Parallel Charging

by ycopter | May 22, 2012 | (27) Posted in Tips

This article explains the benefits of parallel charging lithium polymer (lipo) batteries.

It does not cover lipo battery basics.  It is recommended that you look at this article and become familiar with lipo selection and charging before attempting parallel charging.


When charging batteries SAFETY is critical. The usual precautions apply:

Do not charge batteries unattended.Charge in a safe place (fireproof bag or box is recommended away from flammable materials).

Parallel charging is safe; however, the following additional precautions apply:

NEVER connect batteries of different voltages together in parallel.  Make sure that all the batteries are the same cell count and voltage.

Be aware that once batteries are connected together in parallel, if something does go wrong there is more energy stored in the batteries which in the worst case could damage multiple battery packs and damage property through fire.


I have been charging batteries in parallel for three years and still using some three year old batteries charged by this method. I can detect no harmful effects on battery performance and can only see benefits for the charging and discharging of lipo batteries.

COMMENTS

SuperCub92 on August 15, 2012
i notice that you mention what charger you have but you dont mention anything about what kind of charger you have to have to be able to do this..
i have a skyrc e6650 and would love to be able to parallel charge my batteries but am abit worried about killing my charger/batteries :P
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ycopter on August 15, 2012
Hello SuperCub92, you will be pleased to know that you can use any lithium polymer balance charger for paralell charging.
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SuperCub92 on August 17, 2012
YAY !! this is indeed great news..
on final question.. i think..
is..
how do i work out what is a safe ampage to charge my batteries at..
i kno that no more than 1c is the recommened for most batteries but how do i work this out.. as if i am charging my 5 2200 3s i want to be charging at more than 1amp.. :/
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ycopter on August 18, 2012
Safe standard charge for 5 X 2200mah is 5 X 2.2 Amps = 11 Amps. I normally charge at 70% of C if I am not in a rush 5 x 1.5 Amps = 7.5 Amps. You will probably find you will want a higher output charger now!
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SuperCub92 on August 19, 2012
aha yeah i dont have that issue..
but if it saves me a few hours and the hassle of having to watch it all.. its a bonus for me :)
thanks alot for ur help..

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SuperCub92 on August 19, 2012
and just as another point.. with the nano techs u can charge at 5c..
so for my 1300 does this mean i can charge it at 1.3*5=6.5amps.. or am i way off the mark here.?
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ycopter on August 19, 2012
You are correct, but that is a maximum charge rate, not recommended if you want to keep your batteries in top condition for hundreds of cycles. I have some 5C charge Nanotechs but still charge them at a maximum of 1C. It is also not a good idea to fast charge a hot battery, this is when maximum damage occurs, keep everything as cool as you can during charge and flight and they will last for hundreds of cycles. Also don't leave them fully charged for days or weeks or you will soon turn a 25C battery into a 15C battery! Store them at between 3.7v and 3.8 volts per cell.
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AbsoluteAltitudes on July 12, 2012
Fantastic video. I am going to make a setup like this as soon as i get a chance. I have killed a couple batteries by storing them fully charged, in anticipation of using them soon. It is always just a pain to have to charge up each individual battery one at a time before you can go fly, so I often just leave them charged. With this setup I feel I could go to the field or prepare to fly and charge all my batteries before going. Great idea, and good article. Thanks for sharing!
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ycopter on July 13, 2012
No problem, thanks for taking the time to make a comment. I never charge at the flying field, I charge before I go. Ten 2200mah 3S batteries take just a bit over an hour to charge using my iCharger 206B.
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ronhollenbeck on May 30, 2012
Nice tutorial, I've been parallel charging for about a year now. Sure is a time saver. I'm using a CellPro 4s which charges through the balance connector so I don't need to connect to the main leads. I agree with you on parallel charging different capacity packs at the same time but I also think it could cause problems in extreme cases. Let's say a couple of huge capacity packs are in parallel with a very tiny pack using an automatic charger. The charger thinks it is charging one very large pack and during the constant current portion of the charge it will keep increasing the voltage until it estimates the charge to be 1C or whatever is selected. It seems to me that the tiny pack could be charged too fast during this phase. It won't be overcharged, just charged faster, until the constant voltage phase begins. This will not be a problem as long as the packs are near the same capacity. It also would not be a problem if the charger is taken off of Auto and a reasonable current rate is manually selected.
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Pav on August 7, 2012
Agree! First the ballance plugs and then maybe the mains, altho in extreme voltage differences the ballancing leads may no handle the current.
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ycopter on May 31, 2012
Thanks for the feedback. Yes you could be right about avoiding mixing extreme differences in pack capacities, I don't do it myself. In theory this should still be OK. The lower capacity packs increase charge (voltage) more quickly than the larger ones; therefore they reject further charge until the voltage of the larger packs increases. An automatic charger will self adjust the charge current and this could cause a very small pack to be charged too quickly, but if the charge rate is limited to the safe charging rate for the total capacity of all the batteries being charged, then this should be OK.
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ronhollenbeck on June 8, 2012
Your comment above is exactly right. It took me a while to think it through.
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cwozny on July 24, 2012
I was curious about mixing capacities as well as the HobbyKing parallel charging board says not to mix capacities. I've got a few 2S of varying capacities (only 0.8 Ah and 1 Ah) and wanted to make sure I got this right: you're saying as long as you charge at the 1C rate of the lowest capacity pack everything will remain safe and not overexerted? This was an excellent video by the way, I love the use of the external resistor. I wish all of HobbyKing's chargers supported that feature!
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ycopter on July 24, 2012
In fact a standard charge in parallel is the total capacity of all the batteries. You can safely charge your 1.0 and 0.8AH packs at 1.8amps. I normally charge at 70% of 1C when I am not in a rush, around 1.4amps for your example. Hope this saves you lots of time!
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ronhollenbeck on May 29, 2012
Test
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jetpackninja on May 23, 2012
Excellent- Very well done.
Just curious how you end up with all of your batteries so close to the same voltage. My voltages end up all over the place. I usually end up only being able to charge up two or three together at one time due to the voltage differences.
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ycopter on May 23, 2012
Hello, I fly an FPV Tricopter and time my flights. I tend to land after 6 minutes meaning that most of my batteries are a very similar voltage after use. Having said that I think some of the batteries I used for this tutorial were already at storage charge after parallel discharge. Plugging in batteries within 0.2 Volts per cell difference is no problem at all. So if you do have some variability in voltage between packs after flight, don't worry, they will all even themselves out when plugged together in parallel.
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L33n0x on May 23, 2012
Perfect tutorial !
Thanks !
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ycopter on May 23, 2012
Thanks for your appreciation, just pleased to be able to share some experience with others.
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Parallel Charging