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.
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.
This is the iSDT Q6 Pro Charger
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.
- 2S, 3S, 4S, 6S Balance Lead: Banggood | Amazon
- XT30: Amazon | GetFPV | Banggood
- XT60: Banggood | GetFPV | Amazon
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.
27 comments
There’s one question I haven’t found an answer anywhere. Does lipo charged this way (let’s say it’s 2S) is balanced charged?
Yes it does. Batteries connected are being charged through the balance connector.
Actually, no it doesn’t. It only charges across the battery. You would need to connect the main battery plug in parrallel with the same outside wires of the balance connector, but keep the balance connector at the other end that plugs into the charger as well. So, you only plug the balance connector into the battery, but you plug a main battery plug and a balance connector into the charger.
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.
You don´t need both leads for charging. As you described the charger charges every single cell trough the balance cables. Bigger (normal) chargers can charger more current and so faster than this small ones. For charging over 2-3A safely they the discharge leads and balance (discharge) the cells via balance leads. Sadly often there isn´t a program on the bigger chargers to charge only via balance leads with a limited current. So this balance boards seem the way to go for FPV flyers. I don´t need so much lipos so fast so probably I´ll stay on my 4 channel charger. Although just connecting the balance leads is much more confortable :P
I meant: they charge via discharge leads (XT60 or XT30 and so on) for the full voltage (i.e. 8,4V on 2S) and balance (discharge) every single cell on the single voltage (i.e. 4,2V on 2S) to charge them even.
You can jam 2s balance balance plugs into the 3s balance sockets to parallel charger11 packs at once :p
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?
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…
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?
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.
Also I would recommend to add a fuse into that adapter to avoid damage to the balancing wires and boards.
‘…I always cut the leads off before throwing them away…’
Please do not throw batteries away! Bring them to a dedicated collecting point!
Thx
What is the highest current the balance plug can take safely?
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
18 because I don’t use the adapter… I just plug one of the batteries into the discharge port
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.
You don’t need to do this with 1S, they don’t have balance lead!
Would it still be okay for a 2 s battery since it is only made-up of a first and second cell ?
And here I am thinking parallel charging was a closed chapter since good multi port chargers are so affordable now :D
They are not portable though :(
You can parallel charge like this without an adapter by plugging in the discharge lead of one of the lipo’s.
The danger is that all the current will go through 1 balance lead (the one you plug in the discharge lead)
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.
By doing that you risk all the current going through the balance lead of a single LiPo which you connected the discharge lead.
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.
That’s an interesting thought!