MEGAPULSE BATTERY CHARGER ISSUES
- Megapulse is not a charger!
- Megapulse specification
- How long a battery can power Megapulse without being recharged
- Comparison of Megapulse to other desulphation methods
- Megapulse works well with desulphating chargers
- Battery charger selection guide
- 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
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 (see table to define '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.
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)
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 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:
- 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
|Battery types|| |
|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|| |
100 - 500 Ah
|What it does|| Removes sulphation |
(see note 1)
| Removes sulphation |
Does not prevent sulphation
| Removes 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)
| Requires external power |
|Desulphates while vehicle in use|| |
|Suitable for marine, mining, construction, outdoor use|| Yes |
(fully sealed case,
Normally not ruggedized
|Discharges battery during operation|| |
0.25 - 0.6Ah per day
|Warranty period|| |
Usually much less
|Easy to fit and use|| |
|Requires connection every time it is used|| |
|Compatibility with Megapulse||-|| Yes in most cases |
Pulse interference possible
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.