Battery Desulfators - PeachParts Mercedes-Benz Forum

spock505 · #1 10-30-2016, 02:42 PM

Not strictly diesel related although oil burners do tend to use larger batteries (which need taking care of)

My Mercedes 110ah battery finally gave up this weekend, must be 15 years old as second hand when purchased as a spare. Part of it's longevity maybe down to using a permanently installed Battery Desulfator.

Its a small unit from the US which operates under charging conditions to keep the plates desulphated.

The principal seems sound, so I thought about trying one of these larger units which in essence are hand made -

Battery Desulfators

I would be interested to hear feedback on other models out there.

Diseasel300 · #2 10-30-2016, 03:23 PM

Battery quality, driving habits, charging system health, and ambient weather conditions have a FAR bigger bearing on how long the battery lasts than whether or not it's on a maintainer.

In my climate, you're doing pretty good to get more than 5 years out of a battery of any variety. The last one in the SL lasted close to 10, which I attribute largely to leaving it on a maintainer, parked in a garage, and somewhat rarely driven. The more time the battery spends in the heat, or when parked outside in the weather, the shorter its life is going to be.

spock505 · #3 10-30-2016, 05:53 PM

I'll pop the battery out tomorrow for inspection. If the plates look furred up might give it a go if not will just replace.

Battery web site giving out some figures for service life.

Battery Desulfators

Diseasel300 · #4 10-30-2016, 06:02 PM

At 15 years old, you definitely got your money's worth out of it. Most likely you've lost a cell or the buss bar linking it if it died suddenly. 12V batteries are 6 2V cells in series, so if you lose your buss bar, or one of the cells fails (usually the plates detach from the bar) you'll lose the whole battery.

The battery maintainers DO help with vehicles that sit parked for long periods of time. If the car is driven regularly, the charging/discharging cycle of using the battery helps keep it desulfated. The SL got ~10 years out of it's last battery while kept on a maintainer, while a Ford Explorer that sat for the same period went through 4 batteries since it was NOT kept on a maintainer.

What kills a battery that sits is low charge level and temperature. The acid undergoes a chemical change and actually deposits sulphur compounds on the lead plates (insulating the plates and diluting the acid concentration). The maintainers cycle the battery and keep it in a range that it won't form the sulphur precipitates. Some of them (like the one I use) can even help reverse a light precipitate coating if the rest of the battery is healthy enough. It won't save a wrecked battery though.

babymog · #5 10-30-2016, 07:36 PM

Flooded cell lead-acid battery 101 (all I know, won't take long):

Your battery is basically lead plates (Pb) and sulfuric acid (H2SO4) when charged.

As it discharges, the sulfur in the acid moves to the lead plates, forming lead-sulfate (PbSO4) and water (H2O) (theoretical fully-discharged).

The lead-sulfate is not stable, it tends to sluff off of the plates to the bottom of the cells slowly during battery use if not converted back into lead. This will eventually lead to increased self-discharge from the lead sulfate in the bottom of the cells (short if it gets bad enough to connect the plates). Lead sulfate remaining on the plates will reduce the area available for chemical reaction which will reduce the available current (cranking amps), and the reduced plate mass will also lead to less battery capacity (amp-hours).

This can be converted back into lead and acid, to some degree. The common de-sulfating method is a charge voltage (IIRC) of 15.1vdc, often pulsed to reduce the heat buildup that can warp plates and cause irreversible damage via plates shorting/touching. Proper charging will also help to reduce dendrite buildup, which you can picture as little stalactites growing into the insulating layers between the plate layers, which can eventually cause shorts.

In automotive starting batteries the plates are usually designed thinner, with less mass, less space between them, and are optimized for surface area. They are designed to offer lots of cranking amps for a short time, and most of the time remain fully charged. Deep-cycle batteries often have thicker plates with more fiber reinforcement and deeper wells below the plates, this allows for heavier charge-discharge cycles to not heat-warp the plates, and the fiberglass reinforcement helps to hold the lead-sulfate together as the battery is designed to be operated with much of the lead converted to lead-sulfate. A normal car battery is not designed to take vibration etc. when discharged because the lead-sulfate will more easily sluff off of the plates and settle to the bottom.

