DC arc welder restores sulfated golf cart batteries.

[Cujet]

I can't believe it actually worked.

My lightly used airport 48V golf cart had new batteries about 5 years ago (batts dated 2018). As expected, the range and speed declined over time until the useless thing sat unused for the last two years, as the batteries would not charge with the finicky digital charger.

A year ago, I tried using various tricks to get some power into each 8V battery (they were showing 0.54V to 2V) Then hooking up the cart's charger and so on. Best I got was about 2-3 minutes use, then they'd go dead.

After watching a YouTube video about using an Arc Welder to desulfate flooded lead acid batteries, I thought I'd give it a try. Using care to get a spark free connection. A fan to blow away tons of explosive fumes and a 5 minute limit, I followed the procedure.

Note the DC TIG welder's ground is POSITIVE. So that's where it goes. Started at 10A, until each cell boiled, then 50A for 4 minutes and 100A for a minute, boiling like crazy, a few cells boiled over so I backed it down and up again to reduce losses. That's it, as repeated "zapping" did not seem to be necessary. As each 8V battery was showing 8.4V or so.

Hooked up the charger, and they charged normally. Battery measures at 80% after a number of miles, and 50.4V, or 95% in the morning, after charging and disconnecting overnight. I believe it restored the batteries, as I can now drive it all over the place, down dirt roads, top speed runs, (it goes 30)

Success

 

[SubLGT]

.........Started at 10A, until each cell boiled, then 50A for 4 minutes and 100A for a minute, boiling like crazy, a few cells boiled over so I backed it down and up again to reduce losses.....

What voltage?

 

[f355spider]

 

[JRay’07]

You're flirting with danger!

 

[f355spider]

You're flirting with danger!

I'd definitely do this outside and wear safety glasses and other PPE to protect myself

 

[oldgrayman]

Face shield .

 

[Cujet]

You're flirting with danger!

Correct, I used the fan to reduce the chance of accumulated hydrogen gas. I also screwed on long wires to the terminals (I did not use clamps), and remotely hooked up my welder. That way, there was no chance of a spark. The terminals were clean.


Golf cart was outside, welder inside. Welder is a Syncrowave 180, with variable amps and set to DC, stick weld. Turned on and off from the welder. I wore goggles and had a hose ready in case something happened. Stood back just in case.

What voltage?

Not sure on the voltage, I did not want a meter hooked to the battery during this, just in case acid went everywhere. On the videos I've seen, they measured the voltage somewhere under 20V. Clearly, it's high enough to PUSH plenty of current through a sulfated battery.

Just drove 15 miles, no issues what so ever. I still can't believe it. The thing still hit top speed at the end of the drive. Plenty of power left. I'd say the 95% voltage/capacity reading I get is accurate.

 

[Brad_C]

Sounds like you blew the sulfated surface off the plates. You'll probably find more sludge in the pit under the plates and a reduced capacity, but when compared to useless high resistance sulfated batteries it sounds like a win to me.

 

[Cujet]

Sounds like you blew the sulfated surface off the plates. You'll probably find more sludge in the pit under the plates and a reduced capacity, but when compared to useless high resistance sulfated batteries it sounds like a win to me.

I'm driving it about 20 miles around the neighborhood, even made it home from the other side of Jupiter Farms on a semi-flat tire last night. The range is very close to what it could do before with generally healthy batteries. The batteries measure at 95% and so far, I am in utter disbelief.

I'm sure you are right, there is likely to be some "debris" at the bottom of the cells. I've been driving on washboard dirt roads and maybe this settles the junk to the bottom?

 

[sdowney717]

Good golf cart type batteries have solid metal plates, ASFAIK, versus expanded metal plates of starter batteries.
Expanded plates do give a lot more surface area for the chemical reaction to create electricity, (starting power) but those kinds of plates are also thinner, do fall apart and break, whereas a solid golf cart battery is not going to break up like that and fail in that way.
Will sulphate, as in all lead acid batteries do.

 

[SHOZ]

The high amperage busted the sulfate off the outside of the lead active material of the positive plates So a lot of capacity was lost. And if you topped off with water after loosing electrolyte then the specific gravity is probably low. Again reduces capacity but extends life.

Most cheap auto batteries have the plates separated by the old timey rubberized fiberglass or some other sort of fiberglass. usually the positive plate is completely wrapped in higher quality batteries. This keeps the shed material from accumulating at the bottom and shorting out.

 

[Donald]

I thought the goal was to get the sulfate crystals on the plates back into solution, not just to dump them to the bottom of the cells.

 

[SHOZ]

I thought the goal was to get the sulfate crystals on the plates back into solution, not just to dump them to the bottom of the cells.

No they will not go back into solution. It's a one way road.

But on the original AGM industrial batteries sometimes taking then into reverse voltage of say -1.0v or so per cell, then a recharge would help. A lot different chemistry in the paste for the plates though, much simpler actually then the old red positive and yellow negative lead. Grid alloys make a big difference too.

 

[VersatileGuy]

Partially boneheaded regarding the Epsom salt. He apparently took out all the acid and then further neturalized the remaining acid with baking soda. So the only SO4 ions left were the Epsom salt ions.
My understanding is that Epsom salt is added to the acid to provide more sulfate ions so the remaining exposed lead can work better.

He says he isn't sponsored, but he is little too "bright" to be that boneheaded.

