Boat Electrics (2)

Over the last few weeks I have been having a conversation with various people [on-line] about different battery issues. There is an expectation that the uninitiated people have and there is the reality that electrically aware people have. So I thought I could provide a few hints and tips towards understanding about wear and tear as well as the care of batteries used in a leisure bank on a boat.

Previously I wrote about your need to calculate the size of your boats power budget. Once you have the power budget figure. Only then can you then decide how big your leisure battery bank will need to be. I provided a sample chart with a list of all the electrical items in our boat. Estimate the time of use for each item over a 24 hour period. Typical items include any Bilge Pump, Fresh Water Pump, Shower Pump, Macerator, Navigation lights, Tunnel Lights, Galley lights, Saloon lights, Bathroom lights, Kitchen lights, Bedroom lights, Inverter, Television, Radio, Fans, Heating Pump and Fridge. Estimate the total amps consumption for each item over a period of 24 hours.

TIP: When choosing items such as lighting LED provides a low power options. On my boat if I turned on all the internal lights - the power consumed was over 20 amps. When the lights were replaced by direct LED replacements the load was reduced to just over 2 amps.

A battery is not fit for purpose at the end of its useful life. For instance when it will not supply the needed power budget for a given length of time. It is a false economy to delay replacing batteries that are not performing very well. You will be consuming diesel to make up the charge by running the engine when not on the move.

TIP: Never mix old and new batteries in a leisure bank. An old battery will help to reduce the performance down on a new battery. 

TIP: All electrical devices have a working voltage. Try to keep all your devices on your boat at 12 volts working. 

If the voltage of any device is not 12 volts. Then you will need to use an inverter. Turning on an inverter will consume some power for the inverter itself to work. It will also consume power converting 12 volts DC  to say 230 volts AC.  

Now lets suppose that the item we want to use is rated at 250 watts at 230 volts we can use a simple calculation called ohms law.  This is a typical value for a mains flat screen television.

Ohms law uses four things which are just notional values. They are Resistance, Voltage, Amperes and Watts. If you know the values of two of the items you can calculate the other unknown values.  For instance 1 volt multiplied by 1 amp = 1 watt.  1 volt at 1 amp = 1 ohm of resistance. 

Now lets suppose that the item we want to use is rated at 250 watts at 230 volts we can use a simple calculation called ohms law.  (a typical value for a mains flat screen television) So if we divide the 250 watts by the voltage which is 250 volts we can calculate that 1.08 amps are required to power the device. However, if we are converting 12 volts to generate the same power we can calculate the amps needed at 12 volts.  This is 20.8 amps. However, the inverter will also use some power to work and this would be 1 or 2 amps at 12 volts. rounding the figure out that's about 23 amps. 

The state of charge of a battery will extend or shorten the life of a battery. The more the battery is kept at full charge the longer it will last. If a brand new battery is allowed to remain discharged for a period of just a few weeks it will fail. Under charging or a flat battery will shorten its life as the plates will quickly sulphate. (You don't need to know any more than that)

Tip: when buying new batteries some outlets have a very high turnover and so batteries will have had a short storage time on the shelf.

Tip: some retailers will dry store a battery only filling with acid at the time of sale. Ask the retailer if they dry store their batteries. 

Over charging a battery will shorten its working life and also causing gassing which will release hydrogen which is an explosive mixture. So its a good idea when working with batteries to wear some eye protection as a precaution. High temperature within a battery will shorten its life in some cases by buckling the plates or by driving water out of the acid and  the concentrated acid will damage the plates. (You don't need to know any more than that)

The state of charge of a battery will extend or shorten the life of a battery. The more the battery is kept at full charge the greater the number of cycles it will last. If a brand new battery is allowed to remain discharged for a period of just a few weeks it will fail.

Tip: Batteries have a certain number of cycles of charge and discharge that they will complete. The deeper a battery is discharged the less cycles it will last.

To be continued.

Spring Summer Cruse 2015 ❼❶

Taverners Bridge Atherston to Curdworth Top Lock

Date 7 Sep 2015

Overnight the weather was a clear sky with a heavy dew.

