1. The Battery
An automotive battery is a type of rechargeable battery that supplies electric energy to an automobile.
Battery Types:
Lead-Acid Batteries
Lead-acid batteries are made depending on the application of the battery.
The flooded cell type, liquid electrolyte, is inexpensive but requires more maintenance and can spill or leak.
Some flooded batteries have removable caps that allow for the electrolyte to be tested and maintained.
More costly flooded batteries are valve regulated lead acid (VRLA) batteries, also called sealed batteries.
Explosive hydrogen gas is generated when the battery is overcharged. This makes them dangerous to use in the interior. There can be a venting hose attached to ventilate the gas to the outside. But the acid, which can be spilled, is also very aggressive to the metal and any surface.
Lead acid batteries stored in the interior? Not recommended.
AGM Batteries
The absorbed glass mat (AGM) type uses a glass mat separator, and a gel cell uses fine powder to absorb and immobilize the sulfuric acid electrolyte.
The cells are sealed so the degree of charge cannot be measured by hydrometer and the electrolyte cannot be replenished.
The advantage of being sealed is the usability in the interior of the vehicle since there is no or very little gassing.
AGM batteries have an outstanding life expectancy, if the batteries are not discharged more than 60% between recharge.
AGM automobile batteries are typically about twice the price than standard ones.
The AGM battery does not require to be built-in in an upright position.
AGM batteries have a significant advantage- they do not gas under normal circumstances. That means they can be used safely in the interior. No explosive hydrogengas as compared with lead acid batteries.
Attention:
There are different types of AGM Batteries available on the market:
SLI (Starting, Lights, Interior)
DC (Deep Cycle)
(explanation see below: The Difference Between Batteries)
and a combination of both, the so called starting and supply battery.
So buying an AGM battery does not include mandatory the ability to be used as a supply battery or as a starting battery!
Gel Batteries
Gel batteries are designed as pure supply batteries, they are built exactly like the AGM with the difference of missing the glass mat.
Cycle life is increased dramatically.
The internal resistance of gel batteries is higher than AGM or lead acid batteries.
They are therfor not designed to provide high currents for starting purposes.
Gel batteries can be up to five times more expensive than standard lead acid batteries, plus Gel Cell Batteries must be recharged correctly or the battery will suffer premature failure.
The battery charger being used to recharge the battery(s) must be designed or adjustable for Gel Cell Batteries.
If using an alternator to recharge a true Gel Cell a special regulator must be installed.
Gel batteries, depending on the model and manufacturer can be discharged down to 80%.
The Gel battery does also not require to be built in an upright position.
Gel batteries do also not gas under normal circumstances. They also can be used safely in the interior.
Lithium Ion Batteries
Lithium Ion Batteries are the new star on the sky.
Being 2/3 less heavier than a conventional battery, and occupying only 1/3 of the space as a normal battery.
A Lithium Ion battery has a life exspectancy of 10 years with one complete cycle per day(!).
A LI battery is short resistant and can be recharged within 1 hour!
So far so good:
Now the disadvantages:
You need a battery management system:
- to make sure every cell of the battery gets the same amount of charge
- all currents (in and out must be measured and computed
- the difference between a full and depleted LI battery is only 0.125V
- all cells must be equalized
- the bms must shut doown the cell in an unexpected event like overcharging
the most counting disadvantage: the price $$$
$1000 for 80 Ah and $1200 for 100 Ah(June 2013)
LI batteries are used in emergency vehicles or military applications. They are still way too expensive for the public.
The Difference between Batteries:
Starting Type Battery
The starting type (SLI, starting, lighting, ignition ) is designed to deliver bursts of power for a short time usually about 1% to 3% of the battery capacity, as is needed to start an engine.
Once the engine is started, the battery is recharged by the engine-driven charging system.
Starting batteries are intended to have a low depth of discharge.
They are constructed of many thin plates with thin separators between the plates, and may have a higher specific gravity electrolyte to reduce internal resistance.
these batteries are not designed to provide power for a long duration. Doing so shortens the life expectany drastically. Sometimes down to 3 up to 10 cycles.
