Battery life

I put these same size batteries in computer UPSes; one of them is on its third set of batteries since I got it in about 2000. I have had pretty good luck with Panasonic and Power-Sonic brands, and pretty bad luck with all the others I have tried. All the previous Power-Sonics I have bought were made in Mexico, but the ones I bought in 2013 were made in China. I put them in my old UPS but their longevity remains to be seen.

If the utility power is going out more often in your area for some reason, the alarms will probably go through batteries quicker as well.

How about connecting them to the van's electrical system when the ignition is running? That system is *designed* to charge a 12 volt lead-acid battery. :) Okay, it's not exactly the right voltage for a sealed battery, and you probably don't need to charge them every day. Maybe only hook them up to the van every Monday or every first of the month or something like that.

Power-Sonic claims that their batteries can be stored for a year before recharging is required. They also advise charging a new battery after

6 months of storage after *you* get it, to account for the time it sat in the warehouse.

Paper page 10, PDF page 12 of

has a chart of self-discharge over time at various temperatures. It also claims that if the battery is allowed to self-discharge to less than 60% of its nominal capacity, charging the battery may not restore full capacity. According to the chart, this 60% point is hit in a little over 12 months if the battery is stored at 20 C (68 F). At

30 C (86 F) it happens in 8 months, and at 10 C (50 F) it's over 18 months.

The chart doesn't talk about *how much* capacity is permanently lost, just that it won't be back to 100% capacity.

Matt Roberds

I've similar lifetime problems with UPS batteries. I also deal with weather stations that use the same gel cells. So, besides the batteries from China what has changed?

1. It's difficult to find a real gel cell today, even if it's labeled "gel cell". Most everything is AGM (absorbed glass mat). The gel cell battery has one advantage over the AGM battery. It has a constant plate top plate spacing, which makes it better for use where sulfation is possible. AGM has more surface area, and therefore more capacity per unit volume. They can also be charged at a higher rate than gel batteries. AGM can handle vibration better.
2. Sophisticated charging circuits allow fast and safe charging very close to 100% capacity with temperature compensation. In the bad old daze, a gel cell charger was just a diode and series resistor, that would charge to about 80% of capacity, and consider that adequate. Today, the chargers go much closer to 100%. If overcharged, lifetime is greatly reduced.
3. Sources for batteries have greatly increase. In the bad old daze, there were perhaps 4 sources of gel cell batteries. The gel batteries were fairly close to internally identical and very interchangeable. Today, there are probably about 30 manufacturers with more appearing every day. Subtle changes are constantly being introduced to give each manufacturer a competitive advantage, which introduces divergence in specs and performance. A clue is simply to weigh the battery, which is a very rough indication of the amount of lead used. In general, the junk batteries tend to be light weights.

So, what we have today is a far more critical battery system. The risk of overcharging and going outside the charge profile is high. The quality of the batteries are all over the map. The interchangeability of batteries for both AGM vs gel and for different brands is dubious. Temperature control and compensation is a bad joke.

If you want long life, you'll need to:

1. Don't charge too quickly.
2. Limit the available choice for substitute batteries.
3. Crank DOWN the charge controller to well below 100% capacity.
4. Don't let the battery discharge below about 50%.
5. Put the temp sensor on the battery, not on the controller
6. Don't use gel batteries in vibration prone environments.

Note that most cheap UPS designs break all these recommendations. They want to recharge as fast as possible so that if the power dies again, it's ready. They want as long a runtime as possible for advertising purposes, so they charge as close to 100% as possible. The low voltage shutdown point is often as low as 25%. Battery temp sensors are never on the battery.

Or, think about Li-Ion replacement batteries and a "balance" charger:

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Hmm, I thought that was the idea behind gel cells partly. That the electrolyte is pretty much trapped against the plates and doesn't shlosh arond. Live nd learn I guess.

What about those battery desulfaters ? From what (actually little) I've seen of them, they put an AC current on them, which presumably somehow dislodges the sulfate from the plates.

Anything to that or is it more of a gimmick ?

Another thing, of which I am less unsure, is/was the practice of junkyards rejuving lead acid (car) batteries by adding epsom salt to the electrolyte. I don't suppose there would be any way to do that here. Also, it didn't seem to last forever.

Ask any motorcycle shop about which type they prefer. As I understand it (possibly wrong), the gel type have a wider gap between the plates because the plate assembly is not very rigid and prone to warping and bending. AGM is much stiffer, so the plate assembly can be packet tighter. According one vendor, AGM outsells SLA by 100:1.

