Lead-Acid Battery Charging For Long Life

[Elden DuRand]

Group:

I’m not trying to take business away from any of Harry’s sponsors but I haven’t found anyone who sells good lead-acid battery chargers here, so here goes......(My apologies if anyone does sell 'em).

Most of us in this hobby use lead-acid (Gel Cells or flooded cell like car, lawnmower, etc.) batteries for our engines and a lot of this type of batteries are ruined from over or under charging.

When Frank and I were working on the Delco 750, we needed to get a Group 1, 6-Volt car battery to crank it. Because they aren’t exactly cheap, we wanted the battery to last a long time. The best way to do that is to use a “float” charger that maintains a constant voltage across the battery regardless of the current.

I was going to build a float charger from scratch but Frank found a source of cheap "wall wart" style float chargers from Mouser Electronics (800) 346-6873. They sell both a 6-Volt and a 12-Volt version.

MAKE SURE YOU ONLY CHARGE LEAD-ACID BATTERIES (GEL CELLS OR FLOODED CELL) WITH THESE CHARGERS! If you try to charge other voltage or other types (NiCad, etc.) with them, you’ll either ruin the charger or the batteries or both.

The 6-Volt version is Mouser stock number 632-GHC610003S-A. $16.84 each.

The 12-Volt version is Mouser stock number 632-GHC120003S-A. $17.74 each.

They will charge at a maximum of one Amp and taper off to almost nothing in the float mode. These won't charge a battery fast but will sure make them last a long time. You just leave the battery on the charger all the time you’re not using it. The battery will NOT overcharge and will always be ready for service.

A good feature these little chargers have is two modes of operation. When you first put the battery on the charger, it goes into what is called "boost' mode (the indicator LED glows red) and charges the 6 Volt battery to about 7.3 Volts (about 14.6 Volts for the 12 Volt version). Once this voltage is reached, the charger automatically switches to "float" mode (the indicator glows green) and drops the voltage to about 6.9 Volts (about 13.8 Volts for the 12 Volt version) where it stays.

Anyhoo - I’ve had flooded cell lead acid batteries last over 10 years when kept on a float charger. Gel cells sometimes last even longer. For our hobby, not buying batteries all the time means more moola for buying dirty, rusty iron. After all, that's what we're all about!

Give ‘em a try.

Take care - Elden

[Ken Majeski]

I have several of the small jell cell lead acid batteries I use for gas engine ignition and various other purposes and to charge them I just use a 1157 or 1156 bulb in series with a small ( 4 to 10 amp) battery charger. The bulb acts as a regulator and limits the charging current to what the small battery is happy with.... This has worked good for me for years...

[MoRo]

Ken, what does the bulb do when the battery is fully charged?

[John W]

I have an answer that is a bit more expensive, but I can keep twelve batteries charged at one time. NAPA auto parts sells a charging rack that will hold twelve, twelve volt batteries or ten, six volt batteries. The rack keeps each battery fully charged until you take it off. It isn't like a buss bar, the electronic "brain" moves the charge from battery to battery about every three minutes or so. It charges at about .5 amps so if the battery is dead, it will take a few days to get it up to full charge. Once there, however, it will keep my batteries charged and ready. The part number is SPP1. It is about $175.00 and well worth it. $175.00 won't buy too many new batteries these days.

[Ralph Leonard]

Elden is on target about lead acid batteries lasting longer when kept on float voltage. The batteries in our local telephone office were 32 years old when I retired, as far as I know they are still going. They are kept on precise float voltage to one one-hundredth of a volt.

I keep a regulated charger on my golf car start battery all winter. They cost a little more but are well worth it. Lamps in the ckt will lower the ampere charge rate but not regulate the voltage level.

Connect a volt meter across the battery terminals to measure its state.

A regulated charger will be about 2.5 volts per cell heavy charging, dropping back to and maintaining float voltage of about 2.3 volts per cell. (13.8 for 12 volt battery).

Ok, I'm ready, come after me, LOL

[KidDynamo]

Okay Ralph, here I come ! LOL!

I don't have my charts handy but there's a lot of truth being told here, and some other stuff.

Most lead-acid battery experts will say that you want to maintain a battery (or battery bank) by floating it at battery voltage and then about once a month, an equalizing charge should be done for about 4 to 8 hours.

What is battery voltage? That is where the battery is fully charged. A rudimentary way to detemine battery voltage is to charge it completely! Duh...! Actually some say charge until hydrometer readings of the cells no longer go up and then a little more. Cells will be evolving gases. If you measure voltage at this point, it will be higher than battery voltage, but the overvoltage portion of the charge, known as a surface charge, will disappear if a small load is momentarily put on the battery. Essentially, the surface charge has no significant amp/hours.

