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Car Forum / Ford / Ford Trucks / December 2005How many volts in a battery
How many volts should a healthy charged 12v auto battery read? Thanks.  SignaturePaul O. oplholik@gmail.com > How many volts should a healthy charged 12v auto battery read? Thanks. About 13.2 to 13.6 VDC with no load on it after a fresh charge. Signature----------------- www.thesnoman.com A 12V lead acid battery should read 12.6VDC with the top charge burned off. A small load such as the headlights for 30 seconds will relieve the top charge. The true test of the battery, however, is a load test to see how the voltage holds up under load. A bad battery can measure 12.6V and immediately drop to nothing when a load is placed upon it. >A 12V lead acid battery should read 12.6VDC with the top charge burned > off. A small load such as the headlights for 30 seconds will relieve > the top charge. > The true test of the battery, however, is a load test to see how the > voltage holds up under load. A bad battery can measure 12.6V and > immediately drop to nothing when a load is placed upon it. Ok, thanks guys, shoulda asked this earlier. My truck wouldn't start this morning, just the racheting sound, or click, click. Put the charger on it and it wasn't drawing a lot of amps so figured it wasn't dead. Checked with the volt meter and it showed 12.47 v which I thought was ok. So I thought it must be something else wrong. Not wanting to buy a new battery when I thought the old one was ok, I decided to have it towed to the dealer and let the extended warranty take care of what ever was wrong. Well guess what was wrong, the battery. My dumb cost me a few bucks. SignaturePaul O. oplholik@gmail.com >>A 12V lead acid battery should read 12.6VDC with the top charge burned >> off. A small load such as the headlights for 30 seconds will relieve [quoted text clipped - 11 lines] > the extended warranty take care of what ever was wrong. Well guess what was > wrong, the battery. My dumb cost me a few bucks. A battery with a defective cell (high resistance) can still read good voltage with no load on it, but will not provide enough current to turn the starter. SignatureDavid M (dmacchiarolo) http://home.triad.rr.com/redsled T/S 53 sled351 Linux 2.4.18-14 has been up 12 days 31 min >>>A 12V lead acid battery should read 12.6VDC with the top charge burned >>>off. A small load such as the headlights for 30 seconds will relieve [quoted text clipped - 15 lines] > voltage with no load on it, but will not provide enough current to turn > the starter. Yes good point, if possible check the batttery under load (even blower and headlights will do in a pinch) and cranking voltage should be around 11 volts give or take Signature----------------- www.thesnoman.com >>>A 12V lead acid battery should read 12.6VDC with the top charge burned >>>off. A small load such as the headlights for 30 seconds will relieve [quoted text clipped - 15 lines] > voltage with no load on it, but will not provide enough current to turn > the starter. There is also the opposite problem; a shorted cell. If the battery is otherwise good and the engine is fairly easy to turn over; 10.4-11 volts will start the engine with no problem (for a while). The battery will die rapidly as the good cells will be seeing a constant overcharge. > A 12V lead acid battery should read 12.6VDC with the top charge burned > off. A small load such as the headlights for 30 seconds will relieve > the top charge. > The true test of the battery, however, is a load test to see how the > voltage holds up under load. A bad battery can measure 12.6V and > immediately drop to nothing when a load is placed upon it. Not completely true, when they added calcium to the plates years ago, it raised the fully charged no load voltage some. These modern maintainance free batteries require a slightly higher charge voltage too than the old "lead" ones Signature----------------- www.thesnoman.com Poster did not ask about charging voltage. Go check 50 batteries down at Wal-Mart or any place else that has a supply of charged batteries. None will read anywhere near 13V. Fact is "top voltage" is not meaningful or usable. Fact is the poster had 12.47V and a dead battery. > A 12V lead acid battery should read 12.6VDC with the top charge burned > off. A small load such as the headlights for 30 seconds will relieve > the top charge. > The true test of the battery, however, is a load test to see how the > voltage holds up under load. A bad battery can measure 12.6V and > immediately drop to nothing when a load is placed upon it. Sorry Al; that was true up to the late 50's/ earlier 60's.... not now. Calcium; antimony and other metals have been added to the lead to improve capacity and life. That "top charge" pretty much disappeared as well (you may see about a 0.1v drop depending on condition). Fully charged voltage is usually considered as 13.8 volts; but can vary from 13.3 to 14.1(rarely)volts depending on construction. As you said though; a load test is definitely part of checking a battery's condition. > > A 12V lead acid battery should read 12.6VDC with the top charge burned > > off. A small load such as the headlights for 30 seconds will relieve [quoted text clipped - 13 lines] > As you said though; a load test is definitely part of checking a > battery's condition. I always thought the right answer was about 1.2 volts per cell, and then you multiply the number of cells by 1.2 Volts. H. >I always thought the right answer was about 1.2 volts per cell, and then >you multiply the number of cells by 1.2 Volts. > >H. It is about 2.1 volts per cell with 6 cells. It's 2.1V per cell and you are right. 2.1X6=12.6V Check your battery. Who is getting 13.8V? Come on, really. If that were the case you would need over 15V to charge it properly. This is just silly talk. > It's 2.1V per cell and you are right. 2.1X6=12.6V > Check your battery. Who is getting 13.8V? Come on, really. If that were > the case you would need over 15V to charge it properly. This is just > silly talk. Well; if this is "just silly talk"; I went to clown college. OK Bronco II shows 13.29v (hi-end longlife) Wife's Soobie 12.98v (midrange) Tiny load on both; mebbe 50mA from various "keepalive" circuits; stereo/'puters etc. Ever hear of "float voltage"? When the charging system and the load balance out with a known good battery, that's float voltage. In other words: Real load is 20amps and charger's outputting same 20 amps. "13.8v" is what *was* commonly stated as float voltage for a 12v car battery but you will find that can vary from 13.2v to 14.0v It ain't the same as it was; voltage/current out/current in/charge time/charge heat/ .... |
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