Highly delayed, but ground work for posting video and text results for fixed, variable, and in motorcycle current delivery tests of batteries.
Current delivery ratings are ways to quantify how much juice a battery can deliver in a short period of time.
Amp hour ratings of batteries can be compared to fuel tank size. A larger gas tank will allow you to ride further, but it has little affect on how fast your bike will go.
CCA and other current delivery ratings of your battery are analogous to how many horse power your engine puts out at full throttle.
All batteries have internal resistance as well as other variables that affect high rate current delivery. As current demanded from a battery gets high, the battery voltage lowers temporarily due to the above.
How much the voltage lowers depends on how much current is demanded and the batteries ability to deliver which is quantified by battery current delivery ratings.
Lets say battery (A) has an honest 200 CCA rating. Battery (B) has an honest 300 CCA rating.
Now lets say the bike we are starting is a Moto Guzzi Stelvio 1200 NXT and it’s 70F out. Under these conditions the Stelvio will draw around 180 amps while the motor is being cranked over.
With battery (A) installed in the Stelvio, the battery terminal voltage will drop to perhaps 10.8 volts in the 5 seconds the engine had to crank before starting.
Since battery (A) has a 200 CCA rating that the Stelvio starter did not exceed, is there any difference when using a higher CCA battery?
You bet! With battery (B) installed, the terminal voltage would only fall to, say, 11.3 volts.
So why all the fuss about voltage? Voltage multiplied by current equals POWER, and power is good :)
First is the effect on the starter. We have probably all experienced a bike cranking slowly or maybe not at all due to a low or worn out battery. This happens because such batteries can’t keep the voltage up. Likewise, battery (B) keeps the voltage higher then battery (A) and will crank the engine over that much faster.
Faster is better because it is more likely to start your bike. Either of these batteries will start a well maintained Stelvio on a warm day, but what if the Stelvio is not happy? Lets say the fuel injectors are a little plugged, spark plugs are a little wet or fouled, you filled up with old or shitty gas..... I could go on and on, but suffice it to say, for whatever reason the bike is harder to start then usual. In this case a higher CCA battery will turn the engine over faster which lowers compression loss, reduces the time fuel has to condense when cold, and turbulates and mixes the charge in the combustion chamber more. The above will make the engine more likely to start.
Cranking terminal voltage also has an effect on other things. Fuel injectors can stick from time to time due to internal corrosion or fuel varnish that acts like glue. Fuel injectors are opened by an electric solenoid. A fuel injector that sticks closed with the stock battery will often open and work free if higher cranking voltage is maintained because the voltage the fuel injector solenoid sees is directly proportional to how hard the solenoid pulls. More power is better!
The same is true of the ignition system. When the cranking voltage is higher, the coil(s) produce a stronger spark that is more likely to ignite sub optimal fuel mixtures.
The list goes on, but take it from me, CCA matters and MORE power is BETTER.
During my 20+ years in the service industry, I could not even begin to count the number of vehicles towed in that I started simply by attaching a boost charger or large jump battery. In most of these vehicles something was wrong that had nothing to do with the battery, but more power allowed me to start these vehicles and drive them into my stall, and nowhere was this truer then my time in a BMW motorcycle service department but i’m sure this holds true for other brands as well.
Further, more battery power is better for the bike starting system in several ways. Bikes using a sprag clutch to transmit power from the starter are not damaged by low voltage (though under low voltage they certainly won’t start the bike) but some bikes use starters that must shove a pinion into the flywheel to transmit starter power to the engine. Whether done by bendix or electromagnet, these starting systems can destroy themselves and the flywheel ring gear when repeatedly operated with low voltage because the power applied to the starter can be to low to fully engage the pinion.
Next up, the starter relay contacts are themselves propelled together by an electro magnet. Too low of voltage and these contacts will chatter, arc, weld together or melt down.
Enough power is ok. Too little power is bad. MORE power is better :)
On an adventure bike that just might be 500 miles from a dealership when something goes wrong, more battery power can make the difference between joy and misery.
CCA (Cold cranking amperes) was coined and defined by the Battery Council International and is defined as follows:
“The number of amps a battery can deliver for 30 seconds, without falling below a terminal voltage of 7.2 volts (12 volt battery) when the battery is 0 degrees fahrenheit (-17.7C)”.
Later this definition was standardized and adopted by S.A.E. and precise test methods are contained in SAE J537
CA also called MARINE CRANKING AMPS is the same as above but at a temperature of 32 degrees fahrenheit (0C).
HCA is “hot cranking amps” and is the same values as above but at 80 degrees fahrenheit (26.7C)
PHCA was coined by Odyssey. It seems to be the number of amps that can be supported for 5 seconds which is reasonable as one rarely holds down the start button for 30 consecutive seconds and still has a starter motor that is not on fire, but since Odyssey did not go on to define “down to what voltage” the term is not yet useful.
CCA PBEQ (PB= lead, EQ= equivalent) This term as used by Shorai is meaningless. The reason I call this term meaningless is that it implies that one can use this number and get comparable performance from a Shorai battery to a lead/acid battery with the same CCA rating when You can not.
LiFePo4 power sports battery manufactures certainly can’t use SAE J537 to rate the CCA of their batteries because the test methods do not account for LeFePo4 batteries needing a period of current flow and then rest before full CCA can be realized.
They could however write CCA*1
“*1 CCA achieved after cranking for 5 seconds then resting for 1 minute to internally self heat lithium cells”
unfortunately since battery sales have always been driven by ratings, once Shorai (I believe they were the first) made up this BS term, other manufactures had to follow suit or die.
How to test the for the actual CCA of a battery:
Simple. Take a battery that has been cold soaked at 0F, apply X number of amps continuously for 30 seconds. Record the minimum terminal voltage throughout this test. If the reading remains above 7.2 volts, recharge the battery and apply higher amps until you find that magical number or at least the number you wish to advertise on the battery.
Some time ago, manufactures of cheap batteries successfully petitioned BCI to come up with a gentler field test for battery CCA. I don’t remember all of the posited reasons, but the real reason IMO is that especially as it ages, a cheap battery will have too thin of a buss to sustain a full rated CCA load without the buss burning through or cracking.
There are other reasons, technicians didn’t like wheeling around a carbon load tester and preferred a cute low power hand held, and also if the buss does burn in half during the full scale test, the battery occasionally explodes.
I am a stickler for tradition when tradition works :)
On quality batteries, CCA means this battery really WILL put out this much current when fully charged
Up next, actual CCA tests