After the surface charge is eliminated, then measure voltage. That should be your actual battery voltage. This is where you would float it at, or maybe 1/10th volt higher. Any further voltage applied to a fully charged battery will evolve hydrogen and require adding water.

If the battery is maintained at float voltage, once a month it should be kicked in the rear with an equalize charge. This charge is calculated nominally at 2.33 volts per cell, which is cells in series, not parallel. There are several things which the equalize charge accomplishes, too long to go into here.

Another major factor in battery life is ambient temperature. Ideally, they would be kept cool and dry. High temps increase float current. Battery room temp shouldn't exceed 77 degrees F. Each 18 degree rise in temperature cuts battery life in half. Conversely, if the temp is reduced from 77 degreesF by 18 degrees, battery life doubles ( properly maintained, of course). Obviously, this co-relation ocurrs within a limited temperature band from about 35 degrees to about 160 degrees. At 160 degrees F, your batteries ain't gonna last very long !! Not a problem, for me.......!

In multiple battery banks, ideally, all cells should be of equal voltage. If one cell becomes weak. it's specific gravity will be lower, it will use more water (because its actual float voltage will be lower but it get the same voltage as the rest of the cells), and the "bad" cell will tend to drag all of the rest of the cellls down. This can eventually ruin the entire bank. In the old days, you'd just replace the bad cell.

I get some of my experience from maintaining battery banks on ships and a lot of reading and discussing this with other crackpots like myself. It is not uncommon to have banks of three or more different voltages and maybe 6 different banks. It was common to go on a "new" boat and find the battery situation in total disarray and the guy "in charge" not having much expertise. I also had a large powerboat of my own for a long time. I had 4 separate battery systems on there! Lots of money in batteries and chargers! I used LaMarche Constavolts and Ratelco chargers. More sophisticated chargers have come along but some of them have reliabilty issues.

On the big systems, we had adjustments for float and equalize voltage. This is important because as batteries age, there voltage goes down so the float voltage must be reduced accordingly or you gradually begin to overcharge them more and more. Then they use more water, etc.

Now to Ralph: I know a guy who had a 32 volt system in a boat that used phone company batteries. They were still working fine after 40 years! They are not the same batteries we "civilians" usually get. I don't know about the cell construction, but his were individual cells. They are fantastic if you can get a set in good shape.

A friend of mine got 2 pallets of cells that were used for powerplant circuit breaker emergency backup. He hygraded the good ones and they last him for years! Huge though: 75 lbs per cell, clear Lexan cases. looked coooool, to !!!

My only bone to pick with Ralph is his voltage figure of 13.8 volts. This is too high for floating 12 volt batteries but is a voltage favored by many manufacturers of "cheaper" maintainence chargers. To pick a float voltage number I always say 13.2. The extra .6 volts on a 13.8 volt charger makes a big difference, too. I watched many, many folks slowly ruin their batteries with this output voltage. Guaranteed, it will boil water. It is a voltage used because it is a compromise. A proper float voltage is not a very fast recovery voltage for discharges. Conversely, a good recovery charge voltage is about 14.5 volts, typical for an automotive-type charger, but this is way tooo high to float batteries. The compromise of 13.8 is then arrived at. If you go to marine-swap meets in my area, you can get 13.8 volt chargers pretty cheap from the folks who have learned. It can be an expensive lesson when you have a thousand bucks worth of batteries and they don't last very long.

I know this is long. I hope it is readable. I have spent a lot of years doing this and I've seen "it all".

So: Float at battery voltage: 2.15v/cell for lead-antimony 2.17 to 2.20 for lead-calcium

Equalize at 2.33 volt/cell both types 4 to 8 hrs/month

Make hydrometer readings of all cells and keep a dated record.

Keep all cells well watered with pure water.

Keep battery temp cool

Battery voltage goes down over time

Nickel-cadmium, Nickel-iron ????? I gotta go to work !! (I do have a pal who runs his desk clock on a potato, no kidding!)

[MoRo]

So, then why, in all their infinate wisdumb, do auto manufacturers make the charging systems to put out 13.8 to 14.2 V? Is this a conspiracy to have the car owner buying a new battery every couple of years?

[Ken Majeski]

Originally Posted by MoRo

Ken, what does the bulb do when the battery is fully charged?

As the battery charges the bulb will get dimmer and dimmer due to the battery voltage comming up. This might not be a totaly scientific solution but it sure beats hitting a small battery with a surge of 5 or 10 amps which is over their capacity and can cause damage.

Most manufactures use the 14 to 14.5 voltage so that the battery will absorb a Charge in the case of short trips. You could use the lower voltage if all you did was cross country driving. So it's a kind of a Fits all situation...

[KidDynamo]

Originally Posted by MoRo

So, then why, in all their infinate wisdumb, do auto manufacturers make the charging systems to put out 13.8 to 14.2 V? Is this a conspiracy to have the car owner buying a new battery every couple of years?

