I'm no battery expert. Just going from memory, it seems like batteries 30 years ago used to give more warning before failure. I remember having a weak battery and it was still a few days before payday. I had to push off the car every morning, but it would start up the rest of the day from the alternator recharging it on my drive to work and only fail to start after sitting overnight.
Then say maybe 20 years ago, batteries seemed to just fail outright with no warning whatsoever. Crank fine in the morning then try to go to lunch and nothing. Just a clicking solenoid.
Fast forward to a few years ago and having a few antique cars. My TT battery had gotten so weak, it wouldn't start, but it would still fire the plugs, so I just used the hand crank. But then the ammeter would come down to near zero after only a very few minutes of driving (Has a FP regulator on it). The battery would start it up after a short drive, but not after sitting overnight. I went like this for a year or so and eventually the battery would not start it at all, although the ammeter would show a full charge. Same applied to using a battery charger. You could hook up a charger and its ammeter would drop to near zero after only a few short minutes which would indicate a charged battery, but it wouldn't start the truck. After the battery finally got so bad it wouldn't fire the plugs, I finally replaced it and it works fine, which seems to rule out starter/generator/regulator/wiring problems.
Then today, the Model A wouldn't start. Had to push it off. Same thing happened last time I drove it, but today, even driving for a while did not charge it enough to start the car. Had to push it off again. Went straight to the auto parts and got a new battery. Funny thing is, the ammeter was reading near zero almost immediately after starting the car (FP regulator on this one too). I know the generator and regulator are working. I can turn on the lights and still read near zero on the ammeter. When I turn them off the ammeter momentarily goes to about 10 amps then returns to near zero. Typical operation with a fully charged battery.......Except it's not charged. Same thing the TT did.
What causes a battery to fail in such a way that your charging device, be it a charger or generator/regulator acts as if it was fully charged?
I believe its an old age problem. Just like us as we get old we don't perform as well as we once did.
What make of batteries are you using?
I didn't pay any attention to what was in the A. The one that is in it now came from O'Reily's. The one that was in the TT was a NAPA (I think). The one in it now is from Tractor Supply.
I had trouble with the battry going dead in the Wifes model A. This usually took a week or two but new or not it was dead.With the charger on the battry the windsheild wiper would slightly move back and forth.Now even overnight i pull the fuse and leave the hood open.Bud.
Both of these batteries were just old. It wasn't anything draining them. I'm just wondering why they both seemed to be fully charged (ammeter reading zero) when they didn't have enough juice to turn the engine past one compression stroke. It's gotta be something to do with the failure mode of the battery. I'm not even sure what makes the ammeter come down as a battery charges, but we've all seen it with our battery chargers and the one in the car works the same way if there's a VR installed.
I think it's sulphide build up on the plates. Batteries that don't get "exercised" often are prone to it. I use uninterruptable power supplies (UPS) on all the PCs and the bedroom TV. All but one do periodic tests automatically then alarm if the battery is bad. I've seen the lead-acid batteries from the other show 12+ volts but won't power a small bulb test light. It won't supply enough current (amps).
I think there's a procedure to "shock" a battery back to life but I've never tried it. There some very expensive fleet chargers that do this automatically.
Sounds like the regulator is working as it is supposed to. If the battery is dead in the morning, the battery is shot or you have a unintended drain. Connect a DC ammeter in series with a battery cable and see if there's a noticeable current flow. Set the meter on a high range first like 20 or 30 amps and drop the range to one more suited to what you find. With the ignition off there should be no current flowing.
Well I have done better than you guys but I am not trying to rub it in. Here is my "suggestion". When you buy a new battery make absolutely sure you get a fresh one. When you are shopping for a battery, take along your voltmeter. First make sure you know how to read the date code on the battery so you know when it was built. Never call first to tell the store you are coming for a battery. Go in and test the voltage of the battery you proposed to buy and make certain it is fully "up" - not less than 6.3 volts and be suspicious of a battery that is more than 6.45 since it has just been charged and there is no way to know if it will hold that charge. come back tomorrow and see what it measures. Never buy your battery at a store that rarely sells them. Buy one from the biggest turnover store you can find. If they special order one for you that doesn't mean it isn't one that has been sitting in a warehouse for a few months before it was sent to the dealer for you to then pickup. Never buy a battery that is below 6.3 under any circumstances since the store has let it get discharged and the rule of thumb I like to use is that a batteries life is basically the sum total of all time that it spends in less than a fully charged state so you want the battery to always be fully charged - always. Of course it is normal to pull some charge off of it to start your car but you want to make sure your charging system is always working correctly so that charge is put right back asap. Some brass cars have no charging system so you have to wait till you get home but don't delay putting on the charger when you get home. If your system has run the battery down but you made it home on the battery - don't wait till tomorrow to put the charger on that battery because "tomorrow" will be next week or two and your battery is sitting less than full charge and that is bad.
