Desulfators?

[ed1380]

your battery pooped?

 

[kibble]

It must have been constipated and that's why it had no power, once it "pooped" it was good again.

 

[jr dragster T]

Well today I thought to drain it

And what's weird is... well here's the whole skoop:

1) Lasted about 1 minute before dimming rather... well like at a 4V level.

2) Let it sit there (hey I wanted to drain it all!)

3) Out of nowhere after a couple minutes there's a small *poop* and the light goes up to FULL BLAST

Literally, as in it looked better than it was at full charge. And as good as a 13V measured battery on the same light.

So... weird battery.

It's probably your half *** conections with tie wraps and hot glue.

 

[kibble]

You mean he's not using butt hairs and duct tape? No wonder it's not working...



Oscar, you should use a resistor of something maybe about 24 ohms and 20 watt (1/2 amp draw) and an ammeter so you can measure the amperage for a certain amount of time and see how it holds up, the resistor will probably get very warm so it would probably bee a good idea to keep it cool somehow.

 

[jr dragster T]

Butt hairs lmao, Liquid cooled resistor FTW!

 

[ZnsaneRyder]

I dunno, I was just reading about them, some say that you have to charge them and discharge a few cycles before you'll see the gains.

I was just looking for a schematic so I can build my own.

True! I desulfated a few on my own, but they only kept a good charge after draining and recharging them a few times. I use a modified regular 12V battery charger with a 4700uf capacitor as a filter to filter the rectified DC peaks to give me a no-load voltage of ~18V. Also the automatic circuits (that detect full charge) is bypassed, so I have to keep an eye on it to not overcharge too bad, but it has revived a few batteries already. You can add a capacitor to any battery charger.

When a sulfated battery starts to take a charge again, the acid inside will bubble like a full battery because the voltage is over 15V, but let it keep bubbling and the voltage over time will actually DROP down to 12-13V and the battery will start to charge, then it's full once it gets to about 15V again.

I'm also designing a High Voltage, low current desulfator to leave on really bad batteries for days at a time, using a light bulb as a reliable resistor. It will give up to 120V DC (120Vx1.414=162.6V peak) I'm not sure if I'll use a capacitor or not, well see. I'm about to build it today! Here's a schematic:

To anyone here needing a multimeter, Harbor Freight tools has a sale on their multimeters, $3 for a regular digital, and $7 for the same one with a backlit display! Don't go to RadioShack for a meter, HF has the best deal on a good meter!

 

[ed1380]

sweet. ive wanted to build the one that was at the beginnng of the thread, but i couldn't find a special diode that it needed. i got a couple of lead acids that i want to fix. normal charging dont work

 

[ZnsaneRyder]

Update: It works! Awake the dead!

I got a Marine battery that's been flat dead for over a year to start charging!

It's cool that the light glows when current flows in the battery.

The voltage came up to over 25V at first, then dropped to 12 after 30 mins, then to 10.8V-11V after about 6 hours. After that, I put my bypassed charger on the battery @ 10A, and it sat at 15V for a while, then dropped slowly to 13.5V after 3 hours, then I put it on a 2A charge, and let it sit for more hours, and it's nearly full now. I'm letting it charge overnight.

The desulfator is LOW current, and won't charge the battery much by itself, but it wakes up the acid with the high voltage, so you can charge it again with higher current. Because there's over 120V DC, I decided NOT to use a capacitor, because I don't want to get shocked by the stored voltage in the capacitor, after it's unplugged.

BTW, I got my parts from broken TV's. All free. The bridge rectifiers are easy to spot. (bridge rectifiers are just 4 diodes in one package)

*I'm only using a 4watt bulb, I may try a 60W or 75W bulb and see how it does.

I still say you need an unregulated charger (in addition to the desulfator) of some sort once the battery starts to take a charge again, so you can leave it at a high voltage, but have good amps to charge with. A regulated charger will shut off too soon and not give a full charge. A 3Amp, 12.6V Radioshack transformer with a bridge rectifier and a capacitor would do the trick if you don't have an unregulated charger like mine.

 

[ZnsaneRyder]

In those pics, where does that Desulfator get its power from to feed the batteries?

Does it plug in to the 120V outlet, and the plug is not in the pics? All I saw was two wires.

 

[ZnsaneRyder]

Never mind, I got how the 12V version of that desulfator works, it has to have a 12V battery charger connected in parallel.

I'm about to check that Marine battery today, I'll keep you posted.