Many large battery installations have de-sulfating cycles, my charger/inverter systems on my coaches always do, this is because the batteries are designed for this high-voltage charge without damage, and to outgas heavily during this cycle. Car batteries are not.

You can buy a de-sulfator I guess, but don't expect it to do a lot. You might be able to boil the sulfate off of the surface if you have a de-sulfator with enough current to maintain the necessary 15.1vdc regulated for the pulses. You will likely need to add water after this cycle, it should actively boil the acid and will create lots of corrosive (and explosive) gas.

Much MUCH more important is to properly charge the battery in service to a proper (14.3 bulk -> 13.4 float) operating voltage and avoid creating the sulfated condition. This is one of the complaints I have with these 1980s charging systems, even when my '91 was new you could watch the voltage drop every time you came to a stop with the lights and A/C on, constantly cycling the battery and not really fully charging until you get a long run without stops (which some cars never get). If this is your car, ... upgrade your alternator.

On these old cars there are very few parasitic loads (with the key shut off). My '87 will sit for a month or more in the winter when the roads are salted between starts. When I'm ready to start, turn the key and she lights right off. My new car OTOH cautions against parking the car for more than 2weeks without a battery maintainer. Unless you've added an aftermarket stereo with amps and stuff that draws a lot, you should be fine. You are much better off using no charger and checking your battery periodically than connecting a cheap charger (one without proper regulation, a "smart" charger). A charger without smart regulation will constantly overcharge your battery and it will outgas (corroding all around it) and consume water. I did have a trick years ago for a cheap charger, where I put it on a timer, ... only powering on the charger for an hour each night around 2am (RV parked outside in Michigan). This kept the batteries charged without overcharging, did it at the coldest time of night when they need the most protection from freezing.

240D.Bill · #6 10-31-2016, 12:17 AM

A 15 year service life on any battery is outstanding! Desulfators... don't waste your money. If you can do simple regular maintenance to a free flooded/conventional battery it's still the best bang for the buck. If you are less likely to maintain/service your battery and money isn't a concern AGM is a good option and contrary to popular opinion, does not need modification to your charging system. Just don't leave your car for any length of time with even a small load because it will drain the AGM to 0 volts.

240D.Bill · #7 10-31-2016, 12:21 AM

I just bought a new East Penn MFG. Deka Gold for my 240D. It was $120. I think carquest and several others are made by East Penn but they are one of the largest in the US, have a state of the art facility, and make OEM spec batteries that fit like a glove.

babymog · #8 10-31-2016, 09:09 AM

I don't agree Bill, and a little research will tell you that AGM batteries are less tolerant of an old-school constant charge of 14v like many old cars put out with light or no load.
For motorcoaches many of us would buy charge controllers for alternators when we change to AGM to create proper charge profiles, or if charged by the inverter system we select the AGM settings on the control panels. We have larger investment in our house battery banks than most people's older Mercedes are worth and do extensive research on how to properly maintain them.

Keep your batteries charged when not in use regardless of type and they should last a long time. My boat batteries are walmart flooded cell and just finished their 6th summer without any water added, a quality 3-stage charger year-round. My first motorcoach had a bank of Sam's Club golf-cart GC-6 flooded cell, 10-years old when I sold it and only needed to add water less than once/year, regularly deep-cycled but charged by a proper 3-stage inverter/charger. I don't invest heavily in AGM because flooded cell works well if maintained oroperly. All batteries will live a shorter life if not used and maintained properly.
Buy a good digital volt meter, watch your voltage when you drive, if it constantly dips below or floats above the correct charging voltage for your battery it's going to have a less than optimum life.

spock505 · #9 10-31-2016, 03:44 PM

Cheers for the replies, interesting topic.

This is more out of curiosity than anything else, but tbh I think this one is not recoverable.

Pulled it from the car today, even after a two day charge not enough juice to wind down a window, volt tester showed 11.3v.

