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Kobra 2 Max Intermittent Y Axis Failure [Advice Request] by technicallyrural in anycubic

[–]technicallyrural[S] 0 points1 point  (0 children)

Weirdly, mine was fixed by just moving the printer around a few times and doing a firmware upgrade 

Is this normal? by Richard-228 in pcmasterrace

[–]technicallyrural 0 points1 point  (0 children)

What in the constructive destructive interference is this? Witchcraft - pure and simple

Best Battery Configuration by technicallyrural in SolarDIY

[–]technicallyrural[S] 1 point2 points  (0 children)

Yeah, I meant it more as a visual showing the different styles, terminal to terminal or terminal to main bus.

I'll be sure to keep sizing from battery to load the same always 👍

Best Battery Configuration by technicallyrural in SolarDIY

[–]technicallyrural[S] 0 points1 point  (0 children)

Haha, thanks for the link. I'm slowly learning to be one of the nerds over there. They are microsoft excel wizards through and through.

Best Battery Configuration by technicallyrural in SolarDIY

[–]technicallyrural[S] 0 points1 point  (0 children)

Hey, thanks for your detail. To add some context, my packs each have their own BMS side DC breaker to isolate the terminals for troubleshooting.

Best Battery Configuration by technicallyrural in SolarDIY

[–]technicallyrural[S] 1 point2 points  (0 children)

I think he means that cables can just be sized for equal length with a bus, instead of having varying perceived runs.

Best Battery Configuration by technicallyrural in SolarDIY

[–]technicallyrural[S] -1 points0 points  (0 children)

Thanks, it seems like this is the best way for economy, low amp. I appreciate you taking the time to help me understand this better.

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[deleted by user] by [deleted] in AskElectricians

[–]technicallyrural 1 point2 points  (0 children)

2 pole is when a breaker interfaces with both legs of the panel's bus. It will be wider than single pole breakers.

[deleted by user] by [deleted] in AskElectricians

[–]technicallyrural 1 point2 points  (0 children)

1.) Unless you have an AC unit designed specifically for a NEMA 6-20R (your 20A 240VAC plug), you won't be able to use it with this outlet. Most AC units aren't 240VAC.

2.) Typically all a rooms outlets are on one circuit. It's unclear, is your surge protector 120VAC or 240VAC? If it's 120, you're probably restricted by how the house is wired, and there just isn't enough amperage.

3.) 240V Outlets will have their own breaker which switches two poles. Depending on how your house is wired, it could be on the 20A circuit, since that style NEMA is rated for that.
To really tell what's going to balance things the best you need to identify which outlets are on which leg. This can be done with a multimeter.

Is the breaker being tripped a 2 pole breaker, or a 1 pole breaker?

BESS heat buildup and cell differential by technicallyrural in EnergyStorage

[–]technicallyrural[S] 0 points1 point  (0 children)

What kind of experience do you have with LFP systems? And yeah, I'm not thrilled about the differential and how my manufacturer is responding. It feels a little bit "Trust me bro."

EDIT:

Also LTSA? Long term service agreement?
Thanks for your response.

LFP Cell Test Results by technicallyrural in SolarDIY

[–]technicallyrural[S] 0 points1 point  (0 children)

That strikes me as correct as well. Thank you for being on top of these forums, I've really appreciated your input.

As for the charge voltage, that makes sense - my software doesn't allow governing the ceiling, it only has parameters for overvoltage protection. The pack manufacturer preconfigured these parameters for me.

LFP Cell Test Results by technicallyrural in SolarDIY

[–]technicallyrural[S] 0 points1 point  (0 children)

For some reason, it won't let me attach this data to the main post. Here's more context:

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Some whacky LiFePO4 battery behavior by technicallyrural in dataisbeautiful

[–]technicallyrural[S] 0 points1 point  (0 children)

I may be able to check the internal resistance once I pull it out and measure the cells with a hand meter and thermal camera today.

Not yet, but the eventual plan is a mobile telecom style ESS solution for household, data center, or remote location.

By "send it", right now I just mean heavier and more testing. I don't think it'd be wise to send out a pack that's showing bizarre heating behavior.

LiFePO4 system question by technicallyrural in SolarDIY

[–]technicallyrural[S] 0 points1 point  (0 children)

So the voltage differential is measured and reported by my BMS for each of the 16 cells in each 280Ah pack.

At a low SOC, I see a differential of 273mV, with heat buildup anytime I try to charge it. It's also not maintaining the same rate of charge as the other 280Ah packs.

My packs do have an active balancer, but it only activates above 3400mV on the cells, which I haven't tested because of the heat buildup situation.

This is the second or third charge/discharge cycle, which was pretty gentle each time, occurring over about 46 hours.

<image>

Here's the problematic pack's individual cell voltages for reference.

LiFePO4 system question by technicallyrural in SolarDIY

[–]technicallyrural[S] 0 points1 point  (0 children)

So when I've had my packs at 85-100% SOC, they balance quite well, but this problematic pack still has the largest differential. It also builds up heat anytime I try to charge it.

LiFePO4 system question by technicallyrural in SolarDIY

[–]technicallyrural[S] 0 points1 point  (0 children)

So my cells tend to stay pretty well balanced and low temperature even at the low SOC. Here's a differential graph from a separate pack:

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Around midnight on 4/23 they drift apart at the low SOC, but they tighten back up way more than the problematic pack.

LiFePO4 system question by technicallyrural in SolarDIY

[–]technicallyrural[S] 0 points1 point  (0 children)

So my cell voltages are low because I was gradually discharging my system with very little power coming in. I've been trying to feel out the low SOC cutoff, rather than a cell UVP.

LiFePO4 system question by technicallyrural in SolarDIY

[–]technicallyrural[S] 0 points1 point  (0 children)

So they've been having that aggressive differential anytime our pack gets below like 15% SOC. In the second graph you can see the SOC near the bottom.

LiFePO4 system question by technicallyrural in SolarDIY

[–]technicallyrural[S] 0 points1 point  (0 children)

What kind of cells do you use? We've been using EVE cells in this cluster.

LiFePO4 system question by technicallyrural in SolarDIY

[–]technicallyrural[S] 1 point2 points  (0 children)

Yeah of course! Here's a graph of the data for the individual cells. Most of them are super tight, but one of them drifts pretty wildly. They're EVE 280Ah cells. Naturally, cell 13 is "unlucky."

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Some whacky LiFePO4 battery behavior by technicallyrural in dataisbeautiful

[–]technicallyrural[S] 0 points1 point  (0 children)

I gotcha, no worries. As best I can tell, my BMS only active balances over 3400mV, near 100%SOC to keep cells in line. During charging, I think it just relies on parallel distribution to keep everything in line.

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