Battery Sulfation

Battery Sulfation (last update 6th April 2016)

It is a simple fact that lead acid batteries deteriorate from the day they leave the factory, many will already be suffering from a degree of sulfation even before you buy them and take them home.

In use very few batteries are treated ideally. In simple terms lead sulfate forms on the plates when the battery gives up power and recharging causes this lead sulfate to dissolve again but this process is always less than 100% efficient. It is possible to reduce the rate at which this occurs by following a strict regime of use and recharging the battery but the reality is that this rarely happens in the real world.

In batteries left to stand the electrolyte stratifies and the densest solution forms at the base of the battery and through a process of self-discharge again this lead sulfate builds up.

This build up of lead sulfate obviously blocks electrolyte access to the plates and the sulfate not returning to the electrolyte causes it to weaken and a vicious cycle of deterioration sets in.

Sealed batteries can be even worse as the battery relies on evolved gasses recombining to maintain electrolyte levels. The less than efficient recombination process leads to both sulfation and electrolyte loss, a double 'whammy'.

Lesson No.1 is that the best battery type for recovery by desulfators is the conventional flooded lead acid type and those of us of certain vintage will remember when all lead acid batteries came with 6 screw caps on top allowing routine replenishing of the electrolyte. Desulfators will work on other battery types only not as well as on conventional types.

Trying to improve a tired battery by attempting to overcharge it will only result in excess heat being developed in the battery which will do nothing for recovery.

The number one requirement for successful desulfation is electrolyte replenishment, if there is no, or insufficient, electrolyte desulfation will only be partially successful at best. Sealed Lead Acid (SLA) batteries can still be recovered, check out Accessing a small SLA Battery We don't approve of the desulfating device utilised in this video as it is mains i.e. 230V AC powered which we believe is potentially dangerous.

We offer two ways of dealing with the problem.

EDTA is one, it's not our favourite but it works. The EDTA combines with the lead sulfate and dissolves it thus exposing more active plate material and the battery gives you an improved performance. The downside is that the recovery is only partial as the sulfate isn’t returned to the electrolyte so you have a battery with a weakened electrolyte. Please note that we sell EDTA acid, tetrasodium salt dihydrate, C10H12N2Na4O8.2H2O, CAS 10378-23-1 and that not all adverts for EDTA are the correct type and they do not all do the same job.

Desulfation is the other and this is our preferred method by far as the hardened lead sulfate is bombarded back into solution by high voltage pulses. It is a slower process than EDTA but generally much more effective at returning a batteries original energy levels.

We have one range of devices which are closely based on the original circuit designed and published by Alastair Couper in the American HomePower magazine back in 2000 i.e. the Basic and PIC devices. Recently a customer posted negative feedback in relation to the fact we using an 'old' design of device. Our response would be that lead acid battery technology has been around since 1859 when Gaston Plante 'invented' the technology and the Couper design has been proven to work so it if it ain't broke why fix it?


With the introduction of the recently introduced Voltage Doubler device we have now rationalised our range somewhat and have phased out the previously marketed 12 and 24V 'High Power' devices.

Our 12V Basic device is not much altered with a zener diode offering some protection to the timer end of the circuit, a diode and resettable fuse taking care of those times when you connect the device up the wrong way (we’ve all been there) and, most recently, an additional piece of circuitry to ensure the device cuts out when the battery reaches 12.4V. This latest (optional) addition allows you to fit the device to a battery and walk away safe in the knowledge the device will cut-out and not drag your battery down to a very low voltage level and doing more harm than good. This size device is best suited to the standard car sized battery circa 15-17.5kg.

The 12V PIC (Programmable Interface Controller) takes over from the previously supplied ‘High Power’ device. This is a PIC based version of the original Couper circuit developed by my former Canadian colleague which takes the device to a different level. Essentially it uses larger inductors, a higher rated MOSFET and diodes. In simple terms the Basic device consumes around 100mA, the PIC consumes in the region of 300+mA and delivers a much higher energy pulse to the battery. This device is targeted at batteries in the 17.5 - 30kg range.

We would prefer to supply all our customers with 12V desulfators but, driven by customer demand, we do supply the one 24V Basic device. Those customers wanting a more powerful 24V device should chose the Voltage Doubler device.

Those customers with 6V batteries are recommended to desulfate two 6V batteries in series as a 12V combination. We can produce a 6V Basic desulfator kit or built device on demand.

Our reason for preferring 12V devices over 24V is that you don't necessarily get twice as much energy from a 24V desulfator and it has twice as many plates to treat i.e. the pulse energy gets shared across a larger number of plates.

At the moment our most powerful 12V capable desulfator is our 12/ 24V Voltage Doubler device.

We are currently testing a prototype multi-voltage 6/12/ 24V PIC based device, again a device produced in response to customer 'demands'. A device covering this range of voltages isn't going to 'perfect' but it will handle 6V, 8V, 12V and 24V batteries in the one device so its convenience will outweigh any, minor, design 'compromise' This should be available by the end of April 2016 once a supply of PCB's is sourced.

Voltage Doubler Prototype

Those customers wanting a more powerful device should choose our recently released 12 - 24V Voltage Doubler device as developed by Mark Lockwood (tucsonshooter), Voltage Doubler, for 12 and 24V batteries. This device is currently available as a kit but will be available shortly as a built PCB and a fully built unit.

Development is continuing on a 'Direct Drive' device, also developed by Mark Lockwood) which can be used on 12/ 24/ 36 and 48V batteries. This latter device will come in two forms:-

1. one, the Simple Direct Drive, Simple Direct Drive, will require the end user to provide a suitable power supply, limiting resistors and capacitor bank and

2 the other, the Direct Drive/ Charger, Direct Drive, will come as a more integrated device only requiring the end user to supply a suitable transformer and which will be usable as a battery charger with up to 3A available or as a desulphator. This will be built to order.


Our current hierachy is:-

12/ 24V Basic Desulfator - for use on standard sized small batteries as fitted to normal sized cars

12V PIC Desulfator - suited to 'small' deep cycle batteries such as found in golf carts or battery banks in river cruisers

12 - 24V Voltage Doubler - this is a 'high power' desulfator offering voltage flexibility for larger 12 or 24V battery banks

Simple Direct Drive - a mains powered and quite powerful desulfator device. We anticipate this being used by people with a suitable level of electronic/ electrical knowledge.

An alternative approach would be try one of our 12V/ 5A or 12-24V/ 5A capable TSW kits designed to be driven by solar PV panels or a current limited power supply (this can be a laptop charger and a 1ohm/ 50W resistor in series), see the Solar Battery Charging page:-

12V TSW - a combination battery desulfator/ trickle charger for use with up to a 100W/ 5A solar panel or constant current power souce

12 - 24V TSW - a combination battery desulfator/ trickle charger for use with solar panels up to 200W/ 5A or a constant current power source

A change in my employment circumstances means built units will be available periodically but kits will be available 12 months of the year.

Do our devices work you may well be asking yourself? Well we were awarded a Best Buy award by  Classic & SportsCar magazine and an independent tester of desulfators (Don Plisco) made the report featured below where he refers to our PIC based device as his device of choice.

  Click here for a primary report on desulfators/ pulsers