yoink!
When Not To Let Your AIO Communicate With The Batteries
- Thread starter Kornbread
- Start date
Thanks Tim. I'm going to steal them as well.
Darren67-72
Off grid
Well, I'll just say, a more frequent top balance (using coms, factory settings) may shorten battery life; an unknown value, it is worth having properly balanced cells, without constant babysitting of the system. To each there own. One might take note that shorting the cycle life from 7000 to perhaps xxxxx say even 6000 with a daily cycle of 0.6 (my use) = 10,000 days use. That's 27 years. Calendar degradation is FAR FAR going to kill the batteries before the high knee thinking.
Ok, fire back, I'm ready.
Ok, fire back, I'm ready.
timselectric
If I can do it, you can do it.
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I can't comment because I'm not sure I understand what point you are trying to make. Are you for or against coms?
Darren67-72
Off grid
Please, I'm not trying to push my opinion. But I've tried both. I spent a solid month tweaking USE and USE2 settings. I finally got it in the sweet spot (I thought) just to have a bad run of weather and bam cells all out of balance and a weeks work getting all back to good.
Got back to coms..... 6 months of checking almost every day and everything is always "good".
So, communications always!!!
But be forwarned.... you'll get board, nothing to play with. And this is my full time home power. I can't afford to have things get wacky.
Got back to coms..... 6 months of checking almost every day and everything is always "good".
So, communications always!!!
But be forwarned.... you'll get board, nothing to play with. And this is my full time home power. I can't afford to have things get wacky.
timselectric
If I can do it, you can do it.
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I haven't touched my settings in several months.
I definitely wouldn't want to have to babysit it all of the time. I personally have nothing against coms. It's the best option for some people. I just prefer to set my system up to work the way I want it to.
I definitely wouldn't want to have to babysit it all of the time. I personally have nothing against coms. It's the best option for some people. I just prefer to set my system up to work the way I want it to.
Darren67-72
Off grid
Yes!!! And awsome, I would have preferred it too. My issue came to, several days of bad weather caused a battery bms to turn the battery off. Then when scc charging reconvened, the battery that turned off, didn't charge. Of course. You see where this is going. To mitigate this problem, I would need to raise my cut out voltage. That gives me less battery usage. And lowering the high side voltage also reduces amp hour usage. Although it may seem like its not much, it adds up on both ends and everyday.
I looked at the value of more batteries versus DOD and decided to work, what I have harder and replace as needed. This decision can't, honestly, be calculated based on the hundreds of "professional" opinions and studies. At least, as of, my last research.
I looked at the value of more batteries versus DOD and decided to work, what I have harder and replace as needed. This decision can't, honestly, be calculated based on the hundreds of "professional" opinions and studies. At least, as of, my last research.
Lt.Dan
Solar Wizard
I dont know much about the calendar aging thing, but my first thought is that we haven't had LiFePo4 around for long enough to have calendar aging take effect? Especially with the chemistry being tweaked over the last few years to get more cycles and more energy density etc.
To be honest, I don't think we actually know how calendar aging will affect the battery because it hasn't happened
I'm not a smart feller though, more like a fart smeller. Do we have hard evidence of this?
timselectric
If I can do it, you can do it.
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I'm not sure how having com's solved this. But if you are happy with it that's all that matters.
Darren67-72
Off grid
No, but the manufacture certainly does not boast of a 25 year battery and they would!! And they only warranty them for much less. That's a good indication.
BUT, I agree with you, we don't know, nor do we know that using the knee does the damage stated either.
It's the same argument. We are back to people must make their best decisions based off of the info you have and use your best judgment.
BUT, I agree with you, we don't know, nor do we know that using the knee does the damage stated either.
It's the same argument. We are back to people must make their best decisions based off of the info you have and use your best judgment.
Darren67-72
Off grid
Coms allows the inverter to communicate with all the batteries and their soc a battery will tell the inverter to stop drawing power, before any battery reaches a cut off voltage. They will not allow the inverter to discharge to the shut off voltage or soc.
timselectric
If I can do it, you can do it.
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I have my inverter set up the same way manually.
BMS cutoff should be a last resort. Only used if everything else goes wrong.
BMS cutoff should be a last resort. Only used if everything else goes wrong.
Darren67-72
Off grid
With Manually set, does it use voltage?
I'm really glad to hear this working for you. I have a Generty Solar 12k I will be using in this manner, for a shop and have not been looking forward to it. Now, I have a better feeling about it.
I'm really glad to hear this working for you. I have a Generty Solar 12k I will be using in this manner, for a shop and have not been looking forward to it. Now, I have a better feeling about it.
timselectric
If I can do it, you can do it.
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Yes, mine uses a voltage setting.
Can't cutoff be set in the inverter? IIRC, most bms start to balance somewhere North of 54v, so if you do not use scc/battery communication, wouldn't the battery/battery packs still balance without taking the voltage quiet so high into the knees?
Zwy
Emperor Of Solar
Darren67-72
Off grid
Yes, to first part, but.... voltage is not, the best, gauge of soc, and this can get confusing, even if you set the inverter cut off voltage above the bms shutdown voltage, if a battery soc goes below the bms shutdown charge, it will turn off.
The second part, yes you can top balance at a lower voltage, but it's exponential the lower you go. (Takes longer or even longer)
The second part, yes you can top balance at a lower voltage, but it's exponential the lower you go. (Takes longer or even longer)
Darren67-72
Off grid
Darren67-72
Off grid
It's right in the title people. Just read for yourself. They just don't know!!!
Have a good night
Have a good night
Since it appears most bms passively balance the cells, I can see it taking longer to balance at a lower voltage. After several days of partly cloudy weather and shade due to Mr. Sun moving South for the winter, one of my batteries went into LV warning even though the aio was set 10% above the battery's LV alarm. SOC for the battery bank was something like 38% when the one battery alarmed out, which should't happen till 25%. Pretty sure if I hooked the laptop to the battery bank and looked at individual cells, there would be some rather large imbalances. Don't think the battery bank has been over 54v long enough to get a good cell balance.
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