LIFEPO4 Battery discussion thread

cavedog said:
Charge to 1005 and discharge to 0%. @wingnut771 What do you think about this?

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You are doing that already so not sure what you’re asking me? Well, you’re not going all the way to zero (probably around 5%), if you want to do that then change low to 40V but as mentioned before, not sure what happens when the lights go out.
 
wingnut771 said:
You are doing that already so not sure what you’re asking me? Well, you’re not going all the way to zero (probably around 5%), if you want to do that then change low to 40V but as mentioned before, not sure what happens when the lights go out.
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Actually not. When I had a single battery, I was doing 15 - 95% give or take and the single battery wasn't enough for me but now with 2 x batteries I have plenty of capacity for now. I even have enough to run the geyser for an hour in the morning and still have over 12% SOC left. My situation shifted now since I have grid switched off still my goal is to get the most out of the batteries since grid is not in play unless it rains will see.

So, my inverter shutdown voltage is 45V. Both batteries show discharge voltage as 44V so I assume that might be cutoff I'm not sure the manual is poorly translated from Chinese, I think.

Also what does the bms use to calculate the state of health SOH value? I was looking on Facebook marketplace and see that someone is selling a battery just like mine for like 8k but it has a 13 cycle count and 97% SOH. That seems like a red flag because I'm 200 cycles in and sometimes 2 cycles a day before I got the second battery and mine is perfectly balanced with 100% SOH
 
cavedog said:
Actually not. When I had a single battery, I was doing 15 - 95% give or take and the single battery wasn't enough for me but now with 2 x batteries I have plenty of capacity for now. I even have enough to run the geyser for an hour in the morning and still have over 12% SOC left. My situation shifted now since I have grid switched off still my goal is to get the most out of the batteries since grid is not in play unless it rains will see.

So, my inverter shutdown voltage is 45V. Both batteries show discharge voltage as 44V so I assume that might be cutoff I'm not sure the manual is poorly translated from Chinese, I think.

Also what does the bms use to calculate the state of health SOH value? I was looking on Facebook marketplace and see that someone is selling a battery just like mine for like 8k but it has a 13 cycle count and 97% SOH. That seems like a red flag because I'm 200 cycles in and sometimes 2 cycles a day before I got the second battery and mine is perfectly balanced with 100% SOH
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What makes you say you were doing 15% - 95%? 45V - 56V is 5% - 100% SOC.

SOH is supposed to be the percentage of advertised capacity.
 
wingnut771 said:
What makes you say you were doing 15% - 95%? 45V - 56V is 5% - 100% SOC.

SOH is supposed to be the percentage of advertised capacity.
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Okay the SOC counter. When it switched to grid it was at 16% and when it was floating it was at 95% give or take. 45V wasn't my cutoff before it was 49V. My cutoff is now 45V
 
cavedog said:
Okay the SOC counter. When it switched to grid it was at 16% and when it was floating it was at 95% give or take. 45V wasn't my cutoff before it was 49V. My cutoff is now 45V
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What voltage makes SOC counter turn 100%?
 
cavedog said:
Okay the SOC counter. When it switched to grid it was at 16% and when it was floating it was at 95% give or take. 45V wasn't my cutoff before it was 49V. My cutoff is now 45V
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Anyway, SOC counter is lying. 55.2V (with absorption time) is 100% SOC. 56V is definitely 100% SOC.
 
DTBA said:
I would do it but every one that sell them in south Africa would just blame you if the battery dies. Even if it has nothing to do with it
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The battery label says low cut off 40V or BMS stops you having fun.
 
cavedog said:
Actually not. When I had a single battery, I was doing 15 - 95% give or take and the single battery wasn't enough for me but now with 2 x batteries I have plenty of capacity for now. I even have enough to run the geyser for an hour in the morning and still have over 12% SOC left. My situation shifted now since I have grid switched off still my goal is to get the most out of the batteries since grid is not in play unless it rains will see.

So, my inverter shutdown voltage is 45V. Both batteries show discharge voltage as 44V so I assume that might be cutoff I'm not sure the manual is poorly translated from Chinese, I think.

Also what does the bms use to calculate the state of health SOH value? I was looking on Facebook marketplace and see that someone is selling a battery just like mine for like 8k but it has a 13 cycle count and 97% SOH. That seems like a red flag because I'm 200 cycles in and sometimes 2 cycles a day before I got the second battery and mine is perfectly balanced with 100% SOH
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Some of the pacebms would reset the SOH when you hit CELL undervoltage and charge up to 100% and calculate how much AH the battery took.

Sometimes a unbalance battery would also not show 100%SOH. Only real way to know is getting hands on with battery and doing full charge. discharge cycle at like 20 to 40 amps and checking for no unbalance cell
 
DTBA said:
Some of the pacebms would reset the SOH when you hit CELL undervoltage and charge up to 100% and calculate how much AH the battery took.

Sometimes a unbalance battery would also not show 100%SOH. Only real way to know is getting hands on with battery and doing full charge. discharge cycle at like 20 to 40 amps and checking for no unbalance cell
Click to expand...

My new battery I don't think has the same pacebms. It doesn't show the SOH anywhere I can see. So what is that value actually. Just what the bms think the cells max capacity is after a full charge?
 
I have a second hand revov battery that I run till like 4%.

They wont touch it as I open it up and it was to much hassle to move the warranty over coc and all that ****.
cavedog said:
My new battery I don't think has the same pacebms. It doesn't show the SOH anywhere I can see. So what is that value actually. Just what the bms think the cells max capacity is after a full charge?
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Yea its kinda a this battery has degraded to 80% of its health thing.

I would not look into it to much.
 
cavedog said:
My new battery I don't think has the same pacebms. It doesn't show the SOH anywhere I can see. So what is that value actually. Just what the bms think the cells max capacity is after a full charge?
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You will never know without doing a capacity test. You would need a shunt or something to measure the coulombs.

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cavedog said:
My new battery I don't think has the same pacebms. It doesn't show the SOH anywhere I can see. So what is that value actually. Just what the bms think the cells max capacity is after a full charge?
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Does it have a app or touch screen? Any place for a password?
 
DTBA said:
Does it have a app or touch screen? Any place for a password?
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Its got a a screen but can't seem to link it on my pacebms app so doubting its a pacebms or if it is not one that includes blootooth although the spec sheet says it has an app, wifi and bluetooth. Havn't played around with it much yet except for navigating through the options to see what it has when I was setting up the pack parallel settings.
 
cavedog said:
Its got a a screen but can't seem to link it on my pacebms app so doubting its a pacebms or if it is not one that includes blootooth although the spec sheet says it has an app, wifi and bluetooth. Havn't played around with it much yet except for navigating through the options to see what it has when I was setting up the pack parallel settings.
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Howz bat 2 cell balance at 55.2V?
 
Is buying second hand 100ah lifepo4 cells worth it?
 
cavedog said:
Still unbalanced. I'm trying to top balance today
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Only time can balance them. It can take days or weeks. Is it still same or better? What voltage are you absorbing at? Can we see cells at absorb voltage?
 
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