LIFEPO4 Battery discussion thread

Got out of the shower and phone is very active. Check power is off in the area and today was a lowish generation day I'm only at 50% SOC. Starting nightshift now at 9pm. :unsure:
 
cavedog said:
Got out of the shower and phone is very active. Check power is off in the area and today was a lowish generation day I'm only at 50% SOC. Starting nightshift now at 9pm. :unsure:
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50% of 20kWh is 10kWh. At least you are aware now there is no power so you can ration yourself until sunrise. Nothing worse than not knowing and then land up in the dark.

Only 8h30m to go. That's about 1unit an hour.
 
cavedog said:
Got out of the shower and phone is very active. Check power is off in the area and today was a lowish generation day I'm only at 50% SOC. Starting nightshift now at 9pm. :unsure:
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O forgot to ask, Does solar assistant pick up a new battery if you link the coms? or do you need restart all the batteries or just the master?
 
wingnut771 said:
50% of 20kWh is 10kWh. At least you are aware now there is no power so you can ration yourself until sunrise. Nothing worse than not knowing and then land up in the dark.

Only 8h30m to go. That's about 1unit an hour.
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Yeah and I'm only using ~400w anyways so I think I will good to go.

DTBA said:
O forgot to ask, Does solar assistant pick up a new battery if you link the coms? or do you need restart all the batteries or just the master?
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Yes so I have the usb to RS232 cable directly on the master. Once I connect the comms cable to slave 1 and slave 2 the PaceBMS app immediately picks them up. I just needed to press disconnect and connect again in solar assistant. You don't need to restart anything
 
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denmendez65 said:
So throw away balancing from BMS?
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It depends, opinion divided. :P Definitely don't keep separate active balancer permanently connected.

Yeah, I just posted the video as this was the one I was thinking of when asked the difference between top and bottom balancing when I spoke about EVs. So when I saw it randomly showing on YT I decided to post it.
 
wingnut771 said:
It depends, opinion divided. :P Definitely don't keep separate active balancer permanently connected.

Yeah, I just posted the video as this was the one I was thinking of when asked the difference between top and bottom balancing when I spoke about EVs. So when I saw it randomly showing on YT I decided to post it.
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So my only problem with the no passive or active balancing is are we really saying the cells will stay balanced permanently after a bottom balance and setting the charge voltage correctly?

Why do LA batteries require an active balancer when any kind of series connection is done? And why would LFP not require that?
 
denmendez65 said:
So my only problem with the no passive or active balancing is are we really saying the cells will stay balanced permanently after a bottom balance and setting the charge voltage correctly?

Why do LA batteries require an active balancer when any kind of series connection is done? And why would LFP not require that?
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Nobody said no passive or active balancing. Remember this was 4 years ago too. All that is being said is explaining the bottom balance logic this one DIY EV guy who doesnt use a BMS did.

Bottom balance = all cells hold same capacity. Cut off voltage when cell peaks. No way to maintain bottom balance.
Top balance = all cells hold different capacity. Cut off voltage when cell bottoms out. Will top balance with every charge.
 
Installed the 2 x 250w panels and victron mppt. Will have to see if it makes a real difference.

I can already see an issue with the 55.4v bulk charge voltage. The 2 x panels max power point is a bit lowish so might to be as good as I hoped. Will see how mich it yields in a full day of production.
 

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cavedog said:
Installed the 2 x 250w panels and victron mppt. Will have to see if it makes a real difference.

I can already see an issue with the 55.4v bilk charge voltage. The 2 x panels max power point is a bit lowish so might to be as good as I hoped. Will see how mich it yields in a full day of production.
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3A is 3A.

Do I have to beg for an update on the top balancing?
 
wingnut771 said:
3A is 3A.

Do I have to beg for an update on the top balancing?
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I haven't fully charged recently but last week I did grid full charge and the deviation on new battery 2 was still around 100mV. Battery 3 still struggling but I can't complain because I don't sit at 100% long enough for it to balance.

Battery 4 is well just there. No idea what it's doing but it's contributing I just don't have any info.
 
cavedog said:
I haven't fully charged recently but last week I did grid full charge and the deviation on new battery 2 was still around 100mV. Battery 3 still struggling but I can't complain because I don't sit at 100% long enough for it to balance.

Battery 4 is well just there. No idea what it's doing but it's contributing I just don't have any info.
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So you didnt do the 54, 55, 56 strategy with fancy bench power supply over 3 days?

I'm too pissed to remember which battery is which. Which is the one with the shitty cylindrical cells not getting past 54V?
 
wingnut771 said:
So you didnt do the 54, 55, 56 strategy with fancy bench power supply over 3 days?

I'm too pissed to remember which battery is which. Which is the one with the shitty cylindrical cells not getting past 54V?
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Battery 3.

I was actually thinking of installing a 5am active balancer into that battery. See if 2 months of that can improve it
 
cavedog said:
Battery 3.

I was actually thinking of installing a 5am active balancer into that battery. See if 2 months of that can improve it
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Do I still need to beg? Why are you keeping me in suspense holding back in the details over the last umpteen days working on bat 3 with fancy bench power supply? You just go all dramatic and throw me straight into the deep end with 5A(m?) balancer?

Okay, how will you connect this 5A balancer? You'll have to remove the pack to get to the back right? If you going to go all radical like that, may I suggest to follow the "while I'm in there" doctrine and just source some new flat terminal cells or another (better imho) suggestion, go full "a boer maak a plan" and replace 5pcell8 pack with some thick cables going to one big prismatic that sits on the floor next to it like a proper caveman?
 
DTBA said:

who is going to try one for us?
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I was looking at that one before. Seems like a nice battery. Same with the omnivolt


and the Five Star

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Fivestar LiFePo4 Lithium Battery 51.2V 400AH 20.4KWH 48400

Fivestar LiFePo4 Lithium Battery 51.2V 400AH 20.4KWH Introducing the Fivestar LiFePo4 Lithium Battery 51.2V 400AH 20KWH, a cutting-edge power solution designed to revolutionize your energy storage needs. Engineered with advanced lithium iron phosphate (LiFePo4) technology, this high-capacity...
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If you go for a single big battery like that 1 BMS does the entire load. Even for my small solar setup just running the geyser is 70amp. That is going to be quite a heavy load on a single bms for a very long time in terms of powering loads and charging.

All of them see to use PaceBMS or a custom branded PaceBMS.
 
It's not much but it's more than I had before. The Victron mppt with the 2 x 250w panels. Damn I just wish I got 1 more of the panels.

Screenshot_20260615_143646.jpg
 
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