Battery Genius Needed

[Littleremnant]

If you charge a battery under 12.6 volts or a certain amperage constantly, will it hurt it? Some articles say you don't have to have a regulator if you don't overcharge the battery, but how much can you consistently put in one before it hurts it. Could you make an alternator that puts out lower than 12.6 and let it charge all the time??? Would that hurt it?

[richhagen]

There is a wealth of information on this site regarding batteries here on this site at:  http://www.otherpower.com/otherpower_battery.html  Read the linked pages about 2/3rds of the way down the page as well.  Basically a lot depends upon your battery type.  For the most common flooded batteries, consistantly undercharging them should shorten there useful life, especially if you discharge them very deeply.  I'm not a battery expert, but I'm sure there are a few on here who could give you additional advise.  Rich

[whatsnext]

You can't charge a battery at less than 12.6V . You might be able to charge a very discharged battery a bit but once you get any energy into the cells charging will stop. So to answer your question, you won't ever overcharge your battery because it's not charging in the first place. You need a voltage higher than your battery's or nothing happens exect you waste the energy needed to spin your alt. If you reread those articals that you refer to it's likely that the author is talking about high voltage/low amperage charging, in which case, you need to keep an eye on things to prevent damage. I personally like the idea of unregulated charging from an Eff standpoint but it's not for everyone.

John........

[Littleremnant]

Ok, let me re-phrase my question a bit. If you charge a battery at 12.6 -no more, but low amperage, ?? what would be the result? Would you be able to charge it all the time without overcharging? I think that is what a trickle charge is, but EXACTLY how much amperage could you use?

 Sorry for the stupid questions, but let me say that I have reseached batteries for about two years and can't find answers to my questions. This may be the reason I have questions at all. I have read a lot of articles that say conflicting things, so I am asking the questions to straighten myself out. And by the way, I have not found the answers to my questions anywhere (including otherpower). Please bear with me. Thanks for your replys.

[whatsnext]

There is no way to know how to answer your question for at least two reasons. 1. I don't know how big your battery is. 2. I don't know if, by 12.6V, you're talking about the output voltage of your charger or the final voltage of your battery, they won't be the same no matter how long you charge. If your charger puts out 12.6 volts your final battery voltage will be around 12.2 volts which is WAY less than fully charged. Therefore, no harm being done because you're above the point where sulfation occurs. Hope this helps but if not remember that battery technology is about 100 years old so most dtuff is figured out now, John.........

[scoraigwind]

You need to understand that the battery controls the voltage largely.  A low battery will suck a lot of current at 12.6 volts.  As its state of charge rises, you can get it up to 13 or 14 volts with the same current.

The alternator produces voltage in proportion to its speed when off load and it has to reach a speed high enough to start to charge the battery.  Above this speed, the voltage is not really regulated, it just rises unless enough curent is drawn to hold it down.

the actual system voltage is a balance between the two devices.  The alternator producing current and the battery aborbing it.  Roughly speaking the wind determines the current and the battery state of charge determines the voltage.

As the battery gets full it needs no more charge current, and its voltage rises even with a small current.  Above 14 or 15 volts you begin to shorten the battery's life.  A brief charge at 15 volts is good if the battery has been low and needs waking up.  But prolonged charge at 15 volts will wear it out.

[wooferhound]

here is some great information about use and care of lead acid batteries.

http://uuhome.de/william.darden/carfaq.htm