page 13. 12.6v is the minimum and not where you should charge to. A full charge should be much higher at around 13.3 to soak the cells. My cars over years and chargers go to about 13.3v normaly. If new batteries sold are not fully charged they may never reach 100%.
I just got a free battery from SEARS because they did not do this, and did a bait and switch on oil. I stopped pay on a ck, they filed charges, The Atty General said I was justified in not paying. Free battery - free Mobil One, from your friendly Independantly owned Sears Auto Center.
Forgetting about voltages for a minute, the key here is that it continues to charge indefinitely at 2 amps. That is not normal and very likely a sign that the battery is on the way out. I take it we still don't know how old the battery is? If it's 5+ years, I wouldn't fool around, just get a new one. Or at keast have it tested.
The battery behaves pretty well. I haven't bothered to check cranking voltage because it sounds good. It's in a van belonging to a couple who are away most of the time. I've been charging it occasionally because extended sitting without charging harms batteries. A few weeks ago they were about to replace the battery because the van wouldn't start, but I found resistance at the positive terminal connection.
I checked the meter on a battery that I'd charged two days before. 12.6.
In that connection, I had switched to 10A to check the charging current. Then I checked voltage across the terminals. Zero... uh-oh, the plugs were in the 10A jacks. I've damaged meters that way before, and I never learn. This time there was no arc. At home, I checked it on a 5A source and got a good reading. Could my cheap DMM have circuit protection on the 10A inputs? I need to take it apart and see!
The water level is good. As I don't know where the battery came from, I don't know what it was filled with.
Decades ago, I got a manual a major manufacturer had published for dealers. It said that a battery sold in Toronto may have a stronger electrolyte than one sold in Miami. Higher acid concentrations help in cold weather but shorten battery life in hot weather.
I think some batteries are shipped dry, and the dealer adds a mixture of distilled water and acid drawn from a bulk container. Suppose the dealer used a mixture 30% too weak, perhaps for longer hot-weather life or because he didn't have enough acid or because he wasn't good at measuring. I wonder if that could cause the effect I see.
If the battery has sulfation too hard for the charger to break down, I guess that, too, could keep the battery from charging fully.
The key for me, too, was the failure of the charging to taper off. That's why I checked voltage.
The couple own two cars and three pickups besides the van, so they won't be in a jam if the battery fails. So far, it behaves like a good battery: a good sound from the starter, very little drop when the lights are turned on, and no drop in voltage after the battery sits a week. I'm curious.
It depends what you mean by "their charge". 12.3 is too low. When the connections between the cells were available for voltage measurement, one could measure the voltage on each cell. Are 5 of them at 2.1 and the sixth way too low? Maybe. Are all 6 cells at
2.05? Frankly, I doubt it. You probably have a bad cell. A hydrometer would find it, and I think it is worth the money to have one and to learn something. When I buy things I keep them forever and my hydrometer is probably 40 years old now, so the cost of the item isn't that important. (Unless you are short of storage space.)
A bad cell might have shorted plates. It's more complicated than the explanatory drawings. There are maybe 6 plus and 6 minus (or more) plates in each cell and they alternate. This maximizes the power available for a given size battery. But it also means cells can short, a plus plate can touch a minus plate, and I don't think there is anything you can do about it, because the access hole is so small.
I once had a battery that only shorted when it was pretty hot. If I drove a half hour in the summer and turned off the car, the battery wouldn't work for 30 or 60 minutes. Fortunately for me it only cost me one short taxi ride and one bus ride back to figure this out. By the time we went to dinner and back, the battery was cold enough and the car started. I went home and it started the next day too and I went and got a new battery.
More below.
The charger voltage can be 13.3, to force the recharging of the battery, but the battery itself, when disconnected from the charger, will never show 13.3 volts.
Look at figure 3 on the very page 13 you site,
State of charge in % 100% Open Circuit Voltage 12.65 volts.
That's just a little over the 12.6 volts I said.