Once on the bench it looked as though one of the cell chambers needed topping up, duly did so with distilled water and whilst it did take maybe 100ml the translucent white area stayed as per photo.

The rest of the cells appeared fine but with some powder sitting on top of the fluid - sulfate? (spelling 'sulphate?)

There was probably enough juice for the smart charger to recognize so hooked it up along with the gizmo to see what happens.

Gizmo Infinitum Store - Home | Infinitum Store

240D.Bill · #10 10-31-2016, 06:04 PM

I could be wrong but... I pulled an auxiliary and cranking battery from a 2006 sprinter. The auxiliary was deep cycle(white just like yours), 100 A/h vs. CCA rating and labeled "not suitable for starting". IF you were using that battery for cranking it explains the damage but recovering that cell will be a real challenge with an ultrasonic cleaner. If you've any hope at all for recovering it you will need top off the cells with distilled water, charge normally, recheck and top off the cells as needed, and to put through an "equalition charge". You'll need a charger that's capable of constant charging at 16 volts and you'll have to closely monitor during the cycle. Select a safe, well ventilated, and ignition safe area preferably outside. Cover anything you don't want coated in sulfuric acid, most especially your eyes and the rest of your body. DO NO walk away from it DURING THE CHARGE CYCLE. It will gas profusely and of course hydrogen gas mixed with oxygen is extremely explosive, corrosive, and caustic. If that sounds like something you're willing to undertake don't let the wife in on it.

spock505 · #11 11-01-2016, 07:04 AM

Quote:

Originally Posted by 240D.Bill

I could be wrong but... I pulled an auxiliary and cranking battery from a 2006 sprinter. The auxiliary was deep cycle(white just like yours), 100 A/h vs. CCA rating and labeled "not suitable for starting". IF you were using that battery for cranking it explains the damage but recovering that cell will be a real challenge with an ultrasonic cleaner. If you've any hope at all for recovering it you will need top off the cells with distilled water, charge normally, recheck and top off the cells as needed, and to put through an "equalition charge". You'll need a charger that's capable of constant charging at 16 volts and you'll have to closely monitor during the cycle. Select a safe, well ventilated, and ignition safe area preferably outside. Cover anything you don't want coated in sulfuric acid, most especially your eyes and the rest of your body. DO NO walk away from it DURING THE CHARGE CYCLE. It will gas profusely and of course hydrogen gas mixed with oxygen is extremely explosive, corrosive, and caustic. If that sounds like something you're willing to undertake don't let the wife in on it.

Ultrasonic cleaner, that's a thought but it would need a commercial sized unit to get the whole battery in there, or is there some other method?

I don't have a 16 volt charger, but a non smart type for lead acid batteries, will give that a go.

This chap does a good job explaining battery tech in basic (my language

terms.

https://www.youtube.com/watch?v=hEESf-PoQu4

He mentions the voltage should initially go up as the charger tries to overcome plate resistance and then slowly drop as it starts to absorb power.

As mentioned, it's not really a serious attempt but interesting all the same.

EDBSO · #12 11-01-2016, 10:37 PM

I have used an Infinitum Desulfator for years in continuous use and have not suffered a battery failure, 6 years and then sold the car so no 15 year track record. I believe that they work.

spock505 · #13 11-02-2016, 03:40 PM

There's two of us then, that's good to hear.

Day or so on the large not so smart charger with gizmo, the white translucent area has started to noticeably reduce?

It looks to all intents to be an air lock, diminishes when tipped to one side but the cell appears to be topped off, no idea, however curiosity once again got the better of me - ordered a small cheapo endoscope lol.

Desert Panther · #14 12-22-2016, 07:59 PM

whatever became of this? Curious to hear your experiences.

spock505 · #15 12-25-2016, 06:37 PM

Quote:

Originally Posted by Desert Panther

whatever became of this? Curious to hear your experiences.

I pulled the charger off as needed on other cars, will try again in the next week or so but having read similar battery posts about dropped cells, not too optimistic.