They use higher voltages to assure that almost all users get their battery charged. A lot of cars get stopped and started a lot with short drives in between. A low voltage output means dead battery.

On marine alternators, they often charge at a considerable reduced voltage because they figure that the cabin cruiser turns on and runs for extended periods between starts. Marine stores have carried all kinds of alternator controllers to modify output to meet specific needs. Some of them work, even.

Car batteries last on average, about 5 years, give or take. That ain't very long, but the high alternator output has the benefit of quickly charging your battery so you get more reliable starting.

When I go garage sale picking in my 6 volt car, it is not uncommon for me to park the car on a hill after a long day of starting and stopping because my poor old battery is gradually running down. As it poops out, it takes more cranking to start it and this exacerbates the problem.

I stick it on a charger when I get home. My batteries usually don't last very long.

[Larry]

On the Subject Of Batt, Chargers etc;... I keep a 12V Solar Charger at about 1.8Watt on My JD H Tractor, the Batt is 6VOLT, QUESTION<> Will this harm the 6V batt, ?? Thanks Larry

[Jim McIntyre]

It has the potential to overcharge the battery. I wouldn't do it myself.

[Neale Behm]

Years ago I was taught to never leave a lead-acid battery sitting directly on a concrete floor as it would kill the battery in very short order.
I've seen it happen but never knew why. This seems like a very good thread to ask why.......WHY???

Thanks Harry

[ronm]

Neale, I was taught the same thing, & I too have seen it happen, but watch out...I brought up this subject on another forum once, & I was rode out of town on a rail by the experts...so hang on, let's see what happens...I wasn't goin' there again, but glad you did...
Ron in CO...

[Junkologist]

Neale,
I was told the same thing. It is my understanding that moisture from the ground can make it's way through the concrete, reach the battery, and allow the current to leak to the ground. I would imagine this could happen anytime you set a battery on the ground for a length of time. If you have a battery that leaks electrolyte around the posts, it would probably be even more likely to happen. I'm by no means an expert on this subject, but this is what I've been told. I always put a piece of wood under a battery if I have to set it on the floor for any length of time.

Mike

[Elden DuRand]

Originally Posted by KidDynamo

.............I don't have my charts handy but there's a lot of truth being told here, and some other stuff.........................

....................Nickel-cadmium, Nickel-iron ????? I gotta go to work !! (I do have a pal who runs his desk clock on a potato, no kidding!)

Kid:

Thanks for the dissertation! I knew there was someone here who was a lead-acid battery pro! I've got no bones to pick with anything you say.

That said, I think that I don't think it is extremely important to use a periodic equalizing charge unless the batteries are never discharged. On my Onan plant, the first batteries (2 group 1's) lasted a little over eleven years when floated at 13.65 Volts. I did start the genset once a month or so, running it for an hour or so under load. Since it had a constant current charger, I'm sure that by the time I shut it down, the battery voltage had gone to 14.5 or so, probably qualifying as an equalizing charge.

Charging a lead-acid battery from a constant current charger through a light bulb only limits the starting current and is a very good idea when the charger can supply much more than the maximum the battery can take. With the lamp, as the battery voltage approaches that of the charger, the lamp filament gets dimmer (cooler) and it's resistance decreases. If a battery is left connected long enough, it can easily be overcharged.

If you're talking about a flooded cell battery, this small amount of overcharging doesn't hurt -much- as long as you keep the electrolyte topped off with pure water.

Now, sealed (gel cell) batteries are much more tolerant of overcharge but, in my non-scientific opinion, any voltage over 2.3 Volts per cell for a long time will be detrimental to the life of the battery.

Okay, I'm through.

Oh, yes - PLEASE DO research NiCad and NiFe batteries. NiFe batteries seem to last forever (I had a set of Edison batteries that were over 50 years old and still took and held a charge for a while). Although I don't like NiCads much, they've been much improved lately and there are a bunch of the boogers out there.

Take care - Elden

An

[Elden DuRand]

Originally Posted by Neale Behm

Years ago I was taught to never leave a lead-acid battery sitting directly on a concrete floor as it would kill the battery in very short order.
I've seen it happen but never knew why. This seems like a very good thread to ask why.......WHY???

Thanks Harry

Neale:

I've heard the same stories and personally think that they are mostly urban legend.

A concrete floor is cool and that's good for batteries. Even if the concrete is damp, as long as the battery doesn't have a heavy coating of corrosion and crud on it, there will be no discharge path.

I once kept a 12 Volt car battery in a damp garage on the concrete floor for over 3 months and, when I put it back in the car, it still cranked it (albeit kinda slowly). After driving the car for a while, it was fine.

