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Plan to do a balance charge before capacity check
#1
I am trying to figure out where to hook the balance leads to A BYD 24 volt battery. Theses are the voltages I measured yesterday. All the bms wiring diagrams I have seen start with 1 and go up  in voltage as the numbers increase.
trying to use the icharger x8 first to charge and balance the battery  to full then discharge each cell individually. Am i correct in where I have each wire connected?
The VT# are on the circuit board on either side of the battery
        + 8Th cell voltage  wire 9
vt0=26v
          + 7th cell voltage  wire 8
vt1=22.6v
        +6th  cell voltage    wire 7
vt2=19.4v
        + 5th cell voltage    wire 6
vt3=16.1v
        + 4th cell voltage    wire 5
vt4=12.9v
        +  3 cell voltage    wire 4
vt5=9.6v
        +  2nd cell voltage wire 3
 vt6=6.5v                                                                                      
        +  1st cell voltage wire 2
vt7=3.2v
        connection to negative side of 1st cell
vt8=0v                        wire 1
Or am I making things harder then they need to be?

later floyd
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#2
How the voltages "stack up" like that is correct but which order ie 0V on vt0 or 0V on vt8, not sure - doesn't that manual have a diagram?
You might be able to check for continuity with main -ve or main +ve & pin vt0 or vt8?
Running off solar, DIY & electronics fan :-)
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#3
No manuals with theses batteries. You lost me when you said -ve   Confused floyd gets lost a lot on here. The battery has one positive terminal and one negative terminal and 9 voltage sense terminals least I think that is what vt means. Could you explain what -VE means?

Maybe circuit board was the wrong name, it carrys the balance lead traces and temperature lead traces to an onboard bms which a few people have managed to pull data from but from what I read none have managed to get it to work as a bms. Most people just Wire in there own bms and completely take the bms out.

Guess I need to watch more videos and read some more.

Later Floyd
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#4
No worries :-)
positive terminal = +ve eg "posi" = plus or +, "tive" shortened to "ve"
negative terminal = -ve = OV eg neg or - & ve again!
Most systems use "negative ground" method, so usually negative battery connects to earth/ground & battery positive terminals are positive (relative to ground or 0V).
So battery negative (-ve) = 0V

Temp probes are more of a lead acid thing, ignore them.
The balance leads connect to the junction between cells like you listed.
So usually its like in this pic:
https://i.stack.imgur.com/bEJcV.jpg
or here:
https://www.electriccarpartscompany.com/...ent-System

That model icharger doesn't seem to have a good wiring diagram!
Maybe do some testing with a single cell?
Running off solar, DIY & electronics fan :-)
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#5
Its correct but as said crosscheck so the order on the charger is correct. Ie lowest or highest.
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#6
I will recheck the order prior to connecting the balance charger and am going to do a capacity test on each cell.

Thank you
later Floyd
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#7
Note that you cannot do a capacity check on the balance leads unless you want to wait forever. You need to hook up each cell to be able to properly cap test.

You can of course test the whole pack and when first cell reached its bottom you can let it rest for 5 minutes and estimate capacity left in the other cells by reading voltage
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Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
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#8
Thanks Daromer
I was Thinking about disconnecting each cell and testing that way, But when I take something apart and put it back together there is often n extra part.
I hadn't planned that far ahead. It was extremely windy yesterday so didn't work on the battery. I will test the whole pack soon. I believe that the icharger x8 has to have the balance leads hooked up to do a regen discharge, but could be mistaken need to read the manual again.

later floyd
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#9
The balance need is not needed but IF you run without it you just Lost 98% of the information doing the test Smile
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Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
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#10
Thanks
later floyd
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