A battery is like a piggy bank. If you take out and don’t put back in you’ll soon have nothing.
But, it’s more complicated than that. If you don’t put back in the same amount you take out, or if you leave it empty or partially empty for even a short time, the piggy bank will shrink.
Yes, Batteries are complicated, sensitive and expensive, they need to be cared for.
The most common destroyer of deep-cycle batteries is discharging too deeply and/or leaving in a discharged state. Once a battery has started to shrink it will continue to weaken.
VOLTAGE - Is a difficult and unreliable way of working out how charged your battery is because voltage goes up and down markedly...I f you’re charging, the voltage will go up to 14V+, even if the battery is completely flat. Or, If you have an appliance/s running, it can drop to 12V even if it’s full. It’s only the RESTED voltage (no charging and only light discharging activity for the previous 4-6 hours) that gives you an accurate reading.
A rested 12V battery has only 1 volt between full and empty. A flat battery is around 11.8Volts and a fully charged battery around 12.8Volts. A voltage reading above 12.8 doesn’t mean your battery is full, it just means you’ve recently had a charging source, the battery could be completely flat but show a voltage of 13.9V. The lesson is VOLTAGE IS COMPLICATED… If you don’t completely understand voltage DON’T RELY ON VOLTAGE readings alone!
RECHARGING - As a battery gets full it gets harder to charge so the final 25% requires a higher voltage and can take as long as the first 75%. The recharging speed also varies depending on how large the charging source is. So, what does this mean in real life… A generator running a 15Amp, 3stage charger can offer 15Amps charging and take around 8-10 hours to fully recharge a flat 100Amp hour battery. Alternator charging of 20Amps whilst driving will take 6 hours of driving to get the same battery to 80% charged and probably wont be able to go any further than that because its single stage charging so doesn’t get up to a voltage high enough for full charging. It’s trickier if you’re discharging power at the same time.
It’s a very complicated calculation to work out how long a charging source needs to run in order to replace a fully or partially discharged battery, and It’s very easy to get it wrong.
IF YOU GUESS and get it wrong your battery will suffer.
AMPS – This is the measure of power IN or OUT at a current time. If you use 1Amp for 1hour you’ve used 1Amp hour, 1 Amp for 24 hours = 24Amp hours. If you can work out exactly how much is going in and how much is going out and for how long each day you could work out exactly how much power your battery still holds. Sounds simple doesn’t it, but it’s not! Not unless you have a good battery monitor which carefully counts the AMPS IN & OUT.
BE AWARE : Your battery monitor is simply an intelligent gauge. It doesn’t control or influence the battery or any equipment in the power system, it just lets you know what’s happening. Your battery monitor has no control of anything, except your peace of mind.