Probably what happens in most cases of "concrete death" is that the battery was about gone anyway and, sitting there for a while, it finally died a peaceful death. After all, nothing (including me ) lasts forever!

Take care - Elden

Take care - Elden

[Junkologist]

All this battery talk reminded me of something that happened at work one time. I operate heavy equipment and if it's not running, the boss isn't making any money. One day we shut a machine down for lunch, and when we went back to work, it acted like the battery was dead and it wouldn't crank. I checked the electrolyte levels in the battery and they were way down. I told the boss we needed to get some distilled water and he acted like I was crazy. He then got an old coffee cup and scooped some water up out of a mud puddle and proceeded to pour it into the battery cells! He wasn't careful with it either, spilling it all over the top of the battery and washing more dirt down into the cells. He then gave me a look that said "that's how it's done" and walked away. We jump started the machine and went back to work. Needless to say, the battery got a death sentence that day. It probably would have lived on for some time with the proper care. I am continually amazed at how long the batteries in construction equipment do last under the grueling conditions they exist in.

Mike

[Ken Majeski]

I Agree with Eldon on the Concrete Death legend.... I have never been very fussy about where I set batteries.... True some make it and some don't regardless of where they are stored. Used to be some people would take batteries out and store them inside when they weren't being used. But in all actuallity the best thing to do is charge them up and leave them out in the cold as the lower temp will reduce chemical activity and actually extend battery life..

I've had people come into my shop and there was a battery sitting on the cement and they said how long has that battery been sitting there ? And I said about 3 months.... And they said I bet it's dead.... And I said bet it ain't.... and they are totaly bumfuzzled when I prove it's still very much alive...

Worst thing about a battery on cement is if there is any acid seapage or residual acid on the battery it will eat the cement. What about all the autos with Batteries on steel surfaces.... They should all be dead Right...

[KidDynamo]

Any fool who would leave a battery sitting on cement.......Oh, just kidding LOL !!!

I've read it, too years ago. Don't remember why. I agree it will etch the cement, if the battery is dirty. I can prove it!!

Some of the stuff we learn changes perspective, I guess, but remember that batteries aren't made the way they used to be made. These changes may affect how things react in the "real" world (or on cement).

Elton is equalizing his batteries if he charges them once a month at 14.5vdc. That said, I'm reading now about STANDBY BATTERIES:

"With proper maintenance and under normal operating conditions, life expectancy of a lead-antimony battery is about 14 to 16 years; life expectancy of a lead-calcium battery is about 20 to 25 years. There have been cases in which much longer than normal life has been realized for each type of battery. The combination of reduced maintenance and longer life results in a lower cost of ownership.........

.....Lead-antimony batteries will require periodic equalizing charges; the equalizing charge can be eliminated for lead-calcium batteries if the battery is floated at 2.20 to 2.25 volts per cell........

.......An equalizing charge is a vigorous charge at elevated voltage applied periodically to restore full capacity. Equalizing charges are needed for a lead-antimony battery to counteract the effects of a natural transfer of antimony from the positive to the negative plates of the battery; this transfer changes cell potential, prevents the cell from operating at full capacity, and results in self-discharge (or internal circulating currents in the battery). If a vigorous charge is not applied periodically to counteract this effect and bring all cells up to the same potential, progressive degradation will eventually reduce capacity........

That is basically what I said before, only Piled Higher & Deeper, or PhD !!

Standby batteries aren't really supposed to do any work if things are going well. Batteries that get discharged and re-charged fall into a different category: they are being cycled.....and that brings up additional parameters, but, more or less, the maintenance routine is the same only battery life is considerabley shorter. The more cycles and the deeper the cycles, the shorter the battery life.

The paperwork I was quoting is something I have had on file for 24 years. This has been my source to help a lot of operating engineers get up to speed on batteries. It may be getting a little dated, but still is one of the great hand-outs that I have dispensed to folks seeking to better understand how to maintain batteries in a professional environment. Its probably save people more than a little money. I probably copied and handed out a couple dozen of these over time.....

[Franz©]

First, the 10 battery charger NAPA is now selling is an Exide product, and it's actually a trickle charger/desulfator, developed by Exide to increase shelf life on new batterys. There is some information on it on Exide's site. It was developed to maintain batterys sitting at retail locations, and found market when NAPA followed Interstate's consign to dealer model.

Batterys on concrete, well guys, that ain't urban legend. Until quite recently, battery cases were hard rubber, rather than the thermoplastic we have today, and did die when sitting on concrete thanks to osmosis.

Today's automotive battery isn't very comparable to the lead acid battery of 1950. The "plates" in modern lead/calcium automotive batterys more closely resemble screne door material than they do a battery plate, and the vibration dampers simply don't exist as they did years ago, unless you look at heavy equipment batterys.