*Battery Desulphator Experience*
11 June 2010
After reading mixed reviews for years on desulphators I was a huge skeptic, but after having problems getting the specific gravity up where it needs to be on our large (read very expensive) battery bank and the emergency water supply pump, I decided to try them.
One of our members recommended the BatteryMinder brand so I got a 12VDC unit for the water supply pump battery and a 24VDC unit for the main alt power battery bank. I now have enough experience to recommend them with the following notes.
1. They will not recover a completely dead, very old or abused battery.
2. They take time to work. On a single Wal-Mart 27DC6, 12VDC battery, the unit took 10 days to completely correct the sulphation problem. On the main 24VDC bank made up of L16 deep cycle batteries, it took 3 weeks per string of 4 batteries.
3. You have to pay attention to the capacity of the battery bank. While the manufacturer implies that they will work with any size bank, this is not entirely accurate. The high frequency desulphator will certainly continue to work but it only has so much power. The built-in charger only has so many peas in the pot (Amps) as well and can only service so much capacity. When I first put the 24VDC unit on our 12 battery L16 bank it did virtually nothing for a month - simply too much battery capacity for its 4A charger. When I took a string of 4 batteries at a time off-line and put them on the unit it worked fine, although as noted it took 3 weeks for the first pass. Additionally, the 24VDC model attempts to determine battery type (gel, flooded, AGM) and apply the correct charging scheme. It's not always successful at this, particularly if the bank it's attached to is not close to fully charged. Fortunately you can manually force it to the correct settings.
4. Sulphation is a constant, so you have to keep using the device to keep it down. I now rotate battery strings with it, keeping each string on the unit for 1 week at a time. This seems to be working well.
5. When I first put the unit on, the plates inside the batteries began to develop dendrites (long, tentacle like growths). I was concerned that they may actually short the plates out, but no problems were observed. Over time the dendrites went away.
6. When I first put the unit on, the liquid in the battery turned a very disturbing brownish-grey color and the specific gravity actually dropped over the first few days. This too cleared up and now the electrolyte is a sparkling clear color and the specific gravity went back up.
7. I don't have any suitable instrumentation to measure this but my *impression* is that the bank is operating much more efficiently while charging. It certainly can hold the inverters up longer before the specific gravity in the batteries indicates a 50% drop in charge.
8. These units are supposed to make the batteries last longer. I don't have enough time invested to know for sure but based on what I know about batteries I'm *speculating* that this is true. How much more life, I don't know.
9. These particular units claim to work on AGM type batteries. The batteries they're connected to are flooded lead acid so I don't know if this is true or not. I have an AGM on the diesel fuel tank pump which I hope to try "real soon now".
So, to summarize, this particular brand is working for me and worth the money I paid for it.
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