Welders are just shock value. Anything that can pump 16+ volts does an equalizing charge but because all the auto battery chargers on market don't have them, the companies do not feel threatened that people would go out of their way to buy a dedicated DC charger to perform equalizing charges.

I will say this about pulse desulfation. The Batteryminder's special algorithm does have some sorcery in it that makes it able to revive abused batteries to an extent. The others, might be just a waste of ICs or they might work but people don't want them to show them working.

 

[dnewton3]

Or you can just get a Battery Tender, which has a cycle built into its programming that knocks the sulfates off the plates as part of its charge cycle.
I have a battery in my 2006 Kubota tractor that is still OEM from the day I brought it home; been on a BT charger for these 18 years and still does everything it's supposed to do.

 

[f355spider]

Battery Saver makes a similar claim to "pulse" charging or maintenance profile. I own a couple of them.
See page 12 of their marketing information:
https://www.batterysaver.com/uploads/9/9/4/2/99423532/cat2023-web-compressed_1.pdf

I also have three Battery Minders as well. They all seems to work adequately for me.

 

[bunnspecial]

Welders are just shock value. Anything that can pump 16+ volts does an equalizing charge but because all the auto battery chargers on market don't have them, the companies do not feel threatened that people would go out of their way to buy a dedicated DC charger to perform equalizing charges.

I deal a lot with small SLA batteries(usually gel cells) and have brought a few back to life using a bench PSU that can go up to 30V(usually combined with popping the caps and rehydrating the cells).

I have had a few times that a battery would seem totally open circuit, but cranking the voltage WAY up I would often reach a point where I'd seem to "break through" and it would suddenly start accepting a trickle of current. This is often at 20V+ for a 6V battery.

I wouldn't bother with any of it to be honest except that I deal with one particular 6V cell that quite literally is no longer available. It has to fit in a very tight spot, the original manufacturer no longer makes it, and the cross referenced cells on the market are too large to fit. Doing this is a last resort before I do the really messy job of cutting the battery case to stuff NiCds in it(and yes I can get away with that because the device the battery fits was designed to use either battery chemistry-you just have to tell it that you now have NiCds there).

 

[SHOZ]

I deal a lot with small SLA batteries(usually gel cells) and have brought a few back to life using a bench PSU that can go up to 30V(usually combined with popping the caps and rehydrating the cells).

I have had a few times that a battery would seem totally open circuit, but cranking the voltage WAY up I would often reach a point where I'd seem to "break through" and it would suddenly start accepting a trickle of current. This is often at 20V+ for a 6V battery.

I wouldn't bother with any of it to be honest except that I deal with one particular 6V cell that quite literally is no longer available. It has to fit in a very tight spot, the original manufacturer no longer makes it, and the cross referenced cells on the market are too large to fit. Doing this is a last resort before I do the really messy job of cutting the battery case to stuff NiCds in it(and yes I can get away with that because the device the battery fits was designed to use either battery chemistry-you just have to tell it that you now have NiCds there).

Completely dead AGMs are the same way as far as not taking a charge. I just let them sit on charge for whatever it takes and sooner or later they start taking it. The amperage is low but that will drive up the voltage. As the voltage returns to normal the amperage will increase.

 

[bunnspecial]

Completely dead AGMs are the same way as far as not taking a charge. I just let them sit on charge for whatever it takes and sooner or later they start taking it. The amperage is low but that will drive up the voltage. As the voltage returns to normal the amperage will increase.

AGM and gel cell, at least per my understanding, probably have more alike than different. At lot of the charging behaviors and such are similar. In fact, a lot of really small batteries are labeled "AGM" when in fact they are gel cells(Hawker/Enersys Cyclon cells are a true AGM design, but most small monoblocs are gel).

I have a pair of old HP multimeters on my bench, and when I'm doing this kind of stuff I'll often use one to measure current and the other voltage, and then log the results on the computer.

It's actually really interesting to watch what these "revived" cells do. For a normally operating battery, I'll set my bench PSU to whatever voltage the cell maker says(usually 2.35V-2.40V/cell is good for AGM and gel) and unless I'm in a hurry will generally set the current to .1C. A normal charge will relatively quickly(depending on how low it was before you started) reach your pre-set voltage and the PSU will switch to constant current mode, at which point current starts to drop(and then I will manually reduce the voltage to trickle level once current falls to about .01C).

The behavior during what I've called the "revival" stage is interesting, and I've done enough now that I can usually tell if one is going to come back to life by watching it. Basically you will see an initial constant voltage while current increases until you reach your current set point, at which point voltage will usually start to drop. The amount that voltage drops before starting to recover and the time it takes to do that usually gives me some learned/observed insight as to whether the battery will bounce back or not. If I see say a .1V/cell drop at max current and it recovers in a half hour to full voltage(and current then starts decreasing) chances are good that the battery is relatively healthy. If I'm sitting at say .1C for 12 hours and voltage is still dropping, or even if it's bottomed out and not started to recover, the battery is probably still toast(and at that point it's probably heating up a LOT).

I've done some other pretty unconventional things in here. I have boxes and boxes of dead Powersonic PS-832 batteries, an 8V, 3.2AH monobloc cell(I rebuild/refurbish devices that use these, and they're still readily available and inexpensive) so I've done a lot of experimenting with those. I need to take a bunch to the next county waste collection, but have a few I've brought back to life that actually work fairly well. I generally only bother with those if I pull one with a relatively recent date on it. In any case, though, I've actually had moderate luck by briefly putting the battery case in the ultrasonic cleaner for a few minutes at a time while charging.