Question about car battery sulfation
 

Is sulfation of a car battery a real problem or is it part of some sort of marketing ploy for sellers of "desulfator" devices?

I don't have first hand experience with desulfering a battery, but there is plenty of info online on how to make one:
https://www.flex.com/~kalepa/lowpower.htm

My understanding is that when used normally, 12v starting/accessory batteries don't suffer from sulfation (compared to a similarly constructed battery that is discharged deeply) because full charge is pretty much always maintained by the alternator.

Sulfation occurs when a battery is left partially discharged for a long period of time.

Yup:

I have pretty much ruined my car's 2 year old starting battery from just over a year of regularly running it down without the alternator. (In fact if it wasn't supported by the 2 floodies I'm now carrying, I would have had to replace it already).

EDIT: sulfation is more of a problem for EV's, since the pack may go days (or weeks, in my case) between "full" and needing a recharge. The guy who donated his used floodies to project ForkenSwift runs desulfators on each battery in his Ford Ranger EV (and will also admit he hasn't done any controlled testing to say whether they prolong batt life).

MetroMPG,

Thank you for your reply.

My question about sulfation is if it's true that sulfation is accelerated when the car battery is exposed to high temperatures such as the fact that it's in the engine compartment of the car as well as very hot external atmospheric temperatures?

My (not at all solid) understanding is that lead plate corrosion is more of a problem with high temperatures. Though I suspect a partially discharged battery will sulfate faster in warmer temps as well.

One of the reasons the US military is so interested in improved battery tech is because PBa doesn't hold up well in hot temps (ie. Iraq). As this US military Iraq battery dump attests:

https://www.evworld.com/images/iraq_b..._graveyard.jpg

yikes.

Yeah, no kidding.

And knowing that mil-spec is somewhat (slightly?) different from ForkenSwift-spec, I bet there are more than a couple of batts in that pile that would work quite nicely for my purposes...

I'll attest that desulfation actually does work as I've seen it work first hand. An otherwise "bad" battery was brought back to life in about 24 hours and continued to show improvement over a week of use/pulse charging (desulfation). An easy (but not always accurate) way to tell if a battery is sulfated is to run your hand across the side and see if the cells are bulging. If they are, you likely have a sulfated battery.

But like Metro posted, it's not a big problem as you're not cycling the battery and then leaving it undercharged.

After saying everything I said above... I too wonder if the charging voltage is high enough. At a higher temperature, the surface voltage (and voltage required to fully charge) increases. So I wonder if any of us are, in fact, charging at voltage too low causing the battery to never fully charge on longer runs where heat soak sets in...

Would it have "come back" with conventional charging & discharge cycles? What was the control?

The first thing tried was charging and discharging... The battery was abused to the point that it wouldn't take a charge at all (well, perhaps a few mAh :p).

After that didn't work, the desulfator was put on and after 1 charge cycle (which took a day), what was once a dead battery was a viable battery that was no longer puckered up from sulfation.

So there wasn't so much of a control as there was a try things until you find something that works attitude (as is/was the ethos of that community).

Perhaps it's worth noting that the batteries is and were used for an electric wheelchair - a likely candidate for battery abuse :p

I've had a similar experience w/ a battery that had been flat for about four to six years, although I didn't end up using one of those smart chargers, just a motorcycle tender. I tried taking it in to have an auto parts store charge it but the charging machine wouldn't do it and the sales person said it was dead. Took it home and connected it to a 2A/12V motorcycle charger for about six hours, let it rest for a day, then charged it for a full day and it showed the same voltage as my other good batteries for about a week, and has dropped a couple volts in the past week. I figure on letting it drop a bit more then taking it into the auto parts store so they can charge it w/ something more powerful to hopefully break up the rest of the deposits.

You mean the case bulging actually went down too?

omgwtf: I've read that's the prescribed means for trying to revive a totally flat battery - low charging current for a long time. May not cure hard sulphation, but it'll eventually turn the water back into sufuric acid.

There's a guy in Vancouver, BC who claims he can revive dead batts. He runs them in a converted EV pickup:

https://www2.blogger.com/profile/04941436561350451191

Last time I visited, he had blown up his controller though, and was off the road awaiting repairs.

As I understand it, the bulging is caused by sulfation - the crystals pushing outwards causing higher pressure inside the cells.

