Biggles' Elder Brother - Moderator Posted January 13, 2017 Share Posted January 13, 2017 Pleasure - hope they're useful. Parallel charging certainly looks an interesting idea for lower cell count batterries. BEB Quote Link to comment Share on other sites More sharing options...
MattyB Posted January 13, 2017 Share Posted January 13, 2017 This is my favourite site for parallel charging info. Quote Link to comment Share on other sites More sharing options...
Peter Hill Posted January 13, 2017 Share Posted January 13, 2017 Thanks MattyB. Thats one of the sites I have visited but I still haven't found the answer to the question of charge rates for individual packs when capacities are different. Pete Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted January 13, 2017 Share Posted January 13, 2017 Peter, Hi, what do you mean "individual packs" , your individual cells become 1 "battery", and my charger goes to auto. Putting 7.2 amps in the equation is confusing, as theoretically the least resistive pack would take 7.2 amps for a period. Do you not charge auto? Quote Link to comment Share on other sites More sharing options...
Keith Berriman Posted January 13, 2017 Share Posted January 13, 2017 Hi Peter. From my reading and experience in parallel charging it is well advised that batteries need to be of same capacity eg 2200 with 2200. It is also advising cells need to be of same remaining capacity if possible. Having tried parallel charging I found the flight times were worse than single cell charging I did try two different chargers as well. Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted January 13, 2017 Share Posted January 13, 2017 Reading over everything on offer Peter, I will not be doing parallel charging again. I only do it at the indoor with identical cells, but I will charge dissimilar cell on their own in future Quote Link to comment Share on other sites More sharing options...
Peter Beeney Posted January 13, 2017 Share Posted January 13, 2017 Peter, Just to jump in here for a moment, don’t worry, the parallel charge rate is always fully self controlling, it’s all to do with the voltage. In your example, charging all these packs at 7.2 amps, (that’s the 1 hour rate, or 1C), will allow the 2,3000 mAh packs to charge at 2.3 amps each and the 1.3 mAh at 1.3 amps each. This is because when packs are connected in a parallel configuration all the batteries must remain at the same voltage, it’s impossible for it to be otherwise. I just bung my exhausted packs of different capacities but all the same cell count on a multiple parallel board, set a fairly low charging rate and leave them on overnight in the back of the car; not to be recommended though, this is definitely not advice to do this I hasten to add, but I’ve personally never had any difficulty charging batteries and I personally don’t have any particular worries with lithium batteries either. If I did I wouldn’t use them anyway. I’ve done this for many many years now and it’s always worked well for me. Exactly the same situation applies during discharge too, if a 20A and a 1A battery were connected in parallel and then set to discharge the same voltage must appear across both right throughout the total time, whether that time be fast or slow. Or, of course, any number of packs in parallel… Hope this is of some help… PB Quote Link to comment Share on other sites More sharing options...
Peter Hill Posted January 13, 2017 Share Posted January 13, 2017 Thanks for the replies. Denis, I understand that charger sees the 4 packs as I battery. The 7.2amp charge rate comes from adding each packs capacity together. In the example in my first post ,as there are 4 packs,do they each get 1/4 of the charge rate eg.1.8amps despite the different capacities? I know its possible to parallel charge packs of different capacities but I like to "understand" the process. Having trouble getting my head round this one!! Thanks again. Pete Quote Link to comment Share on other sites More sharing options...
Peter Hill Posted January 13, 2017 Share Posted January 13, 2017 Oooops. Must have posted at the same time.Thanks PB thats the infomation I was after!! Pete Quote Link to comment Share on other sites More sharing options...
MattyB Posted January 14, 2017 Share Posted January 14, 2017 Posted by RC Plane Flyer on 13/01/2017 19:58:03: From my reading and experience in parallel charging it is well advised that batteries need to be of same capacity eg 2200 with 2200.... Having tried parallel charging I found the flight times were worse than single cell charging I did try two different chargers as well. Whatever you are reading, it's incorrect. As Peter B explains above, a 1C charge is a 1C charge for every pack being parallel charged, irrelevant of the notes capacity. As to the lower flight times, if you are charging to the same voltage/cell that can't possibly be the case - duration of flight can be influenced by many things, but if you are getting the packs to the same voltage duration will be identical to if the same pack was individually charged. If you are seeing lower duration you have a charger/setup issue and the packs are not reaching the same final voltage. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted January 14, 2017 Share Posted January 14, 2017 Just a small point but the final charge level is dependent on very small voltages, as small as 0.01 of a volt. Using a parallel charging board you are putting in another 'set' of connectors and each connector can create small extra resistance. The charger may 'see' 4.20 V per cell at its end of the balance leads but that may not be exactly the same as the voltage at the cells hence charging can stop before battery is truly fully charged. I noticed this when the total Watts input parallel charging with a board was just a bit less (about 1%) than the sum of the Watts when the batteries were charged individually using the same charger. Quote Link to comment Share on other sites More sharing options...
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