Just found a Deans Y connector for connecting 2 batteries in parallel. I have slight concerns whether this is safe. I have 2 identical make, identical type (3 cell 11.1v 2200mAh 40C), same age, same usage. But they must be charged separately due to charge sensor cable, and they are bound to charge to slightly different levels due to minor internal differences in cells etc.
Connecting them in parallel in the Deans connector could cause a huge current surge as they balance out, and depending on the internal safety circuitry of the battery, damage to cells.
Should I be worried, or are these parallel connectors routinely used for longer flights?
Replies
same topic at this DIYDrones page!
Parallel connection of power sources, in electrical industrial plants, is strictly forbidden. A separation devices is mandatory to avoid reverse current flow and to protect the load against a single power failure. Use of silicon or shottky diodes is not suggested because of the too high voltage dropout. We developed an ideal diode device to safely connect two or more batteries without any power loss
Marco
I'd like to bump this issue.
I can't see a high current transient being very healthy for the battery no matter how short lived if applied with each charge session.
I don't know what the current would spike to for voltage differences in the region of +/- 0.01v, but without assessing it I wouldn't want to just assume it is small.
Saying people do this all the time is not a good argument. I am computer engineer myself, there is such a thing as the right way and the wrong way. People have batteries that explode all the time as well, so...
I would think that placing a large value resistor between the parallel terminal until equilibrium is reached would be a good idea? This plus an in-series ammeter would reveal when equilibrium has been reached?
I do this all the time but with a twist, I have a Y lead with XT60 connectors and charge the batteries together, they remain together and then plug into a single XT60 on the Quad. no voltage difference exists and the benefits are very real by increasing the C rating and reducing the voltage dip when climbing.
Yes, just treating them a single unit at all times would keep them in equilibrium.
What did you do about the other battery leads for cell measurement? Did you have to do something with the wiring to be able to connect them to your charger?
Thanks for the extra advise - I'll bear it all in mind. Not sure whether I'll need parallel batteries yet - my quad is still in testing, but I have 2 pairs of batteries so the parallel may give me the extra power I need for video + lighting + longer flight
Thanks Guys - the fact it's done all the time is what I wanted to hear - I know just enough electronics to see a possible problem but not enough about LiPo batteries to know it's safe.