Battery rejuvenators good/bad?

I'm considering buying a few of these battery rejuvenation type products to fix the batteries around my shop with. Has anyone had a good or bad experience with these things?

If you're referring to a desulfator, I've had mixed results with mine. I have both a standalone unit and a charger with a desulfator mode. I suppose if they are used regularly they would be successful at keeping a battery working well for longer than typical periods, but for rejuvenating a battery that is already weak/dead, I wouldn't rely on it.

That being said, I do have some empirical results using the standalone desulfator with some AGM batteries used in electric go karts. The place was having issues with the run time on their go karts to the point where they had to lower the race durations after only a few months because the karts were not retaining enough charge. I hooked up a current prove and voltage probe to my datalogging oscilloscope, made several runs to watch the discharge profile, then used the desulfator and ran the same test. The desulfator did help get the charge back to about 70% of the original run time, but never fully brought them back. The place ended up trying a different brand of batteries.

-Rod

Hi Rod, thanks for the info. I've had people tell me these things don't work at all but I don't believe that. There must be something to them. I heard that a "desulfator" is usually built into forklift battery chargers. Can I ask what kind or model you used - about how much did it cost?

Thanks,J

I use a Battery Life Saver (BLS) version as the stand-alone and I have a Vector Power 2/10/20/40/100 charger with the desulfate mode built in. I think I paid around $40 for the BLS several years ago. It works in conjunction with a 2 amp (recommended) charger. The instructions suggest charging the battery, running just the BLS as a load for 24 hours, then running it another 24 hours with the 2 amp charger connected, and repeating that cycle until the battery has its capacity back.

I'll have some more results in about 24 hours. My father in law asked me to check the batteries in his boat. The spare battery for his trolling motor was dead at 8.74 Vdc. I put it on the Vector charger at a 2 amp rate and when I checked on it a couple hours later it had a F01 code which means the battery has an internally shorted cell. Since the marine battery has never been used (but is several years old) I decided to try desulfating using the charger to see what happens. The cycle takes about 24 hours.

-Rod

Wow, good info Rod thanks. I have a friend who has a "revolt" he got from kickstarter that he's had good luck with but it sounds like his works differently than the BLS unit you describe. Thanks for keeping me posted. I'll look into both of them. Are you saying you've had better success with the BLS than the other or just haven't tried the other? Thanks-J

I really only have quantitative data on the BLS results, I haven't really made any measurements on the performance of the desulfator built in to the Vector charger. I'm trying that first on the marine battery basically out of laziness. I already had the charger connected to the battery.

-Rod

Well, the desulfate mode built in to the charger didn't bring the battery back to life, but did gain another 1.2 volts on the battery. The battery still has virtually no capacity though. Now I have the BLS hooked up along with a 2 amp charge.

The charger, without the BLS connected, does attempt to charge this battery, then faults out with either an F01 or F03 code. One code says "Open cell" the other says "Shorted cell". Either way, I really shouldn't expect a desulfator to bring this battery back, so this is more of an experiment than a critique of the desulfation process.

-Rod