Merged LiFeYPO4 1000Ah Winston prismatic cells and all electric galley...

[Catapault]

@Catnewbe

What size copper bar did you use for your install ? Mainly thickness.

I'm looking at 40mm x 4mm, Just not sure if that is going to be bendable enough vs 3mm.

Did you (or anyone) try different thicknesses for their busbars.

Designing for 500A continious. Not that I expect that often, but it is the overall design number I'm using at present.

[newhaul]

Originally Posted by hzcruiser

Ahhh, here we go, you want to balance once a year only.... well that's really apples and oranges.

That's the only time I actually even fully charge my bank solar cutoff is at 3.55v per cell . to date I have not lost a single ah in capacity

[hjohnson]

Originally Posted by hzcruiser

Not sure what you mean... "For 1.5A" ?

The 1.5A is the balancing current, ie how much current the BMS can shunt around between cells to bring them in line. That’s the current that actually flows through the BMS itself. The actual charge and load currents are controlled externally using contactors.

[s/v Jedi]

Originally Posted by Catapault

@Catnewbe

What size copper bar did you use for your install ? Mainly thickness.

I'm looking at 40mm x 4mm, Just not sure if that is going to be bendable enough vs 3mm.

Did you (or anyone) try different thicknesses for their busbars.

Designing for 500A continious. Not that I expect that often, but it is the overall design number I'm using at present.

You have to allow for movement due to heat cycling expansion contraction. The way they do this is using multiple thin layers stacked together.

[wholybee]

Originally Posted by Catapault

@Catnewbe

What size copper bar did you use for your install ? Mainly thickness.

I'm looking at 40mm x 4mm, Just not sure if that is going to be bendable enough vs 3mm.

Did you (or anyone) try different thicknesses for their busbars.

Designing for 500A continious. Not that I expect that often, but it is the overall design number I'm using at present.

If 500A continuous is the goal, have you considered 24 or 48 volts? Smaller currents, less copper, and less loss to heat. Bigger inverters possible. More expensive alternator and DCDC converter needed for 12V though.

[Catapault]

Originally Posted by wholybee

If 500A continuous is the goal, have you considered 24 or 48 volts? Smaller currents, less copper, and less loss to heat. Bigger inverters possible. More expensive alternator and DCDC converter needed for 12V though.

As mentioned previously, not an option. Already have far to much 12V gear, inc the 5kva Quattro, Solar Chargers, etc etc etc.

[Catapault]

Originally Posted by s/v Jedi

You have to allow for movement due to heat cycling expansion contraction. The way they do this is using multiple thin layers stacked together.

Solid copper busbars are totaly fine at this size. They arn't long enough / big enough for that to be a consideration IMO. Seen / maintained solid copper bars much MUCH bigger than this on larger vessels in a past life. Some with expansion releif, some not.

Just need to be used in a manner where movement / vibration isn't an issue. Or if so, some allowance for strain releif movement. (IMO)

As an aside, some math says that 30mm x 5mm will be more than adequate for what I'm after with nice headroom, and should bend fine. Though I'd still like a definitive reference, but thats just me.

[s/v Jedi]

Originally Posted by Catapault

Solid copper busbars are totaly fine at this size. They arn't long enough / big enough for that to be a consideration IMO. Seen / maintained solid copper bars much MUCH bigger than this on larger vessels in a past life. Some with expansion releif, some not.

Just need to be used in a manner where movement / vibration isn't an issue. Or if so, some allowance for strain releif movement. (IMO)

As an aside, some math says that 30mm x 5mm will be more than adequate for what I'm after with nice headroom, and should bend fine. Though I'd still like a definitive reference, but thats just me.

Have you considered cell terminals moving due to the cells expanding? Don’t mind what we say but at least you’ll know why the cells fail at the terminals.

[PaulCrawhorn]

Originally Posted by hzcruiser

Ahhh, here we go, you want to balance once a year only.... well that's really apples and oranges.

