look back at the 4th graph, any battery that is stored in high temperatures will degrade quickly.
Lithiums require the temperature to be between 25 and 10° C to work efficiently.
For this reason we will be installing the batteries in an inside cupboard rather than in the engine bay.
Space is also a consideration, we need to install them in an inside cupboard and we only have a small cupboard where we can install all of the equipment necessary for our new lithium set up, the lithium technology provides a higher amp hour rating than lead acid in a smaller package.
One of the biggest pros for having lithium batteries is that they have a stable voltage output and do not have a sag as much as lead acid. This means that their output remains quite stable and electrical equipment will work better.
Even though the initial investment is considerable, we believe that the overall cost savings on replacement batteries, fuel, engine servicing, stable voltage and ease of control and monitoring will lead to a much improved and worry free electrical system.
In the next of this series of videos we will be discussing out Lithium requirements for now and the future. What we are getting and Why?
Potential future plans and what what other systems we considered.