 

[oscaryu1]

True! I desulfated a few on my own, but they only kept a good charge after draining and recharging them a few times. I use a modified regular 12V battery charger with a 4700uf capacitor as a filter to filter the rectified DC peaks to give me a no-load voltage of ~18V. Also the automatic circuits (that detect full charge) is bypassed, so I have to keep an eye on it to not overcharge too bad, but it has revived a few batteries already. You can add a capacitor to any battery charger.

When a sulfated battery starts to take a charge again, the acid inside will bubble like a full battery because the voltage is over 15V, but let it keep bubbling and the voltage over time will actually DROP down to 12-13V and the battery will start to charge, then it's full once it gets to about 15V again.

I'm also designing a High Voltage, low current desulfator to leave on really bad batteries for days at a time, using a light bulb as a reliable resistor. It will give up to 120V DC (120Vx1.414=162.6V peak) I'm not sure if I'll use a capacitor or not, well see. I'm about to build it today! Here's a schematic:

To anyone here needing a multimeter, Harbor Freight tools has a sale on their multimeters, $3 for a regular digital, and $7 for the same one with a backlit display! Don't go to RadioShack for a meter, HF has the best deal on a good meter!

Zomg! How can I bypass my 12V 1.5A charger ?

Only thing I've used before was a 18V transformer from... an idk what

TELL ME MOAR. I've never actually built anything from scratch... Me'd love to knoes. If it matters, I have two TV's I can scrap for parts.

You can add a capacitor to any battery charger.

Really? I have those "Battery Maintainers" 12V chargers...

Whoops lunch bell rang. BRB

 

[ed1380]

wait so what exactly do you do? hook up the thing in the diagram to the battery overnight and then to a unregulated charger and see if it takes a charge?

 

[kibble]

I don't think it's "overnight", I believe it takes a long time, sometimes days to desulfate a battery to a decent level. You have to have the desulfator in parallel between the charger or power supply and the battery.

I'd been meaning to build that desulfator I linked the schematic to early on in the thread, but I had a problem finding some of the parts myself. I would love to revive some dead batteries I have.

 

[oscaryu1]

Obtw ed - If those SLA's measure below 6V, don't even consider trying to charge them. I've had ones measure .4-2V, they had rusted/crapped out cells.

In other words - if you slap a SLA on the ground, and you shake it around and hear... things, then you got... crapped cells.

 

[jr dragster T]

if you slap a SLA on the ground

I dont like to slap batteries

you got... crapped cells.

And some probelems.

 

[oscaryu1]

Well.. I recently... well... I'll make a thread if it's sucessful

 

[ZnsaneRyder]

wait so what exactly do you do? hook up the thing in the diagram to the battery overnight and then to a unregulated charger and see if it takes a charge?

Exactly.

It will start taking a really slow charge when you use the 120V DC desulfator cord, if you measure the battery voltage, it will go up, then down. That's when you connect the unregulated charger.

 

[ZnsaneRyder]

The Marine battery is still taking a charge, but the cells are in bad shape, so a full charge only gave it 12.4V instead of the 12.6V or so, but still far better than nothing. I've left my 120V Desulfator on it for several days since, and I'm about to drain, and recharge the battery again to see if I can get it a bit better.

I'm glad, that's still another battery I can use, that was just useless before, now it's worth something to me, and great for projects.

 

[oscaryu1]

Hey ZnsaneRyder, do you have any schematics on making that "18V" charger? Or just pretty much raising the voltage of a cheap $19.99 WalMart 6/12V 1.5A Charger?

Thanks!

 

[ZnsaneRyder]

I haven't been inside one of those WalMart chargers, so I'm not sure about those.

An easy for-sure way, Go to RadioShack and get a $15 dollar, 25.2V transformer, 6A bridge rectifier, and capacitor. The transformer outputs more than the specs @ 26V, and about half of that (13V) if you use the center tap to get half voltage. Even though it's a 26V transformer, we are only interested in the 13V since we are charging 12V car batteries. The peak of the AC sinewave converted to DC is (13vRMS x 1.414 = 18.38V DC)

Connect the yellow AC wires to the AC terminals on the Bridge Rectifier. Put the Battery Positive to the + on the bridge rectifier, and the Battery negative to the black center tap wire on the transformer to get your 13V RMS, 18.3V unregulated peak output. Connect the 2200uf capacitor in parallel to the battery. The capacitor is very important, to filter the electric, and to allow it to peak over 18V.

BTW, the transformer in my battery charger is connected this same exact way as the RadioShack transformer. Most old type 12V transformer battery chargers use this topology from a 26V transformer, but without the capacitor.