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 -0600From: [EMAIL PROTECTED]: [EMAIL PROTECTED]: 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, andput it into parallel for charging?Wouldn't that require a contactor for each battery to take it out ofseries, 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 samelevel but that isn't really what you want. You want the best charge forthe individual cell. Any time you have multiple cells charged togetherthe stronger ones will beat up on the weaker ones. In extreme cases with high amp charges one cell will reach max chargebefore the other one and the extra current could cause over heating of theelectrolyte 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 inparallel two batteries who aren't at the same voltage.. clearly they'regoing to try and equalize when you connect them, so there should be alarge 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 thebatteries to the same level... You are clearly making it harder onyourself to have to break the series connections between thebatteries.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®-get your "fix". http://www.msnmobilefix.com/Default.aspx
