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Distribution Block for balance leads?

Lt.Dan

Lt.Dan

Solar Wizard
Joined
Dec 25, 2020
Messages
3,569
Location
Tulare, Ca
Hey guys, I'm going to be putting together a new 2p16s battery and I know the balance leads are wayy too short.

I bought one of these:

Buchanan - Te Connectivity Terminal Block, Barrier, 16 Position, 22-12Awg - 1-1546306-6: Amazon.com: Industrial & Scientific

Buchanan - Te Connectivity Terminal Block, Barrier, 16 Position, 22-12Awg - 1-1546306-6: Amazon.com: Industrial & Scientific
www.amazon.com

I plan on running the balance leads to this, and then my own wiring to each cell, so I can make each wire the perfect length and not have a crazy mess all over. This also allows me to hook up an active balancer to the same terminals and reduce wiring required to each cell, further cleaning up wiring.

My concern is, will I need some sort of over current protection on these? I was planning on getting some 18ga silicon wire to do it all.
 
Lt.Dan said:
Hey guys, I'm going to be putting together a new 2p16s battery and I know the balance leads are wayy too short.

I bought one of these:

Buchanan - Te Connectivity Terminal Block, Barrier, 16 Position, 22-12Awg - 1-1546306-6: Amazon.com: Industrial & Scientific

Buchanan - Te Connectivity Terminal Block, Barrier, 16 Position, 22-12Awg - 1-1546306-6: Amazon.com: Industrial & Scientific
www.amazon.com

My concern is, will I need some sort of over current protection on these? I was planning on getting some 18ga silicon wire to do it all.
Click to expand...
No, provided that the combined current of the balancers does not exceed the capacity of the silicon wire.
 
Lt.Dan said:
Hey guys, I'm going to be putting together a new 2p16s battery and I know the balance leads are wayy too short.

I bought one of these:

Buchanan - Te Connectivity Terminal Block, Barrier, 16 Position, 22-12Awg - 1-1546306-6: Amazon.com: Industrial & Scientific

Buchanan - Te Connectivity Terminal Block, Barrier, 16 Position, 22-12Awg - 1-1546306-6: Amazon.com: Industrial & Scientific
www.amazon.com

I plan on running the balance leads to this, and then my own wiring to each cell, so I can make each wire the perfect length and not have a crazy mess all over. This also allows me to hook up an active balancer to the same terminals and reduce wiring required to each cell, further cleaning up wiring.

My concern is, will I need some sort of over current protection on these? I was planning on getting some 18ga silicon wire to do it all.
Click to expand...
I would.
I did similar to you with 10 awg going back to wago 613 lever nuts in wago din mount carriers.
I didn't use fuses and it bugs me.
I will be redoing the wires with 12 awg thhn and 25 amp fuses.
This is the fuse carrier I plan on using https://www.digikey.ca/en/products/detail/littelfuse-inc/01530003H/183338
 
I used a terminal block similar to yours in an early revision before switching to wago lever nuts.
 
I was more worried about if the wire happened to short out on something else, which caused the battery to overload the wire itself and catch fire.

I wonder if you could actually use a fuse block? Do they make a 16 way Automotive Fuse Block? Lol
 
Lt.Dan said:
I was more worried about if the wire happened to short out on something else, which caused the battery to overload the wire itself and catch fire.

I wonder if you could actually use a fuse block? Do they make a 16 way Automotive Fuse Block? Lol
Click to expand...
I've been wondering about this same situation. It seems that most users here do not choose to fuse their BMS sense/balance wires, but these wires are at different voltages relative to one another and to the rest of the system. A short circuit happening due to pests or damage would seem hazardous to me.
Some people recommend that all the BMS sense wires be the same length so as to not introduce variation in the resistance of the different lines. That variation would create errors or imbalance in the readings of the different cells by the BMS. But here's the thing: how much any of this resistance matters depends of course on the current level which is flowing through them as the BMS senses the voltage each cell.
If the input impedance of the BMS sense circuit (ADC or however it's being done) is sufficienctly high, then no amount of fusing or wire length imbalance or terminal block connection resistance is going to matter, as the voltage error introduced could be small enough as to be insignificant (less than 1 millivolt)

I wish I knew what the currents involved were, as I have located some very tiny fuses with a very high AIC rating. It can't be much at all.

Automotive fuses AFAIK have a relatively low AIC rating, but they're still probably better protection than nothing.
 
I use these Molex Connectors and never have issues. They come in various lengths and can be broken up easily if needed. Also a small screw hole between terminals for mounting, BMS & Active balancer in one side and out to cells with one 14g wire. Also handy for other connections.

molex-block-jpg.56090
 
So it seems the general consensus is the Balance Leads/Sense Leads do not need to be fused? Even if running 10ga from the battery to the distribution block/Molex connectors?

This doesn't seem right, but I'm open to learning!
 
Lt.Dan said:
So it seems the general consensus is the Balance Leads/Sense Leads do not need to be fused? Even if running 10ga from the battery to the distribution block/Molex connectors?

This doesn't seem right, but I'm open to learning!
Click to expand...
Small wires under ~22awg are considered self fusing.
Bigger wires should be fused.
 
What about adding fuses/connections? Will this in turn increase resistance/give false readings to the BMS for LVD or HVD?

Or does the increase in wire gauge counter this?
 
Lt.Dan said:
What about adding fuses/connections? Will this in turn increase resistance/give false readings to the BMS for LVD or HVD?

Or does the increase in wire gauge counter this?
Click to expand...
It doesn't matter much because the current on the wire is trivial.
 
 
Fusing between cell and BMS/balancer ? Those lines carry "very little" amperage and voltage. It is not like you are pushing amperage & hi voltage through them. Even an active balancer at 5A, is not actually moving 5A from one cell to another.. it is concurrently within the device on multiple lines.


Hella makes these Fused Blocks which can also be used, with ATO/ATC fuses at low amp.
hla-h84960091_w.jpg


Available up to 16 Circuits.
One Source:

PS: Summit can provide a lot of goodies, well priced and FAST ! Terminals, Blocks, Lugs etc...
 
Steve_S said:
Fusing between cell and BMS/balancer ? Those lines carry "very little" amperage and voltage. It is not like you are pushing amperage & hi voltage through them. Even an active balancer at 5A, is not actually moving 5A from one cell to another.. it is concurrently within the device on multiple lines.


Hella makes these Fused Blocks which can also be used, with ATO/ATC fuses at low amp.
hla-h84960091_w.jpg


Available up to 16 Circuits.
One Source:

PS: Summit can provide a lot of goodies, well priced and FAST ! Terminals, Blocks, Lugs etc...
Click to expand...
I'm not worried about what the BMS can do at all, I'm worried about the wires getting shorted and the battery providing enough current through those wires to catch fire.

I think the barrel fuses will work best like in the video @smoothJoey posted. That looks like cleanest way and safest
 
Lt.Dan said:
I'm not worried about what the BMS can do at all, I'm worried about the wires getting shorted and the battery providing enough current through those wires to catch fire.

I think the barrel fuses will work best like in the video @smoothJoey posted. That looks like cleanest way and safest
Click to expand...
I use 20 guage wire and these fuses on my boat to extend the balance leads from the BMS.

The Summit fuse blocks look like a good solution as well.

Normally, the fuse protects the wire, and should be rated for the wire gauge.
 

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