But yes, the bulging almost completely disappeared after a day :thumbup:

It's funny. I have the impression from the old hands on the EV List that desulfators are sort of the equivalent of acetone to the fuel economy crowd. Some people swear by it, many have tried it, some question the physics/chemistry behind the theory of operation, and nobody knows of any controlled studies that prove they work (at either prolonging the life of a healthy batt, or bringing them back from the dead to any usable degree).

Sulfation is a real thing. Like its been said above, some cars just don't charge the battery properly and end up doing harm. Also another killer is letting your car sit with the alarm set and various other computer bits draining power. When my daughter was in college her old camry sat for 3-4 days at a time then only make a short trip and repeat.... After I replaced the battery the third time I picked up one of those Volkswagen solar battery chargers on ebay and never had another problem.

You don't need a magic pulse desulfator though. A charger you can adjust the voltage up to about 15vdc will do. I have a very old analoug charger I use for this.

Heres a few links I have on Battery's, theres more than you want to know here:
https://www.e-marine-inc.com/articles..._charging.html
https://www.batterystuff.com/tutorial_battery.html
https://www.batteryfaq.org/

Roll your own desulfator:
https://www.shaka.com/~kalepa/desulf.htm

Interesting tidbit from the second link:

I have a battery charger that desulfates, along with 3 others that don't, along with a number of vehicles, and spare batterys that sit for months at a time, and at least on my motorcycle I end up having the battery last twice as long when I use the desulfater charger, I'm confident that the idea of desulfating is based off science, and I haven't yet heard anyone claming with any confidence that desulfating is bunk.

Some very experience solar electric (PV) dealer/installers swear by the desulfators. We have one on our house batteries, but of course will need another 15 or 20 years of use before we know if it may have made a difference. But I thought that spending about $100 on the desulfator was cheap compared to the $4000 cost of the batteries.

trebuchet03,

Does bulging also occur with batteries that have removable cell caps? Or is the bulging caused by the physical crystals pushing out instead of some sort of built up gas pressure inside the cells?

MetroMPG,

See, I did the charging up of the battery using my Black & Decker VEC1086BBD "Smart Fully Automatic Electronic Battery Charger" until the Full light came on. Then I used a hydrometer on the cell fluids and was getting readings of approximately 1225 "hydrometer units" or worse. A digital multimeter indicated an engine off battery voltage reading of approximately 13.01V. So I'm confused because my battery charger and digital multimeter suggests that my battery is ok but the hydrometer suggests that my battery is possibly bad.

Can you suggest any other tests than can be done at home to help determine if my battery is ok or bad?

Put a load on the battery. Surface voltage won't tell you too much. But if you put a load on the battery, then take a voltage reading ;)

As no authority on sulfation, and simply regurgitating a person I find to be a very reliable source. It's a gas pressure build up. Which reminds me... Bulging only applies to sealed PbSO4 batteries...

Sulfation begins the moment acid is added. Try to get replacement batteries that have not been sitting on the shelf for a long time. Gel cells are usually dated and have shelf life of about 3 years.

I have plans for a desulfator here:

https://www.flapdoodledinghy.com/desulfator.html

There's a few messages earlier in the thread with this link:
https://www.flex.com/~kalepa/lowpower.htm
https://www.shaka.com/~kalepa/desulf.htm
(obviously two links to the same user's stuff)

Unfortunately, the link is dead. Luckily, I was able to find it elsewhere. I started by using archive.org to get a look at it:
https://web.archive.org/web/*/https://...epa/desulf.htm
but the pictures were missing. I googled for some of that page's text and found the original at
https://home.comcast.net/~ddenhardt20...tor/desulf.htm

Note that the page does not actually contain plans for building it. It refers to the plans as being in "Home Power Magazine" issue #77, and offers additional information/corrections.

Walmart use to sell and probably still do a liquid that you could add to your battery that was supposed to prevent sulfation. It was in the sporting goods department. Last time I replaced the battery in my motorcycle I used it, but that was only about a year ago. I did notice that the battery maintained a charge during the off season (Nov.-Feb.). I used to have to recharge the battery about every spring. If I remember right I added 1/2 oz. to each cell when I added the acid to the battery. I think they recommended 1 oz. per cell to a larger battery such as a deep cell or car battery. I think it was about $12. for a 6 oz. bottle a year ago. I thought it would be worth a try since motorcycle batteries usually only lasts about 2-3 years.

My dad used to use something like that in our lawn tractor battery. It always revived a battery that refused to charge. I found one bottle still in its package when he moved recently. I also recently bought some stuff called "Charge It" but haven't tried it yet.

I checked and I still had 1/2 of the bottle, the name of it is Minn Kota battery equalizer.