Quote:
Originally Posted by crash test dummy
ok ???? my turn for stupid question .. if charger shuts off after fully charging batteries and you unplug it and plug it back in , how can it turn back on if batteries are fully charged ? i understand the resting volts and surface charge ... but wont it overcharge batteries ?
jonnie please speak redneck so i understand
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The charger shuts off when the on-charge voltage reaches about 45V and the pack voltage starts to rapidly decrease.
If you wait a couple hours or so after the charger shuts off, it will be down to about a volt or so above the at-rest voltage and the charger will hit them with the full amperage and taper off, until the on-charge voltage is once again up to about 45V.
If you don't wait very long after the charger turns off, the charger won't run very long.
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What is or isn't "Fully" charged is subject to interpretation, therefore "Overcharging" depends on how "Fully" charged is defined...
Technically, a lead-acid deep-cycle wet-cell is not "Fully" charged until the Specific Gravity of the electrolyte in a cell ceases to increase while a charging current is passing through that cell.
Open circuit terminal voltage tracks specific gravity (SG + 0.845 = Cell voltage), so it can be inferred that when a battery's (two or more cells) terminal voltage ceases to increase while a charging current is passing through it, it is fully charged.
Most, maybe all, of the older automatic golf cart battery chargers and many of the newer ones, simply look for a specific On-Charge voltage to terminate the charge, rather than using the far more complex change in voltage over time. The voltage picked (about 45V for a 36V charger) is less than "Fully" charged for most batteries, but close enough on average to adequately charge the batteries used in golf carts and the like, for nominal performance and longevity, while being low enough not to damage older and/or weaker batteries. (Hobson's Choice)
The SoC vs Voltage charts are based on empirical data using matured (broken in) batteries that were charged with typical golf cart battery chargers and rested. The 100% SoC voltage is the average voltage the batteries tested settled down to after 24 hours, rather than what is truly 100% SoC for a truly "Fully" charged battery.
All the charts I've seen are based on studies done by Trojan using Trojan batteries and that is why some brands of batteries don't line up at the top of the chart like most people think they ought to. It is also why my 3.5 year old batteries have an At-Rest voltage that is greater than the 100% SoC voltage listed.
To answer your question if I what I did was overcharging my batteries, I don't think so.
Unless you use a charger that continuously puts out a high constant current, say about 1/10th the AH rating of the battery, or more, there isn't much danger of actually overcharging the batteries since you would have to get the on-charge voltage above 2.8VPC (50.4V for a 36V battery pack) on a good battery and most of the chargers we have won't do that.
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Can a person with yellow skin (like in your avatar) have a red neck, or does it just look orange.
