I am trying to stop assuming that I understand how things work so I do a bit of research on everything I admit I don't know or understand! Crazy endless quest I reckon.
A friend recently had to replace the starter battery on his narrow boat (Listel engine SR2 from the 70's). I found out that he needed a 90Ah/900v starter battery only (not leisure or both use) and which should be the same as his leisure battery, meaning they must both be either sealed or flooded (this will help recharging correctly and ensure a longer life for the batteries).
"when it comes to starter batteries it the cold cranking capacity that the factor here. A cranking motor can draw 300 amps or so when cranking and in winter a cold engine can take some turning. Cold cranking capacity is not the same as the ampare hour rating. However the so common 110 AH batteries will do it. Generally speaking Deep cycles don't work so well a cranking batteries when weather is cold but nothing else can be found these will do. Most battery suppliers with give both AH capacity and cold cranking capacity in amps marked CCA."
(for the boaters and vanners)
"A lot of car batteries are now the sealed type , make sure you get the same as your leisures , either sealed or flooded .
Why would it matter if it was the same type as the domestic/leisure batteries?
answer: When charging from the alternator a sealed will take 14.4 , flooded 14.8 , the alternator will either stop charging at less than 14.4 so your leisures are not getting a full charge or you run the risk of overcharging the starter if it goes up to 14.8"
I found an interesting article entitle
Car battery explained with a few explanatory inages such as these:
and tips like
"Temperature
matters! Heat kills car batteries and cold reduces the available
capacity."
"
Cranking power:
As the temperature
drops, the cranking power required by the car increases. However, as more
cranking power is used, the amount of battery power available decreases.
Cold Cranking Amps (CCA) is critical for good cranking ability. It refers
to the number of amps a battery can support for 30 seconds at 0°F
until the battery voltage drops to unusable levels. For example, a 12
volt battery with 600 CCAs means the battery will provide 600 amps for
30 seconds at 0°F before the voltage falls to 7.20 volts (three cells).
The higher the CCA, the more powerful the cranking ability.
If you live in a cold
climate, you should consider the CCA rating when choosing a battery. If
you live in a very hot climate, you don't need as much CCA."
"An
Amp (or Ampere's) is the stand unit that current is measured at.
If there is a 1 volt drop across a 1 ohm resister, then 1 Amp is
drawn. This formula is know as 'Ohms Law'. However an Amp is a BIG
unit, for smaller electronic devices (i.e. computers) its usually
measured as milliamps (mA) which is 100 th of an Amp."
The FAQ at the bottom of the article sums it up well.
"
What should I consider
when buying a battery?
SIZE: What are the
dimensions of your original battery? Will it fit into my battery tray?
POWER: What are the Cold Cranking Amps (CCA) required to power your vehicle?
WARRANTY: Automotive batteries are backed by a warranty package. Chose
what is right for your vehicle's needs.
When I am replacing
my battery or cleaning the terminals, why is it important to remove the
ground wire first?
Before you start,
always check the type of grounding system the vehicle has. If you remove
the positive connector first in a negative ground system, you risk the
chance of creating a spark. That could happen if the metal tool you're
using to remove the positive terminal connector comes in contact with
any piece of metal on the car. If you are working near the battery when
this occurs, it might create an ignition source that could cause the battery
to explode. It's extremely important to remove the ground source first.
What does CCA mean?
Cold Cranking Amps
is a rating used in battery industry to define a battery's ability to
start an engine in cold temperatures. The rating is the number of amps
a new, fully charged battery can deliver at 0° Fahrenheit for 30 seconds,
while maintaining a voltage of at least 7.2 volts, for a 12 volt battery.
The higher the CCA rating, the greater the starting power of the battery.
How do I safely
jump start my battery?
There is a particular
sequence which should be followed. This reduces the risk of short circuiting
the battery and damaging your alternator etc. The sequence is as follows.
- Switch off the
dead car and ensure all other electric devices (i.e. head unit) are
switched off. Position the dead car and the good car close to each other,
but NOT touching each other (could course a short circuit when jump
starting).
- Connect one end
of the red jump lead to the positive (+) terminal on the dead battery.
- Connect the other
end of the red jump lead to the positive (+) terminal on the good battery.
- Connect one end
of the black jump lead to the negative (-) terminal on the good battery.
- Connect the other
end of the black jump lead to the chassis or large bolt/nut/bracket
on the engine. Anywhere away from the negative terminal of the dead
battery. Do NOT connect it to the negative terminal (-) of the dead
battery (explained why latter).
- Ensure that none
of the jump leads will come in contact with any rotating or moving parts
in the engine bay. Switch on the good car and let it idle for a few
minutes. This will allow the two batteries voltages to 'settle' and
the alternator to do its job.
- Start the dead
car, hopefully as the batteries are now connected in parallel, there
is twice the amount of current available to turn the engine over. Once
running disconnect the jump leads in the opposite order of connection.
Why can't the jump
lead be connected to the negative (-) terminal of the dead battery?
When
a battery is charging a chemical reaction is present. This produces a
waste product, which is flammable gas. When you connected the last jump
lead up to the dead car, there should be a spark (generated from the good
battery). You want this spark as far away as possible from the battery.
Otherwise there is a possibility that the gas will ignite and the battery
could burst! Which means your hands could be covered in sulphuric acid!
See the news snippet on the left . Unfortunately any spark or naked flame can ignite the flammable
gas. Which in this persons case has now lead him to hospital with burns
to his face and hands.
What difference
is there between a petrol car battery and a diesel one?
Not much, only the
storage capacity of diesel batteries are much bigger, hence they are physically
a bit larger. Plus they have a higher CCM so they seem to last longer."
source: topbuzz.co.uk
Deep Cycle Batteries
The difference between deep cycle batteries and more traditional lead
acid car batteries is that deep cycle batteries use much thicker lead
and lead dioxide plates. This diminishes the surface area on which the
chemical reaction can occur. It gives the battery the ability to
discharge over and over, but diminishes its ability to produce a lot of
power over a short time.
Here are a few more links if you want to learn further. I usually need to read 10 times the same thing to get it in(!!)
One to understand
how Volts, watts & amps work for batteries.
One about the
different types of batteries, starting batteries, deep cycle batteries.
And a
quick video from engineering explained (youtube channel) for the lazy reader or those for whom images and sound work better - but i warn you it's a bit far fetched... hopefullyi find something more straight forward soon...
If you find one post it in a comment please!
And a good article from my friend on
leisure batteries for caravaning, boating, marine purpose more specially (approved and recommended by ilve-on boaters I'm in touch with!).
Lastly an article to correlate the previous one on
leisure batteries structures and batteries systems in general.
