MEGAPULSE BATTERY CHARGER ISSUES

Index:

Megapulse is not a charger!
Megapulse specification
Comparison of Megapulse to other desulphation methods
Megapulse works well with desulphating chargers
Battery charger selection guide
Megapulse solar panel trickle charger
Issues with sealed lead-acid batteries
The problems of charging silver calcium batteries
Modern multi-state (adaptive) lead-acid battery chargers
Overview of sulphation and electrolyte stratification
Applying an equalization charge
Megapulse filter unit for sensitive chargers

Important! Megapulse is not a battery charger!

Megapulse uses the battery's power to generate pulses that keep the battery in peak condition.
Therefore, batteries still require to be charged in the conventional way.
At ± 0.36Ah Ah per day (typically less than a dashboard clock), the power used by Megapulse is adequately compensated by the normal charging of electric vehicles and the regular use of petrol/diesel vehicles. In these cases, Megapulse operates completely unobtrusively and requires no further maintenance or adjustment
Batteries that lie idle for a long time require a solar panel or trickle charger to prevent them running flat.
Keeping an idle battery on charge is very important for maintaining it in good condition, whether or not Megapulse is attached.

Megapulse solar panel trickle charger!

The ideal companion for Megapulse - solar battery charging while Megapulse prevents sulphation.
For those batteries left unattended for long periods (e.g. caravans, holiday home vehicles, yachts), a rugged portable solar panel is ideal for keeping the battery charged while Megapulse operates for months at a time in an unattended environment, especially where no mains power is available.
Its small size and portability make it a must-have for 4x4 and caravanning camping trips, sustaining auxiliary battery power during the day
Just connect to the battery, point the solar panel towards the equator, and tilt up from the horizontal at an angle equal to the line of Latitude + 10°. In South Africa, point the panel due North, at an angle of ±40° to the horizontal. Can be mounted behind a window inside a building or vehicle, or outside.

The panel measures 300 x 230 x 5mm. The package includes a 12v 8w solar panel and regulator, 2.5m leads with croc clips.

Solar panel specification
Parameter	Value
Maximum power	8w
Open-circuit voltage	19.6v
Short-circuit current	540mA
Maximum power voltage	15.9v
Maximum power current	510mA
Working temperature	-45°C to 70°C
Specification tolerance	±5%

Modern multi-state (adaptive) lead-acid battery chargers

Good quality bench chargers often use a multi-step approach to charging a lead-acid battery:
- Bulk charge: high current charging to quickly reach about 90% of battery capacity
- Absorption charge: constant voltage decreasing current up to 100% of battery capacity
- Float charge: lower voltage low current charging to keep the battery at 100% capacity
- Equalization charge: see notes below
PWM chargers, commonly used to regulate the varying output of solar panels and wind generators.
These types of charger continually sample the battery voltage to determine the state of charge. After reaching the bulk charge voltage, the absorption phase begins for a set period of time, then the voltage is reduced for long-term float (trickle) charging.
Table of recommended chargers available from Megapulse SA
Table of hybrid battery critical voltages typically used by simple and multistage chargers:
(Click here for tables relating to other types of battery)

Megapulse filter unit for sensitive chargers

This problem rarely occurs, with no known instances with the Mk.4 and Mk.5 Megapulse units. This section is included for completeness only.

The Megapulse Filter unit has been specially designed to prevent pulses from affecting devices sensitive to the pulses, such as battery chargers and voltage monitors.
Some electric vehicles (e.g. golf carts, fork-lift trucks) may require a filter inserted between the battery terminals and the charger socket, if charging problems occur.
Some solar systems may require a filter inserted between the battery terminals and the regulator/charger, if regulator/charger problems occur.
More details about the Megapulse filter unit.

Petrol and diesel engines

The alternator charging systems attached to most engines are insensitive to Megapulse, so are not affected.

Using an equalization charge

NOTE: Equalization only applies to flooded batteries; it must not be used with VRLA or gel batteries.

The purpose of an equalization charge is to mix up the electrolyte which may have stratified, with most of the acid lying in at the bottom of the battery cells.

If electrolyte stratification is allowed to build up over a period of time, the lower layers of high-strength acid will quickly corrode the grid destroying the lower parts of the battery plates. Active plate material will fall off the plates as sludge. A battery thus affected will have greatly reduced capacity and will self-discharge quickly. In the worst case, shorted cells will cause total battery failure.

The method used is to deliberately 'boil' the battery cells by overcharging for a short time. The gas bubbles produced mix up the electrolyte resulting in an even distribution throughout the cell.

The downside of equalization is that electrolyte is used up in the gassing process, requiring the battery to be topped up regularly. If the process is not carefully controlled, the heat produced can warp the plates resulting in shorted cells.

Batteries most likely to require equalization are more those that:
- remain partially discharged for extended periods
- are not subject to vibration, such as occurs during vehicle motion
Sulphation usually forms alongside electrolyte stratification. Equalization will not remove sulphation. However, sulphation is effectively eliminated using Megapulse.

