Battery charging/PulseTech
I have just gone through a steep learning curve about lead acid batteries after puzzling over why brand new batteries from Costco were performing worse than the batteries I took out and deemed unfit for service.
This lead (no pun intended, trust me) me to discover a company called Pulsetech. They manufacture a charger/desulfator that provides current pulses during charging and maintenance cycles of around 25kHz (that's 25000 pulses per second). Many have reported to recover dozens of dead batteries this way. I also learned that many batteries sitting on the store shelf for even a couple of months get sulfated from just sitting there. BINGO! That's why the Costco batteries were so bad. All three Costco batteries that I have purchased this year have not performed to spec. One I exchanged, and the second one died last week.
There are several pulse type desulfators out there, and each claim to work, so take your pick. I got the Pulsetech one to try out. On my Tahoe, the brand new battery gave me about 12.4 to 12.5 V maximum. I put the desulfator on it for a total of about 25 hours and I now have 12.7 V at full charge. So, now I know they really work. At least the Pulsetech.
Many of these pulse type desulfators can be used continuously to maintain a battery. In fact, the longer they are used, the more they desulfate. So now I'm thinking that as we use our deep cycle batteries, they will slowly sulfate over the season. Once my car batteries are brought up to spec, I'm going to put the Pulsetech on my TM battery for the winter and see if I can get even better performance out of it.
But, there's one more thing I learned tonight. A lot of people swear by pairing up 2 6V batteries in series. A research group in Oakland University found may problems with 24 V systems using 2 12 V batteries. They say these problems will exist in any battery of any voltage, so 2 6V batteries in series will have the same problem.
The ideal charge voltage at the end of the charge cycle is 14.7V. If you are charging 2 12V batteries, the charge cycle would end once you reach 29.4V (twice the 14.7V). Now here is the problem. No two batteries are the same, even if you buy the same brand of the same manufacturing date. As they age, they will deteriorate at different rates anyway. So, once you reach the magic number of 29.4 V for a fully charged battery, battery "A" may actually be at 13.84 V (not fully charged) and battery "B" at 15.56 V (overcharged). There is a lot of discussion of the discharge voltage. Once battery can be forced into "cell reversal" which is damaging to the battery.
I had once considered a series 6V battery system, but I think I will stick to the single 12 V battery. The military often use the 12 V batteries in series, as do other groups, so the research in this area continues to refine the charge cycles.
For the complicated full paper: Consequences of Deep Cycling 24 Volt Battery Strings, Henry A. Catherino and Fred Feres, SAE International Journal of Alternative Powertrains, Vol. 4, No. 2 (July 2015), pp. 378-387
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