Parallel Charging Without Plugging in Main Leads

by Oscar
Published: Last Updated on
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

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22 comments

Andrew Sams 29th November 2021 - 1:30 pm

I’m new to charging Lipos. ( I’ve read the warnings I could burn the house down). I have a Parkzone 2-3 Cell charger and it doesn’t have the discharge lead just the balance lead so I’m confused why I would need both to charge a 2S battery. I have a Hitec X4 for the bigger Batts when I ” graduate”. I’ve been using it for NiCads and Nimh up to now.

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Daich 23rd September 2021 - 10:50 pm

You can jam 2s balance balance plugs into the 3s balance sockets to parallel charger11 packs at once :p

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Eduardo 12th November 2020 - 6:09 pm

Hello Oscar, if i want to charge a 4S XT30 battery, i suppose have to make the adapter with a 4s balance conector? Also, for a 450mah battery, should i use 0.5A as my charge rate?

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Fast Furious 10th October 2020 - 11:54 am

Simply connecting 1 single lipo charge plug would have the same effect, wouldn’t it? Also allows for 1 more lipo to be connected to the balance board…

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Alltagsvlog 18th September 2021 - 10:59 am

Is that true ? Would be awesome to do it that way, … no need for an adapter and also having one more battery charged,…
Does anybody know if Fast Furious is right with his claim?

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Oscar 19th September 2021 - 1:45 pm

If you charge slowly that might work, but you are putting all the current through the lipo that you connected the main lead, e.g. if you are charging 6 packs at 1C, the pack that connected the main lead will have 6C of current going through it during charging and that’s not good for it.

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Starfighter81 25th January 2020 - 6:50 pm

Also I would recommend to add a fuse into that adapter to avoid damage to the balancing wires and boards.

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Starfighter81 25th January 2020 - 6:47 pm

‘…I always cut the leads off before throwing them away…’

Please do not throw batteries away! Bring them to a dedicated collecting point!

Thx

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Andreas 26th November 2019 - 3:41 pm

What is the highest current the balance plug can take safely?

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daichFPV 15th October 2019 - 4:02 pm

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

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daichFPV 15th October 2019 - 4:04 pm

18 because I don’t use the adapter… I just plug one of the batteries into the discharge port

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Scott 12th October 2019 - 7:00 pm

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.

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Oscar 15th October 2019 - 5:16 pm

You don’t need to do this with 1S, they don’t have balance lead!

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conrad taggart 8th October 2019 - 8:48 pm

Would it still be okay for a 2 s battery since it is only made-up of a first and second cell ?

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Mogens Kjær 24th September 2019 - 1:58 pm

And here I am thinking parallel charging was a closed chapter since good multi port chargers are so affordable now :D

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Oscar 26th September 2019 - 3:22 pm

They are not portable though :(

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Andrew Wakelin 24th September 2019 - 10:13 am

You can parallel charge like this without an adapter by plugging in the discharge lead of one of the lipo’s.

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Oscar 24th September 2019 - 11:25 am

The danger is that all the current will go through 1 balance lead (the one you plug in the discharge lead)

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Riho Kirss 22nd September 2019 - 6:31 am

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.

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Oscar 26th September 2019 - 3:11 pm

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

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Stephan 21st September 2019 - 9:38 am

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.

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Oscar 26th September 2019 - 2:58 pm

That’s an interesting thought!

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