Battery Desulfators

[DavidBarkey]

I once built the widow maker version just for the fun of doing it. Line voltage, big capacitor, power resistor, large spikes of voltage smashing the sulphation, they say. Never seemed to do a thing. Then I asked myself, do I really know the battery needs desulphation? Maybe it has a different problem. It's still in a box somewhere.

Any Battery less than 5 years old and and maintaining proper reserves won't need it . Sulphation builds over time and is accelerated by repeated deep discharging .. Well at least that what I was taught in a course by a battery manufacture .

Dave

[DavidBarkey]

Pulled this off a battery manufacturing site .



An automotive battery, if left unused over time, starts losing its charge. This happens as the electrolyte in the battery, which is sulfuric acid, keeps reacting with the plates inside the battery acting as cathode and anode. This leads to formation of lead sulfate. Since the battery is not being used, it is not being recharged either. This leads to these sulfate molecules to form crystals on battery terminals. This phenomenon is called Sulfation. This prevents the battery from being fully charged and therefore deliver less power than its capacity. A pulse charger is brought into picture at this point to ensure sulfate crystals can be removed from the battery terminals, making battery revival possible.

Pulse Charger for batteries
Q.How does a pulse charger work?

A pulse charger feeds a series of voltage or current pulses into a decaying battery. These pulses carry DC current and have a strictly-controlled rise time (time taken by a signal to change from specified low value to specified high value), pulse width, frequency and amplitude. A pulse charger is said to work with both regular and valve-regulated batteries.

Q.How does a pulse charger reduce sulfation?

By sending current in pulses, a pulse charger can charge a battery by applying high, instantaneous voltages without overheating the battery. This leads to breaking down of sulfate crystals, thereby increasing a battery's service life.

Q.Are there different types of pulse chargers?

Yes, there are two major types of pulse chargers. The first type is the regular type where upon connecting with the battery, the charger uses pulses to check the state the battery is in, then uses constant current charging for the initial phase and switches to pulse charging later to maintain the charge. The other type consists of chargers using negative pulse charging (also called reflex or burp charging). These chargers use positive pulses with brief negative pulses between positive ones to charge the battery. However, neither charging method is better than the other.

Q.How can I prevent battery sulfation?

The only way of preventing sulfation is to let your car's battery charge fully. If the battery is not fully charged, the lead sulfate inside it will start taking crystalline shape at the battery terminals, leading to sulfation. The worst part about sulfation is even though you can get rid of sulfation, the process itself cannot be reversed. This means reduced electrical capacity of the battery.





Dave

[Gordy]

I once built the widow maker version just for the fun of doing it. Line voltage, big capacitor, power resistor, large spikes of voltage smashing the sulfation, they say. Never seemed to do a thing. Then I asked myself, do I really know the battery needs desulfation? Maybe it has a different problem. It's still in a box somewhere.

That is a fancy one Years ago when the pulsers first came out, I think it was Keylee.net had free plans for one. It used a 15 or 20 watt light bulb as a resistor in the main line then a bridge rectifier. Never had enough to try it


Gordy

[Eugen]

Here's an interesting thread with personal experiences

https://www.diyaudio.com/community/thre ... er.143301/

I do not recommend anyone doing that, lethal voltages are involved. I have extensive experience with electrical work involving lethal voltage and only that's why I tried it. As a side note, I was a moderator for many years on that forum.

[Timj]

yep, you sure don't need to get lit-up trying to save an old battery.

[MattA]

Thanks for the feedback. I'm going to try one of those $20 dedicated desulfators. I've got a few 17-20AH batteries that I'd like to try it on. I'll report back on any measured capacity increases/decreases.

[Gordy]

Here's an interesting thread with personal experiences

https://www.diyaudio.com/community/thre ... er.143301/

I do not recommend anyone doing that, lethal voltages are involved. I have extensive experience with electrical work involving lethal voltage and only that's why I tried it. As a side note, I was a moderator for many years on that forum.

Different site, but that is the circuit I saw. They explain it better than the site I saw, and make it much less scary


Gordy

[MattA]

So far my desulfator experiment hasn't gone great. I'm desulfating one 18AH 12V battery from an old jump pack. It's gotta be close to 15 years old. I'm also desulfating 3x 20AH 12V batteries from an old Xantrex Xpower inverter setup. These are about 10 years old. I'm charging all the batteries in parallel using the Xantrex charger that came with the inverter setup. The negative connection is on one end of the battery string and the positive is on the other. To check the capacity, I've using an electronic load I borrowed from work with a battery test function. I've set the cutoff voltage to 11V and due to the jumper wires that I'm using and the very poor condition of some of the batteries, I've had to set the test current to 1Amp.

Battery #1 (jump pack battery) test results:
Test #1 3.07AH
Test #2 2.95AH
Test #3 2.85AH

Battery #2 Inverter battery #1:
Test #1 0AH, ran about 10 seconds under 1A test load.
Test #2 0.18AH
Test #3 0.14AH

Battery #3 Inverter battery #2:
Test #1 0AH. Cannot support the 1A test load. Battery voltage drops to ~9.5V when the test load is applied.
Test #2 0AH, ran about 5 seconds under 1A test load.
Test #3 0AH, ran about 10 seconds under 1A test load.

Battery #4 Inverter battery #3:
Test #1 3.41AH
Test #2 3.9AH
Test #3 3.73AH

Mixed results so far. I've been desulfating the batteries for 8-12 hours at a time, recharging and checking the capacity. To speed things up, I've been desulfating battery 1 & 4 or battery 2 & 3 connected in series to save time. The desulfator I bought does 12V/24V/36V/48V and autodetects the battery voltage. Since the desulfator is self powered, it will only run for a few hours on battery 2 & 3 (low capacity). To save my time testing, this weekend I connected all four batteries in parallel and hooked up the desulfator the same way I hook up the charger. I'll check it in a few days.

This is the desulfator I've got:
https://www.amazon.com/cleanpower-Batte ... 134&sr=8-4

The only downside to this model so far is it discharges the batteries and will hit its low voltage cutoff on low capacity batteries.

[Eugen]

Very interesting @MattA but maybe it needs more time. Some people mentioned even a week for a battery to get better. Also, perhaps so many batteries in parallel are too much for the device. I found the equivalent device on the Canadian amazon and am probably going to get it, as I have at least two batteries that don't charge up to what I think they should. Thanks for reporting your experience!

[MattA]

I desulfated the batteries by themselves at first and then to speed things up I desulfated the two 0AH and the two 3AH batteries in series (0AH and 3AH were desulfated at different times). All four batteries have been connected in parallel and desulfating since Saturday morning. I don't think this is the correct way to do this and will recharge the batteries and switch back to one battery at a time.