I have read the many opinions etc. on the interweb about these devices. The Lifeline battery dealer here claimed they worked, so I bought one some time ago. I had hooked it up to a few batteries without noticing any dramatic result and then set it on the shelf. This weekend working on my Vespa to take advantage of the sunny weather (sorry you East Coast Swabs...), I had a weak battery. So I hooked up the desulphator. Its green light lit, indicating it was hard at work, but after just a few minutes watching it work I got bored and got out the oscilloscope and probes. I believe the theory behind these devices is that sufficient voltage will dislodge the sulphate from the plates, however this voltage is otherwise damaging to the battery. But if applied in short pulses, it affects the sulphate without harming the battery - or so the mythology goes.

Here are the voltage and current waveforms, hooked to a 10 Ah AGM scooter battery. Fluke 'scope with 200 MHz system bandwidth, Fluke current probe bandwidth is DC - 100 KHz. Red waveform is voltage, blue is current. At the 10 KHz rate, there is a 50 mV depression for about 10 microseconds, followed by a 300 mV positive spike about 200 nS long. In the current waveform you can see about 200 ma being drawn during this interval. I don't think this is going to do anything useful to the battery, except discharge it over time:

Here is the test setup:

The device is well thought of by at least some of the proponents of these types of things (Defender sells them if you want one):

So then I hooked the charger back up, a TrueCharge 10 made by Xantrex. This is a switching charger, so one might expect some noise on the output. Notice that at a higher frequency, it puts similar voltage spikes into the leads, with at least noticeable current spikes associated with them:

Mind you this is a 10 Ah battery, any effect is going to be substantially less on a 200 Ah battery. Unless there is something a very much don't understand, this device - and probably those like it - are a waste of money and coulombs.