Before condemning the battery you should check a few things. First make sure the charger is actually charging it -- in particular, that it's delivering its rated current.
Then cycle the battery a few times (run it flat and recharge it). Many times you can get back a surprising amount of capacity in an old battery just by giving it some exercise. Batteris are like us -- if they don't use their muscles for a while, those muscles weaken and atrophy. To find out what you really have, run a capacity test. This will rule out excessive current draw from the lift itself. Using a dummy load of 100 amps or so (see previous EVDL discussions about this in the archive), and monitoring the battery's voltage, measure how long it takes for the battery to fall to 21 volts WHILE LOADED. From current and time, you can then calculate the battery's capacity in amp hours. Check the specific gravity of the electrolyte in each cell with a temperature compensated hydrometer. A flat cell will measure 1.120 SG or less, and a fully charged one 1.265 or greater. All the cells should be about the same SG. Especially if you find some cells low in SG, try a long equalizing charging cycle. To equalize, charge the battery until it seems full, then keep going at a current of 0.02C (rated amp hours expressed in amps / 50). There may be a setting for equalization on your charger. Or you might be able to use two cheap 12 volt "trickle" chargers (this is about all such chargers are good for, BTW). Monitor the on-charge voltage while equalizing. Stop charging when it stops rising, and especially if it begins to fall. A good 24v battery should be able to reach 30 volts or more. Worn ones might not get past 28 or 29 volts. Measure the voltage of each cell while they're still on charge. The lower a cell is in this test, the weaker it is. You can confirm the cell level diagnosis by testing SG again. Any cell that can't get past about 1.200 SG no matter how long you charge it is probably close to the end of its life. If you have some good cells and some weak ones, you might contact an industrial battery supplier (not an auto parts store) and ask whether they have any compatible used cells they might be willing to sell you to replace the weakest ones. Good luck, keep us posted. 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 Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