I don't think many people in this thread were commenting on the charger voltage. I have two chargers and last measured their voltage
10 or 20 yerrs ago. Say it is 13.3. As the battery approaches 12.65, ays it's 12.5 volts, subtract that from 13.3 and that leaves only 0.8 volts to force the last bit of recharging into the battery to be charged. The other 12.5 volts of the charger only serve to neutralize, to counteract the 12.5 volts of the battery.
Just like stuffing anything, it takes effort.
BTW, same chart points out that even when a car battery is 75 percent discharged, it will still have have 95 percent of its voltage, 12.05 volts**. Twelve sounds like it's almost 12.6 and people might imagine that a battery with 12 or 12.3 volts is nearly charged.
**WE went over the arithmetic on this when I took high school chemistry, and it's pretty simple and clear once you see it done. It's not black magic that the voltage continues to a much higher percentage of normal than the perecentage of charge is.
Chicago is the home of Sears, and when I lived there, I went to Sears a lot. The first time was just after my brother had given me his '65 Pontiac, in the summer of '67, the newest car I had owned, but it had a bad battery. (The dealer said he had replaced the battery, regulator, and alternator each twice, but they never fixed the car, and when the 2-year warranty was up, they refused to do any more.)
So my brother gave me the car when he went to Viet Nam, and I took it to Chicago, and then to Sears, and said I wanted to buy a battery, and the service guy said, Do you want our free two thousand point multi-check, and I said, "Not really. I just need a battery." and he said "It's free. You ought to take it", so not wanting to argue with the guy, I let him test the car, and he found a bad connection between the positive battery cable and the starter motor solenoid stud. He took off the cable, scraped it with a knife on both sides and put it back. And the car worked fine thereafter. The dealer, out of business less than 4 years after I got the car, I think spent too much time replacing big boxes at the end of the wires and too little time looking at the wires that connected the boxes. I was very impressed by Sears.
It did happen that everytime I left the lights on for more than an hour, again the car woudn't start, even with a jump. I used to crawl under the car, remove the nut, clean the cable end with a knife and put it back togehter. By the second or third time this was too much work, too dirty and time consuming, so I just reached down, grabbed the cablen, and twisted it around the solenoid stud. 10 degrees or less was enough to make the car start.
I thought about replacing the battery cable--there must have been something different about it, but I learned not to leave the lights on.
Then I wouldn't worry too much. Especially if they are not there much, now is no time to buy a new battery. It depends on their personalities and how much money they have. I at least would rather have a crummy battery and buy a new one only when i was home, using it every day or two, and actually having trouble starting.
Between the battery cable and the positive post? Certainly possible. Clean it off with baking soda and water. Once I was in a hurry, taking a friend to catch his train back to NYC. The car stalled at a red light something was so bad. I touched the battery posts and one was burning hot. That's not the powerful post, it's the bad connection. Put on a glove and I just twisted the cable back and forth until I got a better connection. After I dropped my friend at the train station, I took the cable off and cleaned it and the post with a two-endded battery brush. The connection was so bad, I couldn't even chargethe battery from the car. (I had been having a bit of trouble but didn't identify it until on the way to the train station.)
OK. Well 12.3 is's low.
That's strange. You probably blew a fuse. Even some cheap ones have a fuse.
You can also replace the resistor if you burned out one of those. If you can't determine what the resistance shoucl be, often there is apattern, 2 ohms 20, 200, 2k, 20K, 200k, 2Meg. Or maybe 5.1 etc. Plus maybe you can find the schematic.
Maybe. It might even have what's it called, that lets the current go ahrough when the voltage is high enough.
More below
Absolutely Delco advertised for decades that its batteries were dry-charged, shipped without acid. I think that means they don't discharge or age in any way when they sit on the shelf in the warehouse or the store. Maybe they don't do that anymore, but the motorcycle I bought 2 years ago was like that. It came with a plastic bag/box of acid for me to add.
