Recovering a sulfated battery

[crcook84]

We have a battery that we've had since 2016. Within the past year, it stopped working properly. Now, we live in Texas, which means we have temperatures well over the suggested operating temperature of car batteries at least half the year. The fluids in the battery were still high enough to keep the cells fully submerged. So, I decided to try desulfating the battery over a month's period of time to see what would happen. After a one month period of time, I check the voltage with a voltmeter and it read 12.8v. I hooked it up to one of our cars to see if the voltage and CCA were high enough to get the car to turn over. I'm able to turn over the car twice.

At this point, I decided to hook up a trickle charger to the battery to see if it'll top it up overnight. The next day, I disconnect it from the trickle charger and check it with a voltmeter again and it shows 13.1v. I tried turning it over twice and the engine was able to start up both times.

I decided to put the battery aside for a couple of days with a tricker charger hooked up to see how it works after it's been sitting for a while. After 4 days, I checked the voltage on the battery and it was at 8v. At this point, I would consider calling it a false reading that I was getting before. But, if I was able to turn my car over twice waiting 24 hours between attempts immediately after my last desulfation process, that doesn't seem like a false reading.

Am I looking at the possibility that a desulfated battery is now more vulnerable to becoming easily sulfated in a short period of time?

[crcook84]

Update: My battery was showing 8v around 12pm. It gradually increased to 10.7v at around 6pm. It seems to be plateauing at that value because I checked it again at 9:30pm and it was showing 10.75v. I'll post what the battery reading is tomorrow.

[Ed_Strong]

Cool, I'm hoping it works out for you! Keep us posted on the outcome.

[crcook84]

Update 2: I checked the battery today and it was sitting around 10.7v. I've hooked it back up to the trickle charger just to see if anything would improve over the next several hours. However, at this point, I'm ready to make an assessment.

The battery managed to get up to 12.8v after I continued the sulfation process inside the house. Now this could just be a coincidence because the battery may have already been improving because it was in the middle of the 4th week that I moved it inside. However, the house was at a temperature controlled 75F, the ideal operating temperature for car batteries. Then, when I took it out to hook it up to our car battery, it was night and the outside temperature was at an ideal 80F. That gave the trickle charger a chance to get the battery up to 13.1v. Then, over the next few days, the temperature went up to 90F....and my car is black.

At this point, I'm going to assume that, because the battery probably went up to 100F within the engine compartment during the next few days outside, it re-sulfated. However, because it had already become sulfated due to 6 years in Texas heat, it's more prone to becoming re-sulfation more easily. If anyone else has any other thoughts on this, I'm open to your opinion. Otherwise, even if you have a de-sulfator, don't expect your car battery to last more than 5 to 6 years if you live in a state like Texas that'll reach temperatures over 80F (because the maximum ideal car battery temperature is 75F to 80F) 4 months out of the year.

[crcook84]

Final Update: So, I plugged in the trickle charger at noon and decided to give it a few hours to see if it would go up from 10.7v. It didn't. Obviously, I could run it through de-sulfation again. However, given the fact that it so quickly went back down to 8v while on the trickle charger, I think there's something else going on with the battery, whether the cells changed their compositional properties or something is wrong with the acid solution. Either way, even if I was able to briefly get it back to 13.1v, if it won't reliably stay at 13.1v, it's not worth a plugged nickel to me. Maybe de-sulfation will give more reliable results to individuals in cooler climates. But, based on my own experience, de-sulfation appears to be a fruitless endeavor for anyone who lives in an environment that stays over 90F at least 1/3rd of the year. If you live someplace like Texas, Arizona, or New Mexico, don't expect your lead-acid car battery to last any more than 6 years.

[crcook84]

So, I found a random website that discusses how old batteries can randomly fail due to high heat regardless of how maintained they are:

https://www.odysseybattery.com/news/...e-summer-heat/

"If a battery has a design life of six years at 77°F (25°C), and the battery spent its life at 95°F (35°C), then its delivered service life would be three years. This dramatic reduction in delivered service life can cause older batteries to suddenly fail in high heat because the accelerated failure rate occurs without warning."

"Lead-calcium AGM batteries are similar to lead-calcium/acid flooded batteries as both have continuous grid corrosion (galvanic corrosion) and this issue is increased due to high heat."

[fredjacksonsan]

6 years is a good run for a car battery in a hot environment. When you said "able to turn engine over twice" was that the limit of what it could do?

Although your experiment was interesting, this ine's done and needs replacing.

[crcook84]

Originally Posted by fredjacksonsan

6 years is a good run for a car battery in a hot environment. When you said "able to turn engine over twice" was that the limit of what it could do?

Although your experiment was interesting, this ine's done and needs replacing.

The car battery was only intended to be just that: a car battery. So, I didn't bother seeing if it could do anything beyond that. And with the core charge discount, I'm not that interested in finding out.