Connecting balance leads for charging and use.

[camerart]

Hi,

I'm just about to make a balance lead wiring harness, for 9x of these batteries: https://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=26664 As can be seen on the photo there is a balance plug, which I will plug into a matrix of sockets.

So far, I've been using them as 3x packs of 3x in series, and they're fine. Now I want to parallel the 3x packs into one pack. If possible I want to leave the harness on while balance charging and while using them.

What I would like to know, is what could be the maximum current that could pass on the balance leads, even if the was a problem with the cells, so that I can add some protection. Fuses or resistors.

Camerart.

 

[selrahc1992]

Hi,

I'm just about to make a balance lead wiring harness, for 9x of these batteries: https://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=26664 As can be seen on the photo there is a balance plug, which I will plug into a matrix of sockets.

So far, I've been using them as 3x packs of 3x in series, and they're fine. Now I want to parallel the 3x packs into one pack. If possible I want to leave the harness on while balance charging and while using them.

What I would like to know, is what could be the maximum current that could pass on the balance leads, even if the was a problem with the cells, so that I can add some protection. Fuses or resistors.

Camerart.

apologies for not answering the question (im running a lipo setup too and am as interested in an answer in fact), I was wondering what made you choose these batteries rather than hobbykings 16Ah 6S which would give much more Ah for the money?

 

[camerart]

apologies for not answering the question (im running a lipo setup too and am as interested in an answer in fact), I was wondering what made you choose these batteries rather than hobbykings 16Ah 6S which would give much more Ah for the money?

Hi Selrahc,

My choice of these batteries, was partly because I could use them in flying models also, although once set-up in the bike, I probably won't mess about with them. In case of one cell failing, it would be cheaper to change one 3s than a 16s. Lastly, impatience in shopping

C.

 

[Deleted member 4366]

Something's going to blow. The only way you can charge them together without disconnecting is to charge them in series with a charger that can do 9S. If you try and parallel the balance leads when the power leads are still in series, Kaboom!. Note te capital k. Sooner or later you'll forget and do that anyway, like the rest of us. Here's a hint: Always wear sungasses when connecting lipos. That plasma ball is very bright.

 

[camerart]

Something's going to blow. The only way you can charge them together without disconnecting is to charge them in series with a charger that can do 9S. If you try and parallel the balance leads when the power leads are still in series, Kaboom!. Note te capital k. Sooner or later you'll forget and do that anyway, like the rest of us. Here's a hint: Always wear sungasses when connecting lipos. That plasma ball is very bright.

Hi D8veh,

We've already had a similar conversation, in another thread, where it was pointed out by other members, that I had missed some connections out, although I think you ok'ed the wiring diagram?

If we accept the diagram for now. What I would like to know is the possible current that could pass along the balance wires?

C.

 

[Deleted member 4366]

That's OK. You need a charger that can do 9S. It's only if you use a 6S charger, you have to disconnect everything.

 

[camerart]

I added 5A fuses between the parallel balance plugs connectors.

C.

 

[selrahc1992]

Hi Selrahc,

My choice of these batteries, was partly because I could use them in flying models also, although once set-up in the bike, I probably won't mess about with them. In case of one cell failing, it would be cheaper to change one 3s than a 16s. Lastly, impatience in shopping

C.

many thanks, by the way do you have a 9S charger (an dif so which, and does one get say 13 S Chargers)?

 

[camerart]

many thanks, by the way do you have a 9S charger (an dif so which, and does one get say 13 S Chargers)?

Hi,

I have the: http://www.hobbyking.co.uk/hobbyking/store/__57095__Turnigy_Reaktor_30A_1000W_Balance_Charger.html

I've not had time to use it much, but it seems ok. It does 10S.

You will need a power supply for it. I bought a Cosel 1000w one second hand.

C.

 

[selrahc1992]

Hi,

I have the: http://www.hobbyking.co.uk/hobbyking/store/__57095__Turnigy_Reaktor_30A_1000W_Balance_Charger.html

I've not had time to use it much, but it seems ok. It does 10S.

You will need a power supply for it. I bought a Cosel 1000w one second hand.

C.

many thanks, for what it is it seems genuinely cheap, I wish it was made in 13S balanced charging (I see it does it unbalanced)

 

[camerart]

BEWARE

I previously said I had added 5A fuses between the each paralleled cells, but after testing found the wires getting hot, so 5A is too high. Perhaps 2-3A should be used.

 

[Deleted member 4366]

Changing the fuse won't stop the wires from getting hot. If the wires get hot, something is wrong. Can you show on your schematic where you put the fuses?

 

[camerart]

After a long conversation with Hobbyking, we agreed that in the worst case, there could be 100A between each cell, or 10A with regard to charged discharged cells, so I should change the fuses to 3Amp, to protect the balance wires.

I accidently connected the last 9s which were run down, to the charged 2x 9s, So they were charging the last 9s, potentially 10A, making them hot. Once I charged the last 9s up, all was cool, and I went for a long ride, all ok.

C.

 

[Deleted member 4366]

Can't you show on your schematic where they are? Just draw Xs on your schematic. It really worries me what you've done.

 

[camerart]

Can't you show on your schematic where they are? Just draw Xs on your schematic. It really worries me what you've done.

Thanks for your concerns.

C.

 

[Deleted member 4366]

That's not as bad as I thought, but it's a complete waste of time. They don't do anything. All the power goes through the power leads, which you haven't shown in that diagram. If you join with wires instead of fuses, the cells in that string will always be exactly the same voltage, so no need for the fuses. How would you know if a fuse were to blow or was otherwise faulty? If one stopped conducting, it wouldn't protect anything. The pack would still function as normal, except the balancing wouldn't work properly on the top two rows of cells, though your meter/charger would show that they were.

 

[camerart]

That's not as bad as I thought, but it's a complete waste of time. They don't do anything. All the power goes through the power leads, which you haven't shown in that diagram. If you join with wires instead of fuses, the cells in that string will always be exactly the same voltage, so no need for the fuses. How would you know if a fuse were to blow or was otherwise faulty? If one stopped conducting, it wouldn't protect anything. The pack would still function as normal, except the balancing wouldn't work properly on the top two rows of cells, though your meter/charger would show that they were.

Hi,

I charge as normal thought the power leads, with the balance connected when used. This board is left on the batteries. The fused links allow for balance charging and if one of the cells goes faulty, it will fuse that link, and I can see it has fused. Later, I'll add LEDs to highlight a fused link.

C.

 

[camerart]

I added the 'extra connections' because of heavy advice on another thread, but now I remember why I didn't have them originally.

If any of the power connections between batteries come apart, then the full current would pass along these 'extra connections' while charging. I will re-wire it as I originally thought, without them.

C.