Parallel Charging Without Plugging in Main Leads

parallel charge lipo without discharge lead only with balance

Here is a quick tip how to parallel charge LiPo batteries without plugging in the discharge leads, only with balance leads. This is inspired by Joshua Bardwell, all you need is a cable that you can easily make by yourself.

If you are new, check out my guide to parallel charging.

The Problem I am Having

I bought this parallel charging board (http://bit.ly/2ksvAux) for my 2S and 3S LiPo batteries with XT30 connectors. For the most part it works really well! However perhaps due to the lack of quality control, the pins in two of the XT30 are somehow bigger, making it quite difficult to insert the XT30 connectors.

Parallel charging board for 1S, 2S, 3S lipo XT30 connectors

Notice the 1st and 3rd XT30 connector from the top, pins are slightly larger

When I came across Joshua Bardwell’s video about parallel charging without connecting the discharge leads, and I thought, this is a bloody good idea to solve my problem!

Parallel Charging with Only Balance Leads

Disclaimer: Use the information on this page at your own risk. I am not responsible if you burn down your house. I am only sharing it because I think it’s a cool hack, I do not encourage anyone to copy this.

All it takes is a “balance to discharge” adapter. Simply connect it to one of the slots on the parallel charging board.

Then you can connect the LiPo to the rest of the slots, with only the balance port, and you can charge them as normal!

It’s so freaking easy when charging a bunch of theses LiPo at once, I only have to plug in one connector instead of two.

Without the adapter, your smart charger will complain and stop charging because it can’t detect the discharge lead.

Using the adapter, basically you are “cheating” the charger that the two outer wires in the balance lead are the discharge lead. (in fact these two wires are connected to the same solder joints inside the battery as the discharge lead, you can confirm with a multimeter in continuity mode)

When you charge your battery this way, all the current will go through these two wires in the balance lead, instead of the discharge lead, as shown in the image below.

However, because the balance lead uses small wires than the discharge lead – usually 22AWG, you should never charge with too much current to avoid overheating/damanging those tiny wires and traces on the board.

How to Make These Adapters?

You will need a balance connector and an XT30/XT60 connector for this adapter (both female).

I have a ton of these connectors from retiring old LiPo batteries, as I always cut the leads off before throwing them away.

If you don’t have any spare, these connectors are cheaply and widely available. Select balance lead based on the LiPo cell count, and use XT30 or XT60 depending on what’s on the parallel charging board.

Here I made three adapters for 2S, 3S (XT30) and 4S (XT60). You can remove the wires in the middle, all you need are the two wires on the outside (first and last wires). Solder these two wires to the XT30/XT60 connector, Positive to Positive, Negative to Negative.

Joshua’s video that inspired me to do this hack

13 thoughts on “Parallel Charging Without Plugging in Main Leads

  1. daichFPV

    This is how i’ve been charging. Also, on a 6 port 6s balance board, you can wedge in 4s packs into the 5s and 6s ports :P
    I’ve charged 18 packs at once before, haha

    Reply
  2. Scott

    Great article! I’ve found so many of these articles on this site so helpful as I’m fairly new to quads. So many thanks! Considering the comment Stephen wrote above.. Would the charger still detect properly if using this method to charge 1s batteries since only 1 cell is involved? I’m considering using this adapter method to utilize the 1s jst balance ports to charge my 1s packs on my 1-3s balance board so I can parallel charge. Would save me buying another board.

    Reply
  3. Riho Kirss

    Why do you need the adapter? Just plug one of the LiPo discharge lead to the xt30 socket and that gives the same result. Basically the same adapter wiring is inside the LiPo.

    Reply
    1. Oscar Post author

      By doing that you risk all the current going through the balance lead of a single LiPo which you connected the discharge lead.

      Reply
  4. Stephan

    Hi Oscar,
    if you connect the Lipos this way, the plus an minus wire of the balancer lead of each Lipo will carry the charge current. This result in a voltage drop for the last and first cell of each pack.
    The charger is not able to measure the real voltage of each cell of the pack. The sense error is pack charge current times resistence of the balancer lead.

    This will result in an longer charge time because the charger will reduce the charge current because of the charge current dependent voltage drop of first and last cell.

    Reply

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