I couldn't find much on the difference in construction (I'm in a rush today) but did find an article that covers the major chemical differences:

I'm going to pass on trying to answer that question. I don't use them and have minimal experience with them. The few times I tried a pulse charger/desulfator, it either didn't do anything useful, or appeared no better than a conventional charger. However, I'm not sure I was using it correctly, didn't do much in the way of measurements, and decided it was easier to replace the battery than to continue testing.

SLA means "SEALED lead-acid". Is there something about the word "sealed" that I'm missing?

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"sealed" that I'm missing? "

No, I was thinking maybe ddrill a hole, suck some electrolyte out and disolve some in to rejuve it. Sorta like refilling an inkjet cartridge.

Some people used to say if I had any brains I would be dangerous, but hey, maybe I can do without !

Epsom salt, that has magnesium in it right ? That's the metal that burns. Not as good as pure sodium, but burns...

That article you linked to mentions deionized water. Recently my sister bought my Mother a clock that runs on water. You have to change the water from time to time and the manual mentions something about cleaning the electrodes every once in a while.

Maybe this thing has a secondary purpose as a water deionizer ? Other than batteries and certain chemical experiments, what else might they use deionized water for ?

Hmmm.

AFAIK, some battery suppliers stock the batteries in a dry charged state - the gel is supplied in ampules with a seal that is pierced when you press the ampules into the top of the vent hole.

Last flooded cell motorcycle battery I bought was done like this, the dealer has a bottle of acid to fill batteries as and when they are sold. It would be reasonable to assume the same applies to car batteries.

No idea what the shelf life is - but certainly a lot longer than pre filled ones.

Another thing to consider; lead acid batteries get lazy if they spend their life on trickle charge and never have to do much work. An occasional heavy discharge cycle can liven them up a bit if they get sleepy.

The Optimate charger I have includes a desulphate function - it applies 29V current limited, AFAIK its also pulsed.

AH rechargeable lead acid gel cell batteries in series. Although fifteen or so years ago you could get up to ten years out of a typical set of Japanes e gel cell batteries, these days it seems that three to five is about all y ou can expect from the Chinese knock offs that have flooded the market. I u sed to keep replacements in my van but I found that if they weren't used wi thin a certain time frame they would sulfate. So now I don't keep any of th ese in stock, instead I buy them as I need them. It's a little more inconve nient but I always get fresh ones this way.

ad bought a case of batteries, he said "a few months ago" and asked me to u se his. I used two batteries that he had in stock. The batteries had a 5/13 date code. Although the batteries came right up and worked fine I have to wonder, how well will these two batteries, that have been sitting in a box for over a year perform as compared to two fresh ones? I guess what I'm ask ing, if anyone knows, how much life span is gone or lost by these batteries just sitting in a box for fourteen months? Thanks, Lenny

I used to read a lot of electronics experimenters books when I was a kid, ( way back). Some of this reminds me of an experiment I once performed. I too k a standard carbon zinc D cell that was dead and soldered two wires, that were connected to a flashlight bulb onto it. I then punched numerous holes in the battery and immersed this contraption into a solution of very salty water. After a few seconds the lamp began to glow.

About fifteen years ago my youngest boy needed an experiment for Science cl ass and I suggested this one, which we named the "Frankenstein battery". It apparently was a big hit at school. Lenny

I grew up on a steady diet of Popular Electronics and Carl and Jerry stories. Actually, I never really grew up, but we won't go there.

Nicely done. I took apart a carbon-zinc alarm battery, and recreated the battery in a mason jar using vinegar and lemon juice as electrolytes. That worked, but made a huge mess in the kitchen. My father moved me to the garage, where I recreated the mess. Lesson learned: The bigger the mess, the better it works.

Some years later, I was pondering if there was something that could be done to revive expensive dead NiCd batteries. I knew that overcharging and overheating NiCd batteries would cause them to "vent". My guess(tm) was that there was some electrolyte loss involved. So, I notched a corner of the cell with a triangular file, and used a syringe to inject some KOH (potassium hydroxide) electrolyte. That worked in about half the cells I tried, but I was only able to obtain about half the original ma-hr capacity. Had I had been able to inject the KOH under pressure, to better distribute it, I might have done better. Later, I increased the KOH concentration from about 20% to 100% KOH and created yet another smoking mess. Lesson learned: A bigger mess does not make a better battery.

Roll forward many years, and I'm still experimenting with NiCd batteries. This time, I want to see how quickly a NiCd can be charged. I now had more test equipment and a source of cheap cells. I would charge the cell from about 10% capacity, to as close to 100% as possible, as quickly as possible, and then test for capacity using a West Mtn Radio CBA-II battery analyzer.

