Battery desulphation needed? Frequency?

[Meeka]

Can you tell if an AGM needs desulphating and how often should this procedure be done? Thanks.

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[ZABSMAV]

Can you tell if an AGM needs desulphating and how often should this procedure be done? Thanks.

Car batteries "can" be desulfated if the sulfation is "soft" (reversible), which involves using a high-voltage pulse or a special charging cycle to dissolve the sulfate crystals.

However, if the sulfation is "hard" (permanent), which occurs when a battery is left discharged for a long time, it cannot be reversed and the battery must be replaced.

Reversible ("soft") sulfation Desulfation mode:

Many modern battery chargers have an advanced desulfation mode that uses high voltage and low current to break up the sulfate crystals.

Electronic desulfators:

These devices send high-frequency pulses to the battery to break up the crystals without using high voltages.

Equalization cycle:

For certain types of batteries like AGM, a manual equalization process can be used by charging the battery at a higher voltage (around 17.8) volts) to break up the crystals, but this should be done with caution and only a few times.

Permanent ("hard") sulfation

When it happens:

This occurs when a battery is left in a low state of charge for weeks or months.

Why it's permanent:

The hardened sulfate crystals are difficult to dissolve, and the battery's internal components may have deteriorated.What to do: In this case, the battery cannot be recovered and needs to be replaced.

Before attempting desulfation Check battery health:

A heavily sulfated battery will have a voltage below 12.4 volts, and it may be too far gone to recover.

Follow instructions:

Always follow the specific instructions for your battery charger and battery type.

Safety first:

Wear safety gear and be careful when working with car batteries, as they contain acid.

 

[Master Blaster]

Car batteries "can" be desulfated if the sulfation is "soft" (reversible), which involves using a high-voltage pulse or a special charging cycle to dissolve the sulfate crystals.

However, if the sulfation is "hard" (permanent), which occurs when a battery is left discharged for a long time, it cannot be reversed and the battery must be replaced.

Reversible ("soft") sulfation Desulfation mode:

Many modern battery chargers have an advanced desulfation mode that uses high voltage and low current to break up the sulfate crystals.

Electronic desulfators:

These devices send high-frequency pulses to the battery to break up the crystals without using high voltages.

Equalization cycle:

For certain types of batteries like AGM, a manual equalization process can be used by charging the battery at a higher voltage (around 17.8) volts) to break up the crystals, but this should be done with caution and only a few times.

Permanent ("hard") sulfation

When it happens:

This occurs when a battery is left in a low state of charge for weeks or months.

Why it's permanent:

The hardened sulfate crystals are difficult to dissolve, and the battery's internal components may have deteriorated.What to do: In this case, the battery cannot be recovered and needs to be replaced.

Before attempting desulfation Check battery health:

A heavily sulfated battery will have a voltage below 12.4 volts, and it may be too far gone to recover.

Follow instructions:

Always follow the specific instructions for your battery charger and battery type.

Safety first:

Wear safety gear and be careful when working with car batteries, as they contain acid.

A brand new battery from Ford will only measure about 12.5V, since they do not charge it fully before installing it, and it is normal for the BMS to keep it below 70% or about 12.3V and Ford will not warranty it until it drops to 11.9V. That's why they are all sulfating and failing. You forgot to mention that all battery types cannot be safely desulfated without disconnecting them from the electronics that cannot handle the high-voltage pulses or any weird high-frequency pulsing. You also forgot to mention that an AGM battery cannot usually be desulfated, as the higher voltage pulses will destroy it, and that you must use a smart battery charger on an AGM battery to keep the voltage below about 14V. There are an awful lot of flooded-type chargers that will run the voltage up to 18V or more in order to try to push more current through a higher-resistance battery and reduce charging time, destroying AGM batteries and destroying your electronics as well.

 

[ZABSMAV]

A brand new battery from Ford will only measure about 12.5V, since they do not charge it fully before installing it, and it is normal for the BMS to keep it below 70% or about 12.3V and Ford will not warranty it until it drops to 11.9V. That's why they are all sulfating and failing. You forgot to mention that all battery types cannot be safely desulfated without disconnecting them from the electronics that cannot handle the high-voltage pulses or any weird high-frequency pulsing. You also forgot to mention that an AGM battery cannot usually be desulfated, as the higher voltage pulses will destroy it, and that you must use a smart battery charger on an AGM battery to keep the voltage below about 14V. There are an awful lot of flooded-type chargers that will run the voltage up to 18V or more in order to try to push more current through a higher-resistance battery and reduce charging time, destroying AGM batteries and destroying your electronics as well.

Common sense tells one to only do any of this with the battery completely removed from the vehicle.

 

[Mavster Mechanic]

Common sense tells one to only do any of this with the battery completely removed from the vehicle.

With a "smart" charger I think just removing the ground cable is fine.
Low to minuscule chance of fire since they won't overcharge and heat up the battery.

 

[ZABSMAV]

With a "smart" charger I think just removing the ground cable is fine.
Low to minuscule chance of fire since they won't overcharge and heat up the battery.

Anytime charging a battery with an external charger it should be removed from the vehicle and placed in a safe environment.

 

[Mavster Mechanic]

I charge mine on cool (not cold) 55°F Driveway. Outdoors. With a "smart" charger.

Negative cable detached.

That's safe enough for me.

 

[HeyBales]

Can you tell if an AGM needs desulphating and how often should this procedure be done? Thanks.

As to the how - you'd have had to get a baseline resistance reading off a not cheapest battery tester, when the battery was almost new.
And on monthly testing discover if resistance heading the wrong direction.



Here's my Rav4 battery test results over the last year. Long periods of non-driving/charging, until this summer at least driven few times weekly.
The fact the resistance increases so easily after a repair mode - I know it's unlikely to make it thru winter, it is old, because the abuse of unused/uncharged for far too long.

Last Dec, before/after after multi-days charging/repair mode with Schumache, but sat for a few days before testing.

After winter and some driving at least, try repair again - Noco this time.

This Nov, 10 days on Noco.

Son said power point V reading was 12.3 before taking off for trip. So 2 weeks later not holding.

For comparison - Maverick original small FLA in Jan, prior full recharge Sep. Made it till Jul.

 

[Tiger Dude]

I don't think this works with sealed batteries. A high voltage charge gasses the battery, which is making oxygen & hydrogen. This was a thing on the submarine decades ago with our large lead acid batteries; we had hydrogen detectors & strict limits. I think the "pulsing" thing on many chargers is snake oil, tho I do use one on my generator battery.

 

[gjallen3]

I don't think this works with sealed batteries. A high voltage charge gasses the battery, which is making oxygen & hydrogen. This was a thing on the submarine decades ago with our large lead acid batteries; we had hydrogen detectors & strict limits. I think the "pulsing" thing on many chargers is snake oil, tho I do use one on my generator battery.

The PulseTech PowerPulse gets some pretty good reviews. It attaches to the battery permanently and will control sulfation without a charger. My concern is will it act like a parasitic drain when the engine is not running. Amazon.com: Pulsetech PowerPulse Battery Maintenance System : Automotive

 

[ZABSMAV]

The PulseTech PowerPulse gets some pretty good reviews. It attaches to the battery permanently and will control sulfation without a charger. My concern is will it act like a parasitic drain when the engine is not running. Amazon.com: Pulsetech PowerPulse Battery Maintenance System : Automotive

Sounds more like some cheap Chinese snake oil device. Couldn't possibly prevent or correct sulfation.

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