Not really a question of "want"

The way many BMS do it, if the cells do not NEED balancing, better to abstain.

Sign of a quality bank in good condition, the less frequently it is required.

In any case the faster it gets done the better, only downside is added cost. For many use cases a very low current rate is simply not enough, even if you want to balance every charge cycle.

[LeighC]

Originally Posted by s/v Jedi

Have you considered cell terminals moving due to the cells expanding? Don’t mind what we say but at least you’ll know why the cells fail at the terminals.

Do you put a roll in the copper bus bars or not then? for some expansion.
The EVE cells I have to use for a friend at the moment have the 6mm (1/4") single welded in post, very poor in my opinion.
The later EVE ones have a welded double 6mm post
Thanks - Leigh

[s/v Jedi]

Originally Posted by LeighC

Do you put a roll in the copper bus bars or not then? for some expansion.
The EVE cells I have to use for a friend at the moment have the 6mm (1/4") single welded in post, very poor in my opinion.
The later EVE ones have a welded double 6mm post
Thanks - Leigh

Laminated from5 layers and the roll you describe. 34mm wide, my terminals are M14.

[newhaul]

Originally Posted by hzcruiser

Ahhh, here we go, you want to balance once a year only.... well that's really apples and oranges.

No not balance once a year I actually have not top balanced since the initial when I commissioned the bank it was .05v difference from the highest to the lowest. Once a year I do run up to 33.655v and disconnect all charge sources on my annual cap test. Has not needed balancing imo.g

[CatNewBee]

Originally Posted by Catapault

@Catnewbe



What size copper bar did you use for your install ? Mainly thickness.



I'm looking at 40mm x 4mm, Just not sure if that is going to be bendable enough vs 3mm.



Did you (or anyone) try different thicknesses for their busbars.



Designing for 500A continious. Not that I expect that often, but it is the overall design number I'm using at present.

I bought 35mm x 5mm x 1000mm pure copper bars for electrical installations, 2 cell bridges per cell and on the exits, two cell connectors connected to the bar.

Regarding expansion: temperatures are very constant, the cells are in a compression case, I drilled and filed the holes of the bus bars a mm longer and I use washers on topp plus a split ring, tensioned to the spec with a torque wrench.

The whole thing doesn't move anywhere. Not sure how the terminals are wired inside of the cells, they are on a super-structure like a lid over the cell block, (1000Ah cells are mechanically different to the other normal cells) I assume this also prevents stress on the cell connectors inside.

[Catapault]

Originally Posted by s/v Jedi

Laminated from5 layers and the roll you describe. 34mm wide, my terminals are M14.

I'm using those flexible interconnects between cells, as provided by Winston. Though they may be a bit light for the 3P4S install, will see.
34mm wide x 3mm thick (nominal) x 4A continious = 408A acc to Winston specs.
I'd prefer 600A rated continous for my peace of mind.

The copper busbars are for connecting between the end cells, and the rest of the system, and between some of the contactors. (Directly to several 400A fuses, and then Remote Battery Switches.

Given the high current, busbars, as CatNewBe did on his install, are a good way to do this, without trying to load up 3 x 95mm2 cables on a battery terminal for a short run. (and even then, where to terminate those cables etc).

[Catapault]

Originally Posted by CatNewBee

I bought 35mm x 5mm x 1000mm pure copper bars for electrical installations, 2 cell bridges per cell and on the exits, two cell connectors connected to the bar.

Regarding expansion: temperatures are very constant, the cells are in a compression case, I drilled and filed the holes of the bus bars a mm longer and I use washers on topp plus a split ring, tensioned to the spec with a torque wrench.

The whole thing doesn't move anywhere. Not sure how the terminals are wired inside of the cells, they are on a super-structure like a lid over the cell block, (1000Ah cells are mechanically different to the other normal cells) I assume this also prevents stress on the cell connectors inside.

Thanks Cat. That's perfect.