Jul 26, 2012, 11:56 AM Registered User United Kingdom, England, Liverpool Joined Mar 2009 1,654 Posts Discussion Parallel charging question Hi, I have a 120SR with a celectra charger, I have made my own parallel charging harness in order to charge 2 batteries at the same time. My batteries are 600mah, so I usually charge at no higher than 0.6 amps. I was wondering, I heard that charging two batteries would make it effectively a bigger battery of 1200mah, does that mean I can now charge 2 batteries at the same time, at a rate of 1.2 amps? Obviously the celectra only goes to 0.7 amps, so I really want to know if I can charge at 0.7 amps, without damaging the batteries.
Jul 26, 2012, 02:39 PM
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Quote:
 Originally Posted by Microbaba Hi, I have a 120SR with a celectra charger, I have made my own parallel charging harness in order to charge 2 batteries at the same time. My batteries are 600mah, so I usually charge at no higher than 0.6 amps. I was wondering, I heard that charging two batteries would make it effectively a bigger battery of 1200mah, does that mean I can now charge 2 batteries at the same time, at a rate of 1.2 amps? Obviously the celectra only goes to 0.7 amps, so I really want to know if I can charge at 0.7 amps, without damaging the batteries.
I think you are using stock celectra charger EFLC1006 for 1s lipo only. Yes, you may charge 2 x batteries in parallel using your own parallel chraging harness at the same charge but at rate of 0.7A only. However, it will double time to charge 2 lipo in parallel as compare to 1 lipo due to stock EFLC 1006 max charging current output is 0.7A. It means you gain nothing put 2 lipo in parallel charging.

Unless you have charger that gives higher output charging current, it spend same amount of time to charge 2 lipo in parallel or individually.
 Jul 26, 2012, 03:23 PM Registered User United Kingdom, England, Liverpool Joined Mar 2009 1,654 Posts Thanks wlee, but usually I charge a battery at 0.4amps, so if I charge two batteries in parallel at 0.7amps I don't think it will take too much longer, maybe half an hour.
Jul 26, 2012, 04:22 PM
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Quote:
 Originally Posted by Microbaba Thanks wlee, but usually I charge a battery at 0.4amps, so if I charge two batteries in parallel at 0.7amps I don't think it will take too much longer, maybe half an hour.
I think you miss my point. Usually, we charge lipo at about 1C of lipo capacity. I had 120SR before and usually charge at 0.7A as per manual instruction. It's not wrong to charge 600mah lipo at 0.4A but just takes longer time as comapre to 0.7A.

It look like no big time difference in charging 2 x 1s 600mah battery in parallel using 0.4A as your charger max output charging current is 0.7A. But I am sure understand the maths when you 0.7A use as charging current to charge 600mah individual lipo or 2 lipo in parallel.
 Jul 26, 2012, 08:25 PM Just fly Australia, VIC, Glen Waverley Joined Jan 2011 2,103 Posts You would also want to consider the max wattage output of the basic eflight charger. You best option is to charge 1 lipo at .6A (1c) or .7A instead trying to charge in para on this charger... Better yet, buy a better charger which then you can take full advantage of para charging. IMHO - eflight chargers are crap and not worth wasting time on.
 Jul 27, 2012, 02:43 AM mutski United States, AK Joined Jan 2011 1,301 Posts
 Jul 27, 2012, 05:26 AM Registered User United Kingdom, England, Liverpool Joined Mar 2009 1,654 Posts Guys, my point is, that with a 600mah battery, you are not supposed to charge at more than 0.6 amps or you destroy the battery, which means that when I charge my 600mah battery, I have only ever charged it as 0.4 amps to be on the safe side. When you parallel charge, does the charger effectively treat two batteries as one battery? Therefore two 600mah batteries, you add the capacity. 600+600= 1200mah, so is it now SAFE to EXCEED 0.6 amps? Is the safety limit now also doubled? So would it be 1.2 amps? I take your point, that my charger is not a very good one, but personally, I would rather charge two batteries simultaneously, if it takes 20 minutes longer than charging one battery, because if I charged one battery individually, then charged the next battery, that would still take longer. EXAMPLE; Charging 2 parallel 600mah batteries at 0.7amps = 2 hours to charge. OR; Charge each individually at 0.4amps, which will take 3 hours to charge. Remember, LOGICALLY, you still end up with less charging time, even if 0.7 amps is not as high a rate as 0.8amps. Sorry if I sound like a smart-ass but I think I have understood it correctly. You are still correct about my charger being rubbish, sure - I admit I could do better with a more sophisticated charger, I take that point, but for now, let us pretend I am skint and just want to make do with what I have. I actually did try to parallel charge 2 batteries at a rate of 0.5 amps because I didn't know whether I could charge them at 0.7 amps without doing damage. I would say it took about half an hour longer than charging one battery, but that is still less time than charging two batteries on their own. remember that I have never charged a 600mah battery at 0.6amps and I never will, so that is not an option, as I want to get as much life as I can from them. Last edited by Microbaba; Jul 27, 2012 at 05:51 AM.
 Jul 27, 2012, 05:35 AM Registered User United Kingdom, England, Liverpool Joined Mar 2009 1,654 Posts I also read that OHMs means less inteference, I know nothing of the subject but apparently, because there is less resistance, parallel charging draws more current? So to charge 2 batteries in parallel would be quicker at the same rate of charge, than charging 1 battery. But I don't know if I have understood that correctly. An analogy might be, that if you get a cyclist to ride one mile, he will go slower than two riders that ride the same mile, because the two riders will be able to slipstream one another. (less wind-resistance). EXAMPLE: Rider on his own will take 5 minutes 30 seconds, Two riders putting in the exact same effort as the individual rider, will take 4 minutes 55 seconds. So to charge one lipo might take 1hr 30min, but to charge two lipos in parallel, at the same equivalent charge-rate, might take 1hr 20min? That's if I understood right, of course, and I claim zero knowledge of electricity. Last edited by Microbaba; Jul 27, 2012 at 05:42 AM.
 Jul 27, 2012, 01:34 PM Registered User United States, NE, Omaha Joined Jan 2012 48 Posts Yes, you have it right. A few thing to keep in mind though. The charger doesn't treat it as one battery, it *is* one battery as soon as you connect them to each other. Each cell will roughly take half the current, as long as they were close in charge state before you connected them, and make sure they are!
 Jul 27, 2012, 02:06 PM Registered User United Kingdom, England, Liverpool Joined Mar 2009 1,654 Posts Yes, thanks - I see what you mean psylence519. Yes, they are connected as one battery - haha, I should have realized that.