Batteries 1S parallel charging concern

[bigone5500]

If I charge 6 1s cells in parallel, how can the charger keep track of the cells' voltages correctly? Should I rig up some kind of balance cable?

 

[Tony]

When you put batteries in parallel, they are all on the same rail. All positive sides are connected together, and all negative sides are connected together. The only time you need to worry about balance is if you put those 6 cells in series.

 

[bigone5500]

When you put batteries in parallel, they are all on the same rail. All positive sides are connected together, and all negative sides are connected together. The only time you need to worry about balance is if you put those 6 cells in series.

Thanks tony. I misunderstood.

 

[Tony]

No worries! Just make sure when you connect these batteries up in parallel, they are within 5% of each other. Last thing you want to do is damage cells because some were really high, and some were really low.

 

[murankar]

Or let them equalize before you charge. That batteries will naturally equalize if the voltages are not close to the same. I let mine sit for about 5 minutes before I press start on my charger.

 

[Tony]

That is when it can get dangerous. If you have a battery at 4 volts, and the other at 3.4 (per cell), plugging those two in can severely overheat the lower voltage battery and possibly cause a fire. I always use the 5% rule when I plug them in. If they are not within that range, they dont' get plugged in together. I will either charge them separately or I will discharge the higher cells to bring them down.

 

[murankar]

since my packs are flown together i d0nt have that issue. but yes i make sure they are not to far apart when i do plug them in.

 

[Smoggie]

I parallel charge a lot, typically I'll parallel charge 12 packs in two sets of 6 every time I fly. Making sure that the packs aren't too far apart on connection is important for sure but I've found that there is a fairly wide range.
0.1V per cell difference (about 20% of capacity) is fine, in fact I've often connected batteries further apart than that without issue. I've tried it a few rimes with an ammeter between the batteries and of course you do get a brief inrush of current to the low battery but it's not nearly as much as you might imagine, it stays within the batteries charge rate limit at all times and it dies down quickly to a trickle.