Could that actually happen? I always thought the acid was pre-mixed. It certainly was with the motorcycle battery I bought. I am opposed to shipping water around (like the pre-mixed windshield washer fluid) but no6 in this case.
Slow charging, with a 1-amp charger, works best, but takes over 24 hours to charge a fully discharged battery. Now that I have a job, I'm happy to use my 10 amp max charger, which puts enough in to start the car after 10 minutes. After the car started, I used to then keep the heater fan on high (which uses a lot more current than headlights do, and is actually sufficient to lower the charging rate) while I drove, so that the battery would charge more slowly. Now that the stupid new cars don't even have ammeters, and the thrill of installing one only lasted me through one car, I don't even bother. It doesn't really seem to have shortened my battery life. I still get 5 years, and I had never been able to get more than that anyhow.
Charging voltage and fully charged voltage are NOT the same. Charging voltage can be as high as 14.6 volts, which can leave a surface charge of 12.9, +/- for a short time after charging, but a FULLY CHARGED Lead Acid battery is 2.1 volts per cell ( so 12.6 volts). It takes 2.15 volts per cell to START to charge the average lead acid battery, so anything less than 12.9 volts is not charging at all.
13.8 volts is the "recommended" maximum charging voltage according to most manufacturers.
Best way to check BATTERY voltage is to turn on the headlights for 2 or 3 minutes, then turn of the lights and check the voltage.
Checking with the headlights on and comparing the voltage will give an indication of the batterie's internal resistance.
I opened the meter. It's about 40mm of wire, about 12 gage, between the
10A and Common terminals. No sign that it has been hot. On meters I've damaged, the only visible sign was discoloration of the wire, but they would no longer give consistent amp readings.
It's a cheap meter. I've often had to use contact cleaner to get continuity at the input jacks. My theory is that due to invisible corrosion, the contact patch between the test-lead plug and the jack was so small that when the battery surge hit, it immediately overheated, breaking contact and protecting the meter. What luck! Cheap stuff works best!
I have another theory now. Whenever you start an engine with a battery that's not fully charged, you may pop sulfate off the plates. Batteries have room at the bottom where it can settle without causing electrical leakage between plates. The sulfate that pops off is lead and acid that can't be recovered by charging.
I'll bet that battery has been used countless times to start when not well charged. I'll bet sulfate at the bottom of the battery accounts for my inability to charge it above 12.3V. (About 60%?)
If five cells charged normally and one was .3V low, that cell would be discharged, and I would not expect the charged battery to run the lights and start the engine normally.
If one cell had serious leakage, I would expect the battery voltage to drop to about 10.5 within a week. It stayed at 12.3.
I'd like to know more about the arithmetic. It seems to me that if the voltage of a certain chemical reaction were 2.1, a 6-cell battery measured with a 10 megohm meter should read 12.6 whether 1% charged or
100% charged.
Neighbors kept calling me when their battery ran down. It seemed to be the regulator built into their Delco alternator, and I couldn't find the problem. One day they phoned when their car wouldn't start at the post office. I happened to touch the positive battery cable and it started. They'd had somebody replace their starter and the cable wasn't tightened down at the starter.
Everything had always looked good idling in their driveway, but I guess sometimes on the road the loose connection would confuse the regulator. My neighbors called me a fool for not fixing their car sooner. They considered me their fool because I helped them for free.
I think it was a little under 14. The charger tapers to less than 500ma on most batteries.
It used to be that a charger's regulator was supposed to be higher for maintenance-free than for conventional. I don't know if that has changed.
High school chemistry was 46 years ago. I don't remember the details.
For sure not. The amazing thing to me was that the voltage stayed as high as it does. But given your expectation of 12.6, that shouldn't amaze you. :)
They often get dirty in there when they run without being tightened. Dirt makes resistance, resistance makes heat and a voltage drop. Or in some other way it doesn't work.
These are the same people whose battery you are working on now? They sound very tactful.
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