Another parallel charging question

[GtD]

btw - this is the video I mentioned in my previous post

Parallel charging 3x 3s packs with a kink - YouTube

this tjinguy I think has done a lot of stuff in to do with electronics (combining 12v CPUs to make 24v etc), I'm sure he know more than I do anyway (not hard! )

[cjcj1949]

so if we add a resister to slow your instantaneous balances and limit the amount of charge that can go from batter cell to battery cell and then let them balance before we connect to are balance chargers would this help and would any1 no how to make this possible if it is resemble

I'm an electronics engineer and parallel charging is very complicated. Using a resistor will make a big difference and allow you to connect batteries without having high C ratings.

What happens does depend on the order you do things in. If you have five low batteries and one high battery and connect all the low batteries first then the high battery then the high battery will have a high discharge and the low batteries will share the charge. So connecting from low to high should be the best way as lipos are specced at much higher discharge than charge rates, usually about 10:1.

After connection when charging the currents will not divide equally, but in the end all cells will end up at the same voltage. Parallel charging is a bodge, but as we don't really know how much abuse lipos can take, we can't say how much damage we are doing to them.

There must be a limit though or otherwise we could charge batteries instantly by connecting flat 150mah to fully charged 5000mah batteries. That is what happens if you connect enough fully charged batteries together and then connect in one flat one. Parallel charging is taking the **** and sooner or later someone will find the limit. Will they tell us though, or just keep quiet?

You can connect 10amp multimeters in series with each battery and see what happens. The meters cost a lot less than the lipos. I would think that using long leads on an equalising rig would be a good idea, followed by charging no more than 3 batteries at 1C each. As I said it is difficult to know what is going on, so nothing can be guaranteed, but lipos are hairy anyway and quite a few people have had to throw them out the window.

[Varelco]

When I want to charge 6 packs I first check the voltages and sort them in order from lowest to highest. I connect the 2 lowest in parallel together and wait a few seconds for them to equalize. The 1st 2 packs must be pretty close. I like them be within 2% of each other. When I connect the 3rd pack it will discharge into 2 packs, sharing the current. The 4th will discharge into 3 packs, the 5th into 4 and the 6th into 5. I've been using this technique for years. It works for me.

+1
This is a great technique, I tend to do the same if the pack differences are pretty big

[AcidDrink]

No one said it will bang or spark. It's just going to expose the batteries to very large charge/discharge C ratings for a brief period. The intenal resistance of a pack is virtually nothing, its literally like putting it to earth. Whether this has a detrimental effect over a long term I don't know, I'm not a battery guru but I still can't see it doing any favours.

I am visual effect specialist and parallel charging is very simple.

Anyway, my personal experience, I never charge single battery because it's waste of time and charger. I've been charging up to 12 packs on one charger at 5s. My regular charge is 6 x 6s at 1-2 c. I've been doing it for last 2 years regularly and there is no noticeable negative effect on the batteries. I charge batteries which have 0.2 - 0.3v difference between them. MPA board with fuses, always connect balance leads first. Never blew a fuse and no magic smoke.
I can't see how someone who flies anything bigger than a 6s heli can not parallel charge. Even with dual chargers.

[milly0812]

Another parallel charging question

Great input thanks chaps there is however a huge dark cloud over this subject. It needs to be addressed. It's all very suck it and see ?

[stocksy27]

generally my packs are any were from 20%-40% i just plug all the EC5 in first any order then connect all balance leads, then set the PL8 and off they go been doing this over a year and nothing bad happens, yes lipos are dangerous but people worry far too much, using 2 PL8 and the MPA boards makes it pretty simple charger will tell you if its not happy. Also if i have some fully charged packs and some flat ones i need to put into storage i just use the full pack to power the PL8, this discharges the full pack to around 50% which is great if the wether turns crap as i don't like leaving lipos fully charged for more than a few days