Odyssey batteries demand an inrush current of at least 1C. Generally speaking a battery can be fast charged at the same rate as discharge as long as it is voltage limited to max 2.45v per cell up to about 80% full, then the charge rate must be greatly reduced for the absorption phase (final 20%). I wouldn't try this with gel cells, but flooded and pure lead AGM's will be fine. If you accidentally outgas an AGM in most cases water can be added back to the cells. But the process is not as easy as with flooded batteries. see http://www.odysseybattery.com/odycharg_a.htm Stay Charged!HumpIgnorance is treatable, with a good prognosis. However, if left untreated, it develops into Arrogance, which is often fatal. :-) -- Lee Hart--- On Sat 03/22, Jeffrey Blamey < [EMAIL PROTECTED] > wrote:From: Jeffrey Blamey [mailto: [EMAIL PROTECTED]: [EMAIL PROTECTED]: Sat, 22 Mar 2008 07:58:50 -0600Subject: Re: [ElectricMotorcycles] Fast charging---dumb idea?I can only comment on SLA: Sealed lead acid aka AGM has limitations asto the voltage used. I you use too hign a voltage the battery can bepushed to outgas and you can create a condition where a cell can fail,then throw away the battery. Battery balance is critical as well.Batteries in packs should be replaced at one time, putting one freshbattery into a pack of 6 old batteries is bad practice. I canunderstand if you had a battery fail in the first 6 months replacingjust the one battery, but after 3 years no.Rule of thumb for long battery life with lead-acid technologies therate should not exceed 10% of the Ah rating of the battery pack (orsingle battery when charging with multiple chargers). So I am using 6- 6 Amp Pulse chargers for 55 Ah Universal 12250 battery. Being justover 10% not a big issue, I would avoid let's say 10 or more amps toget the most life.I expect if I limit my discharge to 50% depletion or less I can getthe rated number of recharge cycles. My charger is rated for 14.2V. Ihave talked to people who live off grid with large battery banks andhave consistently kept the discharge to 50% and often less resultingin battery life of 30% longer than mfg. stated. I have also heard ofbattery lives of far less than rated (gel cells), I think the laterare not too popular in EVs. Anyone out there using Gels?Jeff 84 Franken'ceptor, Denver snow is gone, temps in 50s, the EMCis ridden weekly (over 1100 miles)On Sat, Mar 22, 2008 at 5:49 AM, lyle sloan wrote:> Sorry I dont have a clear cut answer, but here is my> view on charging and batts and maybe it will help:>> All batteries are just trying to contain a chemical> reaction inwhich both sides, the anode and the> cathode, want to reach neutral. This chemical> reaction is controlled by the rate of electrical> discharge and the batteries' internal resistance.>> When we charge, we are using electrolysis to reverse> the neutral state which is why the charge voltage must> be higher than the original 12V. With electrolysis> there will be loss of material because not everything> transfers back over to exactly as it was before> discharge. Some of the material will remain on the> one side unable to transfer back over due to higher> resistance, or lost during gassing. In addition, any> material that transfers back to the original side will> layer ontop of the highest conductive point. This> means the original structure of the anode or cathode> has become pitted or brittle, as well as brittle from> heat. This brittleness can also be seen when fast> charging (hi amps) because only the most conductive> and highest point are going to get the material. If> charging slowly (low amps), more material is able to> transfer back to the other side evenly, filling all> the gaps or holes.>> The life of the batteries is dependant on how well the> structure of the anode and the cathode (both> chemically and physically) remain as close to original> as possible. High discharge and fast charging dont> help in this respect. Moderate discharge and slow> charging will preserve batteries.>> But the reality is, who wants to drive slow or wait> forever on a slow chrage? That's why when charging, a> combination of the two (fast and slow) is used which> affects the life of the battery. So it will be up to> each guy to figure out how long to charge for fast and> then slow for the type of batteries he is using Which> means battery life will vary from person to person.>>>>>> --- Andrew Wowk wrote:>> > Does anyone know exactly how battery life may be> > shorted with fast charging,> > provided the charge voltage is tempreature> > compensated? My B&B batteries> > have a max charging rate spec of .3CA whichseems to> > be pretty universal for> > most Chinese AGMs. I would like to charge them> > faster on an as-needed bases,> > but I'm wondering if this is a bad idea. It seems> > like I could charge faster> > in the bulk phase without too much damage to them.> >>>>>> ____________________________________________________________________________________> Be a better friend, newshound, and> know-it-all with Yahoo! Mobile. 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