We usually do not exceed 10% of total Ah to get the most life out of the battery banks we encounter, and we can get 3 - 10 years depending on the quality of the battery. Discharge to 50% typical. I don't think Damon is suggesting a high rate of charge of 300A in his example, you'll do some serious damage to most LA battery technologies we are using. 10-30 is right on.
Jeff On Thu, Mar 13, 2008 at 11:16 AM, damon henry <[EMAIL PROTECTED]> wrote: > > This will work, and probably work fairly well, but is a lot of work, and > will take a loooong time to charge. One thing you need to keep in mind is > that when you put two batteries in parrallel their capacity becomes the sum > of the two batteries, so if you put 6 12 volt batteries in parallel and they > each have 50 ahrs of capacity you now have one 12 volt 300 ahr battery. If > you have a battery charger that can dish out 300 amps you can charge in > about one hour, 30 amps ~10 hours, 10 amps ~ 30 hours. Also remember that > each of your Anderson connectors will be seeing full discharge current, and > will need to be rated appropriately. If you use the smaller connectors they > will melt. > > I personally would not do this. It actually ends up being more > complicated, and it would drive me nuts to redo the connections every time I > go from charging to riding and vice versa. You can almost always charge > fastest by leaving batteries in series, so that is what I do at least > through the bulk phase. The largest drawback to charging this way is that > towards the end of charge the individual batteries do not get the individual > treatment they require. You overcome this problem either by turning the > charge current way down at the end of charge so the stragglers can catch up > while not hurting the batteries that are already full, or by disconnecting > the series charger and topping off with individual chargers, or as you have > descrbed putting them all in parallel to finish them off. > > damon > > > > ________________________________ > Date: Thu, 13 Mar 2008 10:52:07 -0600 > From: [EMAIL PROTECTED] > To: [email protected] > Subject: Re: [ElectricMotorcycles] 12v charger recommendations, anyone? > > > > On Thu, Mar 13, 2008 at 9:07 AM, Travis Gintz <[EMAIL PROTECTED]> wrote: > > > so, here's a Q, how is he going to take the pack OUT of series, and > put it into parallel for charging? > > Wouldn't that require a contactor for each battery to take it out of > series, and some relays to connect to the 12V charger bus? > > Or is his system going to be 12V.... > > The diagram is attached. Please note that the 12 fuses in the diagram should > be rated for the full pack voltage. > > On Thu, Mar 13, 2008 at 8:54 AM, Johnathan Vail <[EMAIL PROTECTED]> wrote: > > You are right they will balance each other out and charge to the same > level but that isn't really what you want. You want the best charge for > the individual cell. Any time you have multiple cells charged together > the stronger ones will beat up on the weaker ones. > > > > In extreme cases with high amp charges one cell will reach max charge > before the other one and the extra current could cause over heating of the > electrolyte > > > Maybe in a series string, but maybe not in a parallel configuration. > > It is voltage that forces overcharge, and in a parallel configuration of > cells, the voltage would remain constant for each of them. > > On Thu, Mar 13, 2008 at 8:32 AM David Herron <[EMAIL PROTECTED]> wrote: > > One issue I haven't seen Andrew address is ... if you connect in > parallel two batteries who aren't at the same voltage.. clearly they're > going to try and equalize when you connect them, so there should be a > large spark. > > The voltage should be close, and I would not expect much current to flow. > Connecting a fully charged battery in parallel with a discharged battery > doesn't cause an alarming amount of current to flow with a big spark. We do > it when we leave car lights on, and need a jump start. > > A potential problem I can see is if one battery has a shorted cell than it > may draw a lot of current from the others. This appears to be like > connecting a 5 cell battery in parallel with a 6 cell battery. I imagine > this is a good reason for the fuses in the diagram. > > On Thu, Mar 13, 2008 at 7:53 AM Jeffrey Blamey <[EMAIL PROTECTED]> > wrote: > > If you do the one charger how will you properly charge all the > batteries to the same level... You are clearly making it harder on > yourself to have to break the series connections between the > batteries. > > At a CV of 14.7v, and a current of <.01CA, a battery is fully charged. If I > wait until the current is .01CA of any one of n number of batteries in > parallel at 14.7v, than that ensures that all of them will be fully charged > before the charger cuts off. Holding the voltage at 14.7v for a 6-cell > battery ensures that it will not be overcharged at room temperature. > > The intention is really the same as bank charging. I don't want or care to > charge all of the batteries to the same level, I just need to charge every > cell within the battery to 100%, and prevent cell damage due to > overcharging. > > I think I'm making it much easier on myself. I'll have one simple charger > with 1/6 the chance of failure of any one of 6 chargers failing. > > Andrew in NM > > ________________________________ > Need to know the score, the latest news, or you need your Hotmail(R)-get your > "fix". Check it out.
