Cells And Batteries Flashcards
3 types of lead acid battery
Flooded cell, gelled electrolyte, absorbative glass mat (AGM)
Open circuit voltage of a lalanche cell
1.5v
What is the open circuit voltage of a lead acid battery?
2.1v
What happens to effiency of a lead battery when it gets cold? Why?
Its efficiency decreases. Because the water inside the battery begins to freeze.
State advantages to gelled electrolyte over flooded cell lead batteries.
They are sealed
They cant leak
Can use jn any orientation
Almost maintenance free
Corrosion resistant
Which of the 3 lead acid battery types has the lowest internal resistance
AGM Absorptive glass mat
What does VRLA stand for, and what are the two types of them?
Valve regulated lead acid.
Gelled electrolyte
AGM
Open circuit voltage of a nicad battery
1.2v
Advantages to nicad vs lead acid batteries
Higher energy to weight ratio
Low internal resistance
Faster recharge rates
Long storage life no need for mait charging
Not subject to freezing or over heating
Can completely discharge/recharge without damage
Barely have to add water so lower maintenance.
Are nicad batteries sealed or vented
Both
How much power can a 1kg lithium battery store
150 watt hours
Advantages to lithium batteries
Lightweight
Highly reactive
Hold charge well
No memory effect
Can go through hundreds of charge cycles
How much enerygy does a lithium battery lose a month
5%
Disadvantages of lithium batteries
Start degrading as soon as manufactured
Sensitive to hight tempreture
Comete discharge destroys it
Must be internally monitored which increases cost
They can be a fire hazard
Expensive
Lithium cells produce _x the volagge of an alkaline cell
2
What does the ptc do in a lithium battery
Prevents over heating
What does amp hours represent
The total energy capacity of a battery
How do you calculate amp hours
Amps x time
How do you calculate current from amp hours
A-H / time
How do you calculate terminal volatge of a battery
Battery voltage X 91%
What is cranking amps
Current drawn from a charged battery for 30 seconds at a temp of 0 celcius without cell voltage dropping below 1.2v per cell
What is cold cranking amps
Current drawn from a charged battery for 30 seconds at 0 farenhite without cell vtage dropping under 1.2v
Why do we need to know cca
Because not all starters are the same
What is reserve capacity rating
The number of minutes a lead acid battery can deliver 25A at 25 celcius before comgage drops below 1.75v per cell
With a 10 hour rate a 12v battery has a capacity of 56 AH.
What current was used to obtain this result?
What is the minimum allowable terminal voltage for emergency power after this test.
1)current= AH/time = 56/10=5.6A
2) Terminal voltage= 91% of 12v = 10.92V
Reserve capacity is quoted in?
Minutes
What steps do you take to calculate internal resistance of a battery
Take the terminal voltage with no load and subtract the voltage when a load is attached, this is you volt drop from internal resistance
Then use ohms law with the load amperage and voltdrop from internal resistance to calculate resistance.
What is the formula to calculate internal volt drop due to internal resistance in a battery
Vnoload - Vwithload = volt drop from internal resistance
What formula calculates internal battery resistance?
R=Vvoltdrop from resistance/current of load