A charge cycle is a complete discharge down to 10.8V and back to full charge. It is not necessary to deplete the battery completely to recharge it. Recharge can be performed at any charging state. There is no memory as in Nickel Cadmium batteries.
Deep Cycle Battery
The deep cycle (DC) type is designed to continuously provide power for long periods of time.
They can also be used to store energy from a photovoltaic array or a small wind turbine. Deep-cycle batteries have fewer, thicker plates and are intended to have a greater depth of discharge on each cycle, but will not provide as high a current on heavy loads.
The thicker plates survive a higher number of charge/discharge cycles.
Usually the thicker plates consist also of very pure lead around 99.9%.
This is the reason for the higher price.
Battery Depth of Discharge
Different battery types have different types of discharge
. This might be ok as long as they aren't used in a combined application:
(The + stands as an indicator that the true voltage can be higher, depending on the brand)
(To get the real idle voltage the battery must sit disconnected over a period of minimum 24 hours!)
It is very easy to see the difference between different batteries.
Remember: When a battery reaches 10.8V it is totally discharged- this is a dangerous battery level asking for battery damage.
A battery reaching this level of charge must be recharged as quick as possible.
Waiting to long and the battery will take permanent damage.
The slightest damage is costing you valuable battery capacity, serious damage will make the battery not accepting any charge anymore.
General rule of thumb: the less the deep cycle battery is discharged before being properly recharged again, the longer it will last.
Early Aging and deep discharge
The deeper the discharge, the earlier the aging process. There is a certain limit(usually around 80%) when aging starts to be accelerated. Secondly so called sulpahtion of the cell starts. This is a corrosion started at the battery plates.
It is generally said a battery is at the end of its lifecycle when the battery has dropped down to a capacity of 80% of it's nominal capacity.
T
ype of battery: .... DOD: 80%......DOD: 60%..... life span in years: (DoD: depth of discharge)
Starter Batt not usable for cyclic applications, ...... 5 years
VLRA ................. 50............. 350
GEL................... 600 .............900 ................. , up to 10 years
AGM ................. 250 .............450.................. , up to 8 years
round cell ...........400 ........... 650.................. , up to 10 years
(Optima)
What is a Cycle?
A discharge down to 80% with a complete recharge is called a cycle.
If you discharge a battery only down to 50% of its charge, this is called a half cycle. That means two of these half cycles equal one complete cycle. Now you get the idea, why to discharge the battery only down to 50%.
It simply extends the life expectancy of your battery.
Now discharge your battery only down to 25%. As a result you can do this 4 times before you reach one complete cycle.
So choosing the correct battery size is very important.
As a comparison;
A starter batter does deliver only 50 to 80 cycles. Yes, you are reading right!
But if you know that one time starting the engine consumes only is equal to 0.001 cycle you understand why it is possible to have about 50.000 to 80.000 engine starts with a single automotive battery.
Temperature has a huge impact on life expectancy of batteries:
If the normal temperature of 20°C is doubled life expectancy drops into half!
That means you need to store your battery in an as cool place as possible.
No engine bay temperatures, possibly installation into the shade!
Additional information found on batteries:
CCA, CA, Ah and RC.
These are the standards that most battery companies use to rate the output and capacity of a battery.
Cold cranking amps (CCA) is a measurement of the number of amps a battery can deliver at 0°F (-17.7°C) for 30 seconds and not drop below 7.2 volts.
A high CCA battery rating is important in starting battery applications, and in cold weather.
Cranking amps (CA) is measured at 32°F (0°C). This rating is also called marine cranking amps
(MCA).
Reserve Capacity (RC)
This is the number of minutes a fully charged battery at 80°F (26.6°C) will discharge 25 amps until the battery drops below 10.5 volts.
Amp hour (Ah) is a rating usually found on deep cycle batteries.
The standard rating is an Amp rating taken for 20 Hours.
You know this stuff already?
Then continue here, please:
83 pages of boring battery blabla, you can use to shock your mates...
Enjoy:
Introduction into Batteries and Charging Systems