Morning: Early start, so we enjoyed an early breakfast. A few hundred yards saw us arrive at the Atherston top lock.  Quite a few other boats on the move. We were planning a steady day as we aim to return to Birmingham.

Afternoon: Lunch taken on the move, as we proceeded from the Coventry Canal and on to the Birmingham Fazley Canal.  The canal was very quiet with only one other boat seen on the move. However, the Curdworth flight was set against us by a boat in front.

Evening:  Home made Greengage crumble cooked on the move from fruit picked from the side of one of the Atherton locks. Then it was an early evening after a bit of Television watching.

Wildlife:
Birds: House Sparrow, Tree Sparrow, Wren, Magpie, Carrion Crow, Rook, Jackdaw, Starling, Blackbird, Mallard, Mute Swan, Goldfinch, Chaffinch, Robin, Blue Tit, Great Tit, Coot, Moorhen, Cormorant, Grey Lag Goose, Canadian Goose, Grey Heron, Wood Pigeon, Buzzard, Sparrow Hawk, Lesser Black Backed Gull, Black Headed Gull, Swallow, House Martin and Green Woodpecker the highlight being a singing Whitethroat.


Butterflies: Meadow Brown, Common White and Small White.
Bats: Pipistrelle,  Daubentons,
Damselfly: Common Blue Damselfly, 
Dragonflies: Ruddy Darter

 

Today's Total.

Miles: 16.3
Locks: 23
Swing / Lift Bridges: 2
Tunnels: 0
Pump Outs: 0
Engine Hours: 9.8
Solar Panels: 5 Ah

Accumulated Total.

Miles: 2620.8
Locks: 1654
Swing / Lift Bridges: 362
Tunnels: 52
Pump Outs: 24
Engine Hours: 3487.1
Solar Panels: 23840 Ah

Dysfunctional Election.

The elections (plural) are coming. One is for the leader of the Labour party - which if the election goes the same way as the expectation from thousands of people signing up to vote. Should see a return to old Labour policies. The electorate have awakened from their slumbers. Its taken quite some time. However, they have been prodded awake by scandals in Westminster as the MP's selectively fiddle their expenses.

The other election that is taking place is for representation to the Council of the Canal and River Trust. Now you may remember that the positions on council were for supposedly independent boaters. However, in a parallel somewhat akin to shenanigans at Westminster where there is much gerrymandering. Well surprise, surprise a spoon full of gosh and golly and a large portion of shock and horror. The anointed four were by some unhappy coincidence all in the higher echelons of the Inland Waterways Association.

But here is the rub, whereas our MP's like to be seen to represent their electorate. Our MP's  hold surgeries and attend various meetings often with the electorate. Ostensibly to gather the wants and needs of the electorate. Like a Kafkaesque novel, our representatives to the Trusts council went into omerta mode. A sort of secret silence and nothing has been heard of them for the last three years. To be blunt, the silence has been palpable and at the same time absolutely deafening.

Boat Electrics. (1)

Over the last few weeks I have been having a conversation with various people [on-line] about different battery issues. There is an expectation that the uninitiated people have and there is the reality that electrically aware people have. So I thought I could provide a few hints and tips towards understanding about wear and tear as well as the care of batteries used in a leisure bank on a boat.

A typical 12 volt battery consists of six cells. The cells can each hold a charge of up to 2.11 volts. By linking the cells together in series inside the battery, we can obtain a larger output voltage. Often when a battery fails it is just a single cell that has failed. A multi stage or intelligent battery charger should be used from time to time. What this does is equalise the voltage in each cell.  The three stages are Bulk, Absorption and Float. It brings up any cell that is low to match its cell mates inside the battery. Often its called an equalising charge. (You don't need to know any more than that)

A fully charged (wet cell) battery will give a voltage across the battery terminals measured with a volt meter of 12.7 volts. However, when charging a battery we will often use a charging voltage of about 14.4 volts. When the battery is removed from the charger the battery will display an elevated charging voltage for several hours. After about 12 hours the voltage will settle back to its quiescent state of 12.7 volts. (You don't need to know any more than that)