If you have any doubt at all that your car might have a leakage discharge current (usually called a "parasitic" discharge current) find out absolutely for sure and fix it if you do have one. When you buy your new battery you should also buy one of those el cheapo 4 ball hydrometer battery checkers and mark exactly which battery it goes to and never use that tester on any other battery. If you happen to test a battery with a dead cell you can transfer that contamination to a good cell in another battery. Those testers are cheap so buy one for each battery and mark the tester. Throw the tester away when you toss the battery. They can of course be cleaned with distilled water but you may not do that when you are in a hurry so just get one for each battery and then you don't have to remember if you cleaned it or not. At any suspicion that the battery is not right - those testers are exactly the counterpart to a compression tester for your motor. You want all cells of your battery to be exactly equal. If any one cell is down from the others - that cell being in series prevents the other cells from getting charged too so the whole battery is then weak and the signal that you have a bad cell is that it seems to charge up quickly but there is no charge in the battery when you try to use it. If you find you have a weak cell, make a warranty claim immediately if not expired. Forget any "rejuvination" techniques and soda pop additives.
Most of the features that are "sold" to you as features of a charger are NOT in fact charger features. A typical "good" battery charger has a current limit or possibly 2 switchable current limits. Lets say yours is 6 amps. The battery voltage necessary to charge your 6V battery is typically about 7 volts. If the battery is fully charged it will not draw any current from the charger when the charger applies that 7V across the battery. A typical lead acid battery by definition is fully charged when you apply 2.35 volts per cell to it and it draws no current. If the battery draws current then so long as that current is not more than our 6 amp limit the battery will begin to charge at whatever rate the BATTERY requests. The charger has nothing whatever to do with the amount of charge that the battery takes from the charger unless it is above the current limit. If you measured the voltage on the battery that was charging at something less than 6 amps the battery voltage would probably show at 7 Volts but if it is still drawing current then it is not yet fully "up". If the battery draws 6 amps or more then the charge rate will be limited to 6 amps and the voltage if measured at that time will be something less than 7 volts. Once the battery draws less than 6 amps the voltage will be at 7V and the battery will taper off the amount of current it draws from the charger. Again it is NOT the charger that is tapering off the charge rate - it is the battery doing that. Once the battery charge current gets to zero current with the full 7V still on it then it will not draw any more current and the battery is fully charged - UNLESS it is defective with a bad cell. You can tell if you have a bad cell by knowing how to use your balls (sorry couldn't resist that one). There is no advantage I can see to any sort of cycling of a lead acid battery as is advertised by many silly expensive chargers that make all sorts of claims about how that is good for a battery - it isn't any good for a lead acid battery to reduce it from full topped off charge and I have never seen a battery manufacturer say that is good for a battery - just battery charger manufacturers.
Telephone company battery plants used wet cell lead acid batteries basically like your car battery and they typically got 20+ year life out of those. They did that by not letting the battery get discharged any more than they had to when power failed. Just never never never leave the lights on or otherwise drain your battery deeply since that hurts the battery. You may forget you did that but then only get short life from the battery and not remember you were part of the short life scenario last year by leaving the lights on. Keep the battery "topped off" all the time if you can. With my VR and a car that runs on magneto if you end your tour day after a decent length daylight run you can be totally sure that your battery is absolutely topped off since the VR will leave it that way. It will in fact also temperature track the basic ambient temperature and adjust the charging voltage up or down as is desirable to maximize the battery life even further with temperature compensation of the charging voltage. That was free in the design so I did it but it is probably overkill and the most serious battery life extension takes place when you keep your T able to fire right up on a short spin of the starter and then you go for a ride of at least an amount to fully heat up the engine. It is not a good idea for the battery or the motor to just start up a car and then shut it off when it is still cold.
Sorry for the long winded answer but I am also sorry to report that most of the misinformation you will get about batteries will come from those selling batteries and chargers. Most store salesmen really just don't know their product at all. I had a specialty battery shop try to sell me an 8V battery telling me that my Model T actually came with one of those installed. He had convinced a number of my fellow club members that he knew what he was talking about - it was BS.
Well, certainly no battery manufacturer is going to endorse or tell you how to "rejuvenate" a battery. They want to sell more batteries.
Thank you John Regan for sharing your knowledge on batteries and chargers. Saved me from investing in one of those expensive three stage chargers.
After 10 years use of my 6 volt battery, I had to replace it only because I couldn't run the headlights for more than half an hour before the coils would start misfiring.
Such is the advantage of having a hand crank, that you can drive around with a crook battery for a couple of years.
Thanks John. I will have to re-read that one a couple of times to let it all sink in. I REALLY appreciate you taking the time to write such a detailed response. Sounds like my problem was probably a dead cell.
On the plus side...I joked with my wife about getting the auto parts store to install the battery for free (Some advertise that. Not sure about O'Reily). When we got inside, the guy indeed offered to install it. I asked him if he knew what he was getting into. He said he didn't care. My wife and I removed the floor mat then the counter guy and I proceeded to take the screws out of the floor board and remove it so he could get to the battery. It's not a bad job, but more to it than a modern car with a single screw hold down and two battery terminals. He had a good time. Took a picture when he got done.