Hi Peoples from a new member, can you guess what I do for a living ?
This may get boring however, I apologize in advance.
Battery rumor no1. Assuming the battery is clean as in not covered in acid (conductive liquid) it will not discharge sitting on concrete.
You can tell if it had acid on it due to the acid eating your concrete. If your bored with a voltmeter in your hand one day take your pos lead on the pos post and drag the negative lead across the top of your battery. If it reads you have dried acid on it.If you have a sealed battery you have a problem ey.
If you are going to disconnect your battery for a long period of time, clean the top with soap and water and recharge it ever three months.
Specific gravity: 1100 dead flat 1240 to 1260 fully charged read with a hydrometer. The green window in the modern battery is a povo hydrometer.
If you unscrew one of the little windows it has coloured balls in it that float in the acid, when the acid level is correct and charged the green ball floats high ind full charged, when flat the ball floats lower indicating a change in color/flat, when the acid level drops the balls fall to the bottom showing replace battery.Realistically the actual fact is your"maintanance free battery" now requires maintenance that you can not perform due to it being sealed.The window turns black when the acid is no longer touching the window.
Maintenance free batteries make less mess but lifespan is less do to not being able to maintain them.
Specific gravity is close enough relevant to voltage.
Someone mentioned A/H ampere hour rating. This is no longer used today due to marketing but was a usable number. A 9 plt ford battery is around 50 h/r as in you can pull 50 amps for 1 hr and its flat or 1 amp for 50 hrs and its flat. So if someone asked me how long can I leave my radio on I could tell you.
CCA cold cranking amps has replaced this rating years ago due specifically to sales. That battery that had 50amps got a sticker that said 250 amps same battery but which one would you buy ?
CCA Started as... At 0 deg c over 30 sec how many amps can you pull without going under 9 volts......(useless information) lets say this battery rates at 250 cca
Next battery company rates them at 20 deg c over 20 sec and the same battery will now have a rating of around 350 CCA
I sell a old rated 70a/h battery that now reads around 600CCA. No one owns a car that can draw 600 amps short of putting thick battery cables on and bolting them together. Buy the heaviest one it has more plates
Next..Just because its fully charged does not mean its ok it needs a load test.
Without a load tester you can do it rough at home with a voltmeter. On a loadtester you would pull 150 amps on say a ford battery for 30 sec and it should stay over 9.5 V. Your starter draws that amount so make your engine not fire via spark or fuel and crank it for 30 sec and watch your voltmeter.
Lifespan: The lifespan of a battery is approx. 500 cycles. 1 Cycle being from charged to flat and recharged. As in 1 start (part discharge) and replacement recharge (via ALT) is 1 part of 1 cycle. Leaving the parkers on till flat and whacking a charger on is 1 cycle.
Turning something on with the engine running is NOT part of a cycle.
SO the larger the capacity of a battery (how heavy it is) the bigger the cycle is and the longer it will last.
I run a 17 plt truck battery in a hiace that takes one of those stupid little 7 plt jobs and I get around 8 years out of it.
And yes there was crap on TV tonight