Batteries come in different constructions and types.  Some batteries are constructed to give a lot of amps for a short period in time. Typical of this type is a starter battery. It delivers a huge amount of power to turn over the engine. Think in 100's of amps. The other type is a leisure or traction battery which is constructed to supply less amps but for much longer periods and to survive a larger number of  deep discharge cycles than a starter battery. (You don't need to know any more than that)

Leisure battery construction come in several different groupings. Wet cell and zero  maintenance. Wet cell batteries are the cheapest option and require periodic topping up of the cell fluids. Zero Maintenance require little or no attention. My own personal preference is for wet cell batteries as I can check each cell for liquid levels and the first sign of a suspect battery is low fluid within a cell. (You don't need to know any more than that)

When we charge a battery we are putting power into the battery. The battery converts the electrical power into a chemical change inside the battery. When we take power out of a battery the chemical change is then reversed to supply the electrical  power.  (You don't need to know any more than that)

Batteries will not last forever, no matter how well you look after them. From the moment the battery acid is first poured into a battery - the deterioration in performance begins. (You don't need to know any more than that)

The correct size of battery bank needs to be calculated. The battery bank size depending on your requirements. I wanted our battery bank to provide enough power for two typical days operation without needing to run the boat engine or to plug into a shore line.  

You need to calculate the size of your boats power budget. Once you have the power budget figure. Only then can you then decide how big your leisure battery bank will need to be.  

TIP: All electrical devices have a working voltage. Try to keep all your devices on your boat at 12 volts working. 

In this instance an estimated 107 ah are required each day.  Over 48 hours an estimated 214 ampere hours would be required.  In this case I settled on 4 110ah batteries in the leisure bank.  I had a second power source available which would put some guestimated charge into the battery bank (Solar Panels) which was not used in calculating the power budget. 

In my case I decided that a cut off point for battery voltage at 12.40 volts. This is when about 25% of the available battery capacity would have been used leaving 75% available. This has proved to be quite workable. As on sunny days the solar panels often add considerably more that the guestimated 20ah a day.

To be continued.

Spring Summer Cruse 2015 ❼⓿

Rugby VM to  Atherston

Date 6 Sep 2015

Overnight the weather was clear and cold. We lit the stove!

Morning: Decided to have an early start as the weather was so good.  Quite a few boats on the move. However, we ended up behind two hire boats who had no idea how to steer.  From Rugby to Hawkesbury stop lock is was at tick over speed and the hire boats had several coming together with the bankside and boats coming the other way. It was prudent not to pass the boats.

Afternoon: Sutton stop and we met up with Tim West and Pru Scales on their boat. Lunch was then taken on the move. Found an empty  mooring in Atherston that we had used before and settled in to watch Formula one.

Evening:  An evening of television and catching up with a backlog of emails.

Wildlife:
Birds: House Sparrow, Tree Sparrow, Wren, Magpie, Carrion Crow, Rook, Jackdaw, Starling, Blackbird, Mallard, Mute Swan, Goldfinch, Chaffinch, Robin, Blue Tit, Great Tit, Coot, Moorhen, Cormorant, Grey Heron, Wood Pigeon, Lesser Black Backed Gull, Black Headed Gull, Sedge Warbler, Swallow, House Martin and the highlight being a Bullfinch.

Butterflies: Meadow Brown, Common White, Small White and Skipper.
Bats: Pipistrelle,  Daubentons,
Damselfly: Common Blue Damselfly.
Dragonflies: Ruddy Darter and Four Spot Chaser.

 

Today's Total.

Miles: 23.6
Locks: 1
Swing / Lift Bridges: 1
Tunnels: 1
Pump Outs: 0
Engine Hours: 8.2
Solar Panels: 15 Ah

Accumulated Total.

Miles: 2604.5
Locks: 1631
Swing / Lift Bridges: 360
Tunnels: 52
Pump Outs: 24
Engine Hours: 3477.9
Solar Panels: 23835 Ah