Notes on the application of an equalization charge:
- A considerably higher-than-normal charging voltage is applied for a limited time period
  (for example, 15.6v applied to a 12v battery for 30 - 60 mins)
- This leads to electrolyte boiling / gassing, which results in the mixing of the electrolyte.
- If not very carefully controlled, equalization can result in damage to the battery. Excessive current leads to overheating which can permanently damage the battery plates.
- Smart chargers that provide an equalization charge prevent battery damage by limiting the maximum charging current and ending the equalization when the target voltage is reached (typically around 15.6 for a 12v battery - see table for other battery sizes).
More information on electrolyte stratification can be found here

Issues with sealed lead acid batteries (aka VRLA - valve release lead acid batteries)

By maintaining pressure in a 'sealed' lead acid battery, a good portion of the gas produced during charging recombines with the electrolyte, minimizing electrolyte loss. Self-resealing valves allow gas under excessive pressure within the battery to escape into the atmosphere.

Overcharging with voltages in excess of 2.25v per cell (i.e. >13.5v in the case of a 12v battery) will cause gassing and the resultant loss of electrolyte, which unlike flooded batteries cannot be replaced. As electrolyte is lost, the battery capacity is progressively reduced until the battery loses its ability to hold charge. The battery will run flat quickly even after being fully charged.

VRLA batteries most often fail for these reasons:
- Sulphation
- Electrolyte loss due to long-term overcharging resulting in excessive gassing.
- We have a sneaky suspicion that constant float charging also shortens the battery life. This may be due simply to electrolyte loss through gassing, or possibly due to accelerated grid corrosion.
The sulphation problem can be fixed by Megapulse.

Experience suggests that the smaller sealed batteries of the type shown above do not have a particularly long operating life. This applies both to batteries that are not charged after use, and those that are permanently connected to a good multi-stage charger.

After conducting trials for over a year, we have come to the conclusion that the only way to obtain the maximum life from such a battery is to use a time-switch to limit the charging period to ±30 minutes per day (the exact time depends on application and battery size.) More details about this technique can be found in this installation guide. Batteries charged in this way work just as well as batteries left permanently on charge.

Megapulse works well with desulphating chargers

Most chargers that claim to desulphate batteries pulse the charging current to do this. This is quite different to the way Megapulse works, which forms very specifically shaped low-power high-voltage pulses lasting for ±1 µsec. This is the secret to breaking up the sulphation crystals.

Nevertheless, Megapulse works well with desulphating chargers, even if it does all the work and leaves no sulphation for them to remove!

A desulphating charger works only while the battery is on charge. If you don't charge your battery very often, then desulphation won't occur very often either, which makes Megapulse the better long-term option.

Compare that to Megapulse which, powered by the same battery which is being desulphated, operates all the time. Since sulphation is occurring all the time, Megapulse is effective in keeping a battery completely sulphation-free all the time.

In other words, Megapulse works 24 x 7x 365, both during vehicle operation and when it is idle. In this way, Megapulse prevents sulphation whereas a charger will remove sulphation only after it has occurred, and only when the battery is put on charge.

Comparison of Megapulse with other desulphation methods

Feature	Megapulse	Desulphating charger	Chemicals
Battery types	Starter, deep-cycle	Starter, deep-cycle	Starter, deep-cycle
Battery construction	flooded, sealed, AGM, gel, maintenance-free, hybrid, silver / calcium	Most chargers are designed for one specific type only	Only unsealed batteries (no maintenance-free, VRLA, gel, AGM)
Maximum battery Ah	1500 Ah	100 - 500 Ah	No limit
What it does	Removes sulphation Prevents sulphation (see note 1)	Removes sulphation Does not prevent sulphation	Removes sulphation Prevents sulphation
Voltage range	6, 12, 24, 36, 48v	Typically 12, 24v	Not voltage dependent
Works all the time	24 x 7 non-stop (see note 2)	Only when on charge	For as long as the chemical is active
Desulphation power (see note 3)	100%	10%	(unknown)
Requires external power for desulphation	No	Yes	No
Desulphates while vehicle in use	Yes	No	One-time application
Suitable for marine, mining, construction, outdoor use	Yes (fully sealed case, epoxy encapsulated, IP67 waterproof)	Normally not ruggedized foroutdoor use	Yes
Discharges battery during operation	0.25 - 0.6Ah per day	No	No
Warranty period	7 years	Usually much less	(unknown)
Easy to fit and use	Yes	Requires connection every time it is used	Messy chemicals
Compatibility with Megapulse	-	Yes in most cases Pulse interference possible	Yes

NOTES:

1	Megapulse is active in both the charge cycle of the battery and the discharge cycle. This is especially important to note, as sulphation is formed during the battery discharge cycle (i.e. when it is in use)
2	Megapulse is normally installed permanently on a vehicle or ship, providing non-stop desulphation thereafter
3	Megapulse uses a patented pulse technology which is finely tuned to the sulphate particles. This pulse is automatically adjusted by the internal microprocessor for maximum desulphation power (depending on the internal health of the battery). By comparison, desulphating chargers typically use a broad P.W.M. system which equates to approximately 10% of the desulphating power of Megapulse.

Click here to download this comparison chart as a PDF document.