The plate areas in a new battery may not be the same as the other plates when they are pasted to the grids. Therefore the capacity is different even between the plates. As the battery ages, the plate paste is thrown off every time you charge and discharge. If your discharging ampere is high, more of this material is remove from the plates thus decreasing the plate area.
In a new battery, the pasted plates are trowel on the grids and than press in with a roller. This gives a overlay where the area initially is only on the surface of the paste. To increase this area, they use rollers that indent grooves to make more plate area. Now it is up to the user, to increase this plate area by keeping the discharge rate for about 200 or more discharging. This raises the the surface of the plates which increases the plates surfaces or ampere hour. Initially take a specific gravity reading of the electrolyte if you can and record it. Even if the level of the electrolyte is low but is still above the grids, DO NOT ADD WATER to these low cells at this time. YOU WILL DILUTE THE ELECTROLYTE causing a lower specific gravity reading. In my new battery pack from U.S. Battery, I had one cell that was low, it was just not fill up all the way. The specific gravity read 2.275 sg which is consider 100% SOC. I took some 1.800 sg H2SO4 and added some distill water 1.000 sg, until it read the same sg that was in the cell and added that electrolyte to that low cell until the level was the same as in the other batteries. We had one person on this list that added water at the wrong time and that one cell read lower than the other cells. If a cell initially has a lower electrolyte level and the specific gravity is low, it is either a battery that been setting at the dealer for more than three months. I have seen batteries at these large supper stores, that were nine months old. Dealers like to get rid of there old stock first. DO NOT MIX OLD BATTERIES WITH NEW BATTERIES. Take the battery back to the dealer and get a new battery with the same manufacture date as the others if the electrolyte is low and/or the electrolyte is below the SOC of the other cells. In purchasing a battery pack, you specific in writing that you want a balance set of batteries with the same manuf. date, SOC, and capacity. The U.S. Battery Company will only do this for a extra charge. They recommended a battery dealer that has the equipment to do this test for a balance set. I brought my own equipment and had to go through three pallets of of 120 batteries to get a match set. I purchase these batteries on Sept 4, 2009 and today they now have 2388 charge cycles on the batteries. The ah/m is about the same when the capacity of the battery peak at 530 cycles. So initially preparing the battery pack will give you better service and long life. Roland ----- Original Message ----- From: "EVDL Administrator" <[email protected]> To: "Electric Vehicle Discussion List" <[email protected]> Sent: Tuesday, March 19, 2013 10:16 AM Subject: Re: [EVDL] flooded lead acid battery voltage goes down frommorecharging? > On 19 Mar 2013 at 9:37, Roland Wiench wrote: > > > There is a simply check to see if one cell in the battery is shorted. > > Could you please explan what in Cliff's description of the problem > suggests > to you that one of his batteries might have a shorted cell? One battery > charges to 0.2v less than the others, not 2.0v less, so I don't see a > shorted cell as likely. More likely that battery is just depreciating > faster. Perhaps I'm missing something. > > David Roden - Akron, Ohio, USA > EVDL Administrator > > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > EVDL Information: http://www.evdl.org/help/ > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > Note: mail sent to "evpost" and "etpost" addresses will not > reach me. To send a private message, please obtain my > email address from the webpage http://www.evdl.org/help/ . > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA > (http://groups.yahoo.com/group/NEDRA) > > _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
