Multiple battery

[ArthurEld]

What BMS have you chosen?

What would you use for my setup?

 

[HRTKD]

I thought I might buy the cables with connectors on them. Another thing to figure out.
Thanks

They'll either be too short or too long. You never really know how long a cable needs to be until you have the components in place. I put my layout into a cad drawing but had no idea how the curves of the cable would figure in. How much would a cable curve? The thicker the cable, the bigger the curve.

It wasn't cheap but I bought the tools for crimping my own cables. In the long run, it may have been less expensive to do my own. Built cables aren't cheap.

 

[John Frum]

What would you use for my setup?

I would go with the overkill.
Its pushing the limits but @OverkillSolar has tested the limits and demonstrated that he stands behind the product.
It will show current in and out and has all the desirable configurable parameters.

 

[ArthurEld]

I would go with the overkill.
Its pushing the limits but @OverkillSolar has tested the limits and demonstrated that he stands behind the product.
It will show current in and out and has all the desirable configurable parameters.

When I checked their site it didn't have 48v

 

[John Frum]

When I checked their site it didn't have 48v

I guess you could try them just make sure that the low cell and low pack disconnects are configurable at runtime.
And it it doesn't tell you the current in and out you should put a shunt on each battery circuit.

 

[ArthurEld]

They'll either be too short or too long. You never really know how long a cable needs to be until you have the components in place. I put my layout into a cad drawing but had no idea how the curves of the cable would figure in. How much would a cable curve? The thicker the cable, the bigger the curve.

It wasn't cheap but I bought the tools for crimping my own cables. In the long run, it may have been less expensive to do my own. Built cables aren't cheap.

I don't think I need to bend the cable. And I can mount the busbars and on/off switch after the cables arrive.
But I am going to keep digging through information and decide how to handle it. I saw that I can order cables with the ends on them. But I don't know about different ends and rotated at 180 degrees.

 

[ArthurEld]

I guess you could try them just make sure that the low cell and low pack disconnects are configurable at runtime.
And it it doesn't tell you the current in and out you should put a shunt on each battery circuit.

I have been checking on the JK and I think it is fully configurable and some people really like it.
I will only order one BMS at a time. It wouldn't be the end of the world if I decided not to use one.
I see you writing some code in a lot of posts. What is that?

 

[John Frum]

I have been checking on the JK and I think it is fully configurable and some people really like it.
I will only order one BMS at a time. It wouldn't be the end of the world if I decided not to use one.
I see you writing some code in a lot of posts. What is that?

It's not code, it's a pure ascii way to describe system topology.
Thanks for asking.
If you are interested I can give you the 10 cent tour.

 

[ArthurEld]

It's not code, it's a pure ascii way to describe system topology.
Thanks for asking.
If you are interested I can give you the 10 cent tour.

Sure, I'll take the 10 cent tour

 

[ArthurEld]

The 3 terminal should be fine but you will have to stack lugs which could complicate maintenance a bit.

Won't it make a difference that the end terminals are farther from the center if I use 5? I plan to connect the big cable to the center.

 

[John Frum]

Won't it make a difference that the end terminals are farther from the center? I plan to connect the big cable to the center.

Yes it will also make a difference that the lugs are stacked.

 

[ArthurEld]

Yes it will also make a difference that the lugs are stacked.

I guess I might have to do some experimenting and adjusting to keep my batteries balanced to each other. I want to put another BMS around the 4 batteries.

 

[John Frum]

I guess I might have to do some experimenting and adjusting to keep my batteries balanced to each other. I want to put another BMS around the 4 batteries.

That doesn't make sense.
Do you mean shunt maybe?
I could see having 5 shunts.
1 per battery and the 1 aggregate.

 

[ArthurEld]

That doesn't make sense.
Do you mean shunt maybe?
I could see having 5 shunts.
1 per battery and the 1 aggregate.

I meant another balancer around the 4 batteries.

 

[John Frum]

I meant another balancer around the 4 batteries.

That doesn't make sense either.

 

[ArthurEld]

That doesn't make sense either.

I always want more. But I think this is going to work great. I should be able to monitor each battery with the BMS app

 

[John Frum]

I should be able to monitor each battery with the BMS app

You should confirm that your chosen BMS has that feature.

 

[ArthurEld]

A few people here use this BMS-

 

[HRTKD]

I meant another balancer around the 4 batteries.

That shouldn't be necessary. If you were putting the four batteries in series, then balancers for the four batteries might be called for. But your four batteries will be in parallel, so there is no need for a balancer. A periodic check to see what each battery is at (voltage, state of charge, etc) is in order.

 

[John Frum]

A few people here use this BMS-

Looks good.