NiCd batteries do not get warm until they are overcharged. It is possible to charge a depleted battery at almost any charge rate imaginable, as long as it is not overcharged. Overshoot even slightly, and the battery will overheat and possibly explode. The threshold is amazingly sharp and varies with battery vendor, age, condition, past history of battery abuse, and the position of the moon. In short, it wasn't very predictable. I would successfully charge a collection of batteries at a 10C rate but eventually find one battery that would explode without warning or reason. My very fast charger was not going to be a very safe commercial product. Lesson learned: A big mess is a good indication that the idea is not commercially viable.

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

AFAIK - most motorcycle shops are making the transition to AGM batteries - it was still possible to buy a flooded cell battery last time I wanted one.

AH rechargeable lead acid gel cell batteries in series. Although fifteen or so years ago you could get up to ten years out of a typical set of Japanese gel cell batteries, these days it seems that three to five is about all you can expect from the Chinese knock offs that have flooded the market. I used to keep replacements in my van but I found that if they weren't used within a certain time frame they would sulfate. So now I don't keep any of these in stock, instead I buy them as I need them. It's a little more inconvenient but I always get fresh ones this way.

had bought a case of batteries, he said "a few months ago" and asked me to use his. I used two batteries that he had in stock. The batteries had a 5/13 date code. Although the batteries came right up and worked fine I have to wonder, how well will these two batteries, that have been sitting in a box for over a year perform as compared to two fresh ones? I guess what I'm asking, if anyone knows, how much life span is gone or lost by these batteries just sitting in a box for fourteen months? Thanks, Lenny

Lead acid batteries are kind of strange. They share a property with NiCads in that they can be (re)conditioned. This consists of taking them up to full charge then running them down to about 75% and bringing then back to full again. Do this 3 or 4 cycles and it will improve capacity and longevity. Nicads like being discharged to near 0 better though.

?-)

I'm not sure that's correct. I recently saw a reference that basically say s the deeper you discharge a lead acid the less life you get. I'll try and find that again.

They used to develop a memory. I believe that problem has been solved.

I've just found a couple of stories about people seriously injured by flash light explosions involving C123s. They were exposed to hydrofluouric acid gas and had long term lung damage. I wouldn't have expected enough chemica l in those small batteries but i guess I was wrong.

Rubbish. I have to deal with lead-acid batteries of various types constantly. The only sure way to kill them is to discharge the battery below some percent of full charge, which varies with battery chemistry. Run a gel cell battery in a UPS below about 30% of full charge and you will have a very dead battery in a few weeks.

I'm in a rush, so no authoritative URLs today. Instead, think about how a lead acid battery works. When you discharge it, some of the lead goes into solution in the electrolyte. When you recharge it, the lead gets plated back onto the plates. Pull off too much lead, and there's not enough surface for the lead in solution to go during recharge. Eventually, you get a "warped" plate, which is a crude term for uneven plating.

In my never humble opinion:

1. There's no such thing as NiCd "memory effect", except in very unique conditions found only in sintered plate batteries (found in airplane starter batteries).
2. Charge cycling (conditioning) *ANY* battery might produce a short term increase in capacity, but will also accelerate its demise.

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Apparently this especially the case with SLA batteries, I've seen the figure quoted of 11V that you should cut off the load to prevent permanent loss of capacity - You can of course buy a leisure battery which is designed for deep discharge, as long as you don't go too deep too often (and charge it back up again before sulphation sets in).

AFAIK - Ni-Cd cells like to be fully discharged every once in a while - but not in a battery of series cells.

All cells are not created equal, and any that run flat first will be reverse charged by the others - which really does hit capacity!

Yeah, that almost got me disowned, disinherited and thrown into a bag of kittens.

good site with answers about batteries - and they will answer questions too!

John :-#)#

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It's not just NiCd batteries, but all batteries. The RC (radio control) crowd had an ususual opportunity when they started building their own battery packs and found that charging them in series was a guaranteed disaster. So, they came up with the "balance" charger which charges each cell individually. All (and I do mean all) RC battery packs include seperate connectors for charging and discharging. I have a fancy balance charger, that will do many things that ordinary series chargers won't or can't do (if I can decode the Chinese instructions).

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Not as far as I know. Some lead-acid cells can be permanently damaged if run down to zero even once. This happened to a Sony Discman battery that was accidentally discharged slowly, over a period of about a week. It was dead, dead, dead, and would not take a charge.

I won't dispute the Wikipedia article.

However, I remember when the memory effect (or a memory effect) was discovered in rechargeable toothbrushes, back in the '60s. Running the cells all the way down reversed the effect.