Updated March 2016
Battery pulsing claims to extend lead acid battery life, and to restore lost battery capacity. Tests however show it is not effective enough to be worth using. Battery pulsing is claimed to work by reducing active material being shed from a battery’s positive plates and shrinking of its negative plates. Battery pulsing is also claimed to reduce an effect, called sulphation, that affects both plates. Sulphation is inherent but is harmless with batteries that are regularly fully charged and not overly discharged. But if the battery remains uncharged, even for a few hours, or is consistently under-charged, the sulphate hardens into larger crystals.
These crystals reduce the plate’s effective area (because the acid can’t get to it), and hence the battery’s effective capacity. Sulphation may also cause a battery to lose its ‘damping’ effect, allowing high voltage spikes from the alternator to be imposed on connected electronic equipment. This is only a major problem with batteries used intermittently, such as with snow ploughs, some aircraft ground equipment, military hardware. Some cabins, camper trailers, caravans and motor homes are used likewise.
AGM, gel cell and lithium batteries are not so affected. AGMs were initially developed for the military to overcome this very issue.
Battery pulsing generators have been available commercially for many years some time. Their makers’ claims include: enabling more charge to be stored, to enhance starting ability, and to increase battery life. Some claim that can assist resuscitate sulphated batteries. Whilst such claims can be sustained, the gains are too small to be of any real value. Battery pulsing is now rarely used.
Germany’s Institut fur Industrielle Elektronik und Materialwissenschaften conducted tests (of the Megapulse unit) over 10,000 hours with about 80 sulphated batteries. Half had measured amp hour capacities averaging 61.6% (i.e. of new), the other half 36%. A test pulsing unit was connected to each battery for 15 days (and supplied with energy from an external source). The batteries were fully charged at the end of the 15-day pulsing test and then tested for electrical and chemical changes. Tests were also conducted during the test period. Results showed that 97% of the batteries that initially had about 61.6% remaining capacity improved to an average of 87.5%.
The increase in amp hour capacity of those that had 36% remaining capacity increased to about 82.8%. Cranking capacity was also measured and showed roughly comparable increases. The increases were almost linear over time – there was no fall off at the end of the test periods. The results show averages with individual results being closely related to initial battery condition. Fourteen per cent of the batteries tested were not recoverable.
Whilst this report was used extensively for promotion it omitted to note that the battery industry regards battery life as at a useful end at 80% of the original claimed capacity. Both practically and financially, it would seem to make more sense to buy a new battery.
A different form of battery pulsing test by Australia’s CSIRO was less conclusive. It involved four (assumed) identical and new batteries. These were subject to a slightly modified form of the American Society of Automotive Engineers SAE J537 cycling test. This test simulates taxi usage. It counts the number of charge/discharge cycles before the battery fails to maintain cranking at 470 amps for 30 seconds whilst remaining above 7.2 volts. It’s brutal. So-tested batteries are usually useless afterwards.
One battery was left un-pulsed to act as a reference. Two batteries were fitted with (MegaPulse) battery pulsing units operating at 12.8 volts input. One was fitted with a unit working at 10.6 volts input. The CSIRO report notes that, ‘[at the end of the test] all test batteries were in very poor condition. They had suffered different degrees of sulphation, loss of mechanical strength, severe corrosion, material softening and extensive shedding.’ Curiously the reference battery (that was not pulsed) returned exactly the same number of charge/discharge cycles (1233) as another one that was Megapulsed. A further battery, tested at 10.6 volts input, returned 1644 cycles and the remaining one, pulsed at 12.8 volts input, returned 2055 cycles.
The CSIRO summary cautiously notes that, ‘the cycling performance and studies of plate morphology suggest that the use of (MegaPulse) technology can increase the service life of batteries through suppressing the size of lead sulphate crystals. Obviously, more experimental trials are required to establish this preliminary finding at an acceptable level of confidence.’ My own research background leads me to feel the sample was too small to be conclusive. Further, it is unclear whether the results reflect the performance of MegaPulse battery pulsing units, or individual differences between the batteries when new (their standard deviation is fairly high for some parameters). Further, whilst valid for the purposes for which the test was commissioned, the SAE test does not reflect RV home usage.
Be aware that a main local vendor of the product used only (and misleadingly) the term ‘CSIRO tested’ (only) as a heading in subsequent promotion.
Battery pulsing is not a substitute for correct charging
Batty pulsing is not a substitute for regular charging. It draws ongoing energy (about 80 milliamps) from the battery it protects. It must be used in conjunction with a suitable charger – but a continuously charged battery does not sulphate anyway. There’s a possible argument for battery pulsing with systems that routinely run low on power. From the German tests, there’s a good chance of restoring lost battery capacity if sulphation is not beyond the point of no return. The battery capacity recovered however is only a few per cent. The battery will thus fail again shortly after.
In the author’s view, and later anecdotal evidence, the battery pulsing is not a substitute for correct charging. If lead-acid batteries in good condition are maintained correctly (i.e. kept close to fully charged at all times) then sulphation is unlikely to be a problem: and little point in using a pulsing device. For RVs are used only occasionally, a pulse generator may extend battery life by 20% or so. It is not however a substitute for keeping batteries properly charged.
All you will ever need to know about RV electrics is in my Caravan & Motorhome Electrics. It is technically sound (and used by auto electricians) but written in plain English. My other books are the all-new Caravan & Motorhome Book, the Camper Trailer Book, Solar That Really Works (for cabins and RVs) and Solar Success (for home and property systems). For information about the author please Click on Bio.