Wrenches, Sorry for late answer as I was/am busy in meetings.
I will recap as follows: In a nut shell, Todd made a great point: equalizing and cycling are two different necessary steps in a full charge of a flooded lead acid battery. “Floating applications” means exactly that: they stay in floating mode 99% of the time. The float charge address the self-discharge of the battery. If the battery is seeing additional external causes for discharge, then it need to go through the re-charge process, which includes, depending the DOD, going through bulk charge, absorption charge and floating charge. On flooded lead acid technology, we have the luxury to do an equalization charge in lieu of the float charge, approximately after 30 cycles (typical 4 weeks, sometime earlier, sometime later, depending application specifics, size of battery, and, age of battery). For memo: equalization charge address two issues – equalizing the cells so you do not face more than 30 points between the cells (resulting on difference charge acceptance), and, mitigate the acid stratification in the electrolyte (thus improving the charge-discharge performance and reducing corrosion). Having said that, a lead acid battery designed for true deep cycle is best used for cyclic applications that actually cycle the battery due to the application. That battery design will keep the battery in great condition with numerous cycles, provided you actually fully recharge the battery and address equalization periodically after completing absorption, instead of the floating mode. That does not mean that you need to exercise unnecessary cycle the battery for increasing life. Another distinction is that true deep cycle lead acid batteries require 50 to 100 cycles when new to reach full capacity. Maybe that is where some confusion built up regarding “cycling a battery is good”. A “UPS” battery technology is designed specifically for 99% floating applications. They provide power as a “parachute” if & only when there is a power outage. Any exercise cycling on this battery design will ruin the battery. Some applications are necessary full “floating applications”: the “99% of the time” is actually much less than that ( power outage, loads, system losses, shadow loads, …) , resulting into a larger DOD. The floating charge is therefore not sufficient to overcome the DOD. Now we are talking requirement of recharging the battery (thus actually cycling it). Note: On VRLA, equalization is no go, although a boost charge can be considered on AGM (application specifics, too long to describe here on the blog). The issue is to pick the right battery design for the application, and then make sure the battery is full charged at each cycle. Hope this helps, not confusing you more. There are so many perspectives to see from and one is easy confused… John From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of toddc...@finestplanet.com Sent: Tuesday, February 21, 2012 12:45 PM To: RE-wrenches Subject: Re: [RE-wrenches] cycling flooded batteries is not necessary the two battery manufacturers say that cycling of floated batteries is 100% unnecessary. equalizing is still important to prevent stratification of the electrolyte... but equalizing and cycling are different things. todd On Tuesday, February 21, 2012 6:33am, "Drake" <drake.chamber...@redwoodalliance.org<mailto:drake.chamber...@redwoodalliance.org>> said: In my experience, at least my batteries need to be cycled. Here is the data. AC coupled backup system. The batteries are usually only supplying the inverter controls, with the pair of Outback 3524 inverters connected but turned off at the Mate. 80 watts of pv is used for a battery maintainer. The 2160 W of PV usually goes straight to the grid, and is switched over when needed. The batteries will remain essentially dormant with self discharge and control power somewhat balanced by a trickle charge coming from the small sub array. The batteries hold around 25.2 volts over night. When they drop to 25 or 24.8, I charge and often equalize them. Just equalizing will not make them hold at 25.2 V again. Even back to back equalization will not keep the battery V from dropping to 25 almost immediately. If I switch to off grid mode for a night to cycle the batteries and then bulk charge them, they will hold the 25.2 V again. I think cycling really is needed to mix up the acid. Drake Sent from Finest Planet WebMail. This e-mail message and any attachments that accompany it may contain information that is confidential, privileged, or protected from disclosure. It is intended solely for the use of the individual(s) to whom it was intended to be addressed. 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